11th ICRS Abstract book - Nova Southeastern University

Poster Mini-Symposium 10: Ecological Processes on Today's Reef Ecosystems
10.337
Abundance And Destructions Of Acanthaster Planci (L) On Reefs Off Zanzibar
Town
Ali USSI 1 , Christopher MUHANDO* 2
1 Marine Biology and Resources management, Institute of Marine Sciences, University of
Dar es Salaam, Zanzibar, Tanzania, 2 Institute of Marine Sciences, Zanzibar, Tanzania
Outbreak of Acanthaster planci, crown of thorns starfish (COTS), in Zanzibar has been
increasing from the past two decades. COTS plague emerged from year 2000 still persist
in some of off Zanzibar town reefs (Pange, Nyange and Murogo). Recognizing the
significance of outbreaks, both ecologically and economically to the livelihood of local
communities, a study aiming at estimating COTS density, distribution of their population
and comparing feeding rates among size categories (juveniles (¡Ü 19cm), sub adults(20-
29cm) and adults >29cm) was conducted in June 2007 at Murogo. COTS density was
estimated using belt transects (50mx5m, n=30) while the population structure was
evaluated by taking length frequency measurements. Feeding rates were estimated from
scaled feeding patches, using CPCe, photographed from observed feeding individuals (at
least 50m apart, n=32) which were haphazardly selected from the population. Mean
COTS density was 6individuals/100m2. The population was dominated by middle sized
individuals. The mean feeding rates were 113.66cm2/meal/day, 232.26cm2/meal/day and
244.12cm2/meal/day for juveniles, sub adults and adults respectively. However, the rates
were not statistically significant among size categories (1-way ANOVA). Results from
this study are in support of initiating regular COTS eradication programs as a
management option for such small reefs as density is as high as the destruction rate.
However, more studies are needed to determine the most vulnerable coral species and
monitor the rates of reef recovery and recruitment of COTS population after removal so
that the impact of destruction on change of reefs community and patterns of outbreaks
can predicted.
10.338
Scleractinian Coral Recruitment Patterns To Reefs Physically Damaged By Ship
Groundings
Ewelina RUBIN* 1 , Alison MOULDING 1 , Jose LOPEZ 1 , David GILLIAM 1 , Richard
DODGE 1 , Vadimir KOSMYNIN 2
1 Oceanographic Center, Nova Southeastern University, Dania Beach, FL, 2 Bureau of
Beaches and Coastal Systems, Florida Department of Environmental Protection,
Tallahassee, FL
The scleractinian corals of the Florida reef system face a number of environmental stress
factors, among which ship groundings are considered to be one of the most physically
damaging. In particular, a part of the Florida reef tract located near Port Everglades,
Broward County, USA has been commonly affected by ship groundings which have
caused severe injuries to the local reef ecosystem. In 2004, physical damage of at least
30,000 m2 area was caused by the groundings of two large cargo ships, the Eastwind and
Federal Pescadores. The present study was designed to measure any possible differences
of scleractinian coral recruitment patterns (recruit diversity and richness) and rates (# per
area) to these injured sites in comparison to undamaged reef sites. Coral recruitment rates
were measured on unglazed ceramic tiles deployed for a period of one year from
February 2007 to February 2008 at five different locations including: two control sites,
one high coral cover site and the two ship grounding sites. Morphometrics as well as
multiple genetic markers (ITS region, CO1 and beta-tubulin genes) were used to identify
the coral recruits. It is hypothesized that the final results will reveal significant
differences in recruitment rates at the ship grounding sites in comparison to the control
sites. Based on the coral recruitment rates and patterns, this study will increase
understanding of the potential of natural coral recovery after acute physical damage.
