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

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

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

The Great Lakes have experienced arguably the largest short-term ecological shift in their history within the last decade and face a long-term climate shift in the decades to come. The invasion of Dreissenid mussels, the disappearance of Diporeia, and the predicted increasing temperatures and lengthening stratification have altered and will alter the role of benthic metabolism. The nearshore habitat is a complex of newly colonized cobble, gravel, hard clay and silty sands. Deepwater  bottoms have been overrun with mussels. Production and respiration of oxygenare notoriously difficult to measure in such environments since many of the common methods — oxygen and pore water gradients, sediment or chamber incubations — all have limitations. The researchers propose to employ new, nondisruptive eddy correlation techniques to study oxygen exchange at the benthic boundary in a range of Great Lakes environments that have undergone or will undergo significant change. R/HCE-12

Emily Stanley, UW-Madison, (608) 263-2567, ehstanley@wisc.edu

Despite the importance of the St. Louis River Estuary in supporting fisheries, harboring unique ecological communities, delivering water and materials to Lake Superior and bolstering the regional economy, the biogeochemical processes that support this ecosystem are poorly known. In this study, researchers will conduct a spatially explicit characterization of biogeochemical processing rates within the estuary under high- and low-flow conditions. First, they will identify spatial and seasonal hotspots of nutrient and organic matter processing by combining longitudinal surveys of water chemistry with results from a dynamic estuary model. Second, they will characterize dissolved organic matter quality and rates of primary production and respiration at a series of stations along the estuary. Third, they will measure potential denitrification rates and controls at sites throughout the estuary. This will provide a baseline understanding of the biogeochemical processes supporting the estuarine ecosystem and identify the role of anthropogenic stressors in altering these rates. R/RegHCE-09-12

Wisconsin is the beneficiary of funding made available under the Great Lakes Restoration Initiative, a $475 million program to restore fish and wildlife habitat, clean up toxic pollution, reduce nonpoint source pollution, and control and prevent the spread of aquatic invasive species in the Great Lakes.  Wisconsin Sea Grant will be involved in several projects that are regional in nature and will be implemented with multiple partners.  They are: