Tuesday, March 22, 2011

Source of nutrients for ecosystem lost as coastal fisheries decline

A new study by researchers at the University of Georgia and Florida International University has found that the elimination of large marine predators through overfishing and habitat alteration removes a vital source of nutrients for coastal ecosystems.

The study, currently in press in the journal , shows that the influence of these large goes far beyond their role as predators.

“The effects are not just top-down,” said study co-author Jacob Allgeier, a doctoral student in the UGA Odum School of Ecology who led the study with Craig Layman of Florida International University. “When you eliminate these large predators, you also eliminate a major source of nutrients for algae and plants in the food web, especially in tropical and sub-tropical coastal areas.”

Working at study sites on Andros Island, the largest island in the Bahamas, the team, which included UGA associate professor of ecology Amy Rosemond, compared populations of gray snapper – an abundant and economically important species – from areas that experience varying levels of human impact, specifically and habitat alteration. One group of sites was located on the west coast of Andros, an area with virtually no human impacts. The other sites were on the island’s east coast, home to most of Andros’s population. Those sites were affected by fishing and habitat fragmentation in the form of roads that cut off interior wetlands from the ocean. The study sites, deep tidal creek mouths lined with mangrove trees, were otherwise similar. (read more)