Increased levels of water temperature can have critical effects on predator-prey interactions in the marine environment. Increased water temperature, for example, could be beneficial to a predator if the primary effect were to accelerate its level of metabolism, and thus enhance foraging activity. On the other hand, warm temperatures could also enhance the metabolism of the prey, increasing its activity, mobility, and ability to escape from predators.

In a recent issue of the Marine Ecology Progress Series, an article by URI Graduate School of Oceanography fisheries biologists David L. Taylor and Jeremy S. Collie describes the effect of temperature on the feeding behavior of sand shrimp preying on juvenile winter flounder. The study was funded by the National Oceanic and Atmospheric Administration's Cooperative Marine Education and Research program.

Predation by the sand shrimp has been implicated as one of the most significant sources of mortality for recently hatched metamorphosed winter flounder. Experiments conducted by Taylor and Collie found that shrimp consumption rates on post-settlement flounder significantly increased with increasing flounder density, irrespective of water temperature. At low flounder densities, however, significantly more flounder were consumed at warm temperatures than at cold temperatures (16 C and 10 C, respectively, or 61 F and 50 F). Model estimates and visual observations of shrimp foraging behavior suggest that the variable feeding rates at different temperatures are the result of cold temperatures decreasing predator activity at low flounder densities, and conversely, shrimp maintaining high predation rates at low flounder densities when exposed to warm temperatures. These findings indicate that shrimp are capable of driving flounder populations to local extinction during warm water conditions.

The population abundance of winter flounder has declined significantly in parts of its geographic range sin
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Contact: Lisa Cugini
lcugini@gso.uri.edu
401-874-6642
University of Rhode Island
17-Feb-2004

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