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Staff Research

Recent Projects

Mapping and Biological Studies of Shoreline Rock Pools in Three Lake Superior National Parks
Evidence from Isle Royale National Park (ISRO) suggests that shoreline rock pools are used by rare species such as the boreal chorus frog and arctic disjunct organisms. At Apostle Islands National Lakeshore (APIS) and Pictured Rocks National Lakeshore (PIRO), staff have identified rock pools as understudied habitats in need of investigation, due to their rarity and vulnerability to imminent stressors. All three parks are located near commercial shipping lanes on Lake Superior, and are considered highly susceptible to catastrophic events such as shipping-related spills. Given their small size and shallow depths, rock pools and their biota are also highly susceptible to climate change and impacts from visitors. In partner with the NPS and the University of Minnesota, we are conducting a year-long sampling of water chemistry, amphibian use, and insect, aquatic invertebrate, and algal phenology in rock pools at ISRO, APIS, and PIRO. Funded by NPS-Great Lake Restoration Initiative, 2010-2012. Staff Contact: Mark Edlund

The history, mechanism, and drivers of botulism outbreaks near Sleeping Bear Dunes
Outbreaks of type E botulism have occurred at or near Sleeping Bear Dunes National Lakeshore (SLBE) since the 1960s; however, recent severe fish and waterbird kills in 2006 and 2007 have made botulism outbreaks a major health and resource concern. Initial research efforts have suggested that recent type E botulism outbreaks are a result of complex interactions among dreissenid mussels, Cladophora algae growth, anoxia, and round gobies. We take a two-pronged approach to determine the environmental history of potential drivers of botulism outbreaks from 1950-2010 along nearshore Lake Michigan: a multi-proxy paleoecological analysis of sediment cores from depositional basins near SLBE, and a reconstruction of the history and extent of botulism outbreaks and potential drivers. Outcomes will allow resource managers to more clearly understand the history, mechanism, and drivers of botulism outbreaks and provide a conceptual framework for determining conditions likely to generate botulism outbreaks and die-offs. Funded by NPS-Great Lake Restoration Initiative, 2010-2012. Staff Contact: Mark Edlund

Burial of organic carbon in temperate shallow lakes
Recently, burial of organic matter 'between the cracks' in freshwater systems has been recognized as important to the global carbon cycle. Therefore, understanding the controls of organic matter fluxes to and within freshwater lakes and wetland sediments represents an important regulatory mechanism for increasing organic carbon removal through expeditious management practices. If we knew more about the sources and controls of organic carbon burial in these systems, could we manage them specifically for carbon removal? The goal of this research is to determine if differences in the dominant autotrophs (macrophytes vs. phytoplankton) in shallow lakes can significantly impact organic carbon storage. We will explore these linkages in the modern functioning of shallow lakes, and use the paleo-record to determine how carbon burial rates have changed over time. The central hypothesis is that carbon burial rates are highest in shallow lakes dominated by submerged macrophytes rather than phytoplankton.Funded by NSF-DEB, 2009-2012. Staff Contacts: Joy Ramstack Hobbs, Mark Edlund

Watershed outlet monitoring program—Valley Creek
Streams are sensitive to land-use changes in their watersheds, and urbanization is a land-use change affecting nearly all streams in the Twin Cities metropolitan area. Because one of the responsibilities of the Metropolitan Council Environmental Services (MCES) is to develop target pollution loads for all Metropolitan Area watersheds, MCES has established the Watershed Outlet Monitoring Program (WOMP) to monitor loads of common pollutants such as suspended sediment, nitrogen, and phosphorus, among others. The project is intended to run for many years and generate long-term sets of water-quality data to better understand the effects of land-use change on these watersheds. Valley Creek is an important watershed in the monitoring network because it may serve as a relatively pristine end-member, a standard of comparison for the other, more urban-impacted streams. Staff contact: Jim Almendinger

Centennial funding for the St. Croix
The St. Croix National Scenic Riverway is one of 76 national parks to receive funding through a new cost-share initiative, the Centennial Challenge. Funds from the Riverway, matched with funding from the Twin Cities Metropolitan Council and the Minnesota Pollution Control Agency, is supporting development of a watershed model that will help achieve nutrient reduction goals for the St. Croix River. The model, simulating nutrient loading, is being developed under the direction of Senior Scientist Jim Almendinger.

