11th ICRS Abstract book - Nova Southeastern University

Poster Mini-Symposium 10: Ecological Processes on Today's Reef Ecosystems
10.261
Influence Of palythoa Caribaeorum (Anthozoa, Cnidaria) Patches On Reef Fish
Community in Subtropical Rocky Shores
José P. MENDONÇA-NETO 1 , Laís C. T. CHAVES* 2 , Carlos E. L. FERREIRA 3 ,
Cassiano MONTEIRO-NETO 1 , Renato C. PEREIRA 1
1 Departamento de Biologia Marinha, Universidade Federal Fluminense, Niteroi, Brazil,
2 Departamento de Oceanografia, Universidade Federal de Pernambuco, Recife, Brazil,
3 Departamento de Biologia Marinha, Universidade Federal Fluminense, Niterói, Brazil
This work aimed to test the influence of the Palythoa caribeorum, a Zoanthid widely
distributed in the Atlantic, on the fish community of Arraial do Cabo rocky reefs,
Southeastern Brazil. Abundance, diversity and vertical distribution of reef fish inside (ID)
and outside (OD) previously chosen P. caribaeorum dominance patches were compared
among two different sites. Replicated visual stationary censuses were conducted through
different bathymetric zones: shallow (~0-3m); intermediate (~3-6m) and bottom (~6-9m).
Sites were revisited during one year period effort (SEP06/ OCT07). A total of 180
censuses were conducted; 30 censuses on each bathymetric reef zone. Percentage cover
of P. caribaeorum and other benthic organisms were obtained analyzing random points
from replicated photo-quadrats (n = 30). This work resulted in 45 species belonging to 25
families. The ten most abundant fishes for both sites comprised together 65% of all fishes
recorded during this study. Despite sites presented similar components on reef fish
community, they differed in abundance (ANOVA, p=0.003) and richness (ANOVA,
p=***), where OD patches presented higher values. We also recognized two major
benthic communities occupying the same depth zones: the algal community, in which turf
algae was dominant and the zoanthid community, which was dominated by P.
caribaeorum. In overall view, differences between fish community among patches could
be attributed to particular species for swimming ability and ontogeny. Results seem not to
indicate direct effects of P. caribaeorum on reef fish community, despite some evidence
that these areas might play a important role in space limitation by structuring neighboring
benthic community and consequently, fish community.
10.262
Reproductive fitness consequences of parrotfish predation on a tropical reefbuilding
coral: small damage, large consequence
Randi ROTJAN* 1 , Sara LEWIS 2
1 Organismic and Evolutionary Biology, Harvard University, Cambridge, MA,
2 Department of Biology, Tufts University, Medford, MA
The trophic role of Caribbean parrotfish on coral reefs is controversial: while parrotfish
are classically known for their role as important reef herbivores, they are also significant
corallivores that selectively graze species of important reef-building corals in the
Montastraea annularis species complex. While the benefits of parrotfish herbivory for
coral reef resilience and conservation have been extensively documented, the
consequences of parrotfish grazing for coral reproductive fitness have not been
previously examined. We examined colonies of Montastraea annularis corals that had
been recently grazed (within 2 weeks of sampling) by parrotfishes in order to examine
whether grazing was positively associated with coral reproductive effort. We measured
gonad number, egg number and size, and proportional reproductive allocation for grazed
and intact Montastraea annularis colonies 2-5 days prior to their annual spawning time.
We found that parrotfish selectively grazed coral tissue areas with high total reproductive
effort (number of gonads), providing the first evidence that parrotfish selectively target
specific tissue areas within a single coral colony. Our data suggest that the removal of
polyps with high reproductive effort has direct adverse affects for coral colony fitness,
with additional indirect implications for colony growth and survival. However, nearby M.
annularis colonies showing high reproductive effort were not grazed by parrotfishes,
suggesting that some colonies are defended against grazing. We conclude that chronic
grazing by parrotfishes has negative fitness consequences for these reef-building corals,
and that these previously underappreciated impacts have the potential to adversely affect
reef ecosystems.
