Chytrid Fungus Analysis for Soule River Watershed, Southeast Alaska
Chytrid Fungus Analysis for Soule River Watershed, Southeast Alaska
Chytrid Fungus Analysis for Soule River Watershed, Southeast Alaska
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<strong>Soule</strong> <strong>River</strong> <strong>Watershed</strong><br />
Amphibian Data Report<br />
2009<br />
Submitted to:<br />
<strong>Alaska</strong> Power & Telephone Company<br />
193 Otto Street<br />
Port Townsend, Washington<br />
Submitted by:<br />
The Shipley Group<br />
56 North Main Street<br />
PO Box 908<br />
Farmington, Utah<br />
April 2009
TABLE OF CONTENTS<br />
Introduction and Background 1<br />
Boreal Toads 1<br />
Boreal Toads in Canada 1<br />
Boreal Toads in <strong>Southeast</strong> <strong>Alaska</strong> 2<br />
<strong>Chytrid</strong> <strong>Fungus</strong> 4<br />
<strong>Chytrid</strong> <strong>Fungus</strong> in <strong>Alaska</strong> 7<br />
<strong>Soule</strong> <strong>River</strong> <strong>Watershed</strong> Survey <strong>for</strong> Anurans 9<br />
(Boreal Toad, Wood Frog) and <strong>Chytrid</strong> <strong>Fungus</strong><br />
(Batrachochytrium dendrobatidis) (BD)<br />
Water Chemistry 22<br />
Discussion 24<br />
Discussion Summary 31<br />
Literature Cited 40<br />
Appendix A 55<br />
PCR Assay Details from Pisces Molecular<br />
Appendix B 57<br />
Amphibian Declines, <strong>Chytrid</strong> <strong>Fungus</strong>, and Boreal Toads<br />
i
Tables<br />
Table 1. Documented Boreal toad records from 3<br />
<strong>Southeast</strong> <strong>Alaska</strong>.<br />
Table 2 ‐ <strong>Chytrid</strong> fungus infection <strong>for</strong> 3371 post 5<br />
metamorphic and adult amphibians<br />
Table 3 ‐ Survey of Amphibians Populations 6<br />
Table 4 – Survey of Anuran populations <strong>for</strong> Batrachochytrium 8<br />
dendrobatidis (BD) on the northwest Coast of North America<br />
Table 5 – Amphibian <strong>Chytrid</strong> fungus Batrachochytrium 13<br />
dendrobatidis (BD) Survey Data from <strong>Soule</strong> <strong>River</strong> <strong>Watershed</strong>,<br />
<strong>Southeast</strong> <strong>Alaska</strong>, July 2009<br />
Table 6 – Water Chemistry of Delta Tadpole Pond 22<br />
Table 7 – Boreal Toads (Anaxyrus boreas boreas) Observed 24<br />
in the Field, 2007‐2009<br />
Table 8 – Recent Major Amphibian survey <strong>for</strong> <strong>Chytrid</strong> fungus 28<br />
(Batrachochytrium dendrobatidis (BD) in <strong>Alaska</strong> and<br />
Western Canada<br />
Table 9 ‐ Total Field Ef<strong>for</strong>t at <strong>Soule</strong> <strong>River</strong> <strong>Watershed</strong>, 2007‐2009 32<br />
Table 10 ‐ Boreal Toads (Anaxyrus boreas boreas) Observed in<br />
the Field, 2007‐2009 34<br />
ii
Figures<br />
Figures A1 through A4 12<br />
Figures A5 through A7 18<br />
Figures A8 through A 13 19<br />
Figures A14 through A19 20<br />
Figures A20 through A25 21<br />
Figure A26 through A27 22<br />
Map 1 11<br />
Map 2 15<br />
Map 3 16<br />
iii
Amphibians of <strong>Soule</strong> <strong>River</strong> <strong>Watershed</strong>, <strong>Southeast</strong> <strong>Alaska</strong><br />
Introduction and Background<br />
The class Amphibia consists of three orders: salamanders and newts, anurans (frogs, toads,<br />
spadefoots), and caecilians (Gymnophiona). Caecilians are poorly known tropical legless<br />
amphibians with short tails, resembling fat earthworms. It appears that amphibians represent<br />
a major indicator or canary in the coalmine <strong>for</strong> ecosystem assessment and monitoring.<br />
Amphibians, as are all vertebrates, are susceptible to a wide range of diseases and individual<br />
mortality caused by: fungi, viruses, protozoans, bacteria, and macroparasites (e.g., trematodes).<br />
However, only the first three have been implicated in the widespread declines and extinctions<br />
of amphibian populations (Collins and Crump 2009). By far the main pathogen identified with<br />
amphibian declines and extinctions has been the chytrid fungus Batrachochytrium<br />
dendrobatidis.<br />
Boreal Toads<br />
The Boreal Toad (Anaxyrus boreas boreas) has a very extensive distribution, ranging from all of<br />
<strong>Southeast</strong> <strong>Alaska</strong>, all of British Columbia, and western Alberta in the north; south to northern<br />
Cali<strong>for</strong>nia, most of Nevada north of the Mojave Desert, and the mountains of Utah; and east to<br />
western Montana, western and southern Wyoming, the Rocky Mountains of Colorado, and<br />
extending into the northern extreme of New Mexico. The two subspecies intergrade in<br />
northern Cali<strong>for</strong>nia. The Boreal Toad is commonly referred to as the Western Toad in much of<br />
the literature. Nevertheless, the correct and taxonomically accepted nomenclature is that the<br />
Western Toad refers to both subspecies of Anaxyrus boreas.<br />
Boreal Toads in Canada<br />
The Boreal Toad in British Columbia and Alberta is considered secure, the species “can appear<br />
very common and abundant”, and all Canadian populations are apparently doing well, at least<br />
at the turn of the century (Wind and Dupuis 2002). Most of the following assessment is based<br />
on this report and its references. The Boreal Toad is widely distributed in British Columbia,<br />
especially in its central and southern portions. The toad is also relatively common in the<br />
northern portion and spills over into the southern Yukon. The northern populations are in<br />
valleys that receive high accumulation of annual snowfall, assuring safe winter hibernacula.<br />
The Boreal Toad has numerous occurrence records on the Pacific coast of British Columbia from<br />
the Washington state boundary north to Stewart, including Vancouver and Queen Charlotte<br />
Islands (Wind and Dupuis 2002, Figure 3). North of Stewart the distribution record picks up at<br />
Mount Edziza Provincial Park and continues north into the Yukon. The Boreal Toad distribution<br />
gap between Stewart and the Provincial Park may be a lack of surveys or a real absence. Boreal<br />
1
Toads, particularly <strong>for</strong> an amphibian, have good tolerance of brackish and even saltwater, and<br />
there<strong>for</strong>e, are quite capable of colonizing many islands from the large complex of islands<br />
available off the coasts of British Columbia (Wind and Dupuis 2002) and <strong>Southeast</strong> <strong>Alaska</strong><br />
(MacDonald 2003, MacDonald and Cook 2007). They can swim <strong>for</strong> at least several hours in<br />
seawater (MacDonald 2003).<br />
The primary concern <strong>for</strong> the Boreal Toad was the south‐coast population of British Columbia<br />
and adjacent Vancouver Island. Boreal Toad numbers on the lower mainland of British<br />
Columbia and southern, eastern, and central, Vancouver Island, appear to be declining based<br />
on historical records. Amphibian and other biological surveys between 1998 and 2000 found<br />
that Boreal Toads were scarce. However, adequate long‐term data to quantitatively assess<br />
trends is lacking.<br />
The decline of Boreal Toads from coastal southern British Columbia, surrounding islands, and<br />
especially Vancouver, has primarily been attributed to human land use; habitat loss,<br />
degradation, and fragmentation. Human settlements typically drain and fill‐in wetlands,<br />
channelize rivers and streams eliminating quiet backwater sloughs and pools, and significantly<br />
alter landscape hydrology. Additionally, other anthropogenic‐related impacts are to blame:<br />
pollution and pesticides, road and highway mortality, and predators associated with or<br />
attracted to human developments (see Predation Section).<br />
Boreal Toads in <strong>Southeast</strong> <strong>Alaska</strong><br />
Boreal Toads are widespread in <strong>Southeast</strong> <strong>Alaska</strong>, and range northward along the coast to<br />
Prince William Sound, including Montague and Hawkins Islands; with the edge of their range a<br />
short distance north to the Tasnuna <strong>River</strong> (a tributary of the Copper <strong>River</strong>) and west to the<br />
Columbia Glacier (MacDonald 2003).<br />
MacDonald (2003) reported that Boreal Toads “are common and widespread on the mainland<br />
and islands of <strong>Southeast</strong> <strong>Alaska</strong>”. Boreal Toad records are certainly widely distributed<br />
throughout <strong>Southeast</strong> <strong>Alaska</strong> (MacDonald 2003, MacDonald and Cook 2007). There are 70<br />
museum specimen records in <strong>Southeast</strong> <strong>Alaska</strong> documented by geographic location (usually<br />
including latitude and longitude) and a distribution map in MacDonald and Cook (2007, pages<br />
127‐128). The records are particularly prevalent along the coast and near settlements. Records<br />
near the British Columbia border and interior, especially in the southeastern portion of<br />
<strong>Southeast</strong> <strong>Alaska</strong> are absent, because of the lack of surveys.<br />
Island Records of Boreal Toads <strong>for</strong> <strong>Southeast</strong> <strong>Alaska</strong>, museum specimens, MacDonald and Cook<br />
2007:<br />
Admiralty Bushy Etolin Hoyspur<br />
Annette Chichagof Hassler Kosciusko<br />
Baker Chilkat Heceta Kuiu<br />
Baranof Dall Herbert Graves Kupreanof<br />
2
Long<br />
Mary<br />
Mitkof<br />
Noyes<br />
Prince of Wales<br />
Revillagigedo<br />
Sergief<br />
Suemez<br />
Sullivan<br />
Vank<br />
Woronkofski<br />
Wrangell<br />
Yakobi<br />
Zarembo<br />
Only five records are documented (Table 1) in the general southeastern region of <strong>Southeast</strong> <strong>Alaska</strong>,<br />
none of them in the <strong>Soule</strong> <strong>River</strong> <strong>Watershed</strong> area. The number of museum specimens are in parenthesis.<br />
Location North<br />
Latitude<br />
West<br />
Longitude<br />
Hyder (1) 55.9200 130.0200<br />
Hyder Area (1)<br />
Salmon <strong>River</strong>, at mouth of Texas <strong>River</strong><br />
Approx. 40 miles west of Hyder (1)<br />
Approx 5 miles east of Behm Canal<br />
Approx. 25 miles north of Chickamin Bay<br />
Boca de Quadra (3)<br />
A bay approximately 30 miles north<br />
of Portland Fiord inlet<br />
Smeaton Bay (1)<br />
Head of Blackwell Arm,<br />
just north of Boca de Quadra<br />
A bay approximately 50 miles north<br />
of Portland Fiord inlet<br />
‐‐‐‐‐‐‐‐‐‐ ‐‐‐‐‐‐‐‐‐‐‐‐<br />
56.0269 130.9844<br />
55.2000 130.4700<br />
55.2800<br />
Table 1. Documented Boreal toad records from <strong>Southeast</strong> <strong>Alaska</strong>.<br />
130.6300<br />
With the exception of the Hyder sites, the other three sites are west of the mountains where the <strong>Soule</strong><br />
<strong>River</strong> <strong>Watershed</strong> originates, and the <strong>Soule</strong> <strong>River</strong> flows east to the Portland Canal.<br />
The distribution of the Boreal Toad is or at least was certainly widespread in <strong>Southeast</strong> <strong>Alaska</strong> (see<br />
above). However, the species’ actual abundance in terms of population density estimates or encounter<br />
rates in the field, particularly in remote areas, are not actually known <strong>for</strong> most of their <strong>Alaska</strong>n range.<br />
MacDonald (2003) reported that they were “widespread and common” in <strong>Southeast</strong> <strong>Alaska</strong>. There is<br />
anecdotal evidence provided by long‐time residents in the area of Skagway and Klondike Gold Rush<br />
National Historical Park in northern <strong>Southeast</strong> <strong>Alaska</strong> that Boreal Toads were “considerably more<br />
common 20 years ago compared to today” (Hahr 2006). In the same report, a retired National Park<br />
Service trail crew leader recalled that recent metamorph toads were so abundant in summers that<br />
3
thousands of them blanketed portions of trails in Klondike Gold Rush Park, and it was impossible to<br />
avoid stepping on them. The rumored and perceived declines of Boreal Toads in <strong>Southeast</strong> <strong>Alaska</strong><br />
prompted Klondike Gold Rush Park to initiated surveys in 2003. Intensive surveys over two summers at<br />
39 potential breeding sites, found tadpoles in only six of the sites (Hahr 2006).<br />
<strong>Alaska</strong> Department of Fish and Game (ADFG 2007) initiated a pilot study in 2004 to monitor three sites<br />
in <strong>Southeast</strong> <strong>Alaska</strong>: Prince of Wales Island, Admiralty Island, and Upper Lynn Canal (Chilkat Valley and<br />
Skagway area). Sampling protocols were developed and preliminary in<strong>for</strong>mation was provided in this<br />
report. Four hundred and fifty random and “opportunistic” selected wetlands sites were identified over<br />
an area of 9642 km 2 . Encounter rates of Boreal Toads in wetlands were preliminary estimated at 20‐25<br />
percent in the first year of the project (2005). The parameter “encounter rate” was not defined, but a<br />
good assumption was that toads were found at 20‐25 percent of the sites that were visited in this first<br />
year. In the second year of the study (2006), the encounter rate was reported as 5‐20 percent based on<br />
the specific sites that were visited. The data <strong>for</strong> the third year of the study (2007) reported that a total<br />
of 544 wetlands sites were surveyed in the three years of the study over an area of 9642 km 2 . There<br />
were 283 sites surveyed in the last period. Boreal Toads currently occupied 17.5 percent of the<br />
landscape, with significant variation across the study area. Breeding habitats represented only 8.1<br />
percent of the landscape, and the toads favored “shallow margins of larger bodies of water”. The<br />
highest occupancy <strong>for</strong> Boreal Toads was on Admiralty Island (26.3%), while the lowest was on Prince of<br />
Wales Island (14.2%). Wood Frogs (Lithobates sylvaticus) and Northern Roughskin Newts (Taricha g.<br />
granulosa) were also observed in the surveyed wetlands over all three years, and the newts occupied<br />
nine percent of the landscape.<br />
Additional in<strong>for</strong>mation was available in the abstracts of the <strong>Alaska</strong> amphibian conference held in<br />
February 2006 (Tessler 2006). Sanjay Pyare, the project leader of the ADFG sponsored study discussed<br />
above, and others, discussed the paucity of data <strong>for</strong> <strong>Alaska</strong> amphibian distribution and abundance<br />
patterns. The major stumbling block was, of course, the large size of landscapes to sample and their<br />
remoteness, access, and ruggedness. Pyare provided more details from the first year (2005) of the study<br />
discussed above. Encounter rates refer to the occupancy rates of visited wetlands habitat patches.<br />
Amphibian surveys were conducted on 260 (105 random, 155 opportunistic) wetlands habitat patches in<br />
the three study sites during the prime breeding period, 1 May – 15 July. Encounter rates of all life‐history<br />
stages of Boreal Toads ranged from 18‐21 percent among the three areas. Encounter rates <strong>for</strong> evidence<br />
of breeding (eggs, tadpoles, metamorphs, yearlings) were 10‐18 percent. There<strong>for</strong>e, from these data,<br />
the approximate encounter rates of adults ranged somewhere between 0‐11 percent. Among randomly<br />
selected wetlands habitat patches in all three areas, both toad (all stages) and recent breeding<br />
occurrences were encountered at the rate of 10‐40 percent. Roughskin Newts were encountered at 15‐<br />
17 percent occupancy on the random patches on Admiralty and Prince of Wales Islands. Pyare<br />
concluded that their data underestimated true occupancy, because the data were not corrected <strong>for</strong><br />
detection error, which they were still evaluating. Detection error is the major and serious concern in all<br />
surveys using patch occupancy modeling, and is a function of both species and habitat characteristics<br />
(Thompson 2004, MacKenzie et al. 2006).<br />
<strong>Chytrid</strong> <strong>Fungus</strong><br />
A species of chytrid fungus (Batrachochytrium dendrobatidis) (BD) has been conclusively implicated in<br />
amphibian declines throughout the world (Young et al. 2001, Daszak et al. 2003, Briggs et al. 2005, La<br />
4
Marca et al. 2005, Lips et al. 2006, Rachowicz et al. 2006, Skerratt et al. 2007, Collins and Crump 2009<br />
[pages 159‐174], Rosenblum et al. 2010).<br />
<strong>Chytrid</strong> fungi represent a primitive group of fungi, <strong>Chytrid</strong>iomycota, with five orders, approximately<br />
1000 species, and BD is unique and phylogenetically distinct (James et al. 2006). <strong>Chytrid</strong>s are closely<br />
related to protozoans, because of their ancestry. <strong>Chytrid</strong> fungi are globally distributed from the tropics<br />
to arctic regions in diverse habitats. Most species are probably terrestrial and saprophytes, breaking<br />
down and feeding on keratin, chitin, and cellulose. Some soil chytrids are plant pathogens. There are<br />
freshwater and marine species that are parasites of algae and plankton. BD is the only known chytrid to<br />
parasitize vertebrates (Longcore et al. 1999).<br />
Time<br />
Period<br />
Quebec Rest of Canada<br />
Number BD Percent Number BD Percent<br />
Examined Infected Infected Examined Infected Infected<br />
1895‐1959 38 0 0 136 0 0<br />
1960‐1969 217 29 13.4 316 16 5.06<br />
1970‐1979 30 8 26.7 126 2 1.59<br />
1980‐1989 15 6 40.0 45 0 0<br />
1990‐2001 1698 302 17.8 0 ‐‐‐‐‐‐ ‐‐‐‐‐‐<br />
1960‐2001 1960 345 17.6 487 18 3.70<br />
Time<br />
Period<br />
United States<br />
Number BD Percent<br />
Examined Infected Infected<br />
1895‐1959 29 0 0<br />
1960‐1969 122 1 0.820<br />
1970‐1979 89 10 11.2<br />
1980‐1989 63 8 12.7<br />
1990‐2001 7 1 14.3<br />
1960‐2001 281 20 7.12<br />
Table 2. <strong>Chytrid</strong> fungus (Batrachochytrium dendrobatidis) infection <strong>for</strong> 3371 postmetamorphic and<br />
adult amphibians collected from 1895 to 2001 from Canada, United States, and 23 other countries.<br />
The data in Table 2 is summarized from Ouellet et al. (2005, Table 3).<br />
Importantly, Wind and Dupuis (2002) only discussed chytrid fungus as it pertained to amphibian<br />
populations and declines outside of Canada, (e.g., continental United States, Neotropics, and Australia).<br />
They did not mention any identification of chytrid fungus infections in Canada.<br />
5
The first northernmost record <strong>for</strong> chytrid fungus was in a Boreal Toad from northeastern British<br />
Columbia (Raverty and Reynolds 2001). A single specimen that exhibited a prominent mid‐dorsal<br />
cutaneous ulcer was brought in <strong>for</strong> examination in August 2000.<br />
Slough (2009) surveyed 11 sites in northwest British Columbia and one in extreme southeastern Yukon<br />
<strong>for</strong> chytrid fungus infection in three species of amphibians: Boreal Toad, Wood Frog (Lithobates<br />
sylvaticus), and Long‐toed Salamander (Ambystoma macrodactylum). The results are summarized in<br />
Table 3.<br />
Area Species Adult Metamorph/Juv. Larvae<br />
‐ + BD ‐ + BD ‐ + BD<br />
Northwest Boreal Toad 12 5 1 12 ‐‐‐‐ ‐‐‐‐<br />
British<br />
Columbia<br />
Wood Frog 1 0 ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐<br />
(11 sites)<br />
<strong>Southeast</strong><br />
Long‐toed<br />
Salamander<br />
2 0 ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐<br />
Yukon<br />
Boreal Toad 0 1 ‐‐‐‐ ‐‐‐‐ 30 0<br />
(1 site)<br />
Wood Frog 0 6 ‐‐‐‐ ‐‐‐‐ ‐‐‐‐ ‐‐‐‐<br />
Table 3. Survey of Amphibian Populations <strong>for</strong> Batrachochytrium dendrobatidis (BD) in Northwest<br />
British Columbia and <strong>Southeast</strong> Yukon, Canada.<br />
Amphibian surveys were conducted during the summers of 2007 and 2008 at 11 sites in northwestern<br />
British Columbia, and one site in southeastern Yukon (Table 3).<br />
The (+BD) column indicates the number of individuals that were found infected with the fungus.<br />
The (‐) column indicates number of individuals that tested negative <strong>for</strong> BD.<br />
