Lake Erie Study
Colleagues from The University of Tennessee, Bowling Green State University, and Environment Canada sailed the entire length of Lake Erie over three days in late February onboard the Canadian Coast Guard Ship Griffon. The purpose of the voyage was to examine the status of microbial ecology of the lake during the depth of winter.
Lake Erie is commonly ice covered in winter. In late February 2007, Lake Erie had over 90% of its surface frozen with depths ranging from fractions of an inch in newly opened areas to over 10 feet thick in windrows where wind in open leads blows ice into piles on the ice shelf edge. However, as recently as 2002 there was no ice cover on the lake. Moreover, a four-year running average of percentage ice-cover on Lake Erie calculated by the United States Environmental Protection Agency shows a downward trend, possibly a harbinger of regional climate warming. What impact this could have on how the lake functions is not clear. Some suggest that ice protection prevents sediment suspension and keeps phosphorus, a key algal nutrient locked in sediments. Lower phosphorus levels will reduce the bloom of algae that happens every spring. Algal blooms are considered the prime culprit for the absence of oxygen deep in Lake Erie during the summer months due to the sinking of the algae and their decomposition that consumes oxygen.
One important observation on the February 2007 expedition was the presence of high concentrations of filamentous green algae called Zygnema. These blooms were occurring just below the ice surface forming visible brownish green coloration to the ice.
March 7, 2007 6:53 AM | Category: Lake Erie