WRS student and fellowship recipient Kirsten Rhude searches for clues in the disappearance of Diporeia

By Kirsten Rhude
Editor's note: Kirsten Rhude is the first recipient of Water Resources Center Graduate Student Fellowship. 

kirsten

Kirsten stirs sediment in an elutriator aboard the R/V Kingfisher. Elutriation is a process used to collect organisms living in sediment as it quickly separates dense particles like sand from less dense substances like her study organism, Diporeia.

I have been studying a small shrimp-like organism that lives in the sediment at the bottom of Lake Superior called DiporeiaDiporeia are vital to the Great Lakes food web as they are rich in lipids and are eaten by commercial species like whitefish as well as smaller fish. They are one of two invertebrate species that drive the food web in Lake Superior along with the zooplankton Mysis. But Diporeia have been disappearing in all of the Great Lakes except for Lake Superior and researchers don’t yet know why. In Lake Superior, Diporeia have been found in higher abundance at a particular depth range around the lake, from around 30-100m. I have been working to try to determine what about that depth is appealing to Diporeia, analyzing what habitat characteristics they prefer. As part of this work I have been sampling along a transect on the North Shore, running experiments with Diporeia in the lab, and analyzing sediment characteristics along this depth gradient. Laboratory experiments have shown that Diporeia prefer sediment from where they are most abundant in the lake (30m and 60m) even in the absence of predation and other stressors. I am continuing to analyze the chemical and physical properties of the sediment to determine what characteristics Diporeia are attracted to.

Outreach has been an important part of my work at UMD as well. I have spent the past year working with MN Sea Grant’s Shipboard Science program as their chief scientist. This fall 12 teachers from throughout MN and WI went out on the R/V Blue Heron with me to collect samples for my research and spent a day in the lab helping me analyze my data. Teachers learned field techniques, data analysis skills and spent time developing plans to incorporate what they had learned into their classrooms. I am looking forward to continuing to support these teachers throughout the coming months and seeing how they used this experience at a May follow up symposium.

I have also worked with my advisor, Dr. Bob Sterner and a team from MN Institute on the Environment to evaluate the ecosystem services provided by the 21 largest lakes in the world. We scoured the literature to find values for a number of the quantifiable ecosystem services on each of these lakes, like fisheries production, domestic water use and irrigation, power generation (thermal, nuclear, and hydro), marine freight, and recreation.

Over the past six months I have been able to share my work at a number of conferences. I presented a poster of my work on Diporeia Sediment Preference on a Lake Superior Transect at the State of Lake Superior Conference in Houghton, MI in October and gave an oral presentation on the same topic at ASLO’s Aquatic Sciences Meeting in San Juan, Puerto Rico in February. I also shared a poster on Ecosystem Services of Lake Superior and other Large Lakes at the Minnesota Water Resources Conference in St. Paul in October and at the Our Climate Futures Conference in Duluth this March. This summer I’ll be busy attending IAGLR’s Large Lakes Research Conference in June and writing my thesis with plans to defend at the end of the summer.