Because of small sample sizes metamorphs and juveniles were combined.<br />
Three species were found: Boreal Toad (Anaxyrus boreas boreas), Wood Frog (Lithobates sylvaticus), and<br />
Long‐toed Salamander (Ambystoma macrodactylum).<br />
Data are from Slough (2009), where latitude and longitude of the 12 sites are documented.<br />
The data of Raverty and Reynolds (2001) and Slough (2009) indicate that chytrid fungus occurs as far<br />
north as northern British Columbia and southeastern Yukon, and both Boreal Toads and Wood Frogs are<br />
carriers. Table 2 also indicates the difficulty of obtaining significant sample sizes across species and life<br />
history stages. Five of 17 adult Boreal Toads were infected with chytrid fungus, while two of three<br />
juveniles were, and all 10 metamorphs examined were infected in British Columbia sites. The single<br />
Wood Frog and two salamanders found at these sites were not infected. At the Yukon site, the single<br />
adult Boreal Toad found was infected, but 30 tadpoles were not. All six Wood Frogs found at this site<br />
were infected.<br />
Only a single individual that tested positive <strong>for</strong> fungus showed any symptoms, sloughing skin on the<br />
thigh of a Boreal Toad. No other individual had any visual signs of the disease, such as redness on the<br />
legs or lethargy. The author concluded that the low populations encountered may or may not indicate<br />
recent declines, but the data is insufficient to implicate chytrid fungus.<br />
6
Deguise and Richardson (2009) examined 32 adult male Boreal Toads during the breeding season from<br />
Alice Lake Provencial Park, southwestern British Columbia <strong>for</strong> chytrid fungus. Nine (28%) of the<br />
individuals tested positive <strong>for</strong> the fungus, even though none of them showed any external symptoms of<br />
pathology. Interestingly, body condition of fungus infected toads did not differ statistically from toads<br />
that were not infected with the fungus. The dates <strong>for</strong> collecting field data were not presented.<br />
<strong>Chytrid</strong> <strong>Fungus</strong> in <strong>Alaska</strong><br />
The first documented occurrence of chytrid fungus (BD) in <strong>Alaska</strong> was found in a dead subadult male<br />
Wood Frog near a pond on the Kenai National Wildlife Refuge, Kenai Peninsula, on 25 July 2002 (Reeves<br />
and Green 2006). Ventral skin in the pelvic patch area and hind limb digits showed epidermal lesions<br />
with mild hyperkeratosis. Histological examination diagnosed the lesions as mycotic hyperkeratotic<br />
epidermitis due to infection by BD. No other species of amphibian is known at the wildlife refuge.<br />
Boreal Toads have never been documented <strong>for</strong> the Kenai Peninsula, but they occur just to the east on<br />
Montague Island and in the Prince William Sound area.<br />
Additional surveys <strong>for</strong> BD occurrence were conducted from 11 May to 21 July 2006 at three National<br />
Wildlife Refuges: Kenai, Tetlin, and Innoko (Reeves 2008). Wood Frogs were collected opportunistically<br />
near the vicinity of 29 breeding ponds. This is the only species of amphibian in interior <strong>Alaska</strong><br />
(MacDonald 2003). Tetlin is located east‐northeast of the Kenai Peninsula, north of the Wrangell<br />
Mountains, and close to Yukon province of Canada. Innoko is northwest of the Kenai Peninsula and east<br />
of Norton Bay. Ten Wood Frogs from Tetlin and nine from Innoko were examined, each specimen from<br />
a different pond. None were infected with BD. All of these 19 pond sites are remote, requiring a<br />
combination of aircraft and watercraft <strong>for</strong> access.<br />
Ten pond sites were surveyed at Kenai. These were different ponds from the 2002 pond with BD<br />
discussed above, but the access road was the same. One of the four ponds that had road access had BD,<br />
while two of the six remote ponds had BD. At the three ponds that had BD infections, all captured<br />
Wood Frogs were contaminated, but sample sizes were small with respective captures of one, two, and<br />
four. At the seven Kenai ponds without BD infection, 22 frogs tested negative, with sample sizes of: 1, 1,<br />
1, 2, 3, 6, 8. The three infected ponds were near Swan Lake recreational canoe route or its access road.<br />
One pond was adjacent to the road, and the two remote ponds were within 3 km of the road and 1 km<br />
of the canoe trail. Two of the four remote ponds that tested negative had essentially no human access.<br />
The three ponds with road access that tested negative are in an operating oil field with no public access.<br />
It is unlikely that oil workers and the non‐amphibian researchers that use this area go into the wetlands<br />
sampled in this study. Amphibian researchers have visited the oil field wetlands since 2000 and the<br />
other remote wetlands since 2004, but hygiene protocols to avoid BD were always followed.<br />
Thirty Wood Frogs, mostly metamorphs, were surveyed <strong>for</strong> BD in August 2006 at 26 known localities in<br />
the Wonder Lake region of Denali National Park (Chestnut et al. 2008). Frogs were found at 20 of the<br />
sites. BD was not detected in the 12 frogs collected at roadsides, nor at the 18 collected in remote areas<br />
up to 4.5 km from the road. The authors concluded that additional surveys, higher sample sizes, and<br />
examining individuals across all life history stages are required.<br />
Adams et al. (2007) summarized the U.S. Geological Survey’s Amphibian Research and Monitoring<br />
Initiative <strong>for</strong> the northwest coast of North America. Four general areas, from Vancouver Island to<br />
7
Skagway <strong>Alaska</strong> were surveyed <strong>for</strong> BD collecting all life history stages of anurans. BD was found in three<br />
of the four areas, in 11 of 22 populations, and in 52 of 242 (21%) individuals tested <strong>for</strong> BD (Table 4).<br />
Area Pop.<br />
Num.<br />
Skagway<br />
Region<br />
Northeast end<br />
of <strong>Southeast</strong><br />
<strong>Alaska</strong>,<br />
including<br />
adjacent<br />
British Columbia<br />
Admiralty<br />
Island<br />
Prince of<br />
Wales<br />
Island<br />
Species Adult Juvenile Larvae<br />
‐ + BD ‐ + BD ‐ + BD<br />
1 AnBo 8 7 10 0 0 0<br />
2 AnBo 13 4 0 0 0 0<br />
3 AnBo 13 4 0 0 0 0<br />
4 AnBo 0 3 5 2 0 0<br />
5 AnBo 1 0 0 0 0 0<br />
6 AnBo 1 0 2 0 0 0<br />
7 AnBo 0 0 9 1 0 0<br />
8 AnBo 0 0 2 0 0 0<br />
9 AnBo 0 0 2 8 0 0<br />
10 AnBo 2 0 0 0 0 0<br />
10, 11, 12 RaLu 5 0 3 0 0 0<br />
10, 12 LiSy 1 0 1 0 0 0<br />
13 AnBo 17 0 0 0 0 0<br />
14 AnBo 10 0 0 0 0 0<br />
15 AnBo 2 3 3 7 0 0<br />
16 AnBo 14 5 1 0 0 0<br />
17 AnBo 16 6 0 0 0 0<br />
Vancouver Is., 18, 19, 20 AnBo 1 0 10 0 10 0<br />
southern 18, 19, 21,<br />
22<br />
RaAu 6 2 2 0 20 0<br />
Table 4. Survey of Anuran Populations <strong>for</strong> Batrachochytrium dendrobatidis (BD) on the Northwest<br />
Coast of North America.<br />
Amphibian surveys were conducted during the summers of 2005 and 2006 at four general areas, <strong>for</strong> 22<br />
populations, and all life history stages.<br />
Admiralty and Prince of Wales Islands are part of <strong>Southeast</strong> <strong>Alaska</strong>, and Vancouver Island belongs to<br />
British Columbia. Pop. Num. refers to a specific anuran population that was surveyed.<br />
The (+BD) column indicates the number of individuals that were found infected with the fungus.<br />
The (‐) column indicates number of individuals that tested negative <strong>for</strong> BD.<br />
Four species were found: Boreal Toad (Anaxyrus boreas boreas), Wood Frog (Lithobates sylvaticus),<br />
Columbia Spotted Frog (Rana luteiventris), and Northern Red‐legged Frog (Rana aurora).<br />
Data are from Adams et al. (2007), where latitude and longitude of the 22 populations are documented.<br />
Anuran nomenclature is from CNAH (2010).<br />
8
Most of the anurans examined were Boreal Toads. Out of the 10 Boreal Toad populations examined in<br />
the Skagway region, six had BD infections. However, only eight individuals were tested at the four<br />
populations where BD was not found, while 89 toads were examined at the six sites that were infected.<br />
The overall BD infection rate of the 97 Boreal Toads examined in the Skagway region was 30 percent.<br />
The 10 ranids found were not infected. These individuals along with two adult Boreal Toads were from<br />
populations 10, 11, and 12 where BD infections were not found. Two populations on Admiralty Island<br />
were examined, and 27 adult Boreal Toads were not infected with BD. The three populations of Boreal<br />
Toads on Prince of Wales Island were all infected. The overall infection rate of the 57 examined was 37<br />
percent. The five anuran populations examined in southern Vancouver Island were infected at a rate of<br />
3.9 percent, but most of the individuals were tadpoles and juveniles, life stages that may demonstrate<br />
lower infection rates than adults, especially tadpoles. Only a single adult Boreal Toad was available <strong>for</strong><br />
examination from a total sample size of 21, and six adult Northern Red‐legged Frogs were examined<br />
from a total sample size of 30. Interestingly, based on the entire data set, the overall infection rate of<br />
juveniles (18/68, 26%) was similar to adults (34/144, 24%). Tadpoles were not infected (0/30).<br />
Over all these surveys, none of the anuran specimens handled appeared sick or morbid, and dead<br />
anurans were never observed. The authors did not mention epidermal skin lesions or any abnormal<br />
condition of the skin. However, there is still a great deal to learn concerning BD epidemiology.<br />
The 2007 <strong>Alaska</strong> Department of Fish and Game Per<strong>for</strong>mance Report discussed above (see Section Boreal<br />
Toads in <strong>Southeast</strong> <strong>Alaska</strong>) stated that ten sites were surveyed <strong>for</strong> chytrid fungus, all these sites were<br />
infected, and approximately a third of all individuals tested were infected (ADFG 2007). The report did<br />
not discuss the sites, dates, or the pathology of the infected individuals. For example, were the toads<br />
asymptotic (no symptoms of the fungus), or did they demonstrate mild to severe ventral skin lesions or<br />
reddening of the skin; conditions that demonstrate successful attack by chytrid fungus. The 2006 <strong>Alaska</strong><br />
Amphibian Conference did not report on chytrid fungus in <strong>Alaska</strong>n anurans, and only discussed its<br />
pathogen effects globally and in the United States (Tessler 2006).<br />
<strong>Soule</strong> <strong>River</strong> <strong>Watershed</strong> Survey <strong>for</strong> Anurans (Boreal Toad, Wood Frog) and <strong>Chytrid</strong><br />
<strong>Fungus</strong> (Batrachochytrium dendrobatidis) (BD)<br />
Observations of Boreal Toads in 2007 and 2008 were opportunistic while searching <strong>for</strong> wildlife and<br />
collecting a wide variety of ecological data. The collecting of ecological data in the field consisted of:<br />
<strong>for</strong>estry and river measurements, fisheries and big game assessments, documentation of plant<br />
communities, avian surveys, and opportunistic wildlife and amphibian surveys.<br />
Over 30 Boreal Toad metamorphs (< 2 cm) were observed while camping 12‐14 September 2007 on the<br />
delta of the <strong>Soule</strong> <strong>River</strong>. These juveniles trans<strong>for</strong>med from tadpoles during the summer (July – August),<br />
and were observed on the delta in tall dense grass, especially in the association of several large Sitka<br />
spruce with well developed litter. All metamorphs were very similar in size and in the same location,<br />
suggesting that they were from a single egg deposition. The Delta has tidal flooding and numerous pools<br />
develop at the mouth of the <strong>Soule</strong> <strong>River</strong> along with brackish marsh habitat.<br />
Field studies were conducted with three personnel from 21 July – 5 August 2008 in the <strong>Soule</strong> <strong>River</strong><br />
<strong>Watershed</strong>. We were camped along the North Fork of the <strong>Soule</strong> <strong>River</strong> and at No Name Lake. Habitats<br />
where ecological data were collected included: montane conifer <strong>for</strong>est, North and West Forks of the<br />
9
<strong>Soule</strong> <strong>River</strong>, riverine and lacustrine riparian, ponds and wetlands complexes, seeps, and muskeg. Pond<br />
habitats consisted of beaver ponds, backwaters of the river, or pools at the base of steep slopes that<br />
filled with snow melt and groundwater seepage. Intense searches were made <strong>for</strong> amphibians when<br />
ponds and wetlands were encountered.<br />
Similar field investigations were conducted in 2009 with two to four field personnel. See Map 1.<br />
Additional field work was added in 2009 and included: characterization of wetlands, intensive amphibian<br />
and chytrid fungus surveys, measurement of tidal currents at the <strong>Soule</strong> delta, and acoustical Goshawk<br />
surveys. Additionally, we were trying to observe any and all wildlife that we came across, including<br />
amphibians, and specifically searched <strong>for</strong> amphibians in quality habitat, such as ponds, wetlands, and<br />
muskeg.<br />
The only amphibian species observed in the watershed in 2008 was the Boreal Toad (Figure A1). Boreal<br />
Toads blend in well with their habitat and are difficult to see, especially if they do not move (Figures A2<br />
and A3). Adults were seen opportunistically on three different occasions along the North Fork <strong>River</strong>. All<br />
three toads appeared to be active and healthy. They did not have any traces of ventral or dorsal skin<br />
lesions, or ventral skin reddening. Careful searching <strong>for</strong> amphibians in what appeared to be good<br />
habitat failed to find any specimens of adults or tadpoles. Considering the large amount of time spent in<br />
the field, we concluded that amphibians are very rare in the North Fork and No Name Lake area of the<br />
<strong>Soule</strong> <strong>Watershed</strong>.<br />
Field investigations were conducted in the <strong>Soule</strong> <strong>River</strong> <strong>Watershed</strong> 14‐29 July 2009. The most intense<br />
amphibian surveys were conducted from 14 to 19 July. The amphibian survey work was a component of<br />
a much more extensive ecological assessment conducted with four researchers that covered montane<br />
conifer <strong>for</strong>est, wetlands, riparian, river, estuary, brackish marsh, fisheries, wildlife, and goshawk surveys.<br />
Active searches <strong>for</strong> amphibians were conducted in the following habitats: montane conifer <strong>for</strong>est and<br />
<strong>for</strong>est litter, riverine and lacustrine riparian, ponds and wetlands complexes, seeps, muskeg, river<br />
channels and small streams, and river delta brackish marsh. However, most of the search time <strong>for</strong><br />
amphibians during this time period was opportunistic, and occurred when other ecological metrics were<br />
being collected in the field.<br />
Captured amphibians were swabbed <strong>for</strong> chytrid fungus, Batrachochytrium dendrobatidis (BD), (Figure<br />
A4) using currently established protocol (Brem et al. 2007, Brede et al. 2009). The samples were sent to<br />
Pisces Molecular, Boulder, Colorado, <strong>for</strong> detection of BD by PCR analysis. Pisces Molecular procedures<br />
are in Appendix A. Habitat and toad pictures were also from Carstensen (2009). The data are reported<br />
in Table 5.<br />
10
Map 1. Survey routes <strong>for</strong> 2009 Field work<br />
11
Figure A1 Boreal Toad Figure A2<br />
Figure A3 Figure A4<br />
12
Species Date Identification<br />
and field notes<br />
ANBO 14 July A<br />
Adult<br />
ANBO 15 July B<br />
Adult<br />
ANBO 15 July C<br />
Adult, carcass<br />
ANBO 15 July D<br />
Adult<br />
ANBO 18 July E<br />
Adult<br />
ANBO 18 July F<br />
Adult<br />
ANBO 18 July G<br />
Adult<br />
TAGR 15 July H<br />
Adult<br />
TAGR 15 July I<br />
Adult<br />
Pisces<br />
Code<br />
GPS <strong>Chytrid</strong><br />
<strong>Analysis</strong><br />
(PCR)<br />
A (068) 95640 N 55 0 51.639’<br />
W 130 0 10.847’<br />
B (076) 95633 N 55 0 49.923<br />
W 130 0 11.518’<br />
C (079) 95637 N 55 0 49.855’<br />
W 130 0 11.456’<br />
D (112) 95632 N 55 0 49.550’<br />
W 130 0 10.667<br />
E (049) 95635 N 55 0 49.119’<br />
W 130 0 10.012’<br />
F (053)<br />
(054)<br />
95636 N 55 0 49.129’<br />
W 130 0 10.007’<br />
G (026) 95634 N 55 0 49.804’<br />
W 130 0 10.889’<br />
H (021)<br />
(023)<br />
95638 N 55 0 50.546’<br />
W 130 0 11.366’<br />
I ‐‐‐‐‐‐ 95639 N 55 0 50.509’<br />
W 130 0 11.398’<br />
+++<br />
Very Strong<br />
Negative<br />
Negative<br />
Negative<br />
++<br />
Strong<br />
Negative<br />
Negative<br />
Negative<br />
Negative<br />
Table 5. Amphibian <strong>Chytrid</strong> <strong>Fungus</strong> (Batrachochytrium dendrobatidis) Survey Data from <strong>Soule</strong> <strong>River</strong><br />
<strong>Watershed</strong>, <strong>Southeast</strong> <strong>Alaska</strong>, July 2009.<br />
Identification and Field Notes:<br />
A AnBo, Spec #1, SVL = 65mm, Figure A5<br />
Early‐seral surface of a dewatered pond, near Sitka alder fringe<br />
B AnBo #2, SVL = 65mm, Figure A17<br />
Short willow thicket and snags<br />
Identification and Field Notes: (continued) 13
C AnBo carcass, moldy, Figure A7<br />
sphagnum bog<br />
D AnBo, adult, Figure A4<br />
<strong>Soule</strong> <strong>River</strong> Main Stem, West Bank, just downstream of Gauging Station<br />
Habitat: <strong>for</strong>est litter, just above river; beaver ponds along river; well‐developed <strong>for</strong>est of western<br />
hemlock and mountain hemlock, scattered Sitka spruce, pockets of subalpine fir; good shrub and<br />
seedling layer; boulders and downed snags were abundant<br />
E AnBo #5, SVL = 75mm, female, Figure A6<br />
Swam into deep pond and dove, but came up<br />
This pond was one of about 20 clear water ponds with buckbean margin,<br />
in poor fen with Sphagnum but lots of vascular <strong>for</strong>age species<br />
F AnB0 #6, SVL = 68mm, male, Figures A11 and A12<br />
hopped into a shallower buckbean pond, poor fen<br />
G AnBo #4, SVL = 80mm, female, Figure A15<br />
Right on the margins of the tadpole pond,<br />
sedge wetland encompassed by dense Sitka alder thicket<br />
pond on main stem of river<br />
H TaGr #1; male, buckbean pond, Figures A21 and A22<br />
I TaGr #2; female, on land near pond with buckbean<br />
Buckbean (Menyathes trifoliata)<br />
Sitka Alder (Alnus crispa)<br />
Species Codes:<br />
Boreal Toad (Anaxyrus boreas boreas) = ANBO<br />
Northern Roughskin Newt (Taricha granulosa granulosa) = TAGR<br />
All data July 2009<br />
PCR <strong>Chytrid</strong> <strong>Fungus</strong> <strong>Analysis</strong> by: Pisces Molecular, Boulder Colorado<br />
‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐<br />
A total of nine amphibians were swabbed <strong>for</strong> chytrid fungus identification: six adult Boreal Toads, an<br />
adult carcass, and two adult Northern Roughskin Newts. Four toads and the newts were found negative<br />
<strong>for</strong> chytrid fungus. Two adults were positive <strong>for</strong> BD. All swabbed toads, both negative and positive <strong>for</strong><br />
BD, appeared healthy and active with no ventral or dorsal epidermal lesions or reddening of ventral skin.<br />
The toad in Figure A4 (ID D) tested BD negative. The toad in Figure A5 (ID A) tested as “Very Strong” <strong>for</strong><br />
BD infection, and the toad in Figure A6 (ID E) tested “Strong” <strong>for</strong> BD. The moldy toad carcass, in active<br />
decay and covered with fungus, tested negative <strong>for</strong> BD (ID C, Figure A7). This is of interest, because BD<br />
originally evolved as a saprophyte that breaks down keratin, chitin, and other tough tissue (Berger et al.<br />
