Determinants and consequences of spatial pattern in zoobenthos investigations and applications

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Bottom-dwelling aquatic invertebrates (benthos) are an integral component of aquatic food webs, transferring energy and persistent chemicals from the detrital sink to other trophic levels. My research combines laboratory observation/manipulation, inferential field experiments and modeling to describe and understand mechanisms and factors controlling behaviour and microdistribution in selected benthic populations. In studying development, behaviour, direct interactions, and dispersal I have developed novel methods to monitor and predict effects of environmental stress in individuals (biomarkers) and populations of keystone species. These methods complement community-based methods of environmental monitoring. I will continue this approach to address research environmental constraints, interactions, and dispersion of Hexagenia burrowing mayflies (Ephemeroptera). Hexagenia are dominant benthos in fine sediments of mesotrophic systems. Previously eradicated populations are recolonizing the Great Lakes. I will use data on distribution, dispersal, density-dependence, oxygen limitation, and size-fecundity relationships to predict and confirm environmental limits and life history traits in western L. Erie. Measurements from in situ recorders of lake-bottom temperature and oxygen concentrations will be combined with remote-sensed measurements of surface water temperatures to predict basin-wide benthic conditions, which will be used to estimate expected growth and production. These values will be compared to population estimates generated from actual benthic samples. Hexagenia mobilize sediment, nutrients, and associated contaminants, influencing filter-feeding organisms (dreissenid mussels, zooplankton), and alter bottom microtopography. I will address the importance of mayfly bioturbation to the lake's physical and biological processes through laboratory and field studies. The results will help understand the role of this keystone species plays in the changing nutrient dynamics of western Lake Erie and similar mesotrophic systems.