10.263
Evolutionary Ecology Of Sponge-Cyanobacteria Symbioses
Robert THACKER* 1 , Patrick ERWIN 2
1 Department of Biology, University of Alabama at Birmingham, Birmingham, AL, 2 Center for
Marine Science, University of North Carolina at Wilmington, Wilmington, NC
Symbioses between sponges and cyanobacteria are common on coral reefs, with cyanobacterial
symbionts including filamentous Oscillatoria spongeliae and unicellular Synechococcus
spongiarum. We investigated the filamentous symbionts associated with two recently described
species from Caribbean Panama, Haliclona walentinae and Xestospongia bocatorensis, and the
unicellular symbionts associated with Aplysina fulva and Neopetrosia subtriangularis. We
shaded A. fulva and N. subtriangularis to examine the effects of reduced light availability on
symbiont load and host growth. We estimated the photosynthetic capacities of cyanobacterial
symbionts of all four host sponges by measuring changes in dissolved oxygen concentrations in
light and dark conditions. We also amplified and sequenced cyanobacterial 16S ribosomal
RNA genes from each host. Six weeks of shading reduced symbiont load in A. fulva and N.
subtriangularis by over 40%. In A. fulva, control sponges exhibited twice the growth of shaded
sponges. In N. subtriangularis, no significant difference in growth was observed between
control and shaded sponges. We observed no significant differences in respiration among the
sponges tested; however, Haliclona walentinae and Xestospongia bocatorensis exhibited higher
oxygen production than A. fulva and N. subtriangularis. A phylogeny of cyanobacterial 16S
ribosomal RNA genes recovered from each sponge species confirmed that the symbionts of
Haliclona walentinae and Xestospongia bocatorensis are part of the O. spongeliae clade and
that each sponge hosts a unique ribotype of this vertically transmitted symbiont. The
cyanobacteria hosted by A. fulva and N. subtriangularis are part of the S. spongiarum clade,
which shows less host specificity despite evidence of vertical transmission. Ecological
interactions between sponges and their cyanobacterial symbionts vary among host species,
spaning a range of interactions from commensalisms to facultative and obligate mutualisms.
10.264
Growth strategy of a dominant reef-building coral in the southern Caribbean: Agaricia
tenuifolia
Silvia CACERES* 1 , Juan Armando SANCHEZ 2
1 2
Biologia, universidad de los Andes, Bogota, Colombia, Biologia, Universidad de los Andes,
Bogota, Colombia
Shifts have occurred in the coral community structure at Caribbean reefs, particularly regarding
dominance, which are not yet understood completely. The branching scleractinian coral,
Agaricia tenuifolia (thin leaf lettuce coral), is the dominant coral species in shallow reefs at
many Southern and Western Caribbean reefs. To estimate the population fluctuation and growth
strategy colonies of A. tenuifolia in the Southern Caribbean (Cartagena, Colombia) were
followed over a year and a half using photograph censuses and in situ growth measurements. A
size class model was generated in order to estimate colonial growth rate and clonal processes
(e.g., fission and fusion events). Overall population abundance was stable over the monitored
period, but differed between locations. The largest size class was directly responsible to the
dominant abundance of A. tenuifolia. Mortality patterns were not correlated to colonial size
classes and were variable in space and time. Fusion was also an important process in A.
tenuifolia but not as common as fission. Colonial growth rate was correlated to the colony size
class, the interaction between the location and the size class, the aggregation of multiple
colonies and possibly multiple genets. Clonal strategies, as bet hedges, allowed species like A.
tenuifolia to avoid the vulnerability to survive and compete that is often associated with early
post-settlement larvae. The A. tenuifolia population showed a dynamic life pattern with variable
rates for clonal processes that play an important descriptive role of the population together with
the size distribution frequency. A. tenuifolia is normally extracted as a souvenir in the Southern
Caribbean. Quantifying the changes in the population structure and size frequency is important
to manage this resource as it is necessary to perform long-term observations and coral
extraction experiments.
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