2005a). See Map 2 and 3 <strong>for</strong> locations of identified species A through I.<br />
14
Map 2‐ locations of species, example (1A, 1B, 1C etc) is species located on day 1 <strong>Soule</strong> <strong>River</strong>, (2A, 2B, 2C<br />
etc) is species located on day 2 <strong>Soule</strong> <strong>River</strong>.<br />
15
Map 3‐ locations of species, example (3A, 3B, 3C etc) is species located on day 3 <strong>Soule</strong> <strong>River</strong> survey.<br />
A, B, C etc is location of Boreal Toad see page 17 and 18 <strong>for</strong> field notes.<br />
16
Boreal Toad A, the strongest BD infected specimen, was also the most northern specimen captured in<br />
the <strong>Soule</strong> <strong>Watershed</strong>. The toad was found in a beaver pond wetland site on a bench above and near the<br />
bottom of the West Fork of the <strong>Soule</strong> <strong>River</strong>. The habitat was an old beaver pond that lost most of its<br />
water, note breached dam on the left (Figure A8).<br />
The other BD infected toad (E) was the most southeastern toad captured. It was in a wetland fen on a<br />
bench above the west bank of the main stem of the <strong>Soule</strong> <strong>River</strong> (Figure A9). The <strong>Soule</strong> <strong>River</strong> cannot be<br />
seen, but its canyon is in the upper background of the figure. There were approximately 20 small clear<br />
shallow buckbean ponds in the fen, the right side of Figure A9. Figure A10 is an example. The BD<br />
infected toad was found in one of the deeper ponds. Another toad was captured in a nearby pond. This<br />
toad was BD negative (ID F, Figures A11 and A12).<br />
A BD negative toad (ID D, Figure A4) was captured in the <strong>for</strong>est litter also on the west bank, upstream,<br />
and just below the gauging station. The habitat was a well‐developed hemlock <strong>for</strong>est with both species<br />
and scattered Sitka spruce (Figure A13). The site was just above the main stem of the <strong>Soule</strong> <strong>River</strong>, and<br />
there were beaver ponds just above the bank of the river (Figure A14).<br />
Just upstream again on the west bank of the main stem of the <strong>Soule</strong> <strong>River</strong> was another beaver pond<br />
wetland complex. Toad G (Figure A15) was captured here. The habitat is shown in Figure A16.<br />
Just to the west, toad B (Figure A17) was captured in another beaver pond wetland complex, on the<br />
south bank of the West Fork just upstream of its junction with the North Fork (Figure A18). The toad<br />
was in a thicket of short willows in a clear water beaver pond (Figure A19). The toad carcass (ID C,<br />
Figure A7) was found at a small bog 150 meters southeast and uphill from this site (Carstensen 2009).<br />
The two Roughskin Newts were captured and swabbed (both BD negative) in a wetland fen that<br />
contained 10‐15 small shallow buckbean ponds. Figure A20 is an example of one of these ponds.<br />
Figures A21 and A22 show the first newt caught, which was a male. The second one was a female.<br />
Other newts were seen swimming in the ponds. This wetlands complex was upslope of and near the<br />
junction of the North and West Forks of the <strong>Soule</strong> <strong>River</strong>.<br />
At the pond complex where toad G was found there were a number of tadpoles. There were 50‐100<br />
tadpoles in the shallows, <strong>for</strong>eground in Figure A23. There were over 200 at the other end of the pond<br />
complex where toad G was actually captured (Figure A16). These tadpoles were twice as large as the<br />
other tadpoles. These tadpole swarms were separated by 85 meters, and belonged to different broods<br />
(Carstensen 2009, pages 41‐42). There were 7 toadlets caught on 24 Aug 2009 that ranged in size from<br />
8‐11 mm. On 18 October, two toadlets were caught and measured 14 mm. All toadlets tested Negative<br />
<strong>for</strong> BD.<br />
Tadpoles were also found in a tidal pond on the Delta of the <strong>Soule</strong> <strong>River</strong> (Figures A24, A25). There were<br />
at least 50‐100 tadpoles in the pond. The pond was shallow, approximately 20 meters long, with steep<br />
sides, and was close to the Portland Canal. Carstensen (2009, pages 35‐36) provides an excellent<br />
description of the vegetation surrounding this pond. There were 10 toadlets caught on 24 Aug 2009,<br />
they ranged in size from 13‐19 mm. All toadlets tested Negative <strong>for</strong> BD. Figure A26 shows an aerial view<br />
of the tadpole pond and its relationship to other features on the <strong>Soule</strong> Delta. The <strong>Soule</strong> <strong>River</strong> outlet is<br />
on the left, the pond is in the far background of the scene close to the Portland Canal, and the two large<br />
Sitka spruce in the center of the scene is where all the Boreal Toad metamorphs were seen in September<br />
17
2007. There is a third tree, a mountain hemlock, which is difficult to distinguish, and is the closest tree<br />
to the camera sighting.<br />
Note the snag extending over the pond and the large and smaller snags in the background in Figure A25.<br />
Figures A27 and A29 show the pond completely inundated by the high tide. Note that the snag that was<br />
over the pond is now suspended in the tidal water over the pond. Note also, the large and smaller snags<br />
in the background. Compare Figures A27 and A28 with Figure A25.<br />
Figure A5<br />
Figure A6 Figure A7<br />
18
Figure A8 Figure A9<br />
Figure A10 Figure A11<br />
Figure A12 Figure A13<br />
19
Figure A14 Figure A15<br />
Figure A15<br />
Figure A16 Figure A17<br />
Figure A18 Figure A19<br />
20
Figure A20 Figure A21<br />
Figure A22 Figure A23<br />
Figure A24 Figure A25<br />
21
Figure A26 Figure A27<br />
Water Chemistry<br />
A water sample of the Delta tadpole pond was taken on 16 July 2009, be<strong>for</strong>e the pond was completely<br />
inundated by the high Spring Tide (Figure A24). The water in the pond was approximately four inches<br />
deep at this time. Another water sample was taken on 27 July, after the pond was flooded and the tidal<br />
water from the Portland Canal was receding (Figure A29). The water in the pond at this time was<br />
approximately two feet deep. The results of the water chemistry analysis are presented in Table 6 and<br />
compared to the water in the Portland Canal just below the pond.<br />
Pond Water Chemistry<br />
Pond Water<br />
BEFORE<br />
Tidal Flooding<br />
Pond Water<br />
AFTER<br />
Tidal Flooding<br />
Portland Canal<br />
Water<br />
Below Pond<br />
Date of Water Sample 16 July 2009 27 July 2009 27 July 2009<br />
Specific Conductance<br />
(μmhos/cm)<br />
3.5<br />
2.9 3.9<br />
Total Suspended Solids<br />
(mg/l)<br />
7.0<br />
12.0 16.0<br />
Total Dissolved Solids<br />
(mg/l)<br />
1760 1370 1900<br />
Turbidity<br />
(NTU)<br />
0.59 2.5 8.8<br />
Alkalinity<br />
(mg/l)<br />
31.8 33.7 29.9<br />
pH<br />
6.1 6.5 6.3<br />
Ammonia<br />
(mg/l)<br />
0.054 not detectable not detectable<br />
Nitrogen<br />
(NO2/NO3)<br />
not detectable ‐‐‐‐‐‐ ‐‐‐‐‐‐<br />
Total Phosphorus<br />
(mg/l)<br />
0.17<br />
‐‐‐‐‐‐ ‐‐‐‐‐‐<br />
Dissolved Organic<br />
Carbon (mg/l)<br />
6.3<br />
‐‐‐‐‐‐ ‐‐‐‐‐‐<br />
Table 6. Water Chemistry of Delta Tadpole Pond.<br />
22
The water in the pond on 16 July be<strong>for</strong>e it was flooded was approximately four inches deep. The water<br />
in the pond was approximately two feet deep on 27 July, after it was flooded by the Spring Tide. <strong>Alaska</strong><br />
drinking water standards specify less that 500 mg/l Total Dissolved Solids, and less than 1000 mg/l <strong>for</strong><br />
irrigation and stock watering.<br />
The specific conductance of both the pond and canal waters were surprisingly very low, indicating the<br />
very strong influence of the pure glacial melt water of the <strong>Soule</strong> <strong>River</strong>. Correspondingly, note that the<br />
pH ranged from 6.1‐6.5, also confirming that the water chemistry suggested glacial melt water and not<br />
marine. The approximate pH of the oceans is 8.1, but drops accordingly in estuaries and at river<br />
discharges. The pH of pure rainwater is typically 5.6‐5.9 (less than 5.6 is considered “acid rain”), because<br />
dissolved carbon dioxide makes it slightly acidic. Decaying vegetation produces humic acids, which can<br />
further lower the pH of ponds. Sphagnum moss exchanges cations with soils producing acidic<br />
conditions. However, if there is a great deal of aquatic vegetation in ponds, the pH can change<br />
dramatically over a 24 hour cycle, as active photosynthesis takes up CO2 by day (increasing pH), and<br />
respiration at night releases CO2 (decreasing pH).<br />
Note that the pond water was clear (low turbidity) be<strong>for</strong>e the flooding (Figure A24, Table 6), but turbid<br />
after flooding (Figure A29, Table 6). The water in Portland Canal was very turbid, because of the<br />
abundance of glacial flour in the <strong>Soule</strong> <strong>River</strong>. Glacial flour is the fine white silt and clay ground by the<br />
glacier from the granite bedrock. The suspended solids in the water samples, glacially ground silts, were<br />
high and exactly paralleled the turbidity. The total dissolved solids were extremely high in all water<br />
samples, again as expected <strong>for</strong> a river <strong>for</strong>med by an active glacier. These solids were approximately<br />
three times those permitted <strong>for</strong> <strong>Alaska</strong> drinking water standards. The high dissolved solids in the pond<br />
water be<strong>for</strong>e flooding were probably due to the concentration of minerals as pond water gradually<br />
evaporated. The ammonia concentration of 0.054 mg/l in the pond water be<strong>for</strong>e flooding may appear<br />
low, but even trace amounts can stress sensitive organisms. The presence of ammonia in pond water<br />
indicates the breakdown of proteins from decay or organism excretion without adequate bacterial<br />
trans<strong>for</strong>mation to nitrate.<br />
Additional field work was conducted in the <strong>Soule</strong> <strong>River</strong> <strong>Watershed</strong> in September and November 2009.<br />
This presented the opportunity to survey Boreal Toad metamorphs <strong>for</strong> BD infection at the <strong>Soule</strong> delta<br />
pond. In early September, 17 newly trans<strong>for</strong>med metamorphs were swabbed and sent to Pisces<br />
Molecular <strong>for</strong> BD analysis. The mid‐November survey yielded two additional metamorphs. All 19 Boreal<br />
Toad metamorphs tested negative <strong>for</strong> BD infection.<br />
The complete Boreal Toad observation data <strong>for</strong> 2007‐2009 are presented in Table 7. The 19<br />
metamorphs discussed above were not included in this table.<br />
23
Year Dates in<br />
the Field<br />
Field<br />
Days<br />
Observers Observer<br />
Ef<strong>for</strong>t<br />
Boreal Toads Observed<br />
in the Field<br />
Adult Metamorph Larvae<br />
2007 8‐14<br />
September<br />
7 3 21 0 >30 0<br />
2008 21 July –<br />
5 August<br />
16 3 48 3 0 0<br />
2009 14‐29 July 6 & 2 & 44 6 0 3<br />
16 2<br />
Table 7. Boreal Toads (Anaxyrus boreas boreas) Observed in the Field, 2007‐2009.<br />
Most observations were opportunistic while collecting a wide variety of ecological data and searching<br />
<strong>for</strong> wildlife. Habitats included: montane conifer <strong>for</strong>est, riverine and lacustrine riparian, ponds and<br />
wetlands complexes, seeps, muskeg, small streams, and river delta brackish marsh. Intense searches<br />
were made <strong>for</strong> amphibians when ponds and wetlands were encountered.<br />
Observer Ef<strong>for</strong>t = field days X number of observers.<br />
All Metamorphs were very similar in size and in the same location, suggesting that they were from a<br />
single egg deposition.<br />
Larvae = number of ponds or sections of pond complexes where tadpole clusters were observed.<br />
Over the three years of field work in a very wide range of habitats throughout the <strong>Soule</strong> <strong>River</strong><br />
<strong>Watershed</strong>, 13 Boreal Toad observations were made at an ef<strong>for</strong>t of 113 observer‐days. That translates<br />
to 8.7 observer‐days <strong>for</strong> each adult Boreal Toad, tadpole or metamorph cluster observation in the <strong>Soule</strong><br />
<strong>River</strong> <strong>Watershed</strong>.<br />
Discussion<br />
Amphibians are closely ecologically dependent on and linked to their evolved environments. This<br />
represents a double‐edged sword <strong>for</strong> amphibian populations. They are ecological indicators or sentinels<br />
of environmental conditions, but also at the same time, they are highly susceptible to environmental<br />
changes and habitat degradation. Besides their required environmental template <strong>for</strong> moisture,<br />
temperature, and substrate parameters; most species also require habitat mosaics to complete their life<br />
history requirements, specific breeding sites <strong>for</strong> egg deposition and larval (tadpole) development. On<br />
top of these environmental constraints, amphibians have poor dispersal ability, while many populations<br />
and even entire species have very limited geographic ranges. There<strong>for</strong>e, the innate ecology of<br />
amphibians makes them particularly susceptible to habitat destruction and degradation, pollution, and<br />
predation. Importantly, amphibians are particularly sensitive to climate change because of: demanding<br />
physiological needs, habitat and dispersal needs <strong>for</strong> three stages of life history <strong>for</strong> most species, and<br />
close ecological relationship to weather‐its variability‐and predictability. Amphibians are usually very<br />
difficult to monitor <strong>for</strong> population trends, because of their innate patterns of boom and bust breeding<br />
cycles; a direct selection pressure and response to local environmental variability, such as weather<br />
extremes.<br />
24
Habitat destruction, pollution, and predation or competition from introduced exotic species (e.g.,<br />
Bullfrogs (Lithobates catesbeianus), trout stocking in fishless lakes) has long been recognized as prime<br />
drivers in amphibian population declines. A variety of pathogens have also been identified in amphibian<br />
mortality, including: fungi, bacteria, viruses, protozoans, and occasionally parasites. Rapid major die‐offs<br />
of anuran populations associated with pristine habitats in the mountains of Central America, rain<strong>for</strong>ests<br />
of eastern Australia, and the southern and central Rocky Mountains of the United States, signaled<br />
research and additional surveys.<br />
<strong>Chytrid</strong>s are the most primitive fungi known, very widely distributed, and have been around <strong>for</strong> over 350<br />
million years. They include terrestrial and freshwater saprophytes (decay organisms) that break down<br />
keratin, chitin, cellulose, and other complex tough molecules and cellular tissue. There<strong>for</strong>e, evolution<br />
has long ago provided them with the tools to break down epidermal keratinized tissues (i.e.,<br />
chytridiomycosis). BD, the species linked to amphibian declines, has been found in the water,<br />
sediments, and rocks of aquatic habitats (Kirshtein et al. 2007, Walker et al. 2007). Interestingly, BD<br />
zoospores were not detected in water and sediment samples from high elevation lakes in the Rocky<br />
Mountains of Montana and Colorado where amphibians were absent, but in the same region where BD<br />
infected amphibians were found at lower elevations (Hossack et al. 2009).<br />
A single species of chytrid fungus, (Batrachochytrium dendrobatidis) (BD), was identified and linked with<br />
amphibian declines from local to global scales. This pathogen was identified as either solely responsible<br />
<strong>for</strong> at least some global population declines, or a cofactor in the declines (See Introduction and<br />
Background). BD was implicated in the three major global areas identified above where anuran<br />
population declines have been most severe. However, BD occurrences in eastern Canada, and<br />
northeastern and southeastern United States have not been associated with resulting amphibian<br />
declines (Ouellet et al. 2005, Longcore et al. 2007, Rothermel et al. 2008). Many BD infected amphibian<br />
populations survive initial declines and remain viable, despite persistent BD infection (Retallick et al.<br />
2004, Briggs et al. 2005).<br />
An interesting characteristic of BD is that it is most pathogenic at lower temperatures (Berger et al.<br />
2004). Individuals infected with BD and demonstrating clinical symptoms recovered from the infection<br />
when subjected to higher temperatures (Woodhams et al. 2003, Retallick and Miera 2007). Attempts<br />
have been made to implicate climate change <strong>for</strong> optimizing the ideal environmental parameters <strong>for</strong> BD,<br />
and thus increase its virulence to amphibian populations (Thomas et al. 2004, Bosch et al. 2007),<br />
especially in the montane Neotropics (Pounds et al. 2006), but this hypothesis remains controversial.<br />
Recent research suggests that the temperature dependency of amphibian host response to infection by<br />
BD may be influenced by climate change (Ribas et al. 2009).<br />
Complicating matters, it appears that there is a great deal of variation in the severity of BD infection and<br />
subsequent mortality in anuran populations or species. This can be attributed to a number of non‐<br />
exclusive factors. Species or populations innately vary in their susceptibility to BD (Blaustein et al.<br />
2005b, Woodhams et al. 2007). There are different strains of BD that vary in their lethality (Berger et al.<br />
2005b, Retallick and Miera 2007, Fisher et al. 2009, James et al. 2009). There are environmental<br />
parameters that enhance the virility of BD (Pounds et al. 2006, Ribas et al. 2009). There are additional<br />
stressors that weaken or make individuals more susceptible to BD infection. BD was often theorized as<br />
the agent delivering the final blow to a population already stressed by habitat degradation, drought,<br />
pollution, acidic deposition, or excess UV‐radiation (Bosch et al. 2001, Blaustein and Kiesecker 2002,<br />
Blaustein et al. 2003, 2005b). Species specific behavior such as microhabitat selection or basking<br />
requirements may increase susceptibility to BD infections (Lips et al. 2003, Rowley and Al<strong>for</strong>d 2007).<br />
25
Skin peptide defenses (Woodhams et al. 2007) and skin microbes (Harris et al. 2009) protect some<br />
species from BD infections or mortality.<br />
Bullfrogs are frequently identified as reservoirs and carriers of BD, and infect more susceptible species or<br />
populations (Mazzoni et al. 2003, Daszak et al. 2004, Hanselmann et al. 2004, Blaustein et al. 2005b,<br />
Garner et al. 2006, Pearl et al. 2007). Bullfrogs have been widely introduced or they escaped into many<br />
habitats in many parts of the world, including the western United States and southwestern Canada. The<br />
Bullfrog does not occur in <strong>Southeast</strong> <strong>Alaska</strong>. Although Bullfrogs and their larvae are typically considered<br />
predators on or competitors with native anurans, they have not been appreciated by natural resource<br />
managers as carriers of BD and the decimation of native amphibian communities. The Northern Leopard<br />
Frog (Lithobates pipiens) has also been identified as a reservoir and carrier of BD (Woodhams et al.<br />
2008)<br />
Blaustein et al. (2005b) found that Boreal Toad tadpoles were the most susceptible to BD mortality out<br />
of the four species tested. Mortality of tadpoles to BD appears to be primarily from toxins produced by<br />
the fungus. The researchers concluded that the tadpoles of all four species (Boreal Toad, Bullfrog,<br />
