Document: AMI-3-74-18

Patterns of aquatic benthic invertebrate distribution in a series of lakes within a landscape continuum.

POLLARD, A.I.*, T.M.FROST and J.J.MAGNUSON

University of Wisconsin-Madison, Madison, WI 53706, USA ¹

Abstract:
Several important lake features have been shown to be related to a lake's position within a landscape. Here we report on a test of the hypothesis that benthic invertebrate community characteristics are related to lake-landscape position. Specifically we test how the relative position of a lake within a regional flow path influences invertebrate community characteristics. Two lake attributes that can influence invertebrate communities, chemical characteristics and degree of isolation, change predictably with the relative position of a lake in a regional flow path. Understanding biotic patterns in terms of landscape position requires discriminating the effect of these two co-varying attributes. In this study, we examined the interacting effects of chemical attributes and degree of isolation on benthic invertebrate distribution in lakes in northern Wisconsin by a sampling design that crosses high/ low ion concentrations with connected/ isolated lakes. We use this information to infer processes governing landscape-scale patterns of distribution. We evaluated invertebrate community characteristics from 38 lakes in the Northern Highland District. Our comparisons of species number and abundance indicated that benthic invertebrates were non-randomly distributed among lakes within a landscape. Benthic invertebrate richness increased with the degree of isolation and, to a lesser extent, ion concentration. Multiple regression analyses indicated that these patterns were significant at a level of P=0.001 and P=0.060, respectively. The integrated effect of ion concentration and degree of isolation indicated that there were discernable differences between invertebrate communities in lakes within these categories, although preliminary results are not significant. These results suggest that subtle differences in the relative position of lakes within a lake district affect benthic invertebrate distribution.

Keywords: lake landscape position, benthic invertebrate assemblage

This abstract is being presented at: 9:15 AM in session:
Oral Session #54: Lake Ecology.