Date of Award


Degree Type


Degree Name

Master of Science (MS)




Patricia Chow-Fraser




The overall objective of this study is to contribute to general knowledge on bioassessment of Great Lakes coastal wetlands. Coastal wetlands (also referred to as marshes) are uriique systems that experience day-to-day changes due to storms, high winds, and rapid changes in barometric pressure, exposing the shorelines to wave conditions; in addition to this annual and seasonal water level flucations contribute to this distinctive ecosystem.

The first chapter examines the influence of gear type and sampling protocol on fish catch data that are used to calculate biotic indices of wetland quality in Lake Huron. We surveyed fish communities in coastal wetlands of eastern Georgian Bay and Long Point Bay, Lake Erie, to determine biases associated with different gear types and sampling protocols. Parallel data collected from 26 wetlands were used to compare species richness obtained by two standardized protocols: fyke nets (set for 24-h parallel to shore) and boat electrofishing (1500 shock seconds during the day). We found differences between sampling protocols with respect to abundances and type of fish caught. Despite this difference, Wetland Fish Index (WFI; Seilheimer and Chow-Fraser 2006) scores derived from data obtained by the two gear types did not differ significantly. By contrast, when data for 6 exposed sites dominated by Scirpus were compared separately, we found significantly higher WFI scores associated with fyke net data compared with electrofishing data, and these differences were sufficiently large that they should not be ignored. We conclude that both methods can be used interchangeably in routine ecological assessments, as long as methods are used within areas of dense submergent vegetation.

The second chapter used zoobenthos as a bio-indicator of wetland quality. "Zoobenthos" used in this study refers to the invertebrate primary and secondary consumers that are found associated with the sediment-water interface, and includes some of the zooplankton (copepods, cladocerans), which are found floating in the water column and many of the benthic invertebrates that reside on top of the sediment or that emerge from the sediment during the 24-h incubation period. It does not include any of the macroinvertebrates that live in emergent vegetation or that glide on the surface tension of the water. We determined that both water quality and aquatic macrophytes significantly influenced the distribution of zoobenthos. However, we also found that exposure also affected the type of invertebrates found in wetlands, regardless of waterquality conditions. We developed 26 metrics that could be used by wetland managers to assess wetland quality based solely on taxonomic composition of zoobenthos.

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