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Project 19

Project Title: Monitoring and Predicting Concentrations of Cyanobacterial Toxins in Michigan Lakes
Investigators: Howard Wandell/Orlando Sarnelle
Contact: Orlando Sarnelle (sarnelle@msu.edu)

Abstract: A long-standing and well-supported tenet of freshwater ecology is that summer blooms of potentially-toxic cyanobacteria (typically species belonging to the genera Anabaena, Aphanizomenon, Microcystis and Oscillatoria) are a characteristic response to nutrient (particularly phosphorus) enrichment and a symptom of eutrophication (Smith 1986, Trimbee and Prepas 1987, Paerl 1988, Downing et al. 2001).  As a result, much effort and expenditure has been directed toward reducing nutrient loading to alleviate water-quality problems associated with toxic cyanobacterial blooms.  However, recent studies indicate that invasion by the zebra mussel (Dreissena polymorpha) results in a substantial increase in toxin-producing cyanobacteria in lakes with low-moderate nutrient levels.  For example, Gull Lake in southwest Michigan has oligo-mesotrophic levels of phosphorus (summer total phosphorus concentrations of 8 - 12 µg/L) and was virtually free of toxin-producing cyanobacteria in the early 1990's.  Since being invaded by Dreissena in 1994, Microcystis aeruginosa has become one of the dominant phytoplankton species in mid-late summer (Sarnelle et al. 2005).

This project has two major themes.  The first is to assess toxin (microcystin) concentrations at the point of human contact for a large number of lakes.  We are particularly interested in the interaction between phosphorus concentrations and Dreissena invasion, as our previous research has suggested that these two factors interact strongly and in unexpected ways (Raikow et al. 2004, Sarnelle et al. 2005).  We will evaluate a large number of lakes for microcystin concentrations, in the open water and in the littoral zone, where much of the recreational activity occurs.  The second theme is to examine how well traditional indicators of eutrophication predict toxin concentrations in Michigan lakes.  Besides the microcystin concentrations, the traditional trophic state parameters, water clarity, total phosphorus and chlorophyll will be analyzed.  By collaborating with the State’s Cooperative Lakes Monitoring Program (CLMP) a large number of lakes can be sampled in one summer.  The CLMP is Michigan’s lake volunteer monitoring program
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For more information:
Orlando Sarnelle (sarnelle@msu.edu)
Howard Wandell (wandellh@msu.edu)