Pacific Chorus Frog, Cascades Frog) could be carriers of BD to infect other anurans.<br />
BD is a chytrid fungus that is phylogenetically distinct and the only known chytrid that parasitizes<br />
vertebrates (see <strong>Chytrid</strong> <strong>Fungus</strong> section). These data, along with genetic analysis, have suggested that<br />
BD has only recently evolved, and spread rapidly across the globe (Morehouse et al. 2003, Rachowicz et<br />
al. 2005, Morgan et al. 2007). James et al. (2009) recently reported that the BD amphibian epidemic is<br />
the result of a recent emergence of a single successful invasive diploid lineage.<br />
Boreal Toad populations suffered dramatic and widespread population declines and local extinctions<br />
throughout the central and southern Rocky Mountains, since the 1970s. Many of the most closely<br />
monitored populations were in pristine areas (e.g., Rocky Mountain National Park). Boreal Toads also<br />
declined in the northern Rockies, but not to the severe extent as in more southern portions of their<br />
range. The major agent appears to be the chytrid fungus Batrachochytrium dendrobatidis (BD), although<br />
many causes have been proposed, alone or as cofactors with BD and other pathogens. Possibly, Boreal<br />
Toads, or their southern populations at least, are unusually susceptible to this pathogen.<br />
Ouellet et al. (2005) in their seminal study documented that 81 out of 295 Bullfrogs (27%) collected<br />
between 1954‐1999 in the United States and Canada were infected with a chytrid fungus, presumably<br />
BD. Most or almost all of these were from the eastern range of the species. They concluded that chytrid<br />
infections were widespread and naturally occurring in eastern North American anuran populations, and<br />
no single cause could explain population declines.<br />
The distribution of the Boreal species is very extensive; from northeast British Columbia, eastward to<br />
north of Lake Superior and the western extreme of Indiana, and south to Arizona, New Mexico, and<br />
Missouri, with a disjunct population in extreme southern Ontario and Quebec. The Midland species has<br />
a much smaller range, and is found just to the south and east of the Boreal species.<br />
The Wood Frog has the largest range of any North American amphibian: found in northeastern, the<br />
Appalachians, and the upper Midwest of the United States; throughout much of Canada; most of <strong>Alaska</strong><br />
to the north slope; and in three small relict populations in the western United States, extreme northern<br />
26
Idaho, northern Wyoming, and southern Wyoming and adjacent northern Colorado (Stebbins 1962,<br />
2003, MacDonald 2003).<br />
There<strong>for</strong>e, at least four species of western North America anurans are potential reservoirs and carriers<br />
of BD. The Bullfrog appears to be doing very well in both its native and introduced range, many<br />
populations of the Boreal Chorus Frog are in decline, and all species of leopard frogs (at least seven<br />
species are currently recognized) are doing poorly, while the status of the Wood Frog is variable and<br />
unclear (Lannoo 1998, 2005).<br />
Boreal Toads are apparently widespread and secure in British Columbia and Alberta. The main concern<br />
<strong>for</strong> Canadian Boreal Toads is in south‐coastal British Columbia and adjacent Vancouver Island, where<br />
human population increases and associated infrastructure and pollution are taking their toll. Boreal<br />
Toads were historically widespread and abundant on southern Vancouver Island in the 1970s. However,<br />
this species has apparently gone extinct at an extensive and undisturbed wetland, Jordon Meadows,<br />
while Northern Red‐legged and Pacific Chorus Frogs, Rough skinned Newts, and Northwestern<br />
Salamanders are all doing well at this site.<br />
MacDonald (2003) reported that Boreal Toads “are common and widespread on the mainland and<br />
islands of <strong>Southeast</strong> <strong>Alaska</strong>”. There are 70 museum specimen records in <strong>Southeast</strong> <strong>Alaska</strong> (MacDonald<br />
and Cook 2007). However, the records are primarily along the coast and near settlements. Records<br />
near the British Columbia border and interior, especially in the southeastern portion of <strong>Southeast</strong> <strong>Alaska</strong><br />
are absent, because of the lack of surveys. Only five records are documented in the general<br />
southeastern region of <strong>Southeast</strong> <strong>Alaska</strong>, none of them in the <strong>Soule</strong> <strong>River</strong> <strong>Watershed</strong> area.<br />
There is anecdotal evidence provided by long‐time residents in the Skagway area of northern <strong>Southeast</strong><br />
<strong>Alaska</strong> that Boreal Toads were much more common 20 years ago compared to recent times. A retired<br />
National Park Service trail crew leader recalled that recent metamorph toads were so abundant during<br />
summers that thousands of them blanked portions of trails in Klondike Gold Rush National Historical<br />
Park, and it was impossible to avoid stepping on them. The rumored and perceived declines of Boreal<br />
Toads at the Park initiated surveys in 2003. Intensive surveys over two summers at 39 potential<br />
breeding sites, found tadpoles in only six of the sites.<br />
The first northernmost record <strong>for</strong> chytrid fungus was from northeastern British Columbia in August<br />
2000. This was a single Boreal Toad with a prominent mid‐dorsal cutaneous ulcer. The first documented<br />
occurrence of chytrid fungus (BD) in <strong>Alaska</strong> was found in a dead subadult male Wood Frog near a pond<br />
on the Kenai National Wildlife Refuge, Kenai Peninsula, on 25 July 2002. The specimen exhibited<br />
mycotic hyperkeratotic epidermitis due to infection by BD.<br />
Dramatic mortality in amphibian populations blamed on chytrid fungus (BD) infections in the United<br />
States, and indeed globally, along with these two pathogenic cases, motivated amphibian surveys in<br />
<strong>Alaska</strong> and western Canada in 2005. These data are summarized in Table 8.<br />
Boreal Toads Tested <strong>for</strong> <strong>Chytrid</strong> <strong>Fungus</strong>, Batrachochytrium dendrobatidis<br />
Area Years Number BD positive % BD positive<br />
NW BC &<br />
SE Yukon<br />
2007‐2008 31 18 58<br />
Skagway, AK 2005‐2006 97 29 30<br />
27
Area<br />
Admiralty<br />
Island<br />
Prince of Wales<br />
Island<br />
South Vancouver<br />
Island<br />
Southwest<br />
BC<br />
<strong>Soule</strong> <strong>Watershed</strong><br />
(This Study)<br />
2005‐2006 27 0 0<br />
2005‐2006 57 21 37<br />
2005‐2006 11 0 0<br />
Pub. in 2009 32 9 28<br />
2009 6 2 33<br />
TOTAL ‐‐‐‐‐‐ 261 79 30<br />
Wood Frogs Tested <strong>for</strong> <strong>Chytrid</strong> <strong>Fungus</strong>, Batrachochytrium dendrobatidis<br />
Area Years Number BD positive % BD positive<br />
*Danali<br />
National Park<br />
2006 30 0 0<br />
*<strong>Alaska</strong>, 3<br />
Wildlife Refuges<br />
2006 48 7 15<br />
NW BC &<br />
SE Yukon<br />
2005‐2006 7 6 86<br />
Skagway, AK<br />
Area<br />
2005‐2006 2 0 0<br />
TOTAL ‐‐‐‐‐‐ 87 13 15<br />
Table 8. Recent MajorAmphibian Surveys <strong>for</strong> <strong>Chytrid</strong> <strong>Fungus</strong> (Batrachochytrium dendrobatidis) (BD) in<br />
<strong>Alaska</strong> and Western Canada.<br />
The upper table is <strong>for</strong> Boreal Toads (Anaxyrus boreas boreas), and the lower table is <strong>for</strong> Wood Frogs<br />
(Lithobates sylvaticus). BC = British Columbia. No date was given <strong>for</strong> the southwest British Columbia<br />
site, but the data were published in 2009. Asterisk identifies sites where the only amphibian species is<br />
the Wood Frog. Twenty‐two additional amphibians of four species were also found at these sampled<br />
areas, and two of these tested positive <strong>for</strong> BD. Two of 10 Northern Red‐legged Frogs (Rana aurora)<br />
tested positive <strong>for</strong> BD in southern Vancouver Island. See the Results section <strong>for</strong> more details and<br />
literature citations.<br />
The samples of Table 8 may appear large, and they are useful <strong>for</strong> an overall assessment. However, Table<br />
8 combines the data from many individual sampling sites over very large areas. The Results section and<br />
even the original literature need to be consulted <strong>for</strong> additional and specific details on the samples in the<br />
areas identified in the table. Out of the nine general areas where major amphibian surveys <strong>for</strong> BD were<br />
conducted, only two areas were negative <strong>for</strong> BD infection, Admiralty Island and Denali National Park.<br />
The overall Boreal Toad infection rate <strong>for</strong> BD was 30 percent. Interestingly, this was the approximate<br />
infection rate in four of seven areas where this species was tested: southwest British Columbia, Prince of<br />
Wales Island, Skagway area, and <strong>Soule</strong> <strong>River</strong> <strong>Watershed</strong>. Wood frogs were infected with BD at half the<br />
rate of Boreal Toads. Boreal Toads and Wood Frogs from 11 sites in northwest British Columbia and a<br />
28
sample from southeastern Yukon were highly infected with BD. There was a general trend <strong>for</strong> more<br />
remote or wilderness collecting sites to have fewer BD infections, while more accessible sites could be<br />
heavily infected or not infected with BD. However, even remote sites were not free from BD.<br />
Interestingly, in all the surveys reported in Table 8, BD infected amphibians almost never exhibited<br />
chytridiomycosis, and dead individuals were not observed. In other words, BD infected individuals had<br />
no apparent external pathology, such as epidermal lesions or reddening of the ventral skin. In BD<br />
pathology, the ventral skin in the pelvic patch area and hind limb digits show epidermal lesions with mild<br />
to severe hyperkeratosis. Additionally, the authors of the reports often made the observation that<br />
infected individuals were active and did not appear sick or morbid. BD infected individuals appeared<br />
and behaved indistinguishable from BD negative individuals. The two toads from the <strong>Soule</strong> <strong>Watershed</strong><br />
that were “very strongly” infected with BD (ID A, Figure A5) and “strongly” infected (ID E, Figure A6) did<br />
not appear different or behave differently than the four toads that tested BD negative (D, Figure A4; F,<br />
Figure A12; G, Figure A15; B, Figure A17). All BD positive and BD negative toads were active and did not<br />
exhibit any lethargic behavior.<br />
The moldy toad carcass, in active decay and covered with fungus, tested negative <strong>for</strong> BD (ID C, Figure<br />
A7). This was of interest, because chytrid fungi evolved as saprophytes that break down keratin, chitin,<br />
and other tough tissue.<br />
The absence of observable pathology in BD infected Boreal Toads in the <strong>Soule</strong> <strong>Watershed</strong> is consistent<br />
with all the other amphibian surveys in <strong>Alaska</strong> and western Canada. Additionally, <strong>Soule</strong> <strong>Watershed</strong><br />
toads had the same infection rate as the large regional sample (Table 8). Interestingly, out of the six<br />
toads tested <strong>for</strong> BD, the two that were infected were the individuals that were the farthest separated in<br />
the <strong>Soule</strong> <strong>Watershed</strong> landscape (toads A and E). Toad F was not infected with BD, and was found in<br />
proximity to strongly BD infected toad E (Table 5). All of the 19 metamorphs from the <strong>Soule</strong> delta pond<br />
tested negative <strong>for</strong> BD. This is also comparable to other studies, where metamorphs and larvae anurans<br />
typically have much lower BD infection rates than adults.<br />
The <strong>Soule</strong> <strong>Watershed</strong> is considered remote wilderness and not visited by humans. BD has been<br />
documented in remote, wilderness, and pristine landscapes in <strong>Alaska</strong> and western Canada. However, BD<br />
infection rates were much lower in these remote and inaccessible settings when compared to developed<br />
areas and road accessible sites. Reeves et al. (2008) found that road accessible sites in <strong>Alaska</strong>n National<br />
Wildlife Refuges positively correlated with skeletal abnormalities in Wood Frogs. Some of the highest<br />
reported abnormality rates in published literature.<br />
Extensive ecological field investigations and wildlife surveys were conducted in the <strong>Soule</strong> <strong>River</strong><br />
<strong>Watershed</strong> from 2007 to 2009. Most wildlife, including amphibian, observations were opportunistic<br />
while collecting a wide variety of ecological data on the North and West Forks and the main stem of the<br />
<strong>Soule</strong> <strong>River</strong>, at Noname Lake, and at the <strong>Soule</strong> delta on Portland Canal. Habitats included: montane<br />
conifer <strong>for</strong>est, riverine and lacustrine riparian, ponds and wetlands complexes, seeps, muskeg, river<br />
channels and small streams, and river delta brackish marsh. Intense searches <strong>for</strong> amphibians were<br />
conducted in all years at ponds, wetlands, and riparian habitats, but especially 14‐19 July 2009.<br />
Over the three years of field work in a very wide range of habitats throughout the <strong>Soule</strong> <strong>River</strong><br />
<strong>Watershed</strong>, 13 Boreal Toad observations were made at an ef<strong>for</strong>t of 113 observer‐days. That translates<br />
to 8.7 observer‐days <strong>for</strong> each adult Boreal Toad, tadpole or metamorph cluster observation in the <strong>Soule</strong><br />
<strong>River</strong> <strong>Watershed</strong>. Many intense searches were conducted in excellent Boreal Toad habitat, including<br />
29
ponds and wetlands <strong>for</strong> tadpoles. This represents an extremely low encounter rate <strong>for</strong> Boreal Toads,<br />
indeed any amphibian species. Amphibian surveys were particularly intense 14‐19 July 2009 when<br />
individuals were swabbed <strong>for</strong> chytrid fungus. Even during this time period, when a great deal of search<br />
ef<strong>for</strong>ts were in a variety of wetlands, including beaver ponds, fens, brackish marsh, and riparian habitats,<br />
the encounter rate was still poor at 2.7 observer‐days <strong>for</strong> each adult Boreal Toad or tadpole cluster<br />
observation. The searched wetlands, beaver ponds, and fens represented excellent amphibian habitats<br />
(O’Clair et al.1997, Carstensen 2009).<br />
The scarcity of Boreal Toads parallels the scarcity of other amphibians and mammals in the <strong>Soule</strong><br />
<strong>Watershed</strong>. The evidence of rarity is based on visual sightings, the lack of tracks in muddy or sandy soils,<br />
and the lack of other signs of presence. Approximately, 10 Roughskin Newts were seen in the 2009<br />
season, and on at least five occasions a frog was seen that rapidly disappeared into dense litter or grass<br />
and could not be located, despite significant ef<strong>for</strong>ts. The general color and litter‐disappearing behavior<br />
strongly suggested Wood Frogs. The habitats included: North Fork riparian floodplain, a rocky ridge<br />
above the main stem of the <strong>Soule</strong> where there are small pockets of water, and the <strong>Soule</strong> delta marsh.<br />
The only other potential frog in the <strong>Soule</strong> <strong>Watershed</strong> is the Columbia Spotted Frog (Rana luteiventris).<br />
This species has not been observed in the <strong>Soule</strong> <strong>Watershed</strong>, and is typically found closer to aquatic<br />
habitats than the Wood Frog. We have found this species to be easily observed and captured in pond<br />
and river habitats, so it is unlikely that our unknown frog is this species.<br />
The steep and very rugged habitat, deep winter snows, up to 20‐30 feet deep covering the landscape,<br />
and relatively recent retreat from glacial influences, may explain the general lack of amphibians and<br />
mammals. Because of the deep winter snowfall, the snow‐free season may be short in the deep valleys<br />
of the <strong>Soule</strong> <strong>Watershed</strong>. Anuran adults or metamorphs could have poor survivorship or dispersal<br />
potential in this landscape. The short snow‐free season may be particularly difficult <strong>for</strong> recently<br />
trans<strong>for</strong>med metamorphs that do not have sufficient time to grow and accumulate body fat <strong>for</strong> their<br />
extensive winter hibernation.<br />
The low population densities of Boreal Toads in some parts of their northern distribution, but apparently<br />
not in other parts, remain an open mystery. The general consensus is that Boreal Toad populations have<br />
significantly declined since the 1970s throughout their entire range. But most of the evidence is<br />
anecdotal <strong>for</strong> their northern populations, where their habitat consists of huge remote landscapes. By<br />
current estimates, approximately a third of northern Boreal Toads are infected with BD, and there is a<br />
high variability of infection rate among populations. Complicating the logic is that northern BD infected<br />
toads appear asymptotic, and apparent declines and actual rarity occur in both developing areas and<br />
remote pristine wilderness. Climate change, both current and predicted, does not appear to be a<br />
significant factor in these northern populations. The risks of BD from anuran reservoirs and carriers are<br />
not a concern in these northern low diversity amphibian communities, as the alien Bullfrog has been in<br />
the western United States and southwestern Canada. However, the Wood Frog may be a potential<br />
carrier of BD.<br />
A priority among federal, <strong>Alaska</strong>, and Canadian agencies is the planning of additional monitoring, but<br />
statistically valid surveys of extensive, remote, and difficult to access landscapes, especially <strong>for</strong> rare or<br />
becoming rarer species, are challenging both technically and economically. There is still a great deal<br />
to learn concerning BD epidemiology. The final appraisal on a comprehensive assessment of the<br />
detailed causes <strong>for</strong> amphibian global population declines and species extinctions, and the role that BD<br />
plays remain to be settled (Collins and Crump 2009, James et al. 2009, Rosenblum et al. 2010).<br />
30
Discussion Summary<br />
Documentation of amphibian species in the <strong>Soule</strong> <strong>River</strong> <strong>Watershed</strong> are based on 123 Observer‐Field‐<br />
Days in 2007‐2009, while conducting a wide variety of ecological field investigations at the watershed,<br />
the delta, and Portland Canal (Table 9). Most of these observations were opportunistic (see Methods).<br />
Potential amphibian species in the watershed are based on museum specimens and species<br />
documentations <strong>for</strong> <strong>Southeast</strong> <strong>Alaska</strong> from MacDonald and Cook (2007). Amphibians from MacDonald<br />
and Cook refer to verified specimen records in southern <strong>Southeast</strong> <strong>Alaska</strong>, south of Stikine <strong>River</strong>, but not<br />
including Prince of Wales Island. Additional amphibian distribution data are from Nussbaum et al.<br />
(1983), Green and Campbell (1984), Stebbins (1985, 2003), Corkran and Thoms (1996), and MacDonald<br />
(2003). English and scientific nomenclature is from the Center <strong>for</strong> North American Herpetology<br />
CNAH (2010).<br />
Methods<br />
Vertebrate documentations were opportunistic while in the field collecting a wide variety of ecological<br />
data. Nevertheless, several more intensive vertebrate surveys were conducted. Intense amphibian<br />
