11th ICRS Abstract book - Nova Southeastern University

1.17
Carysfort Reef, Key Largo, Florida Keys Is Melting
Phillip DUSTAN* 1
1 Department of Biology, College of Charleston, Charleston, SC
The latest reports on the state of the world’s coral reefs are tragic. At least one quarter of
known reefs are in seriously degraded and over half are seriously threatened.
Photographs, taken from the same vantage point from 1975 to 2004, illustrate the rapid
degradation of coral reefs that has occurred throughout the Florida Keys and Caribbean
Sea. Carysfort Reef, once the largest, most diverse and luxuriant reef in the Florida
Keys, has lost over 92% of its living coral cover. The factors responsible for this
degradation include an accumulation of simultaneous, synergistic, nested stresses
operating at local to global scales (fishing, anchor/grounding damage, watershed effluents
from urban, agriculture, and industry; global warming and ocean acidification). While
this complex milieu makes it extremely difficult to determine the contribution of each
stressor, the impact has been catastrophic.
In 1975 the Acropora palmate zone consisted of large colonies oriented into the
prevailing seas, typical throughout the Caribbean. The high degree of three dimensional
complexity provided habitat for a wide variety of reef fishes and invertebrates. By 1985,
some of the A. palmata colonies had suffered physical damage from boat groundings and
storms. Large fragments were strewn about and decreased urchin grazing allowed for
increased growth of macroalgal turf communities. In 1995, the reef structure continued
to degrade, coral cover was below 5%, and scleractinain corals ceased providing any
significant contribution to reef framework. By 2004, bioerosion had dramatically
reduced the reef’s three-dimensionality and softly rounded the remaining rubble
fragments. Dead skeletons of the once dominant Elkhorn coral appear to be melting as
they are rapidly converted to carbonate sand. Observations based on the remnants of
cement bore-hole fillings suggest that rates of bioerosion match or exceed rates of past
skeletal growth, but in the opposite direction.
1.18
The Effect Of Marine Protection On Carbonate Sediment Production in St. Croix,
Usvi
Alex BURPEE* 1 , Lisa GREER 1 , Robert HUMSTON 2 , Dennis HUBBARD 3
1 Geology, Washington and Lee University, Lexington, VA, 2 Biology, Virginia Military
Instiute, Lexington, VA, 3 Geology, Oberlin College, Oberlin, OH
Previous research has shown that marine preserves contain greater densities of predators,
parrotfish, and live coral than unprotected reefs, as well as decreased densities of algae.
These biological differences associated with reef protection affect carbonate sediment
production on a reef by altering the relative densities of grazers present (parrotfish and
Diadema antillarum), as well as the balance of coral and algal cover. However, it is not
generally understood how altering the two grazer populations might affect sediment
production by bioerosion. In St. Croix, a protected site at Buck Island (BI) and an
unprotected site at Tague Bay (TB) were used as study areas to explore the effect of coral
reef management on the reef carbonate budget. The sites sit on opposite sides of a
channel and are separated by only 5 km. Duplicate 10-minute predator and grazer counts
were compiled along two 10 m transects at 7.5 m, 4.5 m, and 2 m depths for each of the 3
locations at both BI and TB. The primary bioeroders included 7 species of parrotfish,
and Diadema antillarum. Survey data show statistically significant differences in grazer
densities between the two sites (2,286 parrotfish and 400 Diadema at BI versus 1,507
parrotfish and 3,123 Diadema at TB). Although the grazer populations are very different,
initial analyses based on previous estimates of sediment production by individual fish and
urchins show that the difference in sediment production caused by these grazers is not as
different. Efforts are ongoing to determine how present-day sediment production rates at
the two sites compare to those associated with the reefs prior to their degradation by
fishing, disease, hurricane stress, and nutrification. Hopefully these will allow us to
compare patterns of carbonate cycling in pre- and post-decline reefs to fossil reefs.
Poster Mini-Symposium 1: Lessons from the Past
1.19
A Possible Epibiont Signature for White Band Disease and/or Bleaching in Acropora
palmata, Buck Island National Monument, St. Croix, USVI
Anne LAGOMARCINO* 1 , Dennis HUBBARD 1
1 Geology, Oberlin College, Oberlin, OH
The role of poster-child for recent reef decline is shared by White Band Disease and bleaching.
Monitoring has documented the catastrophic decline of Acropora palmata and numerous other
species, but is an ineffective way to understand change in the context of longer-term community
turnover. With A. palmata, both stressors share one important characteristic that separates them
from the common and presumably "natural" cause of death. Storm action reduces colonies to
rubble that either recruits asexually or dies and is bound into the substrate. In contrast, disease
and bleaching leave the colony standing and subject to increased grazing and encrustation. Over
150 colonies of standing, dead colonies of A. palmata were collected from two sites off Buck
Island, where White Band Disease was first described. At the same sites, samples were
recovered from 1-2 meter deep pits that were dominated by broken, toppled and encrusted
branches. As a pilot study, a subset of 15 "standing-dead" and 15 "pit" samples were chosen
randomly from the larger group at one site. Each was impregnated with epoxy, slabbed and cut
into large-format thin sections. The relative importance and order of ebibionts were quantified
along ten randomly chosen transects on each slide. Cluster analysis and Bray-Curtis ordination
revealed two clusters that separate standing-dead and pit samples. Within these clusters, thick
and conformable coralline algae, vermetid gastropods and worm tubes were statistically more
abundant on the standing dead colonies (α = 0.05), while Carpenteria utricularis, Biarritzina
carpenteriaeformis and high-relief morphs of Homotrema rubrum were more common within
the pits. While this is only a subset and we still have to examine our reef cores in the intervals
where A. palmata apparently had difficulty in the past, the differences described here involve
easily distinguished organisms that have a high potential for preservation in cores and
Quaternary outcrops.
1.2
Results of Scleractinian and Reef Investigation Conducted 1983-1984 in Southeastern
Mexico
Vassil ZLATARSKI* 1
1 Independent Consultant, Bristol, RI
From 1983 to1984, the Center for Advanced Studies and Research in Mérida, Yucatán, Mexico
(CINVESTAV-Unidad Mérida) conducted an extensive study of scleractinians in southeastern
Mexico. The results were not published. The aim of this work is to preserve the unique
information of two dozen years ago regarding species richness, community data and the
scleractinian role in building different reef types and to make it available for better reef
understanding and preservation.
The area of investigation included waters all around the peninsula of Yucatán, from Cayos
Arcas to the border of Belize. Scleractinians were the object of day and night scuba diving,
from the coast to a depth of 60 m on the shelf edge, in transects with 141 sites and 168 stations.
4, 579 coralla were collected and identified. 630 color pictures were taken, from which 231
were selected for an atlas. In 1985, CINVESTAV donated 801 coralla to the Smithsonian
Institution in Washington, D.C., and these remain well preserved. With the exception of three
azooxanthellate species identified by Dr. S. Cairns, the rest were identified by the author. The
species presence and their participation in reef formation were given for each site and station.
In total 42 species and one hybrid of 27 scleractinian genera were determined and four reef
types were established.
In 1983-84, the severe negative impact of oil exploitation was evident in Cayos Arcas.
Poorly conducted tourism and fishing damaged the reefs in Cozumel, Punta Brava and Isla
Mujeres. Scleractinian health did not show significant anomalies. No epizootic phenomena
were established. Recruits frequented non-damaged locations.
The results offer a quarter-century baseline for prognosis and recommendations concerning
reefs in southeastern Mexico.
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