Caribbean: "Overfishing of Sharks Key Factor in Coral Reef Decline."

"Jordi Bascompte and Carlos Melián of the Integrative Ecology Group, Estación Biológica de Doñana, Consejo Superior de Investigaciones Científicas, in Sevilla, Spain, and Enric Sala of Scripps Institution of Oceanography at the University of California, San Diego, developed an unprecedented model of a Caribbean marine ecosystem and details of its intricate predator-prey interactions.

This food “web” covered 1,000 square kilometers to a depth of 100 meters and included some 250 species of marine organisms. The study, published in the April 12 edition of the Proceedings of the National Academy of Sciences, included an intricate network of more than 3,000 links between these species.

The project was one of the largest and most detailed investigations of marine food webs and the first study to integrate food web structure, dynamics and conservation.

One of the most striking products of the study is a stark picture of human impacts on marine ecosystems and the consequences of targeted fishing. In the Caribbean, overfishing of sharks triggers a domino effect of changes in abundance that carries down to several fish species and contributes to the overall degradation of the reef ecosystem. Overfishing species randomly, the study shows, is not likely to cause these cascading effects.

“It appears that ecosystems such as Caribbean coral reefs need sharks to ensure the stability of the entire system,” said Sala, deputy director of the Center for Marine Biodiversity and Conservation at Scripps.

Red full report: "Overfishing of Sharks Key Factor in Coral Reef Decline." NewsWise, 11 Apr 2005. Based on: Bascompte, J., C. J. Melián & E. Sala, 2005. Interaction strength combinations and the overfishing of a marine food web. Proc. Natl. Acad. Sci. USA, 10.1073/pnas.0501562102. Published online, 31 Mar 2005. Abstract.