PARENT SESSION
Oral Session #70: Invasive Species: Aquatic.
Presiding: S. Juliano
Wednesday, August 7. 1:00 PM to 4:45 PM. Grand Ballroom East, Radisson.
Zebra mussel impacts on phytoplankton across a productivity gradient in Michigan lakes.
Raikow, David*,1, Sarnelle, Orlando1, Wilson, Alan2, Hamilton, Stephen1, 1 Michigan State University, East Lansing2 University of Georgia
ABSTRACT- A survey of 60 inland lakes across the State of Michigan was conducted in 1998 and 1999 to assess the interacting effects of total phosphorus (TP) and exotic zebra mussels on phytoplankton abundance and community structure, transparency, and nutrient concentrations. Lakes with zebra mussels had lower phytoplankton abundances (chlorophyll a concentration and total algal biovolume), different algal communities, and lower dissolved organic carbon concentrations (DOC) than lakes without zebra mussels. Differences in phytoplankton communities included increases in the relative abundances the colonial cyanobacterium Microcystis at low TP concentrations. Lakes with and without zebra mussels were equally transparent and had similar ammonium and soluble reactive phosphorus (SRP) concentrations. Total phytoplankton abundance and abundance of cyanobacteria were positively related to TP, but many individual cyanobacterial species were not. Zebra mussels may contribute to Microcystis blooms in low-TP lakes, as previously observed in several Michigan inland lakes. The reduction of DOC may render inland lakes more susceptible to UV-B radiation.
KEY WORDS: Zebra Mussel, Phytoplankton, Inland Lake, Biological Invasion