searches were conducted in all years at ponds, wetlands, and riparian habitats, but especially 14‐19 July<br />
2009, when we conducted a survey <strong>for</strong> amphibian chytrid fungus. <strong>Chytrid</strong> fungus infections have been<br />
implicated worldwide in amphibian population declines. A great deal of time was spent looking <strong>for</strong> birds<br />
and large mammals, and listening <strong>for</strong> bird territorial singing. This included extensive scanning with<br />
binoculars: mountain slopes, ridges, boulder outcrops, talus slopes, <strong>for</strong>est canopies, wetlands, beaver<br />
ponds, muskeg, subalpine and alpine zones, river and lake shores, and habitat edges. This was<br />
particularly the case when camping along the North Fork, at No Name Lake, and on the <strong>Soule</strong> Delta.<br />
During all of these ef<strong>for</strong>ts we were on the lookout <strong>for</strong> toads, frogs and newts.<br />
Our total field ef<strong>for</strong>t is presented in Table 9. The entire field ef<strong>for</strong>ts in 2007 and summer 2008 were<br />
conducted while camping in the field. This dramatically increased our early morning, evening, and<br />
nighttime observations. A total of 123 observer‐days were spent in the field:<br />
Spring 2008 6 observer days<br />
Summer 2008‐2009 96 observer days<br />
Fall 2007 21 observer days<br />
Survey times are heavily biased <strong>for</strong> the summer. Although the spring survey season was short and the<br />
weather was poor, a number of migratory bird species and even nesting species were documented. The<br />
major time <strong>for</strong> singing territorial male birds is late May through June, so we missed the major activity of<br />
these species. Nevertheless, we documented most of the breeding birds of the watershed.<br />
31
Year Dates<br />
in the Field<br />
Field<br />
Days<br />
Total<br />
Observers<br />
Observer<br />
Ef<strong>for</strong>t<br />
2007 8‐14<br />
September<br />
7 3 21<br />
2008 14‐16<br />
May<br />
3 2 6<br />
2008 21 July –<br />
5 August<br />
16 3 48<br />
2009 14‐21 July 8 & 2 & 48<br />
14‐29 July 16<br />
2<br />
TOTAL 49 12 123<br />
Table 9. Total Field Ef<strong>for</strong>t at <strong>Soule</strong> <strong>River</strong> <strong>Watershed</strong>, 2007‐2009.<br />
Most observations were opportunistic while collecting a wide variety of ecological data and searching<br />
<strong>for</strong> wildlife. Observer Ef<strong>for</strong>t = field days X number of observers, summed by individual field seasons.<br />
The status of amphibian species in the <strong>Soule</strong> <strong>River</strong> <strong>Watershed</strong> is as follows:<br />
Documented Amphibians<br />
Boreal Toad<br />
Northern Roughskin Newt<br />
Unidentified Frog: Has the appearance and behavior of wood frogs, but Columbia spotted frogs<br />
are more likely, based on the geographical distribution of the limited specimens from MacDonald<br />
and Cook (2007).<br />
Unknown Potential Amphibians<br />
Wood Frog<br />
Columbia Spotted Frog<br />
Northwestern Salamander<br />
Eastern Long‐toed Salamander<br />
Unlikely Amphibians<br />
Northern Red‐legged Frog<br />
Pacific Chorus Frog<br />
Pacific Tailed Frog<br />
32
Documented Amphibians<br />
Boreal Toad (Anaxyrus boreas boreas)<br />
Local Range: British Columbia; <strong>Southeast</strong> <strong>Alaska</strong>; disjunctive and coastal northward<br />
MacDonald and Cook (2007): >10; well distributed south of Skagway, mainly coastal and islands<br />
(see below)<br />
Elevation Range: Sea level to 2250m<br />
Habitat:<br />
A terrestrial and wetlands species found in humid open <strong>for</strong>ests with moderate to dense undergrowth,<br />
including old fields and meadows, often near surface water. Boreal toads breed in permanent or<br />
temporary quiet pools of streams and sloughs, wetlands, lakes and ponds; including brackish pools. The<br />
use of at least occasional brackish pools <strong>for</strong> breeding is very unusual <strong>for</strong> North American frogs and toads.<br />
The species tolerance <strong>for</strong> brackish and even sea water have enabled it to disperse widely in <strong>Southeast</strong><br />
<strong>Alaska</strong>, including the colonization of islands.<br />
Boreal Toads are widespread in <strong>Southeast</strong> <strong>Alaska</strong>, and range northward along the coast to Prince William<br />
Sound, including Montague and Hawkins Islands; with the edge of their range a short distance north to<br />
the Tasnuna <strong>River</strong> (a tributary of the Copper <strong>River</strong>) and west to the Columbia Glacier (MacDonald 2003).<br />
MacDonald reported that Boreal Toads “are common and widespread on the mainland and islands of<br />
<strong>Southeast</strong> <strong>Alaska</strong>”. Boreal Toad records are certainly widely distributed throughout <strong>Southeast</strong> <strong>Alaska</strong><br />
(MacDonald 2003, MacDonald and Cook 2007). There are 70 museum specimen records in <strong>Southeast</strong><br />
<strong>Alaska</strong> documented by geographic location (usually including latitude and longitude) and a distribution<br />
map in MacDonald and Cook (2007, pages 127‐128), including records <strong>for</strong> 30 islands in the archipelago.<br />
The records are particularly prevalent along the coast and near settlements. Records near the British<br />
Columbia border and interior, especially in the southeastern portion of <strong>Southeast</strong> <strong>Alaska</strong> are absent,<br />
because of the lack of surveys.<br />
Only five records are documented in the general southeastern region of <strong>Southeast</strong> <strong>Alaska</strong>, none of them<br />
in the <strong>Soule</strong> <strong>River</strong> <strong>Watershed</strong> area. The number of museum specimens are in parenthesis.<br />
North West<br />
Latitude Longitude<br />
Hyder (1) 55.9200 130.0200<br />
Hyder Area (1) ‐‐‐‐ ‐‐‐‐<br />
Salmon <strong>River</strong>, at mouth of Texas <strong>River</strong><br />
Approx. 40 miles west of Hyder (1) 56.0269 130.9844<br />
Approx 5 miles east of Behm Canal<br />
Approx. 25 miles north of Chickamin Bay<br />
Boca de Quadra (3) 55.2000 130.4700<br />
A bay approximately 30 miles north<br />
of Portland Canal inlet<br />
33
Smeaton Bay (1) 55.2800 130.6300<br />
Head of Blackwell Arm,<br />
just north of Boca de Quadra<br />
A bay approximately 50 miles north<br />
of Portland Canal inlet<br />
With the exception of the Hyder sites, the other three sites are west of the mountains where the <strong>Soule</strong><br />
<strong>River</strong> <strong>Watershed</strong> originates, and the <strong>Soule</strong> <strong>River</strong> flows east to the Portland Canal.<br />
Boreal toad <strong>Southeast</strong> <strong>Alaska</strong> populations, as well as in other parts of their range, are experiencing sharp<br />
declines.<br />
<strong>Soule</strong> <strong>River</strong> <strong>Watershed</strong><br />
The complete boreal toad observation data <strong>for</strong> 2007‐2009 are presented in Table 10.<br />
Year Dates in<br />
the Field<br />
Field<br />
Days<br />
Observers Observer<br />
Ef<strong>for</strong>t<br />
Boreal Toads Observed<br />
in the Field<br />
Adult Metamorph Larvae<br />
2007 8‐14 7 3 21 0 1 cluster 0<br />
September<br />
(>30)<br />
2008 21 July –<br />
5 August<br />
16 3 48 3 0 0<br />
2009 14‐19 July 6 & 2 & 44 6 0 3<br />
14‐29 July 16 2<br />
TOTAL 45 10 113 9 1 3<br />
Table 10. Boreal Toads (Anaxyrus boreas boreas) Observed in the Field, 2007‐2009.<br />
Most observations were opportunistic while collecting a wide variety of ecological data and searching<br />
<strong>for</strong> wildlife. Habitats included: montane conifer <strong>for</strong>est, riverine and lacustrine riparian, ponds and<br />
wetlands complexes, seeps, muskeg, small streams, and river delta brackish marsh. Intense searches<br />
were made <strong>for</strong> amphibians when ponds and wetlands were encountered.<br />
Observer Ef<strong>for</strong>t = field days X number of observers.<br />
All Metamorphs were very similar in size and in the same location, suggesting that they were from a<br />
single egg deposition. Larvae = number of ponds or sections of pond complexes where tadpole clusters<br />
were observed.<br />
Boreal toads are diurnal in <strong>Southeast</strong> <strong>Alaska</strong>, especially on rainy days, and tadpoles are present in ponds<br />
during July and August (MacDonald 2003). At Juneau <strong>Alaska</strong>, Boreal Toads deposit eggs in late April –<br />
early May, tadpoles are present mid May – early July, and metamorphs are present late July – early<br />
August (Pyare et al. 2004). Juneau is located approximately 230 miles northwest of the <strong>Soule</strong> <strong>River</strong><br />
<strong>Watershed</strong>, but possesses a more maritime climate, so these dates are probably extended at the <strong>Soule</strong>.<br />
34
Over the three years of field work, mostly during July, including many rainy days, in a very wide range of<br />
habitats throughout the <strong>Soule</strong> <strong>River</strong> <strong>Watershed</strong>, only 13 Boreal Toad observations were made at an<br />
ef<strong>for</strong>t of 113 Observer‐Days: nine adults, a scattered metamorph clump, and three larval (tadpole)<br />
clumps. An observation consists of an adult or an independent cluster of larvae (tadpoles) or<br />
metamorphs. That translates to 8.7 observer‐days <strong>for</strong> each Boreal Toad adult and tadpole or<br />
metamorph cluster observation in the <strong>Soule</strong> <strong>River</strong> <strong>Watershed</strong>.<br />
Many intense searches were conducted in excellent Boreal Toad habitats, including concentrated<br />
searches in numerous ponds and wetlands <strong>for</strong> tadpoles. This represents an extremely low encounter<br />
rate <strong>for</strong> Boreal Toads, indeed any amphibian species. Admittedly, adult Boreal Toads are difficult to<br />
observe, because of their excellent camouflage color and pattern, coupled with their behavior to remain<br />
quiet. Additionally, much of their habitat is rugged, consisting of large downed snags, boulders, rocks,<br />
and <strong>for</strong>est or riparian litter. Nevertheless, the extremely low encounter rate <strong>for</strong> tadpoles is especially<br />
revealing, because tadpoles should be readily revealed in ponds and wetlands during July, when most of<br />
our field work and amphibian searches were conducted. Amphibian surveys were particularly intense<br />
14‐19 July 2009 when individuals were swabbed <strong>for</strong> chytrid fungus. Even during this time period, when<br />
a great deal of concentrated search ef<strong>for</strong>ts were in a variety of wetlands, including: beaver ponds, fens,<br />
muskeg and bogs, brackish marsh, and riparian habitats; the encounter rate was still poor at 2.7<br />
observer‐days <strong>for</strong> each Boreal Toad adult or tadpole cluster observation. All these wetlands represented<br />
excellent amphibian habitats (O’Clair et al.1997, Carstensen 2009).<br />
Our records <strong>for</strong> Boreal Toads in the <strong>Soule</strong> <strong>River</strong> <strong>Watershed</strong> are the first reported <strong>for</strong> the southeastern<br />
interior area of <strong>Southeast</strong> <strong>Alaska</strong>, outside of Hyder.<br />
Locations <strong>for</strong> Boreal Toads:<br />
3 adults, July 2008: lower North Fork, east bank, riparian/floodplain<br />
1 adult, 14 July 2009: middle North Fork, west side, fen wetlands complex<br />
1 adult, 15 July 2009: lower West Fork, south side, near junction, fen wetlands complex<br />
1 adult, 15 July 2009: middle Main Stem, west side, mature hemlock <strong>for</strong>est, above beaver ponds<br />
2 adults, 18 July 2009: middle Main Stem, west side, fen wetlands complex, downstream of above<br />
1 adult, 18 July 2009: upper Main Stem, west side, fen wetlands complex<br />
1 metamorph clump, 12‐14 September 2007: <strong>Soule</strong> Delta, south side, interior uplift, high grass and<br />
under spruce canopy.<br />
1 tadpole clump, 14‐29 July 2009: <strong>Soule</strong> Delta, small pond on south side of Delta, close to Portland<br />
Canal, completely flooded over during spring high tides 50‐100 individuals, the tadpoles are slowly<br />
growing in size, but decreasing in number over the observation period.<br />
2 tadpole clumps, 18 July 2009: upper Main Stem, west side, fen wetlands complex, two different<br />
clutches at distant ends of wetlands complex, 50‐100 individuals in one clump, over 200 individuals in<br />
second clump, and tadpoles twice as large.<br />
35
Northern Roughskin Newt (Taricha granulosa granulosa)<br />
Local Range: Coastal British Columbia; <strong>Southeast</strong> <strong>Alaska</strong>, as far north as Juneau<br />
MacDonald and Cook (2007): >10; well distributed south of Juneau, coastal and islands<br />
Elevation Range: Sea level to 1900m<br />
Habitat:<br />
Humid coastal <strong>for</strong>ests to high mountain lakes. Found in and around ponds, lakes, and stream<br />
backwaters; where there is an abundance of aquatic plants.<br />
All of the records in MacDonald and Cook (2007) are coastal and on islands. One is at Stikine <strong>River</strong><br />
<strong>Soule</strong> <strong>River</strong> <strong>Watershed</strong><br />
At least 20 roughskin newts were seen in July 2009. The newts were closely associated with clear water<br />
ponds, typically with an abundance of buckbean (Menyanthes trifoliata) emergents. The ponds were<br />
typically in fen wetland complexes. One tannin stained pond was associated with a series of pools on a<br />
rocky boulder ridge above the Main Stem of the <strong>Soule</strong>, not far downstream from the junction of the two<br />
<strong>for</strong>ks on the eastern side.<br />
Our records <strong>for</strong> Northern Roughskin Newts in the <strong>Soule</strong> <strong>River</strong> <strong>Watershed</strong> are the first reported <strong>for</strong> the<br />
southeastern interior area of <strong>Southeast</strong> <strong>Alaska</strong>.<br />
Locations <strong>for</strong> Northern Roughskin Newts:<br />
5 adults, 15 July 2009: lower West Fork, north side, just north of confluence, ponds in fen wetlands<br />
complex.<br />
15 adults, 15‐29 July 2009: middle Main Stem, east side, ponds in extensive fen wetlands complexes.<br />
Unidentified Frog<br />
Frogs were seen on at least five occasions. The individuals rapidly disappeared into dense litter or grass<br />
and could not be located, despite significant ef<strong>for</strong>ts. The general color and litter‐disappearing behavior<br />
strongly suggested wood frogs. The habitats where the frogs were observed included: lower North Fork,<br />
east side, riparian floodplain, a boulder‐rocky ridge on the east side of the middle Main Stem where<br />
there are small pockets of water, and the <strong>Soule</strong> Delta grassy marsh. There are at least six wood frog<br />
museum records <strong>for</strong> the Stikine <strong>River</strong> drainage area, the southernmost documented locality <strong>for</strong> this<br />
species in <strong>Southeast</strong> <strong>Alaska</strong> (MacDonald and Cook 2007). The <strong>Soule</strong> <strong>Watershed</strong> is over a 100 miles<br />
southeast of this locality. The only other potential frog in the <strong>Soule</strong> <strong>Watershed</strong> is the Columbia Spotted<br />
Frog. We have found this species to be easily observed and captured in pond and river habitats in the<br />
northwestern United States, so we thought it unlikely that our unknown frog was this species. There are<br />
four records <strong>for</strong> this species at Hyder, two at Salmon <strong>River</strong> and two at Fish Creek (MacDonald and Cook<br />
2007). There is also a record of two at Unuk <strong>River</strong>, approximately 40 miles west of Hyder. These records<br />
are also the southernmost localities <strong>for</strong> this species. The lack of museum records <strong>for</strong> these two frog<br />
species in southern <strong>Southeast</strong> <strong>Alaska</strong> appears to represent an actual absence or rarity, because both<br />
boreal toads and roughskin newts are clearly documented on islands and south coastal areas of<br />
36
<strong>Southeast</strong> <strong>Alaska</strong>, clearly indicating field surveys in these areas (MacDonald and Cook 2007).<br />
Nevertheless, the interior eastern boundary of <strong>Southeast</strong> <strong>Alaska</strong>, outside of the Hyder area, lacks<br />
museum records <strong>for</strong> all amphibian species. The unknown frog remains a mystery, acting like a wood<br />
frog, but closer in range to a documented Columbia spotted frog locality.<br />
Amphibians with Unknown Status<br />
Wood Frog (Lithobates sylvaticus)<br />
Local Range: Widespread in interior <strong>Alaska</strong>; <strong>Southeast</strong> <strong>Alaska</strong> north of Stikine <strong>River</strong>;<br />
The Wood Frog is North America’s only amphibian or reptile found in the Arctic Circle<br />
MacDonald and Cook (2007): 4; all at Stikine <strong>River</strong><br />
Elevation Range: Sea level to 2140m<br />
Habitat:<br />
Wood frogs occur in a wide variety of habitats: open <strong>for</strong>ests, meadows, riparian, muskeg, and tundra.<br />
They are exceptionally cold‐tolerant and active at near freezing temperatures, and they are also drought<br />
and dehydration tolerant. Wood frogs breed unusually early in the season throughout their range in<br />
permanent or temporary shallow pools. They hibernate or are dormant during drought under <strong>for</strong>est,<br />
meadow, or tundra litter.<br />
<strong>Soule</strong> <strong>River</strong> <strong>Watershed</strong>:<br />
Unknown – see above section discussing unidentified frog<br />
Columbia Spotted Frog (Rana luteiventris)<br />
Local Range: British Columbia; <strong>Southeast</strong> <strong>Alaska</strong> south of Taku <strong>River</strong><br />
MacDonald and Cook (2007): 7; 3 at Stikine <strong>River</strong>, 3 in vicinity of Hyder<br />
Elevation Range: Sea level to 2440m<br />
Habitat:<br />
This is a riparian species that is closely associated with permanent water: lakes, beaver and muskeg<br />
ponds, rivers, streams, and fluvial backwaters. Foraging, breeding, and hibernation all take place in<br />
these habitats.<br />
<strong>Soule</strong> <strong>River</strong> <strong>Watershed</strong>:<br />
Unknown – see above section discussing unidentified frog<br />
Northwestern Salamander (Ambystoma gracile)<br />
Local Range: Coastal British Columbia; 2 records <strong>for</strong> <strong>Southeast</strong> <strong>Alaska</strong><br />
MacDonald and Cook (2007): 1; Mary Island, southeast of Ketchikan<br />
Elevation Range: Sea level to 2000m<br />
37
Habitat:<br />
Moist <strong>for</strong>ests or open woods; breeding in usually permanent water, but also temporary pools, including<br />
beaver ponds and stream backwaters; breeds in early to mid‐spring. Highly fossorial, and are primarily<br />
active nocturnally and after heavy precipitation.<br />
<strong>Soule</strong> <strong>River</strong> <strong>Watershed</strong>:<br />
Unknown<br />
Eastern Long‐toed Salamander (Ambystoma macrodactylum columbianum)<br />
Local Range: British Columbia; 4 records <strong>for</strong> <strong>Southeast</strong> <strong>Alaska</strong><br />
MacDonald and Cook (2007): 3; 2 Stikine <strong>River</strong><br />
Elevation Range: Sea level to 2500m<br />
Habitat:<br />
Moist <strong>for</strong>ests, open woods, and grasslands; broad habitat tolerance; breeding in permanent or<br />
temporary quiet pools, including beaver ponds, stream backwaters, and wet meadows; breeds in winter<br />
to early spring. Highly fossorial and are primarily active nocturnally and after heavy precipitation.<br />
<strong>Soule</strong> <strong>River</strong> <strong>Watershed</strong>:<br />
Unknown<br />
Unlikely Amphibians<br />
Northern Red‐legged Frog (Rana aurora)<br />
Local Range: Coastal southwestern British Columbia<br />
