PARENT SESSION
Contributed Oral Session 139: Landscape Ecology: Streams; Wetlands
Thursday, August 11, 1:30 PM - 5:00 PM, Meeting Room 520 A, Level 5, Palais des congrès de Montréal
Evaluating geographic and geomorphic influences on indicators of Great Lakes coastal wetland condition across multiple taxonomic groups.
Brazner, John*,1, Danz, Nick1, Niemi, Gerald1, Hanowski, JoAnn1, Johnston, Carol2, Johnson, Lucinda1, 1 University of Minnesota - Duluth, Duluth, MN, USA2 South Dakota State University, Brookings, SD
ABSTRACT- Developing effective indicators of ecological condition requires calibration to determine the geographic range and ecosystem-type appropriate for each indicator. An integrated multi-taxa approach which examines responses among a variety of biotic assemblages should provide a more comprehensive assessment of anthropogenic influences than approaches with a single assemblage focus. The indicators we evaluated here were developed from data that were collected as part of the Great Lakes Environmental Indicators (GLEI) Study to develop and test indicators of ecological condition for coastal ecosystems in the Great Lakes. GLEI included collection of site-specific abundance information on six biotic assemblages (birds, fish, amphibians, invertebrates, wetland vegetation, and diatoms) from over 450 coastal locations during 2002-2004. We focused on coastal wetlands spread along a multivariate disturbance gradient that spanned the entire U.S. shoreline of the Great Lakes. We examined some of the most promising species- and function-based indicators from those assemblages, compared their responses to stressor gradients, and examined the effects of large scale geographic factors (ecoprovince and lake) and wetland geomorphology (riverine, protected or coastal) on each indicator type. Hierarchical variance partitioning revealed that geographic (lake) rather than geomorphic factors (wetland-type) had the greatest influence on the proportion of variance explained across all indicators, and that a significant portion of the variance was also related to response to disturbance. Wetland vegetation and fish indicators were the most and invertebrates the least responsive to human disturbance, but invertebrates were the one taxa strongly influenced by wetland-type. Only about one-third of total variance was explained by the factors we examined, suggesting other environmental factors must play important roles. Surprisingly, there were few clear differences in the performance of species and function-based indicators. Among other things, these results suggest that incorporating the influence of individual lakes will be crucial to developing effective indicators for Great Lakes coastal wetlands.
Key words: ecological indicators, Great Lakes coastal wetlands, GLEI, multi-taxa approach