Thursday, May 29, 2008 - 4:45 PM
622

Spatial and temporal variability in periphyton response to simulated nonpoint source (NPS) inputs in the Muskegon River watershed, Michigan

Mary E. Ogdahl, Alan Steinman, and Scott Kendall. Annis Water Resources Institute, Grand Valley State University, 740 W. Shoreline Dr., Muskegon, MI 49441

Nonpoint source (NPS) pollutants threaten the ecological integrity of aquatic habitats. On a watershed scale, NPS pollutants have the potential to influence biota across multiple habitat types. Our objectives are to 1) evaluate the effects of NPS effects on multiple trophic levels and 2) assess whether or not the influence of NPS is consistent among three different habitats in the lower Muskegon River watershed. In each habitat (river, wetland, lake), we simulated NPS pollution events concurrently during four seasons in 2006 and 2007.  Periphyton biomass and metabolism data indicate that each habitat responds independently to nutrient inputs.  In the wetland, nutrients had a negative influence on periphyton biomass and metabolism during several events, with significantly lower gross community production (GCP), community respiration (CR), and chlorophyll a in treatment than control areas.  In the river, periphyton responded variably with NPS resulting in greater net community metabolism (NCM) during winter and fall, but lower NCM during spring. In the lake, NPS led to significantly greater chlorophyll a during spring and summer and greater GCP during fall and winter. Within each habitat, seasonal factors influenced the magnitude and direction of periphyton response.  Our data indicate that within the lower Muskegon River watershed, local controls have greater influence over periphyton response to NPS pollution than the regional influence of hydrologic connectivity.


Web Page: nonpoint source pollution, periphyton

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