Research Areas

Saginaw Bay is a eutrophic embayment of Lake Huron with excess nutrient loading from a largely agricultural watershed. Despite ongoing efforts to reduce nutrient loads, phosphorus levels remain elevated. My lab is assessing the potential importance of internal phosphorus loading; focusing on influences of sediment type, oxygen levels and Zebra and Quagga mussels on sediment phosphorus fluxes. We collect sediment cores from the bay and bring them back into the laboratory for incubation experiments to evaluate: 1) sediment P flux under aerobic and anaerobic conditions, and 2) nutrient remineralization from mussel biodeposits when added to the surface of the cores. Preliminary results indicate that the anaerobic treatments exhibit higher P release back to overlying waters when compared to aerobic treatments. This release was greatest in sediments collected from the depositional zone. These results may indicate that contributions of P from sediments in Saginaw Bay are controlled by episodic anoxic events in this region. Results from our mussel experiment found no P release from dreissenid biodeposits in the timeframe of the study. We are continuing to research these results and the influence of multiple disturbances on phosphors load. This is part of a larger collaborative project: Investigating the role of multiple stressors in Michigan’s Saginaw Bay (http://www.glerl.noaa.gov/res/projects/multi_stressors/index.html);

Water contaminated with bacteria presents a serious health risk at beaches and in streams throughout the United States. Monitoring for bacterial contamination is not currently mandated for the approximately 560 bathing beaches along the American coast of the Great Lakes. Identifying sites with high bacteria levels that people are likely to be exposed to is necessary to protect public health. Affluent counties in Southeastern Michigan such as Oakland and Macomb conduct frequent water quality monitoring to identify periods of high bacterial loads resulting in beach closure posting; however, the city of Detroit, home to large numbers of economically disadvantaged people, does not. Beaches (e.g., Belle Isle) and rivers (Detroit, Rouge, etc.) in the city of Detroit are less frequently monitored, resulting in an unknown but likely greater health risk to this underserved community. Contributing to the high bacterial loads in Detroit surface waters are sewer overflows, surface runoff, failing septic systems, illicit sewer pipe connections, and erosion of sediment. In addition, current federal and state supported monitoring fails to identify human-specific pathogens whose presence would more precisely and accurately indicate potential impacts on human health, compared with the current monitoring programs using E. coli and Enterococci. Ongoing and proposed research seeks to address these issues taking a community-based approach by working with local community groups to empower residents to understand the risk and participate in monitoring efforts of their local beaches. Our ultimate goal is to develop rapid, reliable, accurate, simple and cost effective methods that are feasible for routine water quality monitoring for fecal contamination, and to apply fecal marker technologies, such as microbial source tracking, for identifying the sources of fecal contamination.

We are interested in both how immature veligers and adult mussels respond to different stressors including harmful algal blooms, flame retardants, and PCBs. This information is important to understand their range expansions, competitive interactions with other species and each other, and vulnerability to control methods.

Watersheds of the Great Lakes vary widely in land use, and human modification of the terrestrial landscape can impact stream ecosystems and biota by altering habitat structure and water quality.In-stream obstructions such as dams and culverts also can affect stream ecosystems by increasing sedimentation rates and blocking immigration by animals from the Great Lakes . For instance, the massive spring migrations of suckers may play a seasonally-important role in stream productivity and nutrient dynamics, as is well known in the case of Pacific salmon. We are evaluating the effects of landscape attributes and sucker migrations as drivers of carbon and nutrient dynamics Michigan streams. We are assessing landscape influences by comparing concentrations of dissolved organic carbon (DOC) among sites as a function of landscape attributes such as land use, canopy cover, dominant vegetation, watershed area, and slope.

This project presents a new method for studying past environmental change and long-term anthropogenic disturbances in the Great Lakes. Results from this project can aid in improved modeling, predictions and management for issues surrounding long-term change in the Great Lakes. Our lab is resurrecting historic daphnid populations for use in a series of carefully controlled bioassays aimed at determining the pace of evolutionary responses to environmental change. Ephippia, which are modification of the daphnid carapace containing diapausing eggs, accumulate in the sediment and can be viable for decades. It is expected that historic daphnid populations will be more sensitive to persistent Great Lake contaminants than modern populations. We have initially focus on the critical pollutants such as DDT and toxaphene through a series of bioassays comparing and contrasting environmentally relevant concentrations looking at mortality and sublethal endpoints such as fecundity, growth rate, and sex-ratio. We expect that adaptation to contaminants over time has resulted in modern daphnid populations which are more tolerant than historic populations to pollutants such as DDT and toxaphene.