Staff Research - Recent Projects
Read about our Recent Projects here.
Current Staff research
St. Croix River Watershed
Jim and Roberta Harper volunteer their time each month to sample water quality at seven sites in Lake St. Croix
Lake St. Croix nutrient loading and ecological health assessment
This project has two overall goals. The first is to improve existing phosphorus mass-balance estimates for Lake St. Croix. Measurements of phosphorus outflows are now possible with the flow gage on the St. Croix River at Prescott, WI, but mainstem inflows must be estimated by scaling the flow record measured at St. Croix Falls, WI. This project will install a new USGS flow gage on the St. Croix River at Stillwater, MN. In addition, previous estimates of internal loading were based on the assumption of dominantly oxic conditions in Lake St. Croix, an assumption that has come under question with increasing evidence of anoxic conditions in depth profiles. The second goal of this project is an improved understanding of the relationship between water quality and ecological health of Lake St. Croix. The 20% phosphorus reduction goal is derived from conditions that were last recorded in lake cores during the 1940s, and is expected to restore Lake St. Croix to benthic algal dominance. Phosphorus concentrations in Lake St. Croix have declined by an average of 0.2 μg/L per year during the period 1976-2004, but the response variable chlorophyll has lagged behind these improvements. The study is monitoring the direct response of chlorophyll and algae biomass to seasonal changes in lake nutrient concentrations to develop a predictive relationship between bioavailable nutrient supply and planktonic chlorophyll. Changes in nutrient concentrations will be related to changes in external loading from upstream and internal loading from sediments estimated under the first goal, providing a basis for estimating the future success of TMDL implementation controlling plankton chlorophyll in Lake St. Croix. Funded by: St. Croix River Association. Staff contact: Sue Magdalene.
Minnesota Lakes and Rivers
SCWRS scientist Shawn Schottler in front of an historic machine which was used to install drainage tile
Intensified tile drainage evaluation
Vast areas of Minnesota have been extensively altered with artificial drainage, including sub-surface tile, ditches, wetland drainage, and surface inlets. The effect of these manipulations in altering hydrology and sediment erosion is not well understood. Sediment cores from Lake Pepin provide an integrated historical record of erosion rates in Minnesota. Sediment accumulation rates have increased by nearly tenfold since European settlement and are currently dominated by erosion of non-field sources such as streambanks, bluffs and ravines. The increase in non-field sources coincides with the intensification of artificial drainage and with periods of increased precipitation. The impacts of artificial drainage networks on destabilizing near-channel sediment sources and increasing riverine sediment loads cannot be examined until the installation history and density is inventoried. Equipped with the knowledge of how tile density varies among watersheds, it will be possible to do comparative assessments of long-term changes in hydrology in watersheds with and without artificial drainage, and relate these effects and temporal trends to the observed sedimentation rates in Lake Pepin. Specifically this project will (1) Quantify artificial drainage density and extent in ∼23 watersheds contributing to Lake Pepin and estimate the time trends of installation; (2) Provide a comparative assessment of changes in 14 hydrologic parameters in watersheds with and without intensive artificial drainage to determine the effect of drainage and precipitation in changing river hydrology/erosive potential; and (3) Estimate the role of drainage in accelerating non-field sediment erosion by correlating time trends of artificial drainage and precipitation/climate to the historical sediment loading trends in Lake Pepin. Funded by: LCCMR and Environmental Protection Agency. Staff contacts: Shawn Schottler, Dan Engstrom, and Jim Almendinger.
