The condition of coral reefs in South Florida (2000) using coral disease and bleaching as indicators

Abstract

The destruction of coral reef habitats has occurred at unprecedented levels during the last three decades. Coral disease and bleaching in the Caribbean and South Florida have caused extensive coral mortality with limited recovery, often coral reefs are being replaced with turf algae. Acroporids were once dominant corals and have diminished to the state where they are being considered as endangered species. Our survey assessed the condition of reef corals throughout South Florida. A probability-based design produced unbiased estimates of the spatial extent of ecological condition, measured as the absence or presence and frequency or prevalence of coral diseases and bleaching intensity over large geographic regions. This approach allowed us to calculate a quantifiable level of uncertainty. Coral condition was estimated for 4100 hectares (ha) (or 41.0 km2) of coral reefs in South Florida, including reefs in the Florida Keys National Marine Sanctuary (FKNMS), New Grounds, Dry Tortugas National Park (DTNP), and Biscayne National Park (BNP). The absence or presence of coral disease, 'causal' coral bleaching, partial bleaching and coral paling were not good indicators of overall coral condition. It was more useful to report the prevalence of anomalies that indicated a compromised condition at both the population and community levels. For example, 79% of the area in South Florida had less than 6% of the coral colonies diseased, whereas only 2.2% (97.15 ha) of the sampled area had a maximum prevalence of 13% diseased coral colonies at any single location. The usefulness of 'causal bleaching' might be more important when considering the prevalence of each of the three different states at a single location. For example, paling was observed over the entire area, whereas bleaching and partial bleaching occurred at 19 and 41% of the area, respectively. An index for coral reef condition might integrate the prevalence and species affected by each bleaching state at individual locations. By establishing these baselines, future surveys can examine changes and trends in the spatial distribution of coral conditions in South Florida and able to score the reefs as to their health status.

Resilience of Florida Keys Coral Communities Following Large-Scale Disturbances

“…A stratified random sampling design was used for selecting survey stations and has been detailed previously [8,28]. Briefly, hard coral bottoms were demarcated as reefs within each geographic region using a prototype of the Florida Marine Research Institute benthic habitat maps of the Florida Keys [29].…”

“…If a site was suitable for sampling, a permanent station was installed and surveyed. The random stations were matched by approximate depths between regions to allow comparison of condition ( All stations were assessed using a radial belt transect survey by SCUBA that has been used in coral reef surveys in US and Australia and has been detailed in other reports [7,8,28]. Transects were conducted by positioning a 2 m long rod into a permanent stainless steel pipe in the center of the survey station.…”

“…Ten coral disease categories were assessed including black-band disease, red-band disease, white-band disease, aspergillosis, white plague, white pox disease/patchy necrosis, dark spots disease, yellow blotch/band disease, skeletal anomalies and unknown. The unknown category was recorded when a disease condition was encountered which had not been previously described [8,28]. Colonies were evaluated as diseased only if they contained active lesions.…”

Pigmentation changes in Siderastrea spp. during bleaching events in the costal reefs of northeastern Brazil

“…Bleaching is associated with stress conditions that decrease the di-sease resistance of coral colonies (Rosenberg & BenHaim, 2002;Borger, 2005;Santavy et al, 2005;Weil et al, 2006;Palmer et al, 2008Palmer et al, , 2010, and brakes down the symbiotic relationship with zooxanthellae (Kaczmarsky, 2006;Weil et al, 2006).…”

Impact of the 2005 coral bleaching event on Porites porites and Colpophyllia natans at Tektite Reef, US Virgin Islands

“…Coral bleaching occurs when coral polyps loose pigment or expel zooxanthellae due to physiological stress, which recently has been most-often related to high water temperatures and high solar radiation (Brown 1997;Winter et al 1998;Santavy et al 2005). Since the 1980s, reports of coral bleaching in the Caribbean have increased, with major Caribbean-wide bleaching occurring in 1997-1998(HoeghGuldberg 1999Aronson et al 2000;Gardner et al 2003).…”