The Canal was constructed in the late 1800s to convey sewage away from Lake Michigan and to provide a navigational corridor between the Illinois River and the Great Lakes. Historically, the water quality of the Canal was so poor that pollution formed a barrier of sorts to the cross-basin transfer of aquatic organisms.

Harvey Bootsma, UW-Milwaukee, (414) 382-1717, hbootsma@uwm.edu

Since the mid-1990s, quagga mussels have been displacing zebra mussels in Lake Michigan. Although the effects of zebra mussels in the nearshore zone have been well studied, the quagga mussel has spread into the profundal region, and there has been virtually no assessment of profundal mussels’ effects on nutrient cycling or food web dynamics in Lake Michigan. The objective in this Wisconsin-Illinois cooperative effort is to determine the role of the deepwater quagga mussel community in Lake Michigan’s energy flow pathways and nutrient cycling. The project’s main goals are 1) to quantify plankton consumption by the mussels,2) to quantify their phosphorus recycling,3) to assess the impact of mussels on food supply to higher trophic levels and 4) to implement a hydrodynamic/biogeochemical model, with the specific goal of simulating the water column response to C and P dynamics within the benthic boundary layer. R/HCE-02-10

M. Jake Vander Zanden, UW-Madison, (608) 262-9464, mjvanderzand@wisc.edu

The introduction of zebra and quagga mussels has had a dramatic economic and ecological impact on lake ecosystems due to their remarkable ability to change primary productivity. Most research has focused on the open-water system, but this new research project will examine the impacts of mussels on primary production in bottom- and open-waters across the variable nutrient-enriched gradient of Green Bay and study the impacts across the aquatic food web. The researcher will measure primary productivity across the trophic gradient of the mussel-invaded Green Bay; use productivity models to estimate the impact on primary productivity, including the nuisance alga Cladophora glomerata; examine how changes in nutrient and sediment loading will affect autotrophic structure; and use stable isotopes to examine the trophic pathways supporting fish. R/HCE-5

M. Jake Vander Zanden, UW-Madison, (608) 262-9464, mjvanderzand@wisc.edu

Lake productivity has long referred to the productivity of the pelagic, open-water zone, but recent work indicates that bottom habitats may also be important contributors. Additionally, the ongoing spread of Dreissenid mussels in North America generally increases the importance of benthic production and processes in lakes. In this project, researchers define lake autotrophic structureas the distribution of the overall primary production between benthic and pelagic habitats. They propose to quantify changes in autotrophic structure along Green Bay’s dramatic trophic gradient (ranging from hyper-eutrophic to oligotrophic) and use their field data to parameterize models estimating how changing Dreissenid grazing, nutrients and suspended sediments might be expected to affect autotrophic structure. They will also use stable carbon and nitrogen isotopes on contemporary fish and invertebrate samples, as well as archived scale samples, to test the hypothesis that the carbon sources underlying fish production track autotrophic structure across Green Bay’s trophic gradient. R/HCE-07

Harvey Bootsma, UW-Milwaukee, (414) 382-1717, hbootsma@uwm.edu

The development of management goals and strategies for Lake Michigan relies on conceptual and numerical models that reliably simulate critical ecosystem processes. In the past decade, it has become apparent that these models require revision because of fundamental changes that have occurred in nutrient dynamics and energy flow. A number of these changes, including the decline of offshore plankton and invertebrate densities and the excessive growth of nuisance algae in the nearshore, have been attributed to the effects of filter-feeding Dreissenid mussels in the nearshore zone. Yet the mechanisms by which mussels influence energy and nutrient flow remain more conjectural than proven, leaving managers and policy makers without reliable models. This project will combine measurements of physical and biogeochemical processes in the Lake Michigan nearshore zone to quantify and model critical carbon and phosphorus fluxes, with an emphasis on the role of Dreissenids in mediating these fluxes. R/HCE-09

Qian Liao, UW-Milwaukee, (414) 229-4228, liao@uwm.edu

The presence of invasive zebra and quagga mussels in coastal areas of the Great Lakes may have a fundamental effect on the transport and redistribution of contaminants among the sediments, water column and biota because mussels are capable of removing a large amount of suspended particulates through filter feeding. This project will evaluate the interactions between the mussels in the coastal water near the Sheboygan Harbor and the river plume resulting from resuspension due to physical forcing and human disturbance (during and after dredging). State-of-the-art field instruments will be deployed to quantify the transport and deposition of contaminated sediment plume after resuspension. The exchange rate of suspended sediment particles between the water column and the benthic community colonized by Dreissenid mussels will be  measured and calculated. Data will be used to validate hydrodynamic-biogeochemical numerical models with the purpose of  facilitating the assessment of ongoing and future remediation efforts. R/HCE-11

Val Klump, UW-Milwaukee, (414) 382-1700, vklump@uwm.edu