Dan McEwen Ph.D. Candidate (Dr. Malcolm Butler) Office: Stevens 214 Phone: (701) 231-6561 daniel.mcewen@ndsu.edu B.A. Minnesota State University Moorhead, Biology (2003)

Research Interests: trophic coupling of benthic invertebrates and fish, Chironomidae, water-level fluctuation, shallow lake ecology, boreal shield lakes, ecological stoichiometry, and limnology

Current Projects:

Voyageurs National Park Water-Level Fluctuation Impacts on Benthic Invertebrate Communities

My research will address questions related to the consequences of water-level regulation on aquatic communities in lacustrine habitats within Voyageurs National Park (VOYA) at the United States and Canadian International Border. VOYA was established in 1975 to preserve the historical fur trade routes, geology, ecology, and recreational opportunities afforded by these unique systems. Rainy Lake and Namakan Reservoir, which includes 5 lakes (Namakan, Kabetogama, Sand Point, Crane, and Little Vermilion Lakes), comprise 96% of the park's water and are part of a watershed that is over 3,800,000 ha in size. Since the early 1900's, water levels in VOYA have been controlled by privately owned hydroelectric dams at the outlet of Rainy Lake and regulatory dams on two outlets from Namakan Lake . An International Joint Commission (IJC) manages for multiple use including power generation, navigation, flood control, pollution abatement, and fish propagation. Prior to 2000, the IJC maintained higher-than-natural fluctuation on Namakan Reservoir that caused subsequent lower-than-natural fluctuations on Rainy Lake . Not only were water levels unnatural, but also the timing of drawdown was managed such that water-levels rose earlier and stayed higher longer than what natural regimes would have provided based upon historical modeling. Some researchers have documented negative effects on the ecological structure of the aquatic system especially of Namakan Reservoir. The IJC was petitioned to change the rule curves to adhere to a different water-level regime that would lessen the annual drawdown in Namakan while keeping levels in Rainy Lake similar to mimic a more natural fluctuation. In January 2000, a new regulation regime went into effect, on a 15-year experimental basis, to see if ecosystem functioning would improve. In order for the IJC to maintain the new regime, they require monitoring and indication that it's having a positive effect on ecosystem functioning based on selected aquatic community data. I am modelling the effects of water-level regulation on benthic invertebrate community diversity and production and associated impacts for higher trophic levels.

Stoichiometry of carbon, nitrogen, phosphorus and mercury of benthic invertebrates and fishes

A primary motivation for managing many aquatic systems is enhancement of fisheries production and community structure. Economic and recreational pressures prevail for creating and maintaining good fisheries. Millions of dollars are spent in Minnesota and North Dakota on fisheries management. Successful implementation of management programs calls for an understanding of the kinds of environmental characteristics that are amenable to the production of desired fish species. While many environmental factors contribute to the structuring of fish communities, the role of food quality in terms of benthic invertebrate stoichiometric constraints is not known but may be significant. The reason that little is known about benthic invertebrate constraints is that high quality data on body stoichiometry is not available. I am currently working on the issue of benthic invertebrate food quality for fish by determining stoichiometric values for common benthic invertebrates in Minnesota and North Dakota lakes a with an emphasis on fine taxonomic resolution in the family Chironomidae. By relating the elemental composition of various benthic invertebrate communities to the stoichiometric requirements of different fish species, I hope to determine the importance of variation in prey community quality to fish community composition. Additionally, I am modelling the effects of stoichiometric variability on mercury transfer from benthos to fishes.

Lake Christina Reclamation

Lake Christina, in west central Minnesota, is an important staging area for waterfowl during their autumn migration. There is interest from both public and private groups to maintain quality habitat for waterfowl, and, as such, Lake Christina has underwent intense management to promote and sustain conditions that foster high waterfowl populations. Specifically, the lake cycles between stable clear and turbid water equilibria with the clear state being desirable for waterfowl production. The lake is managed via top-down remediation by fish kills with the use of Rotenone. By killing plantivorous fish, large-bodied cladoceran populations are allowed to flourish with the result that phytoplankton is reduced, increasing the transparency of the water. I am involved in biomonitoring by characterizing zooplankton population dynamics, water transparency and quality.