11th ICRS Abstract book - Nova Southeastern University

18-9
Long-Term And Large-Scale Trends in Caribbean Coral Reef Fish Populations
Michelle PADDACK* 1,2 , Isabelle CÔTÉ 1 , John REYNOLDS 1 , Andrew WATKINSON 2
1 Biological Sciences, Simon Fraser University, Burnaby, BC, Canada, 2 School of
Environmental Sciences, University of East Anglia, Norwich, United Kingdom
Coral reefs worldwide have become severely degraded within the past several decades.
This is particularly so in the Caribbean, where live coral cover across the region has
declined by 80%, resulting in reefs with dramatically changed benthic community
structure. Despite awareness that a fundamental shift in ecosystem structure has
occurred, there is currently no quantitative estimate of temporal trends for other aspects
of the coral reef community. Consequently, we have little understanding of how these
organisms are responding to changes driven by increasing stressors. The aims of this
project were to: (1) assemble, for the first time, all available abundance data on
Caribbean coral reef fish communities, and (2) analyze these data to test predictions
about how abundance and community composition respond to variation in both natural
and anthropogenic stressors. Data from over 30 published and unpublished scientific
surveys, spanning the entire range of years in which fishery-independent surveys have
been conducted (1973 – 2007), and over 80 sites across the Caribbean were compiled and
analyzed using meta-analytic techniques. Overall, there has been surprisingly little
change in abundance of coral reef fishes over the past 34 years. However finer-scale
examination reveals a mixture of significant declines and increases within specific guilds.
These findings suggest that Caribbean coral reef fish community assemblages are
experiencing shifts concomitant with changes in benthic structure, but that some groups
of fishes may be less resilient than others to ecosystem-wide stressors.
18-10
Population Status Of The Long-Spined Sea Urchin Diadema Antillarum in The
Florida Keys 25 Years After The Caribbean-Wide Mass Mortality
Mark CHIAPPONE* 1 , Dione SWANSON 2 , Leanne RUTTEN 1 , Steven MILLER 1
1 Center for Marine Science, University of North Carolina-Wilmington, Key Largo, FL,
2 Division of Marine Biology and Fisheries, RSMAS-University of Miami, Miami, FL
The 1983-84 Caribbean-wide mortality of the long-spined sea urchin Diadema antillarum
Philippi was followed by a second mortality event in the Florida Keys in 1991. The
demise of this once ubiquitous urchin is considered a key factor responsible for the
changes observed on Florida and Caribbean reefs during the past 25 years, including
increases in algal cover and declines in crustose coralline algae, reef coral abundance,
and coral recruitment. Over an 8-year period from 1999-2007, we examined densities and
test sizes of D. antillarum at over 800 sites spanning ~350 km of the southeast Florida
shelf encompassing Biscayne National Park, the Florida Keys National Marine
Sanctuary, and Dry Tortugas National Park. Visual surveys along belt transects were used
to enumerate the number of individuals and test sizes in a two-stage stratified random
sampling design that incorporated benthic habitat types, geographic regions, and nofishing
management zones. While pre-1983 densities in the Florida Keys were reported to
be as high as 5 individuals/m2, surveys since 1999 at over 850 sites in a variety of hardbottom
and coral reef environments from < 1 m to 27 m depth reveal that current
densities are still well below 1 individual per m2. During seven different annual sampling
periods, the maximum site-level density was only 0.33 individuals/m2, with the highest
densities of large (> 5 cm test diameter) individuals reported from shallow-water hardbottom
and reef sites in the Dry Tortugas and the upper Florida Keys. While the relative
importance of larval survivorship, predation pressure, suitable recruitment sites, and
reduced fertilization success are poorly known, these surveys provide baseline
information from which recovery can be monitored across multiple habitat types,
geographic regions, and managed areas.
Oral Mini-Symposium 18: Reef Status and Trends
18-11
Was The 1998 Coral Bleaching in The Southern Seychelles A Catastrophic Disturbance?
