Cooperative Habitat Research in Deep Lakes

Deep, cold-water lakes have different physical properties and support different wildlife than their more numerous shallow counterparts. The Minnesota Department of Natural Resources (DNR) is using this appropriation to conduct a study that will help identify, monitor, and predict the consequences of climate change and land use changes on water quality, habitat dynamics, and fish populations in deep, cold-water lakes. Using 24 "sentinel" lakes as their study area, this effort is expected to help inform revisions to lake monitoring programs, provide an empirical foundation for proposed watershed "best management practices", and inform climate change adaptation policies related to lake management.

Overall Project Outcome and Results
We designed a long-term lake monitoring program that incorporates a synoptic view of lakes, including understanding historic and current lake conditions along statewide gradients of nutrients, climate, ecoregion, and land use. Twenty-four lakes and their associated watersheds were established as sentinel systems to serve as focal points of collaborative long-term monitoring, research, and environmental education. The research funded here focused primarily on the 7 deep-water sentinel lakes with coldwater fish populations. With our project partners, we examined current and forecasted relationships among resident lake biota, water quality, and lake habitat features, and extrinsic factors including watershed inputs, climate, and invasive species. Key deliverables include:

• U.S. Geological Survey developed biophysical water quality models to predict responses in the distribution of temperature and oxygen in Carlos, Elk, and Trout lakes based on current conditions. In Phase 2, models will be used to simulate the consequences of land-use change and climate dynamics on lake ecosystems, including sensitive cold-water fish communities.
• St. Croix Watershed Research Station provided a reconstruction of the historical water quality and diatom communities of seven sentinel lakes. Results provide a context for interpreting future community-level shifts based on land-use changes and climate trends.
• A data visualization tool has been developed that enables interested scientists and others to interact with SLICE data. Improvements are planned to make the tool more user-friendly and provide greater access to databases currently managed by DNR, PCA, and other partners.
• Analysis of zooplankton collections from 24 sentinel lakes suggests that zooplankton will be a sensitive indicator of current and changing lake conditions. Data collected thus far has allowed us to focus sampling on specific times and components of the zooplankton community.
• Our understanding about cisco behavior and population status in Minnesota lakes has been greatly enhanced. We developed and refined sampling techniques, and now have baseline information to understand climate and land use impacts to cisco lakes.

Project Results Use and Dissemination
The information gathered during the SLICE project has been invaluable to fisheries and lake managers in a number of ways. First, the ability to collect water quality, zooplankton, fisheries, and historical lake data over consecutive years from a suite of lakes has been foundational for the implementation of a long-term monitoring program for Minnesota lakes. That information will provide researchers and managers with a wide variety of specialties and interests to focus on specific metrics that are most likely to reflect change from various stressors. The ability to identify those metrics and their response to specific stressors will enable managers to quickly respond and develop best management practices in lakes facing environmental changes. Second, techniques developed and refined during the project have strongly influenced our basic understanding of the ecology and behavior of cisco population in Minnesota. Understanding how cisco populations, vulnerable to both biotic (i.e. invasive species) and abiotic (i.e. climate change) stressors, respond to change will be important for the management of not only cisco but other cold and cool water species as well. Third, by including partners with differing discipline backgrounds and expertise, e.g., USGS, St. Croix Watershed Research Station, et al., the project was able to provide unique and holistic insights into how lake ecosystems function now and in the future (models), as well as how they may have in the past (sediments).
 

Project Publications:
Assessing the Water Quality and Habitat Dynamics of Deepwater Lakes with Coldwater Fish Populations (PDF - 8.5 MB)
Reconstruct historical water quality and habitat conditions in the seven coldwater sentinel lakes (PDF - 1 MB)
Exploring Hydraulic Residence in Minnesota's Sentinel Lakes: Implications for Management (PDF - .7 MB)