Larry Crowder, who is Stephen Toth Professor of Marine Biology at Duke's Nicholas School of the Environment and Earth Sciences, will discuss these potential long range impacts of nutrient runoff from distant farm fields at a 1:45 p.m. Feb. 20 symposium during the American Association for the Advancement of Science's 2005 annual meeting in Washington, D.C.
The symposium will take place in Workshop Room E of Exhibit Hall B North at the Marriott Wardman Park Hotel.
Crowder's research group has been studying a so-called "dead zone" that forms annually off Louisiana in the Gulf of Mexico. Water within this approximately 20,000 square-kilometer-wide bottom feature is robbed of much of its dissolved oxygen each spring in a biological response to farm fertilizer runoff that may originate far upstream along the Mississippi River, he said.
After entering the Gulf, these fertilizer nutrients fuel population explosions among microscopic marine plants. As the marine algae grow and then die, they consume most available oxygen in bottom layers.
Crowder described how fish and shrimp can evade death simply by relocating to the zone's edge. "Basically, it's the same as the way forest wildlife might aggregate on the edge of a forest fire," Crowder said in an interview. And shrimpers and fishermen exploit that knowledge by positioning their nets at the zones' periphery too, he added.
Crowder's group is studying whether this annual convergence may result in overfishing, in significant upsurges in inadvertent nettings of other untargeted marine species, called "bycatch," or in other less obvious delayed effects that may reduce commercial production.
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Contact: Monte Basgall
monte.basgall@duke.edu
919-681-8057
Duke University
19-Feb-2005