A new study by researchers at the Virginia Institute of Marine Science shows that turbulence from boat propellers can and does kill large numbers of copepodstiny crustaceans that are an important part of marine food webs.
The studyby VIMS graduate student Samantha Bickel, VIMS professor Kam Tang, and Hampton University undergraduate Joseph Malloy Hammondappears in the March issue of the Journal of Experimental Marine Biology and Ecology.
The researchers don't expect their findings to lead to any new "No Wake" signs in local waterways; their interest instead is to better understand how significant levels of propeller-induced mortality among copepods might affect local food webs in Chesapeake Bay and other highly trafficked waterways.
"Non-predatory mortality such as this is rarely considered in the literature," says Bickel, "but it could be important for properly understanding zooplankton ecology and food-web dynamics in coastal and estuarine waters, particularly during summer months when recreational boating increases."
Zooplankton are small drifting animals that consume algae and other microscopic floating plants. Copepodsshrimp-like crustaceans about the size of a rice graintypically make up a major part of the zooplankton community and serve an important role by moving energy up the marine food chainfrom microscopic plants that are too small for most fish to eat up to larger game-fish and, ultimately, humans.
"If turbulence from boat propellers is killing off large numbers of copepods," says Bickel, "it could be reducing the supply of food energy available to fish, and reducing zooplankton grazing of algal blooms." "It's like cutting down the number of zebras in a herd," she adds. "That would affect not only the zebras, but also the grass they eat and the lions that eat them."
This type of shift could potentially have a noticeable impact on marine food webs and water quality. "If a large portion
|Contact: David Malmquist|
Virginia Institute of Marine Science