NOAA GREAT LAKES SEMINAR SERIES
Thursday, November 20, 2003
"The benthification of freshwater lakes: Exotics turning ecosystems upside down"
Assistant Professor, Department of E.E.E.S.
University of Toledo, Lake Erie Center
GLERL Main Conference Room
2205 Commonwealth Blvd.
Ann Arbor, MI 48105
We define benthification as an increase in the importance of benthic processes following increased water clarity promoted by nutrient reduction and Dreissena introduction. However, the relative contributions of these two factors to the process of benthification are not yet understood. In a benthified system, the extent of potential benthic primary production increases. Benthic grazers may respond positively to increased benthic algal production. In contrast, pelagic primary production may, or may not change as standing crop declines, but detrital rain to the profundal zones should decrease whereas direct importation of organic material will increase in Dreissena colonized areas. Therefore, the overall flux of material from the pelagic to benthic zones may not change. In contrast, the flux of materials from benthic to pelagic zones should increase, as visually feeding fish will forage more efficiently on benthic invertebrates. The overall effect of benthification will be to increase the production and flux of organic material from the lake's bottom. Long-term data from six aquatic ecosystems for which a minimum 15 years of data on nutrient concentration, water clarity and time of Dreissena invasion were examined to determine whether nutrients or Dreissena more strongly influence increased water clarity. Our results suggest that Dreissena introduction has had more influence on the increase in water clarity of each lake examined. Data from Oneida Lake, NY show that the rate of benthic primary production and flux of material to the water column have increased.
For more information, contact:
NOAA Center for Research on Aquatic Invasive Species
- - - David F. Reid, Ph.D. U.S. Department of Commerce National Oceanic and Atmospheric Administration Great Lakes Environmental Research Laboratory 2205 Commonwealth Blvd. Ann Arbor, MI 48105-2945 Voice: 734-741-2019 FAX: 743-741-2055 GLERL home page: http://www.glerl.noaa.gov