11th ICRS Abstract book - Nova Southeastern University

Oral Mini-Symposium 10: Ecological Processes on Today's Reef Ecosystems
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Plasticity of the Corallivorous gastropod Coralliophila abbreviata: Implications
for Imperiled Caribbean Coral
Lyza JOHNSTON* 1 , Iliana BAUMS 2 , Margaret MILLER 3
1 Rosenstiel School of Marine and Atmospheric Science, University of Miami, Miami,
FL, 2 Department of Biology, The Pennsylvania State University, University Park, PA,
3 Southeast Fisheries Science Center, NOAA, Miami, FL
Coralliophila abbreviata is a corallivorous gastropod that lives and feeds on several
species of scleractinian coral in the tropical Western Atlantic and the Caribbean.
Throughout the region, gastropod populations found on branching acroporid corals
display different morphological, behavioral, and life-history characteristics than those
found on massive and plating corals, prompting hypotheses about host-associated genetic
differentiation within C. abbreviata. Although damage to massive and plating corals
appears minimal, these gastropods cause substantial and chronic mortality of Acropora
palmata and Acropora cervicornis, two species recently listed as Threatened under the
U.S. Endangered Species Act. Under the premise of one plastic species of C. abbreviata,
massive and plating corals may serve as reservoir hosts, producing a continuous supply of
predators even as acroporid populations continue to dwindle. The species status and
population dynamics of C. abbreviata thus have important conservation and management
implications for Caribbean coral reefs. To address this issue, we used mitochondrial and
microsatellite markers to assess the genetic structure of C. abbreviata populations from
two coral host taxa (A. palmata and Montastraea spp.) and three locations spanning the
species range (Florida Keys, Navassa Is., and St. Vincent and the Grenadines). We found
no significant genetic structure between hosts or among geographic locations, indicating
that C. abbreviata is one plastic species with unrestricted gene flow throughout the range
sampled. Based on these results, it seems pertinent that strategies be implemented to
mitigate the impact of C. abbreviata on vulnerable acroporid coral populations.
10-66
Strong Interactions From Hidden Species: Vermetid Snails Have Large Deleterious
Effects On Corals
Craig OSENBERG* 1 , Jeffrey SHIMA 2 , Adrian STIER 1
1 Department of Zoology, University of Florida, Gainesville, FL, 2 School of Biological
Sciences, Victoria University Wellington, Wellington, New Zealand
The dynamics and restoration of coral reefs is of critical concern given their ecological
importance and the deleterious impacts caused by disease and anthropogenic activities.
Previous research has demonstrated important potential effects of nutrients, algae,
disease, and disturbance, but may have overlooked other key factors. Vermetid
gastropods, which are sessile and feed via an extensive mucus net, are poorly studied
members of the coral reef community, yet also may interact strongly with corals. We
examined the possible effects of vermetids on coral growth and survival in a field study
in a lagoon of Moorea, French Polynesia. Vermetids were either left at ambient densities
or removed from small (~3m2) patch reefs. Coral nubbins were collected, weighed
(using the buoyant mass technique), and outplanted to these patch reefs. Growth was
assessed after ~7 weeks and survival after ~8 months. Eight experiments were conducted
using four different species of coral (Pocillopora, Montipora, Porites lobata, and Porites
rus). Growth and survival were both greater offshore than inshore, although effects of
vermetids were similar in both regions. Effects of vermetids were strongly deleterious
but varied among coral taxa. Vermetids reduced the growth of coral by as much as 90%
(Pocillopora) and by as little as 30% (Montipora). Survival was reduced from >98% in
the “removals” to 79% (P. rus), 70% (P. lobata), and 45% (Pocillopora). These large
short-term effects can have dramatic consequences for coral regeneration and dynamics.
We projected changes in coral community composition resulting from observed effects of
vermetids and found that the effects rival those documented from other factors.
10-67
Cultivation Mutualisms Between Territorial Damselfish And Algae in The Indo-West
Pacific
Hiroki HATA* 1
1 Graduate School of Science, Kyoto University, Sakyo, Kyoto, Japan
This research aims to understand the origin and evolution of cultivation mutualisms on coral
reefs in the Indo-West Pacific. Territorial damselfishes defend territories individually against
intruding herbivores and manage algal farms on which they exclusively feed in the territories.
We revealed that some territorial damselfish farm species-specific Polysiphonia algae in
Okinawa, Japan. Molecular genetics enabled us to detect four cryptic species of Polysiphonia
algae, each of which were collected from territories of four different damselfish species.
Notably, one Polysiphonia algal species dominated the farms of a damselfish Stegastes
nigricans and was found nowhere else. S. nigricans feeds on this highly digestible alga as a
staple food, whereas Polysiphonia sp. is exclusively protected and grown by the damselfish. In
this way, the two species rely on each other; this situation is described as an obligate cultivation
mutualism.
I studied damselfish territories in the Indo-West Pacific (Mauritius, Kenya, Egypt, Maldives,
Thailand, Malaysia, and Australia) and revealed that the general pattern of species-specificity
between Stegastes damselfishes and Polysiphonia algae was relatively stable throughout the
Indo-West Pacific, but the dependency on the specific partner varied remarkably. Polysiphonia
sp. 1, which is dominant in algal farms of S. nigricans in Okinawa, was also found in territories
of the same fish species in Mauritius, Egypt, and Australia. However, Polysiphonia sp. 1 did not
always dominate the farms in those areas, and therefore the fish did not always depend on the
alga as a staple food. In addition, a new sibling Polysiphonia species was found. The farms of S.
nigricans in Kenya, Maldives, and a part of Mauritius were inhabited by other Polysiphonia
species, instead of Polysiphonia sp.1. These results imply that the cultivation mutualisms
between damselfish and Polysiphonia algae have coevolved under geographic selection mosaics
with host shifts across regions.
10-68
Effects Of Farmerfish On Coral Community Structure
Jada-Simone WHITE* 1
1 Department of Zoology, University of Florida, Gainesville, FL
Complex ecological interactions, coupled with abiotic processes, underlie the structure of
diverse communities. In Moorea, French Polynesia, an abundant algal-farming fish, the dusky
farmerfish Stegastes nigricans, alters the coral reef community by farming algal turf and
exerting resource control through territorial defense. These behaviors affect coral indirectly by
modifying their interactions with two guilds of community members: 1) increased interactions
with farmed algal turf; and 2) decreased interactions with mobile grazers and predators due to
reduced reef access. Small scale experiments involving farmerfish and / or turf removals
indicated dominant massive Porites were more vulnerable to competition with turf than
branching Acropora, Pocillopora, or encrusting Montipora. In contrast, delicate branching
corals were more vulnerable to predation by mobile corallivores and grow and survive better in
the presence of S. nigricans defense. I assessed these indirect effects in a demographic context
using a combination of recruitment tiles and size specific population monitoring in the presence
and removal of S. nigricans. Experimental parameter estimates were tested by comparing
projected size distributions with spatially explicit size distributions of corals in the presence and
absence of this abundant farmerfish. The disturbance history has played a pivotal role in the
types of community changes observed. While S. nigricans usually colonizes Acropora thickets,
a series of disturbances on the north shore virtually eliminated these habitats and farmerfish
subsequently colonized disturbance tolerant, but turf sensitive, abundant massive Porites. The
relative resistance to competition with turf allowed recovering, disturbance sensitive, species to
utilize the dead portions of massive coral. This increase in substrate availability, when coupled
with lower predation rates, has led to enhanced recovery of rare and branching corals within
territories relative to outside.
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