Coexistence of low coral cover and high fish biomass at Farquhar Atoll, Seychelles.
We report a reef ecosystem where corals may have lost their role as major reef engineering species but fish biomass and assemblage structure is comparable to unfished reefs elsewhere around the world. This scenario is based on an extensive assessment of the coral reefs of Farquhar Atoll, the most southern of the Seychelles Islands. Coral cover and overall benthic community condition at Farquhar was poor, likely due to a combination of limited habitat, localized upwelling, past coral bleaching, and cyclones. Farquhar Atoll harbors a relatively intact reef fish assemblage with very large biomass (3.2 t ha(-1)) reflecting natural ecological processes that are not influenced by fishing or other local anthropogenic factors. The most striking feature of the reef fish assemblage is the dominance by large groupers, snappers, and jacks with large (>1 m) potato cod (Epinephelus tukula) and marbled grouper (E. polyphekadion), commonly observed at many locations. Napoleon wrasse (Cheilinus undulatus) and bumphead parrotfish (Bolbometopon muricatum) are listed as endangered and vulnerable, respectively, but were frequently encountered at Farquhar. The high abundance and large sizes of parrotfishes at Farquhar also appears to regulate macroalgal abundance and enhance the dominance of crustose corallines, which are a necessary condition for maintenance of healthy reef communities. Overall fish biomass and biomass of large predators at Farquhar are substantially higher than other areas within the Seychelles, and are some of the highest recorded in the Indian Ocean. Remote islands like Farquhar Atoll with low human populations and limited fishing pressure offer ideal opportunities for understanding whether reefs can be resilient from global threats if local threats are minimized.
Fisheries Ecology Research Lab, Department of Biology, University of Hawaii, Honolulu, Hawaii, United States of America.
Alan M
AM
Friedlander
Coastal Research and Development in the Indian Ocean (CORDIO), Mombasa, Kenya.
David
D
Obura
Island Conservation Society, Mahé, Republic of Seychelles.
Riaz
R
Aumeeruddy
Centre d'Estudis Avançats de Blanes, Blanes, Spain.
Enric
E
Ballesteros
UniquEco Designs Ltd, Nairobi, Kenya.
Julie
J
Church
Centre d'Estudis Avançats de Blanes, Blanes, Spain.
Emma
E
Cebrian
Centre d'Estudis Avançats de Blanes, Blanes, Spain ; National Geographic Society, Washington, DC, United States of America.
Enric
E
Sala
D063147:Animal Distribution; D000818:Animals; D037421:Anthozoa / Q000502:physiology*; D018533:Biomass; D003247:Conservation of Natural Resources; D057894:Coral Reefs; D005399:Fishes / Q000502:physiology*; D058086:Microalgae / Q000502:physiology; D012750:Seychelles