MacDonald and Cook (2007): None; Northeast Chichagof Island, Pavlof Bay drainage,<br />
Introduced?<br />
Elevation Range: Sea level to 920m<br />
Habitat:<br />
This is a species of riparian zones of lakes, ponds, and streams; and marshes. It can also be found in<br />
nearby <strong>for</strong>ests, woodlands, and meadows, especially in wet weather. It prefers dense ground cover,<br />
aquatic vegetation, and vegetation hanging over water. For breeding, it prefers deep permanent pools<br />
of quiet or slow‐flowing water.<br />
<strong>Soule</strong> <strong>River</strong> <strong>Watershed</strong>:<br />
Unlikely<br />
Pacific Chorus Frog (Pseudacris regilla)<br />
Local Range: Southern British Columbia;<br />
Introduced to Queen Charlotte Islands<br />
MacDonald and Cook (2007): 2; Introduced to a muskeg pond near Ward Lake, Revillagigedo Island<br />
38
Elevation Range: Sea level to 2440m<br />
Habitat:<br />
This species inhabits a wide variety of habitats: <strong>for</strong>ests, open woodlands, dense meadows, shrub‐lands,<br />
even oasis in desert scrub. It prefers high ground cover and is usually close to permanent water: lakes,<br />
muskeg ponds, streams, springs and oasis.<br />
<strong>Soule</strong> <strong>River</strong> <strong>Watershed</strong>:<br />
Unlikely<br />
Pacific Tailed Frog (Ascaphus truei)<br />
Local Range: Coastal British Columbia<br />
MacDonald and Cook (2007): None; A “watch <strong>for</strong>” species in southeastern <strong>Alaska</strong><br />
This species has not been documented in <strong>Alaska</strong>, found in coastal British Columbia close to the <strong>Alaska</strong><br />
border.<br />
Elevation Range: Sea level to 2140m<br />
Habitat:<br />
This is a species adapted to living adjacent to and breeding in fast running mountain streams. Their<br />
tadpoles have a sucker mouth to live and feed in stream rapids.<br />
<strong>Soule</strong> <strong>River</strong> <strong>Watershed</strong>:<br />
Unlikely<br />
39
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54
Test samples:<br />
Appendix A<br />
PCR Assay Details from Pisces Molecular<br />
<strong>Chytrid</strong> <strong>Fungus</strong> Test Results<br />
PCR assay <strong>for</strong> B. dendrobatidis<br />
Organization: Shipely Group<br />
Received From: Paul Rusanowski<br />
Received Date: 7/31/09<br />
Number of samples: 9<br />
Type/condition of sample(s): Swabs in ethanol<br />
Need to be pooled? No<br />
Comments<br />
The labels on the tubes were hard to<br />
read.<br />
Sample Preparation:<br />
The liquid in each of the skin swab samples was mixed by pipetting the liquid up and down repeatedly.<br />
The entire volume of each sample was then transferred into individual microfuge tubes. The tubes were<br />
spun in a microcentrifuge at ~16,000 x G <strong>for</strong> 3 minutes. Next, the supernatant was drawn off and<br />
discarded. Lysis buffer was added to the tubes and any pellet present was resuspended by vortexing. 10<br />
μg of carrier DNA was added to the lysis buffer.<br />
Total<br />
DNA was extracted from all samples using a spin-column DNA purification procedure.<br />
PCR assay:<br />
The sample DNA(s) prepared was/were assayed <strong>for</strong> the presence of the Batrachochytrium dendrobatidis<br />
ribosomal RNA Intervening Transcribed Sequence (ITS) region by 45 cycle single-round PCR<br />
amplification using an assay developed by Seanna Annis and modified <strong>for</strong> greater specificity and<br />
sensitivity<br />
at Pisces.<br />
Each PCR run included the following controls:<br />
Positive DNA: DNA prepared from a laboratory culture of B. dendrobatidis, Strain JEL<br />
270,<br />
kindly provided by Joyce Longcore. This sample was previously<br />
demonstrated to<br />
be positive by PCR. The signal from this sample is the standard <strong>for</strong> a very<br />
strong positive (+++) signal.<br />
Negative DNA DNA prepared from an uninfected amphibian. This sample has been<br />
previously demonstrated as negative (-) by PCR.<br />
No DNA: H2O in place of template DNA. This reaction remains uncapped during<br />
addition<br />
of sample DNA to the test reactions, and serves as a control to detect<br />
contaminating DNA in the PCR reagents or carryover of positive DNA<br />
during reaction set-up.<br />
55
PCR<br />
Results <strong>for</strong> the B. dendrobatidis ribosomal RNA ITS region:<br />
Number of positive (+) samples: 2<br />
Number of negative (-) samples: 7<br />
Individual sample results are shown on the following page(s).<br />
Scoring: +++ = very strong positive signal<br />
++ = strong positive signal<br />
+ = positive signal<br />
w+ = weak positive signal<br />
- = no signal/below limit of detection<br />
56
APPENDIX B<br />
Amphibian Declines, <strong>Chytrid</strong> <strong>Fungus</strong>, and Boreal Toads<br />
Anthony J. Krzysik, Ph.D.<br />
28 February 2010<br />
Introduction and Background<br />
Scientists were seriously concerned with the widespread evidence in the 1970s and 1980s that<br />
amphibians, especially anurans, were undergoing dramatic population declines from local and regional to<br />
global scales (Barinaga 1990, Blaustein and Wake 1990, Czechura and Ingram 1990, Phillips 1990,<br />
Wyman 1990, Tyler 1991, Wake 1991, Hedges 1993, Blaustein et al. 1994c). The class Amphibia<br />
consists of three orders: salamanders and newts, anurans (frogs, toads, spadefoots), and caecilians<br />
(Gymnophiona). Caecilians are poorly known tropical legless amphibians with short tails, resembling fat<br />
earthworms. They are very secretive and primarily subterranean, and their population stability or declines<br />
are unknown. The rather sudden comprehension of amphibian declines motivated the origination of “The<br />
Declining Amphibian Populations Task Force” at the First World Congress of Herpetology in England in<br />
1989. Through this organization a concerted ef<strong>for</strong>t was made to assess the status and trends of United<br />
States and Canadian amphibians (Green 1997, Lannoo 1998, 2005).<br />
The amphibian population declines continued into the 1990s and new millennium, and the declines were<br />
often catastrophic and global in scale (Lips 1998, Carey 2000, Houlahan et al. 2000, Young et al. 2001,<br />
Stuart et al. 2004, Mendelson et al. 2006, Wake and Vredenburg 2008, Collins and Crump 2009). Indeed,<br />
the current global extinction rate of amphibians, when including species in eminent danger of extinction,<br />
may range from 25,039 to 45,474 times the background extinction rate of amphibians in the fossil record<br />
(McCallum 2007). Amphibians are the most endangered taxa of vertebrates (Stuart et al. 2004), and are<br />
in the dubious position of representing the <strong>for</strong>erunners in the sixth mass extinction on earth (Leakey and<br />
Lewin 1995, Novacek 2007, Ward 2007, Avise et al. 2008, Wake and Vredenburg 2008). At least 2468<br />
(43.2%) amphibian species are experiencing declines, and 1856 (32.5%) are globally threatened, listed on<br />
IUCN Red List (Stuart et al. 2004). It appears that amphibians represent a major indicator or canary in<br />
the coalmine <strong>for</strong> ecosystem assessment and monitoring.<br />
The proposed reasons <strong>for</strong> the decline were an equally dramatic laundry list of readily apparent to<br />
hypothesized causes: habitat destruction and degradation, habitat and landscape fragmentation, water and<br />
air pollution, pesticides, heavy metals, acidic deposition, de<strong>for</strong>estation, increased UV radiation, disease<br />
caused by pathogenic organisms, and introduced species (e.g., Bullfrogs [Lithobates catesbeianus], trout<br />
stocking in fishless alpine lakes). The well known stratospheric ozone depletion increases the amount of<br />
ultraviolet radiation striking earth’s surface. The biologically UV of concern is in the 290 to 320 nm,<br />
UV-B (Blaustein et al. 1994a). Although most of the increase of UV is at Polar Regions, there is<br />
evidence <strong>for</strong> increased UV-B radiation in undisturbed temperate latitudes (Blumthaler and Ambach 1990).<br />
All amphibian common and scientific names have been updated to reflect current taxonomic status<br />
(CNAH 2010). There<strong>for</strong>e, common or scientific names in this report may differ from cited publications.<br />
Phillips (1994), Al<strong>for</strong>d and Richards (1999), and Collins and Crump (2009) provide comprehensive<br />
references <strong>for</strong> all the potential agents implicated or suspected in amphibian declines.<br />
57
Amphibians, as are all vertebrates, susceptible to a wide range of diseases and individual mortality caused<br />
by: fungi, viruses, protozoans, bacteria, and macroparasites (e.g., trematodes). However, only the first<br />
three have been implicated in the widespread declines and extinctions of amphibian populations (Collins<br />
and Crump 2009). By far the main pathogen identified with amphibian declines and extinctions has been<br />
the chytrid fungus Batrachochytrium dendrobatidis. Eight viral groups infect amphibians, but only<br />
iridoviruses are common, and at least eight Ranavirus strains were involved with amphibian epidemics<br />
(Collins and Crump 2009). See <strong>Chytrid</strong> <strong>Fungus</strong> section <strong>for</strong> more in<strong>for</strong>mation.<br />
UV Radiation<br />
Habitat loss and fragmentation along with pollution were the obvious suspicious culprits <strong>for</strong> amphibian<br />
declines. Habitat loss is the greatest threat to amphibians, impacting almost 90% of listed species<br />
(Mendelson et al. 2006). Excess UV radiation was also a major suspect, because of the global scope of<br />
the declines, and that the declines were frequently associated with montane habitats. A great deal of<br />
research, especially in Andy Blaustein’s laboratory, was directed to the effect of UV radiation on<br />
amphibian eggs, embryos, larvae (tadpoles), and adults (Worrest and Kimeldorf 1976, Blaustein et al.<br />
1994a, 1997, 1998, 2005a). The eggs of Boreal Toads (see Boreal Toads section) and Cascades Frogs<br />
(Rana cascadae) are deposited in open water highly exposed to sunlight. Laboratory studies of Boreal<br />
Toad embryos from the Cascade Mountains of Oregon have increased mortality from UV exposure<br />
(Worrest and Kimeldorf 1976). Eggs of this species show high mortality at some sites (Blaustein and<br />
Olson 1991). Boreal Toads and Cascades Frogs both have undergone dramatic declines (Fellers and<br />
Drost 1993, Blaustein et al. 1994a).<br />
Subsequent research found the UV issue to be a great deal more complex, contradictory, and suggested<br />
potential additional interactions with other stressors such as pollution or disease (Corn 1998, Palen et al.<br />
2002, 2004, Blaustein et al. 2003, 2004, Collins and Crump 2009). The complexity was magnified by the<br />
distinct possibility of cumulative effects and independent synergistic interactions.<br />
Pesticides<br />
The Moutain Yellow-legged Frog (Rana muscosa) was divided into two full species in 2007 (CNAH<br />
2010). Both species have undergone significant population declines in both distribution and abundance.<br />
The combined species have lost approximately 99% of their original distribution (Stebbins 2003). The<br />
Sierra Nevada Yellow-legged Frog (Rana sierrae) is restricted to the Sierra Nevada Mountains north of<br />
Mather Pass (Cali<strong>for</strong>nia Herps 2010a); while the Sierra Madre Yellow-legged Frog (Rana muscosa), with<br />
a clear relict distribution, is now only found in tiny local isolated populations in the southern Sierras south<br />
of Mather Pass, and in the San Gabriel, San Bernardino, and San Jacinto Mountains (Cali<strong>for</strong>nia Herps<br />
2010b). It is now extinct on Palomar and Breckenridge Mountains. The Foothill Yellow-legged Frog<br />
(Rana boylii) and Cali<strong>for</strong>nia Red-legged Frog (Rana draytonii) have also suffered dramatic distribution<br />
and abundance declines. There is strong evidence <strong>for</strong> pesticides as a major factor in the dramatic declines<br />
of all these species, but there were often multiple stressors involved (Davidson et al. 2001, 2002, 2007,<br />
Davidson 2004, Davidson and Knapp 2007). The decline of Cali<strong>for</strong>nia Red-Legged Frogs is closely<br />
associated with upwind borne agrochemicals (Davidson et al. 2001). Pesticides have apparently<br />
contributed to inhibiting natural immune defenses against chytrid fungus susceptibility. Skin peptide<br />
defenses were significantly reduced in Foothill Yellow-legged Frogs after sublethal exposure to carbaryl<br />
(a cholinesterase inhibitor), suggesting that pesticides may inhibit this innate immune defense and<br />
increase chytrid susceptibility (Davidson et al. 2007). Rachowicz et al. (2006) reported that 96% of<br />
Moutain Yellow-legged Frogs died in controlled field experiments at chytrid fungus infected sites in the<br />
Sierra Nevadas of Cali<strong>for</strong>nia. They concluded that this pathogen is a severe threat <strong>for</strong> local extinctions at<br />
many sites in the Sierras. Additionally, introduction of nonnative rainbow and brook trout into Sierra<br />
58
Nevada’s fishless alpine lakes over the last 50 years were responsible <strong>for</strong> a major reduction of native frogs<br />
(Knapp et al. 2001, 2007).<br />
Sublethal concentrations of pesticides may also cause unexpected mortality in amphibian communities.<br />
Relyea and Diecks (2008) reported that a sublethal malathion concentration <strong>for</strong> amphibians, a globally<br />
widespread and commonly used insecticide, had a significant impact on the reduction of zooplankton and<br />
periphyton. The resulting trophic cascade dramatically affected the growth and development of Northern<br />
Leopard Frog (Lithobates pipiens) larvae, and this species was subjected to higher mortality. Leopard<br />
Frog tadpoles take longer to develop than the Wood Frog (Lithobates sylvaticus) tadpoles that also<br />
inhabited the pond. Wood Frogs were not affected, because of their shorter larval period.<br />
Predation<br />
Predation by introduced species has always been hypothesized as a major factor in the decline of western<br />
anurans. The primary culprits have been Bullfrogs and stocking trout into fishless lakes (Hayes and<br />
Jennings 1986, Fisher and Shaffer 1996, Knapp et al. 2001, 2007). Nevertheless, Jones et al. (1999)<br />
found that neither brook trout or cutthroat trout would prey on tadpoles.<br />
Toads are typically assumed to be less susceptible to predation than other native anurans, because of their<br />
toxic skin secretions. Licht (1968) reported that fish would not eat toad eggs. Experiments demonstrated<br />
that Boreal Toad skin secretions are unpalatable to fish (Kiesecker et al. 1996). However, Gunzburger<br />
and Travis (2005) in a review of 142 papers that dealt with unpalatability as a defense against predation<br />
on amphibian eggs and larvae found that the studies were inconsistent and often the results were<br />
influenced by experimental method. Several interesting patterns emerged from their review. Eggs and<br />
hatchlings were more unpalatable than mobile larvae. Temporary water amphibian breeders were more<br />
palatable to predators than species that breed in perennial waters. Fish and salamanders were more likely<br />
to find amphibians unpalatable than insect predators. They concluded that unpalatability is rare, but when<br />
it occurs it is a property of a particular predator-prey system and a life-history stage, and not a speciesspecific<br />
attribute.<br />
Kagarise Sherman and Morton (1993) provide an interesting literature review and their own observations<br />
of avian predation on toads. Three species of corvids were involved in predation on toads in the Boreal<br />
Toad species group. The Common Raven was implicated in predation on Boreal and Black Toads, Blackbilled<br />
Magpies also attacked the Black Toad, and Clark’s Nutcracker was responsible <strong>for</strong> most of the<br />
attacks on Yosemite Toads, but also Cali<strong>for</strong>nia Gulls. Beiswenger (1981) reported another corvid<br />
predator, Gray Jays feeding on Boreal Toad tadpoles. American Crows have also preyed on toads<br />
(Brothers 1994). Brewer’s Blackbirds and American Robins have also been documented to feed on<br />
tadpoles or metamorphs. Probably most of this predation occurs when temporary pools are drying up.<br />
Pacific Chorus Frogs (Pseudacris regilla) have been observed to feed heavily on Cali<strong>for</strong>nia Toad<br />
(Anaxyrus boreas halophilus) eggs (Wind and Dupuis 2002). Predatory aquatic insects, especially<br />
hemipterans (e.g., Lethocerus, Notonecta) and diving beetles (Dytiscidae) feed on tadpoles.<br />
Raccoons and Striped Skunks were suggested as the likely predators on American Toads (Anaxyrus<br />
americanus) in the eastern United States (Schaaf and Garten 1970, Groves 1980). Additional documented<br />
predators on Boreal Toads include: garter snakes (Thamnophis sp), Tiger Salamanders (Ambystoma<br />
mavortium), Red-tailed Hawks, and Raccoons (Pierce 2006). Predators are commonly attracted by the<br />
presence or activity of humans. This has been appreciated and well-documented <strong>for</strong> nesting success in<br />
birds, but has not received attention <strong>for</strong> amphibian and reptile populations. Residential and agricultural<br />
development, water management, wastewater treatment, landfills, landscaping, roads, and the creation of<br />
edges and habitat fragmentation have all attracted predators with resulting impacts on both avian nest<br />
success and presumably amphibian and reptile populations. Examples of these predators include:<br />
59
Common Raven, American Crow, Raccoon, Coyote, Mallard, Spotted Sandpiper, jays and additional<br />
corvids, grackles and blackbirds, foxes, skunks, domestic and feral geese and ducks, and of course cats<br />
and dogs.<br />
Population Monitoring Difficulties<br />
Additionally, researchers who work with amphibians are well aware that many species are “explosive<br />
breeders”, an evolutionary adaptation to take advantage of optimal environmental conditions, after a<br />
series of poor reproductive years, because of drought, cold, excess predation, or other unfavorable<br />
environmental conditions during the breeding season (e.g., Pechmann et al. 1991, Pechmann and Wilbur<br />
1994). The resulting strong oscillations of local population trends make statistical time-series analysis<br />
very tenuous. Another population monitoring problem is that many amphibian species exist as<br />
metapopulations in the landscape. Tracking metapopulations dynamics when conducting local amphibian<br />
surveys appreciably adds to the uncertainty of assessing the status and trends of populations (Al<strong>for</strong>d and<br />
Richards 1999).<br />
Amphibian Declines in Pristine Areas<br />
Amphibian declines were often associated with anthropogenic local impacts, even on global scales, such<br />
as: habitat loss and fragmentation, pollution, <strong>for</strong>est logging, over grazing, extended droughts, and<br />
competition or predation from exotic species. However, even these still did not completely explain the<br />
dramatic global amphibian declines, particularly the many well-documented declines in pristine<br />
landscapes in the United States (Brad<strong>for</strong>d 1991, Carey 1993, Kagarise Sherman and Morton 1993, Drost<br />
and Fellers 1996, McMenamin et al. 2008); Neotropics (Heyer et al. 1988, Crump et al. 1992, Pounds and<br />
Crump 1994, Pounds et al. 1997, Lips 1998, Young et al. 2001, Ron et al. 2003, Burrowes et al. 2004);<br />
and Australia (Czechura and Ingram 1990, Gillespie and Hollis 1996, Laurance et al. 1996). For example,<br />
considering the data <strong>for</strong> all global species of amphibians based on their general habitat: 90.3% of <strong>for</strong>est,<br />