-1999-2006 Reef Fish Responses To Coral Substrate Changes
Raymond BUCKLEY* 1,2 , Nigel DOWNING 3 , Ben STOBART 4 , Kristian TELEKI 5
1 College of Ocean and Fishery Sciences, School of Aquatic and Fishery Sciences, University of
Washington, Seattle, WA, 2 Fish Program/Marine Resources, Washington Department of Fish
and Wildlife, Olympia, 3 Cambridge Coastal Research Unit, Cambridge University, Cambridge,
United Kingdom, 4 Marine Reserves, Spanish Institute of Oceanography, Mallorca, Spain,
5 International Coral Reef Action Network (ICRAN), Cambridge, United Kingdom
Responses of reef fish communities to massive losses of live coral habitat are influenced by preimpact
richness of corals and fishes, and by anthropogenic disturbances which can also
confound determinations of natural responses. Aldabra Atoll, a protected UNESCO World
Heritage site, and neighboring unprotected islands of Assomption, Astove and St Pierre, were
coral-rich sites prior to the 1998 bleaching-event loss of up to 50% of live coral. Hard coral
recovery has been minimal except for significant increases at St. Pierre. Multivariate
comparisons are made of fish populations at 10m and 20m depths at Aldabra (1999-2006; Sites
1-8), Assomption (2002-2006), Astove (2002-2005), and St Pierre (2002-2005). Aldabra fish
abundances by species were not different between years and sites, except at Sites 2 (10m), 4
(20m), and 7 (20m), where between year differences were driven by high annual variability in
schooling, reef-resident planktivores (Serranidae 5 species, Labridae 1 species, Pommacentridae
5 species). Removing these species from analyses eliminated differences at Sites 2 and 4, but
Site 7 remained different, likely due to storm-induced inundation by sand that caused habitat
changes. Assomption, Astove and St. Pierre fish abundances by species were not different
between years, and were similar to high fish counts at Aldabra Site 6. These results support
earlier analyses that post-bleaching reef fishes at Aldabra represent pre-bleaching community
structure, and abundance changes appear to be within the natural ecology of the system. Similar
responses at neighboring unprotected islands suggest that any local harvest primarily affects
non-reef-resident species. The massive1998 losses of live coral habitat in these rich coral and
reef fish communities do not appear to represent catastrophic disturbances that changed the
basic structure of the reef fish assemblages.
18-12
Spatiotemporal Trends in Biodiversity And Coral Reef Communities Structure At A
Decade Scale (Reunion Island; Southwest Indian Ocean)
Lionel BIGOT* 1 , Bruce CAUVIN 2 , Emmanuel TESSIER 2 , Pascale CHABANET 3 , Vianney
DENIS 1
1 ECOMAR, University of Reunion Island, St Denis, Reunion, 2 APMR - Reunion Marine
Reserve, St Leu, Reunion, 3 IRD La Réunion, Ste Clotilde, Reunion
Since 1998, the GCRMN standardised methodology (LIT) has been used to assess the coral
reefs and fishes in Reunion Island through a monitoring survey realized each year. Fourteen
stations have been surveyed on the reef flats and the outer reef slopes at St Gilles / La Saline,
St-Leu, Etang Sale and St Pierre reef complexes. Spatio-temporal trends of benthic community
structure and fishes were studied in the context of the BIOCOR and PAMPA scientific project
related to the implementation of the new Marine Reserve. The first results on St Gilles / La
saline reef show that 75 species of corals have been recorded during the 10 last years and
highlight the dominance of the “habitat” factor on the time (year) factor. Main trends in benthic
community structure show that algal coverage became dominant after 2000 on reef flat and reef
slopes. On the outer reef slopes, temporal trend is associated with a decrease of coral cover
(from 56 to 32 % in 2007) and coral diversity (from 29 in 1998 to 15 species in 2006), and a
progressive shift of coral communities. St Leu outer reef slope are characterized by the highest
live coral coverage and diversity and a moderate temporal changes in benthic communities
between 1998 and 2007.
Overall, fish densities increase after 2002 on all sites that could be due to a massive recruitment.
Moreover, results on trophic structure highlight important fluctuations through time of
herbivore groups while carnivorous group remains at a very low level, results probably related
to overfishing.
All these results displayed contrasting spatial and temporal situations of Reunion Island coral
reef ecosystems that are subjected to several natural disturbances (cyclone, bleaching)
surrounding the chronic anthropogenic pressures affecting coral reef communities according to
their degree of resilience.
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