Community Structure in the Great Lakes

In Professor Allan's lecture on community structure (Nov. 9th), we discussed how the concept of trophic cascades can be applied to lake plankton systems. Currently, there are significant changes occurring in the community structure of the Great Lakes, which has lead to studies by NOAA's Great Lakes Environmental Research Laboratory (GLERL) examining both the overarching effects and causes of these changes. One of the most striking indicators of these changes has been the dramatic decline of Diporeia, a small, shrimplike crustacean that is high in energy-yielding proteins and lipids. Diporeia is an integral component of Great Lakes ecosystems as well as the economy of the Great Lakes region because it is a vital part of the food web and serves as a major food source for nearly every fish species in the Great Lakes, including game fish such as Whitefish and Yellow Perch. While several factors may be involved in the decline, the most likely suspects seem to be invasive species such as Zebra and Quagga mussels, which filter algae from the water, and pollutants from inputs such as pesticides . U of M's own Tom Johengen, David Jude, Mike Wiley and Wendy Stott as well as researchers from NOAA/GLERL, Purdue, and SUNY/Brockport are currently in the process of investigating these important ecosystem changes. Knowing the underlying causes and factors contributing to the decline in Diporeia will be essential in implementing effective management decisions. I have included links for further reading on this current and highly relevant issue below.

Great Lakes: 'Amazing Change'
Mapping the Condition of Diporeia: Insights into Mechanisms of Declines
Why Is Shrimplike Diporeia Disappearing From Lake Michigan?

Whole eco-systems experiments have taken place in several lakes where curtains where used to create a control experiment. This evidence of the effects of phosphate based detergents.

In marine based systems, this type of nitrogen affects much of the life presents in systems. The Gulf Coast Dead zone is a good example.

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