The watershed model, known as the Soil and Water Assessment Tool, or SWAT, will identify sources of tributary loading, the management practices that will be effective in reducing loads, and where those practices would be most effective. It can be used by communities, watershed districts, county conservation districts, private landowners, and others to help achieve water quality goals for the St. Croix.

The effect of water-level drawdown on methylmercury production and bioaccumulation in the Agassiz Pool of the Agassiz National Wildlife Refuge
Water-level fluctuations in lakes and reservoirs are known to increase methylmercury (MeHg) production, principally through changes in sediment chemistry and microbial activity associated with drying and rewetting of bottom sediments. Although well documented in boreal systems, such effects have not been investigated to any extent in prairie regions where underlying hydrochemical conditions are quite different. Water-level manipulation is a well-established management technique for habitat improvement at the Agassiz National Wildlife Refuge, and refuge management now wishes to understand if enhanced mercury methylation and increased biotic exposure are unintended consequences of such hydro-management. In the fall of 2009 a one-year water-level drawdown was begun in the largest of the Agassiz NWR wetlands, the Agassiz Pool. The previous drawdown at the Agassiz Pool was 10 years ago. This study will evaluate the effect of these water-level manipulations on mercury cycling and methylmercury production in the Agassiz Pool. Funded by US Fish and Wildlife Service. Staff contact: Dan Engstrom.

Historical water quality and ecological change of three lakes in the Riley Purgatory Bluff Creek Watershed District
The primary aim of this project is to use paleolimnological analysis of dated sediment cores from three lakes in the Riley Purgatory Bluff Creek Watershed District (Lotus and Mitchell Lakes in Carver County and Round Lake in Hennepin County) to reconstruct ecological histories using biogeochemistry, sediment accumulation, diatom-inferred total phosphorus (DI-TP), and diatoms as biological indicators. The lakes currently have marginal to poor water quality and are the subject of local and state concern to develop management plans that include an understanding of presettlement conditions, historical lake response to land use and past management, and development of management targets through TMDL planning. These goals are well-suited to a paleolimnological study. Analytical tools include radioisotopic dating of the cores, geochemical analyses to determine local sediment accumulation rates, and analysis of subfossil algal communities. Multivariate analyses, diatom-based transfer functions, and comparison of algal assemblages with an 89 Minnesota lake data set will be used to relate changes in trophic conditions and algal communities to human impacts in the local watershed. Funded by: CH2M Hill. Staff contact: Joy Ramstack.

SLICE—Sustaining lakes in a changing environment
A large multi-institutional project headed by the Minnesota DNR. Water quality, habitat, and fish in Minnesota lakes are or will be facing substantial levels of stress primarily due to two very large drivers of change: land use changes (both urban and agricultural) and climate change. This 3-yr cooperative study in several sentinel lake watersheds throughout the state will help us understand, predict, and monitor the consequences of climate change and land cover alterations. Multiple national, state and local government and academic partners are focusing on monitoring basic watershed, water quality, habitat, and fish indicators in 24 sentinel lakes across a gradient of ecoregions, depths, and nutrient levels. The SCWRS has received funding to conduct detailed paleolimnological assessments in a subset of seven cold-water deep lakes from the 24 sentinel lakes. This work will assess cause-effect mechanisms affecting the past, present, and future status of cold-water habitat and identify the appropriate indicators to monitor to track the status of these habitats. Funded by Minnesota DNR, LCCMR, 2009-2011. Staff Contact: Mark Edlund

Resolving the cause of the recent rise of fish-mercury levels in the Western Great Lakes Region
Recent reports of rising fish-mercury levels in lakes of the western Great Lakes region raise concerns that atmospheric mercury deposition may be increasing. Deposition-monitoring data are inconclusive on this matter, and other ecosystem factors, possibly related to climate change, may have increased biotic exposure to methyl-mercury, the bioaccumulative form present in fish. This project would help determine which factor(s) are most responsible for the upturn in fish-Hg and whether atmospheric Hg inputs to area lakes have actually risen or not. There are two parts to the study: (1)the reconstruction of recent Hg accumulation changes at high resolution in dated sediment cores from 40 regional lakes, and (2) an in-depth comparison of fish trends with lake and watershed characteristics to determine why some lakes show increasing levels of fish-Hg while others do not. This analysis should help address public concerns regarding the efficacy of emission controls in reducing Hg deposition and ultimately Hg levels in fish. Funded by: Great Lakes Commission/Great Lakes Air Deposition Program. Staff contact: Dan Engstrom.

