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COASTAL WETLAND-NEARSHORE FOOD WEB LINKAGES ALONG A TROPHIC GRADIENT IN GREEN BAY: A FISH-EYE VIEW
Citation:
Brazner, J. C., J. Keough, P. Schneeberger, B. Belonger, AND M. Sierszen. COASTAL WETLAND-NEARSHORE FOOD WEB LINKAGES ALONG A TROPHIC GRADIENT IN GREEN BAY: A FISH-EYE VIEW. Presented at 44th International Conf. of International Association for Great Lakes Research, Green Bay, WI, June 10-14, 2001.
Description:
To identify ecological interactions among Green Bay coastal wetlands and lake habitats we analyzed stable isotope signatures of organismsa from wetland and adjacent nearshore food webs in Green Bay, Lake Michigan. We were interested in the influence of nutrient loading/trophic status on base energy sources and food chain length in coastal wetlands, and factors contributing to differences in wetland and nearshore isotope signatures for fish. Spanning the south-to-north productivity gradient in Green Bay, we sampled five wetland and three nearshore sites during the summer in 1995. Dominant primary producers and consumers were analyzed for stable isotopes of C and N. We found as eutrophy increased contributions from phytoplankton supporting higher trophic levels in wetland food webs increased, and contributions from periphyton and macrophytes decreased. There was also a trend toward decreased food chain length in wetlands as macrophyte diversity increased, suggesting greater omnivority where macrophyte complexity was higher. Isotope differences between wetland
and nearshore food webs appear to be more related to wetland geomorphology and connectivity to adjacent bay waters than differences in nutrient sources. These results suggest food web analyses using stable isotopes may provide system level indicators of eutrophication and food web overlap for coastal Great Lakes ecosystems.