Patterns in habitat and fish assemblages within Great Lakes coastal wetlands and implications for sampling design

Discerning fish–habitat associations at a variety of spatial scales is relevant to evaluating biotic conditions and stressor responses in Great Lakes coastal wetlands. Ordination analyses identified strong, geographically organized associations among anthropogenic stressors and water clarity, vegetation structure, and fish composition at both whole-wetland and within-wetland spatial scales. Lacustrine-protected wetlands were generally internally homogeneous in fish composition, whereas riverine or barrier-beach lagoon wetlands could be more heterogeneous, especially if they had large tributaries and complex morphology or if the mouth area was more directly exposed to the adjacent lake than were other areas. A tendency towards more turbidity-tolerant fish but fewer vegetation spawners, nest guarders, or game and panfish differentiated both more-disturbed from less-disturbed wetlands and open-water from vegetated areas within wetlands. Variation in vegetation structure related to wetland hydromorphology and anthropogenic impacts makes standardizing fish sampling protocols by microhabitat impractical across broad spatial or disturbance gradients. We recommend distributing sampling effort across available microhabitats and show that both fish and habitat can be adequately characterized with a single field day of effort.