Habitat or food? The demise of the benthic food web in Lake Michigan
The Great Lakes have been inextricably impacted by natural and anthropogenic changes. The multiplicative impacts of these stressors are manifested in dramatic shifts in water quality, energy flow, food web dynamics, and fisheries structure. Among the most noted stressors in Lake Michigan has been the establishment of zebra and quagga mussels in the late 1980s-1990s and their subsequent spread throughout the basin. Coincident with establishment of these anchored, filter feeders in the Great Lake have been increases in water clarity, changes in nutrient loading and dynamics, shifting of energy from the pelagic to the benthic zone, colonization of available substrates, creation and colonization of large shell zones, botulism outbreaks, bottom-up fish condition and community shifts, and major changes in benthic invertebrate dynamics, noticably through the loss of the keystone benthic gammarid Diporeia. We use paleolimnological analysis of four dated sediment cores from nearshore and offshore areas of Lake Michigan to resolve the historical relationships among the diversity, quantity, and quality of the algal food resources, particularly diatoms, and how these parameters impacted or linked population dynamics of zebra/quagga mussels and Diporeia. Funded by Great Lakes Fishery Trust, 2009-2012. Staff Contact: Mark Edlund

Diatom analysis of Crater Lake sediment cores
This project will investigate if changes have occurred in the epiphytic diatom algae community in Crater Lake over the last 5,000 years and if those changes may indicate changes in growing conditions of the deepwater moss community. Sediment cores from Crater Lake that document conditions up to 5000 years ago will be analyzed for diatom community changes and compared to present day taxa. The analysis of diatoms within ancient sediments presents a unique opportunity to assess the historic conditions within the deepest lake in the US and one of the clearest lakes in the world. Funded by: National Park Service/CESU. Staff contact: Joy Ramstack.

PICEA—Terrestrial and aquatic linkages in the Arctic
There is strong consensus that climate is changing rapidly in the Arctic as evidenced by a 0.4°C per decade rise in temperature over the past 40 years. Pan-arctic ecological responses to this warming include increases in lake productivity, permafrost thaw, shrub expansion, and northward shifts in the subarctic tree line. Paleoecological studies have played an important role in understanding modern and historic climate change in the Arctic but relatively little is known about how landscape, in particular peat development and exposed till, constrains terrestrial, aquatic, and wetland responses to climate. We are conducting a multi-lake (6), multi-proxy (+20) study in the forest-tundra region of northern Manitoba, an area that currently represents a major gap in the paleoecological record. Our objectives are to (1) understand the role of landscape in mediating lake and terrestrial ecosystem responses to climate, and (2) investigate the impacts of changes in terrestrial and wetland ecosystems on adjacent lakes. Funded by NSF-DEB, 2008-2011. Staff Contact: Mark Edlund

Assessing pelagic zooplankton in Lake St. Croix in anticipation of invasive Asian carp
Invasive Asian carp (Hypophthalmichthys spp and Mylopharyngodon piceus) are expected to move up the Mississippi and lower St. Croix Rivers. These fish are destructive in many ways, including direct impacts on zooplankton, small crustaceans and other fauna that graze on algae and in turn provide food for fish. Zooplankton mediate top-down food web changes with bottom-up processes (like nutrient inputs), and are sensitive indicators of how an aquatic system is functioning. Zooplankton assessment in Lake St. Croix is critical for understanding current ecosystem function and for evaluating future changes due to invasive carp. Current TMDL efforts and the unique mussel populations of the system will be difficult if not impossible to evaluate without pre-carp understanding of the pelagic ecology of Lake St. Croix. Funded by: National Park Service, St. Croix National Scenic Riverway.

Provide SCUBA dive support and native mussel identification on the St. Croix National Scenic Riverway
The St. Croix National Scenic Riverway is involved in several studies and projects on the river, which involve native mussels and scuba diving. This effort provides scuba dive support and mussel identification during several studies. Funded by: National Park Service, St. Croix National Scenic Riverway.