79.2% of flowing water, and 74.9% of tropical montane habitats represent rapidly declining species where<br />
suitable habitat remains, and the reasons <strong>for</strong> the decline are not obvious (data from Stuart et al. 2004,<br />
Table 1). Concurrently, no statistically significant amphibian declines are known to have occurred with<br />
savanna (0%), shrublands (6.8%), or marshes/swamps (6.8%) species.<br />
Climate Change<br />
Significant ecological changes have been documented <strong>for</strong> climate change, including predictions <strong>for</strong><br />
biological extinctions (Pounds et al. 1999, Harvell et al. 2002, McLaughlin et al. 2002, Thomas et al.<br />
2004, Lovejoy and Hannah 2005, Parmesan 2006, Schwartz et al. 2006, Rosenzweig et al. 2008).<br />
Amphibians are particularly sensitive to climate change because of: demanding physiological needs, three<br />
stages (at least <strong>for</strong> most species) of life history environments, multiple habitat mosaics <strong>for</strong> most species,<br />
close ecological relationship to weather-its variability-and predictability, and of course poor dispersal<br />
ability. Climate change has been frequently implicated with amphibian population declines (Pounds and<br />
Crump 1994, Ovaska 1997, Blaustein et al. 2001, Carey and Alexander 2003, Corn 2003, Daszak et al.<br />
2005, Pounds et al. 2005, 2006, McMenamin et al. 2008). For a contrasting view, see Alexander and<br />
Eischeid (2001) <strong>for</strong> an interesting analysis, where they could not find unusual regional weather directly<br />
responsible <strong>for</strong> amphibian declines in Colorado, Puerto Rico. Costa Rica/Panama, and northeast<br />
Queensland, Australia, but they did not rule out indirect effects. Recent work predicting climate-driven<br />
shifts <strong>for</strong> the period 2071-2100 in the distribution of 413 western hemisphere amphibian species identified<br />
a number of areas of high species turnover (Lawler et al. 2010). The areas of greatest stress <strong>for</strong><br />
amphibians were primarily in the Neotropics, especially in mountainous habitats, but also included the<br />
Southwest of the United States. These also appear to be the same areas of dramatic current amphibian<br />
population declines.<br />
60
Climate change can be implicated in amphibian declines in three general categories. First of all, are<br />
specific physical and/or chemical environmental changes to the habitat at some portion of amphibian life<br />
history. This would include: drought, thermal extremes, severe or prolonged storms, and changes in<br />
aquatic or soil chemistry. Additionally, climate can change the biological environment of species. This<br />
list can be lengthy, but if the amphibian literature represents any guide, disease and their related<br />
pathogens would unarguably rank first on the list, particularly chytrid fungus. Nevertheless, even after all<br />
the current research and experiments, the detailed relationships of climate change to amphibian diseases<br />
and pathogens are still highly controversial (see next paragraph). Other biological influences include:<br />
vegetation changes, soil changes, competition and/or predator dynamics, and a wide range of prey<br />
requirements. Amphibian relationships to their prey are many and include seasonal parameters: life<br />
history needs such as algae or micro-invertebrates <strong>for</strong> larvae, prey abundance or diversity, prey taxa and<br />
their spatial distribution, prey availability, and life history phenology of prey. And finally, climatic<br />
parameters can affect one or more amphibian life history parameters: behavior, physiology, reproduction,<br />
development, and phenology. All of these life history attributes affect survivorship, population viability,<br />
and species persistence.<br />
The dramatic anuran declines documented in the western United States and the Neotropics were mainly<br />
montane species. This suggested climate change. The Golden Toad (Incilius [<strong>for</strong>merly Bufo] periglenes,<br />
Bufonidae), a mountain cloud <strong>for</strong>est species with a very small distribution in the Monteverde Cloud<br />
Forest Preserve of Costa Rica, has often been cited as the first known extinction caused by climate change<br />
(e.g., Flannery 2005, pp 114-122). However, a good case was made <strong>for</strong> a strong El Nino effect (Crump et<br />
al. 1992). Although storms and extreme weather can be amplified in strength and/or frequency by climate<br />
change (Mann and Kump 2008), the effect of climate change on the natural El Nino and La Nina events<br />
are not clear and currently a major research question (NCDC 2010). There were also the confounding<br />
effects of de<strong>for</strong>estation near the preserve (Nair et al. 2003). Pounds et al. (2008) concluded that the<br />
Golden Toad was extinct, and the cause was a combination of global warming, chytrid fungus<br />
(Batrachochytrium dendrobatidis), and airborne pollution, including its restricted range. The Monteverde<br />
Harlequin Frog (Atelopus varius, Bufonidae) also vanished at the same time with the Golden Toad, and an<br />
estimated 67% of the approximately 110 species of Neotropical endemic Atelopus followed (La Marca et<br />
al. 2005).<br />
The montane Neotropics have provided some of the best evidence <strong>for</strong> climate change as an important<br />
driver <strong>for</strong> biodiversity impacts, and especially, amphibian declines and extinctions. The data are most<br />
extensive and conclusive <strong>for</strong> anurans, anoline lizards, and breeding birds; but also include salamanders,<br />
other lizards, snakes, and tree squirrels (Pounds et al. 2005). Nevertheless, direct evidence <strong>for</strong> climate<br />
change as the primary cause of amphibian declines and extinctions has often been elusive and<br />
controversial. This is because climate change directly affects physical and biological environmental<br />
attributes that are either critical <strong>for</strong> amphibian life history or phenology, or affect biotic interactions.<br />
Precipitation, moisture, snow cover, and evolved optimal temperatures are critical <strong>for</strong> amphibian<br />
population viability. Competition, predation, parasites, and disease pathogens are critical biotic<br />
interactions that are certainly driven by changing physical and habitat environments. Lotters et al. (2004),<br />
Thomas et al. (2004), Pounds et al. (2006), and Bosch et al. (2007) make strong cases <strong>for</strong> the interaction<br />
of climate change and chytrid fungus as responsible <strong>for</strong> amphibian declines.<br />
Pounds et al. (2006) used a detailed analysis, including satellite imagery, to support the “chytrid thermal<br />
optimum” hypothesis driven by climate change. They hypothesized that cloudier cooler days and warmer<br />
nights in the montane Neotropics would produce the ideal atmospheric envelop <strong>for</strong> optimal chytrid fungus<br />
growth, and address the paradox that chytrid fungus is a cold tolerant pathogen, but amphibian mortality<br />
was in warm years. <strong>Chytrid</strong> fungus is more pathogenic to amphibians at lower temperatures (Berger et al.<br />
2004, Retallick et al 2004). Analyzing the timing of amphibian losses in relation to changes in air and sea<br />
61
temperatures in the montane Neotropics Pounds at al concluded with very strong confidence (>99%) that<br />
large-scale warming is the key factor in these declines and extinctions. Greenhouse warming intensified<br />
the hydrological cycle and was accompanied with aerosol pollution. These agents influenced cloud<br />
<strong>for</strong>mation patterns, and thermal, moisture, and light regimes; resulting in warmer nights and increased<br />
daytime cloud cover. The local climatic change shifted mid-elevation sites into the thermally optimum<br />
environment <strong>for</strong> chytrid fungus. This is the elevation band (1000-2400 meters) where most of the<br />
Atelopus extinctions have occurred.<br />
Despite all the apparent associations among climate change, chytrid fungus infections, and large-scale<br />
amphibian population declines and direct mortality, recent research has found these relationships complex<br />
and often contradictory. The chytrid – climate change hypothesis has been rigorously challenged (Al<strong>for</strong>d<br />
et al. 2007, Lips et al. 2008, Rohr et al. 2008).<br />
Climate change is almost certainly the direct cause of the severe decline of Yellowstone National Park’s<br />
amphibian fauna (McMenamin et al. 2008). Northern Yellowstone’s lower Lamar Valley was<br />
characterized by its rich amphibian fauna, as a direct resulted of its glacially sculptured landscape of<br />
moraines, kame terraces, and kettle ponds (Koch and Peterson 1995). These fishless ponds were<br />
recharged by groundwater and spring runoff. However, the ponds have been drying up. The Palmer<br />
Hydrology Drought Index <strong>for</strong> Yellowstone between 1895 and 2005 clearly reveals the climate changes<br />
(McMenamin et al. 2008, Figure 2). Yellowstone had a relatively wet climate between 1895 to the early<br />
1950s. Drought years have increased since the mid 1970s, and drought years have been severe and<br />
consistent after 1995.<br />
McMenamin et al. compared Yellowstone amphibian pond surveys that were conducted in 1992-1993 to<br />
ones conducted in 2006-2008. In 15 years, more than half of the ponds disappeared, and permanently dry<br />
ponds increased by a factor of four. The ponds with water held fewer species, and the proportion of<br />
ponds supporting amphibians had steeply declined. In the 1950s, all four of Yellowstone’s native<br />
amphibian species were considered common (Koch and Peterson 1995). Three species were common in<br />
the 1992-1993 surveys: Blotched Tiger Salamander (Ambystoma mavortium melanostictum), Columbia<br />
Spotted Frog (Rana luteiventris), and Boreal Chorus Frog (Pseudacris maculata). The new surveys<br />
documented that the Tiger Salamander declined by 50%, the Columbia Spotted Frog by 68%, and the<br />
Boreal Chorus Frog by 75%).<br />
The Boreal Toad was once very abundant in the Greater Yellowstone Ecosystem (see section Boreal<br />
Toad). In the 1992-1993 surveys, the Boreal Toad (Anaxyrus boreas boreas) was present, but<br />
uncommon. Three populations of the Boreal Toad were found in 1993, and these were also found in the<br />
2006-2008 surveys, based on eggs and tadpoles; but there were no ponds that supported all four species of<br />
amphibians. Interestingly and significant, was that in the entire 2006-2008 survey period only a single<br />
adult Boreal Toad was seen by surveyors!<br />
The role of chytrid fungus in the Yellowstone declines is unknown, but the fungus is known to attack all<br />
four species. McMenamin et al. observed severe mortality of Tiger Salamander larvae in three different<br />
ponds. However, the role of pathogens, lethal high temperature, or increased mineral or salt<br />
concentrations could not be established. This species has been susceptible to mortality from bacteria<br />
infections (Worthylake and Hovingh 1989).<br />
Amphibian populations have been surveyed at the Savannah <strong>River</strong> Site in South Carolina continuously <strong>for</strong><br />
35 years. This site is a large relatively natural restricted area used <strong>for</strong> nuclear research and ecological<br />
investigations. Daszak et al. (2005) examined archived museum specimens of 15 anuran species <strong>for</strong><br />
chytrid fungus infections. The fungus was detected (1978 to 1981 specimens) in three individuals of two<br />
species out of 137 individuals, but lesions were not present to indicate fatal pathology. Population<br />
62
trajectories over 26 years <strong>for</strong> six anurans and three salamanders indicated that two species of anurans and<br />
two salamanders showed statistically significant declines, one salamander showed a significant increase,<br />
while the other four anuran populations remained stable. Daszak et al. based on the specific requirements<br />
of life history requirements of these species, concluded that the population declines were the result of<br />
insufficient precipitation and shortened hydroperiod at breeding sites, related to a regional drying trend in<br />
the 1990s. This suggests climate change, but cannot rule out random long-term regional weather<br />
fluctuations. The research does point out that at least in some amphibian communities chytrid fungus<br />
infection does not necessarily result in population declines.<br />
<strong>Chytrid</strong> <strong>Fungus</strong><br />
A species of chytrid fungus (Batrachochytrium dendrobatidis) (BD) has been conclusively implicated in<br />
amphibian declines throughout the world (Young et al. 2001, Daszak et al. 2003, Briggs et al. 2005, La<br />
Marca et al. 2005, Lips et al. 2006, Rachowicz et al. 2006, Skerratt et al. 2007, Collins and Crump 2009<br />
[pages 159-174], Rosenblum et al. 2010). Nevertheless, the importance of BD to explain global<br />
amphibian population declines has been challenged as being inconclusive (McCallum (2005). A<br />
chytridiomycete fungus was first associated with anuran die-offs in Australia and Central America<br />
(Berger et al. 1998). This fungus was described as a new genus and species of chytrid fungus (Longcore<br />
et al. 1999). The prevalence and infection potential of BD may be seasonally dependent (Kriger and Hero<br />
2007). Attempts have been made to predict the distribution of BD based on modeling environmental<br />
variables in a GIS environment (Ron 2005). Although the complete pathogenicity and virulence of BD<br />
has yet to be settled, <strong>for</strong> a brief and easy to understand life history and currently understood pathogenesis<br />
of BD see Rosenblum et al. (2010).<br />
<strong>Chytrid</strong> fungi represent a primitive group of fungi, <strong>Chytrid</strong>iomycota, with five orders, approximately<br />
1000 species, and BD is unique and phylogenetically distinct (James et al. 2006). <strong>Chytrid</strong>s are closely<br />
related to protozoans, because of their ancestry. <strong>Chytrid</strong> fungi are globally distributed from the tropics to<br />
arctic regions in diverse habitats. Most species are probably terrestrial and saprophytes, breaking down<br />
and feeding on keratin, chitin, and cellulose. Some soil chytrids are plant pathogens. There are<br />
freshwater and marine species that are parasites of algae and plankton. BD is the only known chytrid to<br />
parasitize vertebrates (Longcore et al. 1999). In most habitats, a few species may by widespread and<br />
abundant, especially in freshwater or disturbed soils, but most species are infrequent and rare (James et al.<br />
2006). <strong>Chytrid</strong> fungi are recognized from as far back as the Devonian (Hass et al. 1994), which ended<br />
354 million years ago.<br />
<strong>Chytrid</strong> infection (chytridiomycosis) initiates when fungal zoospores first encounter amphibian skin and<br />
quickly give rise to sporangia, which produce new zoospores, and the disease progresses as zoospores<br />
keep reinfection the host, resulting in the sloughing of epidermal tissue and reddening of ventral skin<br />
(Berger et al. 2005a). BD causes complex cellular changes resulting in reorganization, dissolution, and<br />
premature keratinization of infected cells (Berger et al. 2005a). The resulting histology suggests that<br />
toxicity is the cause of death, but inhibition of skin function and overgrowth of bacteria may contribute to<br />
pathogenesis. Amphibian skin is extremely critical to the physiology, respiration, osmotic balance, and<br />
moisture homeostasis of amphibians (Feder and Burggren 1992). BD has specific adaptations that<br />
suggest it has evolved <strong>for</strong> a long time to live within the cellular tissue of stratified epidermis (Berger et al.<br />
2005a). The original evolutionary selective <strong>for</strong>ces <strong>for</strong> chytrid fungi were their saprophytic ecological role<br />
to decompose cellulose, hemicellulose, chitin, and keratin. This was there<strong>for</strong>e, a preadaptation <strong>for</strong> BD<br />
amphibian pathology attacking highly keratinized skin tissue, and other species to infect plant cell walls.<br />
Besides the metabolic toxicity and physiological degradation caused by BD, associated behavior includes:<br />
lethargy, reduction of reflex actions, abnormal posture, and a failure to seek shelter or flight. All of these<br />
result in high mortality to infected anurans.<br />
63
It is widely recognized that trying to detail and pinpoint the causes <strong>for</strong> the dramatic widespread amphibian<br />
declines are complex, confounding with multiple potential causes, and often contradictory (Kiesecker et<br />
al. 2001, Carey and Alexander 2003, Lannoo 2005, Blaustein and Bancroft 2007, Collins and Crump<br />
2009, pages 123-158). The complex and often inconclusive associations of BD with climate change,<br />
pesticides, and UV radiation was discussed above.<br />
There are a number of theoretically potential hypotheses to explain BD epidemics. First of all, there is the<br />
“novel pathogen” hypothesis, where the pathogen is transferred and spread geographically over time and<br />
space from a source. A competing hypothesis is that the pathogen was always widespread and endemic,<br />
but not virulent. It has recently become deadly <strong>for</strong> potentially three reasons. BD evolved into a new<br />
virulent infectious strain. BD switched hosts. BD is only virulent or increases its infection if its host is<br />
already stressed or subjected to one or more other insults. In other words, BD may not have previously<br />
involved with amphibians; BD may have been a minor amphibian parasite easily controlled by its host;<br />
BD may have infected one or more non-amphibian hosts (seriously or minimally); BD may have only<br />
attacked amphibians as they were dying from other causes or were already carcasses. Another possibility,<br />
of course, is that frogs evolved a strong susceptibility to BD. However, it is extremely unlikely that so<br />
many species from so many diverse families of anurans from all around the world all suddenly “evolved”<br />
into susceptibility to also a new species of chytrid fungus.<br />
Anurans and chytrid fungi were certainly around together <strong>for</strong> a very long time. The first known true frog<br />
(Vieraella herbstii) was from the Lower Jurassic (205 million years ago) of Argentina (Lecointre and Le<br />
Guyader 2006), but anuran ancestors go back to at least the early Permian, close to 300 million years ago<br />
(Anderson et al. 2008). Because chytrids have been around <strong>for</strong> over 354 million years there was certainly<br />
time to get acquainted. There<strong>for</strong>e, if BD was a novel spreading pathogen it must have already evolved<br />
into a virulent species in at least a single locality.<br />
Ouellet et al. (2005) examined epidermal chytrid fungus infection <strong>for</strong> 3371 postmetamorphic and adult<br />
amphibians collected from 1895 to 2001 from Canada, United States, and 23 other countries. The data are<br />
summarized in Table 1. Note that most of the data is from Quebec (N=1998), while the remaining data<br />
were from: rest of Canada (N=623), United States (N=310), and 23 other countries (N=440). Most of the<br />
Quebec data were in the St. Lawrence <strong>River</strong> Valley, including Montreal and Mont Saint-Hilaire Biosphere<br />
Reserve. Cutaneous chytrid fungus infections were found in 383 (13.1%) specimens of 12 common<br />
amphibian species from five Canadian provinces and seven U.S. states. <strong>Chytrid</strong> infection was not found<br />
on any of their 440 specimens from 23 other countries. However, they did not investigate specimens from<br />
severe BD infected areas in Australia and Central America (e.g., Costa Rica), although, they did have<br />
