Linking temporal changes in crayfish communities to environmental changes in boreal Shield lakes in south-central Ontario

Abstract

When aquatic ecosystems are among those most intensely affected by local and regional environmental change, it is crucial that stressors are identified to set priorities for future research and mitigation. Studies relating changes in important or sensitive assemblages to environmental changes provide a means to quantify potential stress on aquatic biota. Crayfish are ideal taxa for this type of study because they influence ecosystem structure and function and are sensitive to biotic and abiotic changes. We used historical and contemporary crayfish abundance and select environmental data for 100 inland lakes in central Ontario, to identify factors that are correlated with community membership and species distributions at each time and to elucidate environmental factors that can be directly linked to changes in relative abundance between the two time periods. Our results show that declines in lake calcium, invasions of warm-water centrarchids, and anthropogenic shoreline development have increased in their relative influence over time. These stressors may be affecting other freshwater biota directly, or indirectly through food web changes or altered abiotic interactions among the environmental changes.