T234 Urban and Suburban Lakes: Paleorecords of Human Impacts and Opportunities for Geoscience Education

Wednesday, 12 October 2011
8:00 AM - 12:00 PM
Room M100DE

NANDA-GIKENDAASOWIN NAAWIJ GAA-IZHIWEBAKIN MANOOMINI-ZAAGA'IGANIING: CORE-BASED RESEARCH BY NATIVE STUDENTS ON WILD RICE LAKES IN NORTHERN MINNESOTA

Paper number: T234-11
Program: Technical Sessions
Time: 10:30 AM – 10:45 AM

Authors

Abstract

Little is known about how local and global environmental changes affect the habitat of wild rice (manoomin in Ojibwe; Zizania sp.). Using transects of sediment cores from wild rice lakes on the Fond du Lac Band of Lake Superior Chippewa Reservation (FDL) in Minnesota, undergraduate student researchers are working to reconstruct the lakes’ ecological history in order to better manage future change. Reservation Resource Management personnel and University science mentors work together to develop research questions and mentor small groups of students during short (two-week) and long (ten-week) summer internships. Cores are collected during the winter from the frozen lake surface with “Lake Teams” of mainly Native junior high and high school students attending weekend science camps, who also visit LacCore in Minneapolis to conduct initial core description and basic analyses. At the same time as the Fond du Lac Band gains information about the long-term history and variability of the Reservation’s lakes, young Native people are exposed to primary research, natural resources management and academia as occupations, and scientists as people.

Lead-210 dated records of the past ~150 years cover the period of European settlement, logging, and the massive ditching of FDL lakes to convert wetlands to agricultural land. Phytolith, pollen, plant macrofossil, and diatom studies by interns, as well as sediment composition and mass accumulation rate data, show anthropogenic lake level and vegetation fluctuations associated with these activities. Earlier in the record, the processes of lake infilling and encroachment of shallow-water vegetation are the dominant processes controlling the ecology of the lakes. Wild rice macroremains are rare in the cores, and so we use phytoliths, which are better preserved, as a proxy for past Zizania abundance. We also test the relationship between the abundances of grass pollen and wild rice phytoliths. This multiproxy approach is necessary for understanding the complex interactions between lake depth, nutrient levels, plant and diatom communities, sediment chemistry, land-use change, and wild rice growth; it also emphasizes the interrelationships of the different parts of the ecosystem that are sometimes treated separately in scientific studies.