Wild rice stands along the Kawishiwi River, Boundary Waters Canoe Area Wilderness
Evaluation of the sulfate standard to protect wild rice in Minnesota lakes
The St. Croix Watershed Research Station in collaboration with scientists at the University of Minnesota will: (1) plan and execute a sampling program for water and sediments to help evaluate potential environmental factors important in the distribution and abundance of wild rice in Minnesota lakes, and (2) evaluate methods for effective sampling and analysis of sediment pore-waters for chemical constituents important to wild rice distribution and abundance. The data and information gained from this study will inform further evaluation of Minnesota's sulfate water-quality standard for the protection of wild rice. The study will document the range of water-column and sediment chemistries at sites with robust, declining, and absent wild rice stands in lakes and flowages throughout the northern and central regions of the State. These results will be combined with laboratory growth experiments to determine the relationship(s) between surface-water sulfate, porewater chemistries, and wild-rice survival and growth. Funded by Minnesota Pollution Control Agency. Staff contacts: Dan Engstrom
The measurement of changes in oxygen and pH below the lake sediment surface, using undisturbed sediment cores
Carbon burial dynamics in shallow lakes, Minnesota, USA
Shallow lakes can act as effective carbon sinks. This work revolves around the modern C-cycling of shallow lakes in turbid (algal-dominated) and clear water (aquatic plant) dominated states. We are also investigating whether the rate of C burial varies between these states. We will be looking at the recent sediments in approximately 140 lakes across the state, with a subset of 12 being studied more intensively. Staff contact: Will Hobbs
Dan Engstrom and Shawn Schottler take a core through the ice of Lake of the Woods
Lake of the Woods historical phosphorus
Elevated nutrients and their biological consequence – increased frequency and extent of cyanobacterial blooms – continue to dominate resource concerns for Lake of the Woods (LoW). The conundrum is that there is a well-documented decrease in nutrient loading to the lake, which should have mitigated nutrient and blue-green problems. Monitored inputs of phosphorus from LoW's major tributary, the Rainy River, have decreased in the last 30 years, and point source loadings have declined, yet comparison of monitored water quality variables between the 1980s and 2000s show little change in most in-lake nutrients. In this project we will use whole basin seismic mapping and analyze 8-12 sediment cores from Lake of the Woods for multiple geochemical and biological lines of evidence to determine the historical sources, fate, and impacts of phosphorus (P) loading. Results will be synthesized to generate a whole basin and historical model of nutrient loading, nutrient burial, and in-lake nutrient levels that will answer these management questions: (1) How has P loading to LoW changed over the last 100 years relative to background or pre-European levels? (2) How have biological communities (cyanobacteria and diatoms) changed over the last 100 years? (3) Are trends in biological communities, nutrient dynamics, and sedimentation related to changes in external nutrient loading? (4) Do trends in biological communities, nutrient dynamics, and sedimentation reflect legacy nutrient effects? Funded by Minnesota Pollution Control Agency. Staff contact: Mark Edlund
Great Lakes Region
The Great Lakes mercury (Hg) cycle, from Engstrom, D.R. 2009, PNAS
Great Lakes Restoration Effects on Fish Mercury Levels
Several issues associated with Great Lakes restoration will affect mercury cycling and bioaccumulation in Great Lakes waters, including climate change, invasive species, wetland restoration, and reduced atmospheric mercury deposition. Policy makers need predictions of these effects individually and cumulatively in order to make sound science-based decisions. This project uses a combination of field work and mass balance modeling to provide decision makers with an assessment of the potential effects of Great Lakes restoration activities on mercury cycling and bioaccumulation. Funded by: US Environmental Protection Agency, Great Lakes Restoration Initiative. Staff contact: Dan Engstrom.
Staff scientists Mark Edlund (center) and Dan Engstrom (standing) take a
sediment core from Ahmik Lake at Isle Royale National Park
Biomonitoring prospects for diatoms and paleolimnology in the Western Great Lakes National Parks
In Great Lakes Network (GLKN) National Park units, climate change, environmental contaminants, exotics, and land and resource uses including shoreline and urban development, recreation, water level management, logging, and agriculture have raised concerns about the state of the parks' resources and how to best manage them in a future certain to bring change. In this project we developed a strategy to integrate the use of paleolimnological techniques and diatom analysis in an inventory and monitoring framework. Results will provide a management foundation by determining the natural variability or reference condition of national park lakes. Because lake-sediment records integrate across both spatial and temporal scales, research results will be further used as a biomonitoring strategy by revisiting lakes on regular intervals (3-5 years) to quantify modern environmental conditions relative to historical conditions, to detect early ecological change and recent trends, and to evaluate success of management actions. Funded by National Park Service-GLKN. Collaborators: National Park Service. Staff Contact: Mark Edlund
The Lake Superior Shoreline near Grand Marais
Synthesis of national coastal assessment data for Great Lakes National Parks
We will analyze data from the 2010 Coastal Assessment in order to 1) summarize coastal conditions on a park-specific basis, 2) determine whether or not coastal conditions in national parks differ from those of surrounding Great Lakes waters, and 3) conduct additional exploratory analysis of coastal datasets. Funded by National Park Service/CESU. Staff contact: Will Hobbs.