10.340
Estimation Of Fish Herbivory On Antillean Coral Reefs
Dorothée KOPP* 1,2 , Yolande BOUCHON-NAVARO 1 , Sébastien CORDONNIER 1 , Alexandre
HAOUISEE 1 , Max LOUIS 1 , Claude BOUCHON 1
1 Laboratoire de biologie marine, Université Antilles-Guyane, Pointe-à-Pitre, Guadeloupe,
2 UMR 5119 CNRS-IFREMER-UM2 ECOLAG, Université Montpellier 2, Montpellier, France
Worldwide, coral reefs present alterations of their coral communities in the way that corals, are
progressively supplanted by macroalgae. In this context there is a need to identify the processes
able to limit the proliferation of algae. Herbivores have a certain capacity to maintain low
macroalgal covers on the reef, but the importance of the role of herbivorous fishes in the
resilience of this ecosystem is not yet well known. For that purpose an experiment was
conducted in Guadeloupe Island (French West Indies) on several reefs located in protected and
non-protected areas. The grazing pressure by Acanthurid and Scarid fishes was evaluated by
counting fish bites in different algal facies (algal turf on rocky substrate, algal turf on coral
rubble, macroalgae assemblages, calcified Chlorophyta). Algal consumption by these fishes was
evaluated by quantitative analyses of their gut contents combined with the evaluation of their
density on the reefs by visual censuses. In parallel, an experiment was designed to estimate the
algal turf productivity throughout the year and at different depths.
In situ counts of fish bites revealed that species feed preferentially on algal turf and avoid
macroalgae. The algal consumption (dry weight) varied between 0.4 and 2.8 g.m-2.d-1 and was
higher inside marine protected areas than on fished reefs. Herbivory pressure was also higher on
reef flats than on reef slopes, where it decreased according to depth and, in parallel, with the
algal turf coverage which also diminished with depth. The results confirm that herbivorous
fishes exert a control on the reef algal asssemblages and that they play a significant role in
maintaining low algal covers where they are abundant enough (marine protected areas). On
overfished reefs, brown macroalgae have the possibility to proliferate and are no longer
consumed by herbivores if the plants can reach their full size.
10.341
Spatial Distribution Of Herbivorous Reef Fishes in Guadeloupe (Fwi): The Influence Of
Environmental Factors
Dorothée KOPP* 1,2 , Yolande BOUCHON-NAVARO 1 , Max LOUIS 1 , Claude BOUCHON 1
1 Laboratoire de biologie marine, Université Antilles-Guyane, Pointe-à-Pitre, Guadeloupe,
2 UMR 5119 CNRS-IFREMER-UM2 ECOLAG, Université Montpellier 2, Montpellier, France
The exuberant development of benthic macroalgae that enter in competition with corals is one
of the major phenomena that threaten coral reefs in the Caribbean. As herbivorous fishes have a
preponderant role in maintaining low macroalgal cover on the reefs, it is important to
understand the influence of environmental factors on their distribution. For that purpose, the
quantitative distribution of herbivorous fishes was studied on seven reef sites distributed around
the island of Guadeloupe (FWI). Fifteen stations were distributed on reef flats and outer ref
slopes to 30 m deep. Fish density was evaluated by visual censuses on band-transects of 150 m
long by 2 m wide. In parallel, 15 environmental descriptors concerning the habitat and the
benthic communities were collected on the same transects, using a linear points intercept
technique. The descriptors were separated into different data sets: algae (Rhodophycea,
Pheophycea, algal turf), benthic Invertebrates (corals and others), substrate characteristics
(sand, rubble, rock) and three other variables related to the status of protection, the season and
depth. Data were analyzed by variance partitioning in association with canonical redundancy
analyses.
Whatever the type of data considered (presence-absence, density or biomass), herbivorous
fishes were mostly controlled by the coverage rate of corals and other Invertebrates (from 17,1
to 20,1% of the total variance of the data) and algal assemblages (15,3 to 18,3%). Depth is the
third variable explaining 13,2 to 19,9% of the data variance. The status of protection of the reefs
plays a significant role only for the biomass distribution of herbivorous fishes (17,5% of the
variance) that are more abundant in marine protected areas. These results suggest that
herbivorous fishes are closely related to certain characteristics of their habitats and that they are
likely to be very sensitive to changes of the composition and structure of benthic communities.
347