A tiny copepod. Photo: Uwe Kils / Creative Commons.
Minuscule and often transparent, zooplankton are little noticed as they float through bodies of water, but their absence can have a big impact on aquatic ecological systems, in which they serve as a key source of nourishment for larger animals. That essential food chain is being disrupted, new research has found, by speeding motor boats, which can wipe out zooplankton in droves."Experiments on copepods, tiny crustaceans that live and float in water, show that a third die in waters frequented by propeller-driven boats. That is significantly more than in bodies of water not used by boats," the BBC's Earth News channel reported yesterday.
The study, published in the Journal of Experimental Marine Biology and Ecology, is the first to look at the effects of motor-boat turbulence on the tiny aquatic creatures. Previous research had showed that even small disruptions to the water in which they live can affect copepods' abilities to feed and grow.
High Zooplankton Mortality Rates
So "it seemed intuitive that the sudden and intense turbulence created by a boat could harm or even kill copepods," Samantha Bickel, a Ph.D. student at the Virginia Institute of Marine Science in Gloucester Point, told Earth News.
To test their theory, Bickel and two other researchers sampled copepods from three locations in tributaries of the Chesapeake Bay. They found twice as many copepod carcasses inside boat wakes than outside them, and seven times as many of the zooplankton dead in a channel traversed by boats than closer to the shore.
According to the researchers, high copepod mortality levels could have a significant impact on local ecosystems, leaving small fish without enough to eat, encouraging ecologically dangerous phytoplankton blooms, and contributing to bacterial growth in bodies of water.
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