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Monitoring the abundance and health of the organisms occupying the lower trophic levels in the Great Lakes is critical both for understanding current conditions in, and for identifying potential threats to, these unique ecosystems. Although such changes may be hard to see from the surface, the structure of food webs in the Great Lakes has changed rapidly in the past several decades due both to the proliferation of aquatic invasive species and to improved nutrient management and control. In terms of the former, invasive species have impacted the food web in a variety of ways, by outcompeting native species for food sources or habitat and by altering the flow of energy through the existing food web. In terms of the latter, nutrient control and abatement efforts in the 1970s initially led to substantial improvements in water quality in the region; however, water quality in many of the lakes remains less than desirable due to run-off from agricultural and urban areas.
Because the lakes are dynamic systems, monitoring programs such as the one described here are critical for tracking large-scale responses of the Great Lakes to changes associated with lakewide responses to things such as invasive species, climate change, and nutrient loadings.
Beginning in March of 2007, scientists from the Cooperative Institute for Limnology and Ecosystem Research (CILER  ), at the University of Michigan (UM ) will initiate the Great Lakes Biological Monitoring Progran, in collaboration with the US Environmental Protection Agency (USEPA ). This $2.5M, five-year program (2007-2012) focuses on the collection and analysis of field samples of chlorophyll a, zooplankton, and benthic invertebrate communities from all five Great Lakes.
USEPA's Great Lakes National Program Office (GLNPO ) has been running this annual Great Lakes research and monitoring program since the early 1980s. This effort was originally initiated to fulfill EPA's obligations under the Great Lakes Water Quality Agreement (GLWQA ) and has focused on whole lake responses to change in loadings of anthropogenic substances, such as phosphorus and contaminants, and to the establishment of nonindigenous species. In order to assess lakewide responses to these events, sampling generally occurs in the offshore waters of each lake ().
- Improved phosphorous control strategies
- Improved monitoring for new invasive species
- Improved ability to predict impacts on the lower food web from invaders and to determine their effects on fisheries
- Improved management for the Great Lakes fish stocking program
The GLBMP will involve two sampling surveys per year for each Lake aboard the USEPA research vessel Lake Guardian. During these surveys, University of Michigan researchers will collect and analyze water samples to determine chlorophyll a concentrations and will determine the quantity and biomass of zooplankton and benthos from water and sediment samples. These data are essential for determining ecosystem health, since these trophic levels form the base of the food web. Changes at the base of the food web have the potential to reverberate throughout the ecosystem, impacting important fishery resources and altering ecosystem function.
In addition to these monitoring efforts, University of Michigan scientists will augment the program with research to enhance the understanding and application of the monitoring data. To do this, we have proposed a range of possible research elements including: 1) evaluating optimal sensor technologies for measuring chlorophyll concentrations; 2) tracking the status and conditions of Mysis relicta through the Great Lakes; 3) assessing the impacts of changes in the lower trophic web to fish production; and 4) analyzing current changes in the food web in the context of historical conditions. The results from these efforts should help optimize sampling efforts and provide new insight into recent changes in the Great Lakes ecosystem.
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