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The USEPA  monitors the ecological conditions of the Great Lakes in order to identify water quality trends over time and to identify emerging problems or changes in the Great Lakes Basin ecosystem. To help the USEPA meet these objectives, University of Michigan researchers are collecting water samples and sampling organisms two times a year from all of the Great Lakes. Because of temporal seasonal changes in lake conditions, samples are currently being collected during the spring isothermal period (with samples collected in April) and during the stable and stratified summer period (with samples collected in August). Although the lakes contain many different types of habitats, this monitoring program collects samples primarily from the relatively homogenous offshore region, also known as the pelagic zone (link here to sampling stations for GLNPO).
During the shipboard surveys, researchers collect a range of information about lake conditions. To do this, they use equipment to measure physical and chemical parameters such as temperature and oxygen. They also collect samples of pelagic (open water) and benthic (bottom water and sediment) organisms. Water samples from the Great Lakes have been analyzed for phytoplankton and zooplankton since the beginning of the program. In 1997, samples of benthic invertebrates were added to the monitoring program to help evaluate observed changes in populations of Diporeia , an important and sensitive bottom water organisms.
Phytoplankton are small (microscopic) plants that form the basis for the food web in the Great Lakes. In general, phytoplankton communities in the Great Lakes in the spring are dominated by diatoms, which tend to have the highest biomass in western Lake Erie and the lowest biomass in Lake Superior. By mid- to late summer, the phytoplankton communities tend to change from diatoms to dinoflagellates, chrysophytes, and chlorophytes. The phytoplankton identification and community analysis is being conducted by a team from the University of Minnesota, Duluth, led by Dr. Euan Reavie .
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Definition here plus some background information about chlorophyll trends in the Great Lakes.
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 Additional details on sampling methods and protocol.
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Crustacean zooplankton communities in the Great Lakes tend to consist primarily of cyclopoid and calanoid copepods, with rotifers dominating at later parts of the summer. Note here any temporal or spatial variations.
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Additional details on sampling methods and protocol.
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The benthic community of the Great Lakes has undergone pronounced changes over the past decade. Historically, the amphipod Diporeia dominated deeper benthic communities in the upper Great Lakes and in Lake Ontario, while oligochaetes were more predominant in shallower waters. Beginning in 1998?, researchers began to note and document a dramatic decline in the abundance and biomass of this organism (side bar here?). Continued monitoring of the benthic community has become increasingly important, so that scientists and managers can better understand the potential implications of this change for the ecology of the Great Lakes, especially in terms of implications for fish growth and survival.
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Additional details on sampling methods and protocol.
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