11th ICRS Abstract book - Nova Southeastern University

18.742
Continued Degradation Of Tobago’s Coral Reefs Linked To The Prevalence Of
Coral Disease Following The 2005 Mass Bleaching Event
Simon HARDING* 1 , Jan-Willem VAN BOCHOVE 1 , Shay O'FARRELL 1 , Owen DAY 2 ,
Keith GIBSON 1 , Katherine YATES 1 , Peter RAINES 1
1 Coral Cay Conservation, London, United Kingdom, 2 Buccoo Reef Trust, Carnbee,
Trinidad and Tobago
In the summer of 2005, the Caribbean region experienced a widespread coral bleaching
event. In order to determine the extent and effect of this event on the reefs of Tobago, the
Buccoo Reef Trust (BRT) and Coral Cay Conservation (CCC) conducted a targeted coral
reef survey programme at 22 sites around the island between October and November
2005.
A two-phase campaign was launched. In Phase I the reefs were assessed to establish their
current status. In Phase II, a long-term monitoring programme was installed in order to
monitor the reefs to record subsequent degradation or recovery from the event.
Results from Phase 1 found overall mean bleaching of hard corals to be 66%. Although
bleaching by geographic region was found to be consistent with sites exhibiting greater
than 85% bleaching throughout the area, some local reefs on the northeast of Tobago had
less then 20% bleaching, perhaps indicating localised tolerance. Bleaching was also
found to be highly variable, both between and within species. Notably, Acropora palmata
stands all appeared to be unbleached. No significant coral diseases were observed during
Phase 1 surveys.
Results from Phase 2 indicate a high prevalence of coral disease at many sites throughout
the area. Yellow Blotch Disease was commonly seen on Montastrea species. There were
also high levels of White Plague Disease and Aspergillosis. Initial findings suggest that
diseases were generally prevalent on reefs adjacent to areas of high coastal development
and/or agricultural land use.
18.743
Sediment Accumulation Rates And Coastal Land Use Change Impact in Abrolhos
Reef Complex, Brazil
Augusto NETTO* 1 , Roberto ARGOLLO 2 , Ruy KIKUCHI 1
1 Geophysics and Geology Research Center, Universidade Federal da Bahia, Salvador,
Brazil, 2 Institute of Physics, Universidade Federal da Bahia, Salvador, Brazil
The effects of sediment influx on coral reefs are important factors limiting the
development of this ecosystem. In the southeastern state of Bahia, Brazil, during the last
fifty years, rapidly increasing human pressure, due to deep changes in the coastal zone
land use threatened coral community of the coastal arc of Abrolhos Reef Complex. This
work evaluates sedimentation rates in one sediment core in the river mouth, in Caravelas
strandplain, and in four cores of the coastal arc of Abrolhos. Sediment accumulation rates
were determined by measuring 210Pb decay. The resultant rates vary between 6.68
mm.yr-1 in the river mangrove systems, and 1.28 mm.yr-1 in the reefs distant 80 km
from the coastline. However, no trend change was recorded along the core, thus
challenging the idea that deforestation in the last century has impacted negatively reef
environment, or else, no measurable impact was found in sedimentation rates, yet. This
lack of change may result of a sedimentary fencing role by oceanographic processes such
alongshore currents, or else, of mangrove systems buffering the river sediment discharge.
Thus, the deforestation of mangrove forests observed in the last decade and the
possibility that shrimp farming might begin in the coastal area adjacent to Abrolhos reefs
is a gloomy scenario to these reefs.
Poster Mini-Symposium 18: Reef Status and Trends
18.744
Historical Impacts On Coral Reefs At Rosario Islands, An Mpa in The Colombian
Caribbean
Oscar DELGADILLO* 1 , Paula ZAPATA-RAMÍREZ 1,2
1 Marine Biology, UJTL, Bogotá, Colombia, 2 UJTL, Bogotá, Colombia
The degree of natural and anthropogenic impacts on coral reefs at Rosario Islands does not have
been established in spite that the research in this area began in 1960. We attempt to determine
the extent of the different impacts on this ecosystem in the last 30 years. Five stations with
distinct coral reef development and historical research were assess at two depth levels (6 m and
12 m) with the quadrant method (80 m2 per station) to record coverage percentage of main
categories and secondary components. Actual information and historical data were evaluated
with graphics, cluster and similarities analysis (ANOSIM) to define distribution patterns and
differences in coverage through time and between stations. Time series analysis for historical
data of sedimentation and chlorophyll concentration as well as the graphic tendencies observed
in population growth, tourist income, water temperature, nutrients concentration and dredging
volumes, were performance to find out its relationship with changes in benthic coverage. A
decrease in coralline coverage in all stations in the eighties and a slightly recuperation in the last
15 years was evident, particularly in two stations declared intangibles islands. On the other
hand, a consistence change in dominance of coral species, high algae and abiotic substrate
coverage, mainly in stations nearest to human presence (overpopulation, fishing pressure,
sewage discharges, tourism and nautical activities), high sedimentation and chlorophyll
concentration, suggest that each station have different responses to the magnitude of the impacts
with regard to their own features which is a key point for conservation strategies.
18.745
Reef Structure Of Anegada: 30 Years Of Change
Shannon GORE* 1 , Mervin HASTINGS 2
1 Conservation & Fisheries, Government of the British Virgin Islands, Cruz Bay, Virgin Islands
(U.S.), 2 Conservation & Fisheries, Government of the British Virgin Islands, Road Town,
Virgin Islands (British)
The low-lying island of island Anegada in the British Virgin Islands is fringed with the
Horseshoe Reef that extends 51km and is one of the largest continuous reefs in the Caribbean.
However, few studies of this particular reef exist today, possibly due to its remote location
where dangerous northern Atlantic swells occur. A study from 1975 was replicated to produce a
semi-quantitative measure of the diversity and abundance of coral species and reef structure that
exists today. This study was combined with a literature review of all reef related research on
Horseshoe Reef that was compiled and analyzed to create a timeline of how the reef has
changed over the past 30 years. Natural events such as storms and disease outbreaks were added
to the timeline to help identify why changes occurred. Key threats to the future of the reef and
island itself are identified and recommendations are made for management plans.
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