some specimens from New Zealand and Panama.<br />
Time<br />
Period<br />
Quebec Rest of Canada<br />
Number BD Percent Number BD Percent<br />
Examined Infected Infected Examined Infected Infected<br />
1895-1959 38 0 0 136 0 0<br />
1960-1969 217 29 13.4 316 16 5.06<br />
1970-1979 30 8 26.7 126 2 1.59<br />
1980-1989 15 6 40.0 45 0 0<br />
1990-2001 1698 302 17.8 0 ------ ------<br />
1960-2001 1960 345 17.6 487 18 3.70<br />
64
Time<br />
Period<br />
United States<br />
Number BD Percent<br />
Examined Infected Infected<br />
1895-1959 29 0 0<br />
1960-1969 122 1 0.820<br />
1970-1979 89 10 11.2<br />
1980-1989 63 8 12.7<br />
1990-2001 7 1 14.3<br />
1960-2001 281 20 7.12<br />
Table 1. <strong>Chytrid</strong> fungus (Batrachochytrium dendrobatidis) infection <strong>for</strong> 3371 postmetamorphic and<br />
adult amphibians collected from 1895 to 2001 from Canada, United States, and 23 other countries.<br />
The data is summarized from Ouellet et al. (2005, Table 3).<br />
There were a number of important conclusions from the research by Ouellet et al. (2005). The earliest<br />
chytrid infections found were in two Green Frogs (Lithobates clamitans) collected in July 1961 in<br />
Quebec. Importantly, the 1990-2001 data included 1698 specimens from Quebec, none from the rest of<br />
Canada, and only seven from the United States. All of the data <strong>for</strong> the 1698 specimens from Quebec were<br />
obtained from live captures in the field. Quebec infection rates did not differ statistically between the<br />
1960-1969 through 1990-2001 sampling periods (chi square: P=0.10), and the infection rate over this time<br />
frame was 17.6 percent. Over the same time frame the infection rate was 7.12 percent in the United States<br />
samples, and very low in the rest of Canada. However, sample sizes were low, and no samples were<br />
examined in the critical 1990-2001 time frame in the rest of Canada. The United States samples from<br />
1960-1969 had a very low infection rate, and if this time frame were excluded from analysis, the infection<br />
rate rose to 11.9 percent. Despite the fact that 17.8 percent of the live Quebec amphibians captured in the<br />
field between 1990 and 2001 tested positive <strong>for</strong> chytrid fungus, the individuals appeared healthy. Ouellet<br />
et al stress that even this unexpected high level of infection was very conservative, because the fungus<br />
assay was conducted from toe clips tissue. <strong>Chytrid</strong> fungus infection is most intense in the ventral pelvic<br />
region, ventral hind limbs, and hind feet (Berger et al. 1998). <strong>Chytrid</strong> infection was most prevalent in the<br />
spring and fall <strong>for</strong> the live specimens data. This corresponds to the reports of Longcore et al. (1999) and<br />
Carey (2000) the BD grows better at lower temperatures. Additionally, the immune system of amphibians<br />
functions more effectively at higher temperatures (Cooper et al. 1992, Carey 2000).<br />
The third time was not a charm <strong>for</strong> amphibians: first Homo sapiens, then HIV/AIDS, and now<br />
Batrachochytrium dendrobatidis. The oldest known identification of chytridiomycosis was in a 1938<br />
African Clawed Frog, Xenopus laevis (Weldon et al. 2004). The individual was found in a series of 697<br />
archived Xenopus frogs (3 species, 84% X. laevis), collected between 1879 to 1999 in southern Africa.<br />
All three species were infected with a prevalence of 2.7%, and all regions of southern Afrtica were<br />
infected by 1973. There<strong>for</strong>e, this evidence is frequently cited <strong>for</strong> the out of Africa origin of BD.<br />
However, this question remains unsettled, because recent genetic evidence shows low diversity of BD in<br />
Xenopus and high allelic diversity in North American Bullfrogs (James 2009, Rosenblum 2010). See<br />
Discussion section <strong>for</strong> more detailed in<strong>for</strong>mation.<br />
The next oldest date of known BD infection was 23 years later in a Green Frog from Quebec (Ouellet et<br />
al. 2005), and was discussed above. X. laevis is a completely aquatic species that does not exhibit clinical<br />
symptoms in wild populations, and has not experienced sudden die-offs. Importantly, only subclinal<br />
65
chytrid infections have been observed in captive colonies of this species (Weldon et al. 2004). Typically,<br />
anurans in captivity that become infected with BD suffer rapid and complete mortality, because the<br />
fungus spreads rapidly by contact (Young et al. 2007, Une et al. 2008).<br />
Exceedingly large numbers of X. laevis were caught in the wild in southern Africa and spread around the<br />
world after 1934, the year of the discovery that this species was a rapid and effective test <strong>for</strong> human<br />
pregnancy (Weldon et al. 2004). Additionally, many specimens were used as experimental laboratory<br />
subjects and widely distributed in the pet trade. African Clawed Frogs were very abundant and available<br />
in both research laboratories and pet stores in the eastern United States during the 1970s (A.J. Krzysik,<br />
personal observation). X. laevis has been recorded in the wild in ten states, but has only been established<br />
and breeding in seven counties of southwestern Cali<strong>for</strong>nia and golf course ponds in the Tucson area of<br />
Arizona (Crayon 2005). It was first recorded as a feral species in Cali<strong>for</strong>nia in 1968.<br />
Boreal Toads<br />
Results<br />
The Western Toad (Anaxyrus sp [<strong>for</strong>merly Bufo]) group consists of five currently recognized taxa, three<br />
of them isolated endemic relicts that are extremely local (Goebel 2005). The Amargosa Toad (Anaxyrus<br />
nelsoni) is found in a ten-mile stretch of the Amargosa <strong>River</strong> and associated springs in Oasis Valley in<br />
southwestern Nevada near Beatty. The Black Toad (Anaxyrus exsul) is found in Deep Springs Valley<br />
between the Inyo and White Mountains in eastern Cali<strong>for</strong>nia near the Nevada border. The Yosemite Toad<br />
(Anaxyrus canorus) is found in the high Sierras, mainly between elevations of 9000 to 12000 feet in the<br />
vicinity of Yosemite National Park. The Cali<strong>for</strong>nia Toad (Anaxyrus boreas halophilus) is found<br />
throughout most of Cali<strong>for</strong>nia with the exception of deserts and the highest mountain elevations, into<br />
extreme western Nevada, and south into Baja Cali<strong>for</strong>nia Mexico. The Boreal Toad (Anaxyrus boreas<br />
boreas) has a very extensive distribution, ranging from all of <strong>Southeast</strong> <strong>Alaska</strong>, all of British Columbia,<br />
and western Alberta in the north; south to northern Cali<strong>for</strong>nia, most of Nevada north of the Mojave<br />
Desert, and the mountains of Utah; and east to western Montana, western and southern Wyoming, the<br />
Rocky Mountains of Colorado, and extending into the northern extreme of New Mexico. The two<br />
subspecies intergrade in northern Cali<strong>for</strong>nia. The Boreal Toad is commonly referred to as the Western<br />
Toad in much of the literature. Nevertheless, the correct and taxonomically accepted nomenclature is that<br />
the Western Toad refers to both subspecies of Anaxyrus boreas.<br />
The three taxa with very local distributions are always in danger of extinction from epidemics, climate<br />
change, unusual weather, or some local habitat/environment insult. The habitats of all three are currently<br />
protected, conservation plans are in place, populations are monitored, and only the Yosemite Toad has<br />
shown a decline (Davidson and Fellers 2005, Fellers 2005, Goebel et al. 2005). Boreal and Cali<strong>for</strong>nia<br />
toads have shown severe declines in most of their range (Muths and Nanjappa 2005).<br />
Goebel (2005) actually recognized nine phylogenetic clades of this complex based on mitochondrial DNA<br />
parsimony analysis, and concluded that additional analyses are needed <strong>for</strong> any final Linnaean<br />
classification. She verified the three recognized species, and produced six clades of Anaxyrus boreas.<br />
The phylogenic higher order clade covering <strong>Southeast</strong> <strong>Alaska</strong> is the Northwest clade (at Node 8). Node 8<br />
gave rise to four terminal nodes: Anaxyrus canorus, West Coast, Midwest, and Far North. These three<br />
clades were not further defined. <strong>Southeast</strong> <strong>Alaska</strong> Anaxyrus boreas is a component of four terminal<br />
phylogenetic clades, presumably the Far North clade, and it is interesting that it is related to the Yosemite<br />
Toad.<br />
All species of native true frogs (Ranidae) have dramatically declined in the western United States (Hayes<br />
and Jennings 1986). Although much of the decline can be attributed to habitat loss or degradation, the<br />
66
dramatic decline of nine ranid Cali<strong>for</strong>nia frogs in pristine habitats is puzzling (Jennings 1995). There has<br />
been a general decline of five species of anurans, including the Boreal Toad, from northern Colorado to<br />
southern Wyoming (Corn and Fogleman 1984). The decline of Yosemite Toads was blamed on drought,<br />
disease, and predation, with the conclusion that multiple factors could be particularly devastating<br />
(Kagarise Sherman and Morton 1993). Kagarise Sherman and Morton (1993) provide an interesting<br />
literature review and their own observations of avian predation on toads. Three species of corvids were<br />
involved in predation on toads in the Boreal Toad species group. See Predation Section <strong>for</strong> details.<br />
Boreal Toads in the Central and Southern Rocky Mountains<br />
The Boreal Toad, a once very widely distributed and very abundant species, underwent extensive declines<br />
in both distribution and abundance in the central and southern Rocky Mountains from the late 1970s to<br />
the present (Carey 1993, Stuart and Painter 1994, Corn et al. 1997, Livo and Loeffler 2003, McGee and<br />
Keinath 2004, Carey et al. 2005, Collins and Crump 2009, pages 135-142). This region covers the states<br />
of Colorado, Wyoming, Utah, and a small area of extreme northern New Mexico. The Boreal Toad may<br />
be extinct in New Mexico (Degenhardt et al. 1996). Boreal Toads were historically common up to the<br />
1960s in the Wasatch and Uinta Mountains in northern Utah, but appear absent or in decline throughout<br />
the state (Ross et al. 1995, Stebbins and Cohen 1995). Recent surveys found northern populations scarce,<br />
but three scattered small new populations were discovered in southern Utah (Ross et al. 1995). There<br />
were only five previously know populations in the southern portion of the state based on museum records.<br />
Ross et al. concluded that the state has not been adequately surveyed <strong>for</strong> Boreal Toads, and that the<br />
disjunct montane habitats in the state make it difficult <strong>for</strong> recolonization of local population when they go<br />
extinct.<br />
Corn et al. (1989) reported that Boreal Toads were absent at 49 out of 59 (83%) of their historical sites in<br />
Colorado and Wyoming. Populations appeared stable until there were major die-offs in 1996 and in 1999<br />
(Carey 2000, Carey et al. 2005). Some early population mortality was attributed to bacterial infections<br />
(Carey 1993). Corn (1998) concluded that UV radiation was not responsible <strong>for</strong> Boreal Toad declines in<br />
the pristine landscape of Rocky Mountain National Park in northern Colorado, but there were<br />
contradictory results in other studies of UV radiation. <strong>Chytrid</strong> fungus was identified with declining<br />
Boreal Toad populations, as well as other anurans, in Colorado and Wyoming (Daszak et al. 1999, Muths<br />
et al. 2003, Keinath and McGee 2005). Scherer et al. (2005) concluded that chytrid fungus and not<br />
weather conditions were responsible <strong>for</strong> the significant decline of two major populations of Boreal Toads<br />
in Rocky Mountain National Park.<br />
Many factors have been blamed <strong>for</strong> the decline of populations in the Boreal Toad group, but the reports<br />
have often been inconclusive and even contradictory. The typical agents identified as potentially<br />
responsible <strong>for</strong> the decline of Boreal Toads, either alone or in concert are: chytrid fungus, pathogens such<br />
as other fungus or bacteria, habitat destruction and degradation, increased predation from both introduced<br />
and native predators, pesticides, acidic deposition, acid and minerals from mine water seepage, increased<br />
UV radiation, timber harvest, livestock grazing of wetlands, fire and fire management, and competition<br />
from introduced fathead minnows (McGee and Keinath 2004, Keinath and McGee 2005, Muths and<br />
Nanjappa 2005, Maxell et al. 2009).<br />
Collins and Crump (2009, page 142) concluded that as of January 2008 there were only 33 known<br />
populations of Boreal Toads in Colorado. Most of the northern populations are infected with chytrid<br />
fungus, but it appears that most of the southern populations are free of the fungus. The status of the<br />
Boreal Toad in the central and southern Rocky Mountains is currently under rigorous investigation.<br />
Boreal Toads have dramatically declined in the Greater Yellowstone Ecosystem (Koch and Peterson<br />
1995, Patla and Peterson 1999, McMenamin et al. 2008). Carpenter (1953, 1954) referred to the Boreal<br />
67
Toad as the most widespread amphibian in the Jackson Hole region, and reported that it was found in<br />
every locality in a great variety of habitats. Turner (1955) remarked about the large numbers of crushed<br />
toads he observed on the roads around Yellowstone Lake and Fishing Bridge over the Yellowstone <strong>River</strong>.<br />
Koch and Peterson (1995) reported that they observed only two Boreal Toads in this same area over the<br />
last six years (pre early 1990s). They also reported that only three of 48 sites examined in northern<br />
Yellowstone National Park had Boreal Toads in 1992-1993, but at times the region supported successful<br />
reproduction in some areas. They concluded that this species had declined over the last 40 years (1950s<br />
to early 1990s) in the Greater Yellowstone Ecosystem. The same three populations of Boreal Toads<br />
found in 1993 were also found in 2006-2008 amphibian surveys (McMenamin et al. 2008). However, the<br />
documentation of Boreal Toads was based on the presence of eggs and tadpoles, because during the entire<br />
2006-2008 survey period, only a single adult Boreal Toad was seen by surveyors! The 1992-1993 and<br />
2006-2008 Yellowstone amphibian survey comparison was discussed above (see Climate Change,<br />
McMenamin et al. 2008).<br />
Boreal Toads in the Northern Rocky Mountains<br />
The Montana Natural Heritage Program has put in a great deal of ef<strong>for</strong>t conducting extensive amphibian<br />
and reptile surveys on at least six National Forests, Glacier National Park, BLM lands, Flathead Indian<br />
Reservation, and National Wildlife Refuges. At least 15 reports have been submitted from 1994 to 2000,<br />
totaling over a 1000 pages (Montana Herps 2010). The data from these surveys and the available<br />
literature were synthesized to develop a comprehensive conservation and management plan <strong>for</strong> the state’s<br />
herpetofauna, including the Boreal Toad (Maxell et al. 2009). The following data on the Boreal Toad is<br />
from these series of reports.<br />
Biologists were of the opinion that Boreal Toad population in the northern Rocky Mountains were more<br />
stable, and did not undergo the dramatic declines of the central and southern Rockies. However, these<br />
surveys revealed that although Boreal Toads were still widespread in distribution, that were absent from<br />
many of their historical localities, and they occupied typically less than ten percent of suitable habitat, but<br />
often even less than five percent. The Montana 2000 systematic inventory of 40 randomly chosen 6 th<br />
level Hydrologic Unit watersheds found the toads widespread but very rare. They were only found in 11<br />
(27%) of the watersheds, and of the 33 watersheds with suitable breeding habitat the toads were breeding<br />
(eggs, larvae, or metamorphs observed) in only seven (21%). A total of 347 standing ponds and pools<br />
were surveyed in these watersheds, and adults were only found at 13 (3.7%), while toads were breeding in<br />
only 9 (2.6%). Importantly, at sites where toads were found, only few adults, larvae, or eggs were<br />
observed. Similarly, approximately 400 standing bodies of water were surveyed at Glacier National Park<br />
during the summers of 1999-2000, and Boreal Toads were only found and breeding at approximately five<br />
percent of the sites. Again, the surveys at the Flathead Indian Reservation in 1999-2000 were similar,<br />
where toad breeding occurred at four of nine historical sites, and years between breeding were often<br />
skipped.<br />
The Boreal Toad in Montana has received the following status (MNHP 2009).<br />
Global Designation G4<br />
Uncommon but not rare (although it may be rare in parts of its range), and usually widespread;<br />
apparently not vulnerable in most of its range, but possibly cause <strong>for</strong> long-term concern.<br />
State Designation S2<br />
At risk because of very limited and/or declining numbers, range, and/or habitat,<br />
making it vulnerable to global extinction or extirpation in the state.<br />
Montana CFWCS Tier I<br />
68
Montana Fish, Wildlife, and Parks; Comprehensive Fish and Wildlife Conservation Strategy identifies<br />
fish and wildlife species that are in greatest need of conservation by ranking them into one of four Tiers.<br />
Tier I represents the highest level of species protection.<br />
“Tier I: Greatest conservation need. Montana Fish, Wildlife & Parks has a clear obligation to use its<br />
resources to implement conservation actions that provide direct benefit to these species, communities, and<br />
focus areas.”<br />
Boreal Toads in the Pacific Northwest<br />
Despite the severe well-documented declines of Boreal Toads in the central and southern Rocky<br />
Mountains of Colorado and Wyoming, and also to probably a smaller degree in the northern Rockies of<br />
Montana, there is no evidence that this species has experienced serious declines in the mountains of the<br />
Pacific Northwest (Muths and Nanjappa 2005). Boreal Toads are rare in the lowlands of the Pacific<br />
Northwest (Richter and Azous 1995, Adams et al. 1998, 1999). Pearl et al. (2007) examined 210 anurans<br />
of seven species from 37 sites in Oregon and Washington. Four of the seven species tested positive <strong>for</strong><br />
chytrid fungus, with infection rates ranging from 9-57 percent. The introduced Bullfrog tested positive<br />
<strong>for</strong> 15 of 48 (31.2%) individuals. The fungal infections were from all parts of Oregon, and none were<br />
found <strong>for</strong> Olympic National Park, Washington. All stages of anurans were infected (adults,<br />
metamorphs/juveniles, and tadpoles). Infection rates were six times greater in winter and spring than in<br />
summer. None of the 13 Boreal Toads examined was infected.<br />
Four species of anurans and a salamander are currently abundant within the blast zone of the 1980 Mount<br />
St. Helens eruption, and they colonized all available lake habitats within five years of the eruption, despite<br />
the complete lack of dispersal corridors (Crisafulli and Hawkins 1998). However, the terrestrial family of<br />
Plethodontidae salamanders was apparently eliminated.<br />
Blaustein et al. (1994b) found that the widespread fungus Saprolegnia ferax had contributed to Boreal<br />
Toad egg mortality of 50 to 95 percent in three populations in the Cascade Mountains of Oregon since<br />
1989. However, from 1980 to 1989 natural mortality of eggs had been less than five percent.<br />
69