Climate change research on Lake Desor, Isle Royale National Park; Dan Engstrom (SCWRS) and Jasmine Saros (Univ. of Maine)
Modeling the effects of past and future climate change on GLKN Lakes
Remote interior lakes in national park units of the Great Lakes Network (GLKN) are experiencing unexpected ecological change, including blooms of noxious blue-green algae. Sediment-core data indicate that these changes are unique in the recent history of the lakes. The lakes may be responding to a warming climate, as indicated by a lengthening of the ice-free season and stronger thermal stratification during summer. This project will explore whether there is a causal link between observed temperature increases and ecological conditions in GLKN lakes, the likely physical and biological controls, and how these effects vary among different types of lakes. This study will: (1) Compare diatom-based reconstructions of ecological change among four general lake types likely to represent a range of sensitivity to climate warming; specifically shallow and deep lakes and lakes with small and large surface areas; and (2) Reconstruct the thermal conditions (stratification, ice-free season, temperatures) of the study lakes based on local climate records and hydrodynamic lake models. These lake-thermal records will then be compared with ecological reconstructions from the sediment cores to develop predictive relationships between lake type and climate-induced ecological risk. Funded by National Park Service/CESU. Staff contact: Dan Engstrom.
Mark Edlund observes as University of Maine graduate student Kristin Strock retrieves a sediment core from Isle Royale's Wallace Lake for isotope analysis
Nitrogen deposition to lakes of the National Parks within the Great Lakes Network
Excess deposition of reactive nitrogen from the atmosphere is a major component of global change, and ecosystem responses are widespread in both terrestrial and aquatic ecosystems. Within the Great Lakes region, nitrogen deposition is elevated but has not received much attention since the era of acid deposition research. This pilot study will explore the potential role of nitrogen in recent widespread biological changes in diatom communities in Great Lakes parks. Using nitrogen stable isotope data from archived and well-dated sediment cores, we will determine historical nitrogen trajectories for Great Lakes I&M Network lakes, relate these trajectories to measured nitrogen deposition and concentration data, and evaluate relationships between nitrogen and diatom communities. Funded by National Park Service/CESU. Staff contact: Will Hobbs.
National and International Watersheds
Deployment of the oceanographic Multi-Corer in Lake Superior from the R/V Blue Heron
Using triclosan and polyhalogenated dibenzo-p-dioxins to elucidate the importance of natural and anthropogenic sources of OH-PDBEs in fresh and estuarine waters
For the past 20 years soap manufacturers have added the bactericide, triclosan, to liquid hand soaps and other personal care products. However, recent scientific findings raise questions about unintended consequences of widespread triclosan use. It appears that a portion of the triclosan that goes down our drains is discharged to surface waters, where it is transformed by sunlight into dioxins, an infamous class of toxic pollutants. Two studies are exploring the extent of triclosan-dioxin pollution in Minnesota and beyond. These studies are a collaborative effort between scientists at the University of Minnesota, ETH-Zurich (Switzerland), and the Research Station. Much of the focus will be on sediment-core records of historical dioxin pollution from lakes and estuaries receiving wastewater discharge. In Minnesota, that includes Lake St. Croix, Lake Pepin, the Duluth-Superior Harbor, Lake Superior, and a number of smaller lakes. The overall aim of the studies is to quantify the relative importance of triclosan and related compounds such as PDBEs (flame retardants) to the total dioxin contamination of our surface waters. Funded by: National Science Foundation and Legislative Citizens Commission on Minnesota Resources. Staff contact: Dan Engstrom.