Ohio Sea Grant researchers at BGSU have discovered a winter-loving algae that may be contributing to the summertime “dead zone.”
Drs. Michael McKay and George Bullerjahn, biological sciences, first observed the algae, Aulacoseira islandica, in brownish pockets floating under Lake Erie’s ice in February 2007 while they were on a research trip aboard a Canadian Coast Guard icebreaker. The pair determined that the plankton sometimes made up as much as 80 or 90 percent of the biomass in collected samples. (See http://www.bgsu.edu/offices/mc/monitor/11-19-07/page40719.html)
Their goal now is to determine whether the diatoms get eaten by zooplankton and other organisms or simply die and sink to the bottom of Lake Erie.
“If it turns out that most of these diatoms end up on the lake floor, they would provide a large source of organic carbon for bacteria to decompose, which would consume oxygen,” McKay said. “If this decomposition happens mainly when the water warms up and stratifies—forming a warm upper layer and a cold lower layer in the summer months—and not during the frigid winter months, it has to be contributing to the dead zone.”
The group will use Sea Grant funding to collect data for the next two winters, including taking part in several more science cruises. In addition, Environment Canada will use its icebreaker to deploy sediment traps that will sit on the bottom of the lake during the coldest months of the year, which should help determine if the diatoms are indeed sinking to the bottom. Preliminary data should be available in summer 2010.
To read more about the research, visit http://ohioseagrant.osu.edu/_documents/twineline/v31i3.pdf.
Ohio State University’s Ohio Sea Grant College Program is part of the National Oceanic and Atmospheric Administration’s Sea Grant, a network of 30 programs dedicated to the protection and sustainable use of marine and Great Lakes resources. For information on Ohio Sea Grant, visit http://www.ohioseagrant.osu.edu.