GLOBES Research Summary
Patrick Shirey
Email: Patrick Shirey
Department: Biological Sciences
Advisor: Gary Lamberti
Historical Ecology of Rivers
The ecological conditions of aquatic ecosystems worldwide have been altered by flow regulation, habitat destruction, pollution, and non-indigenous species introductions. For many aquatic ecosystems such as rivers, specific conditions prior to major manipulations are not well known and long-term physical, chemical, and biological data are often lacking. My research uses techniques from historical ecology and paleolimnology to examine human modifications of river systems. Historical ecology examines human impacts on ecosystems by using historical records such as natural history observations, photographs, published literature, and public records to answer scientific questions. River paleolimnology uses diatoms and stable isotopes to examine past ecological conditions. I am primarily interested in using historical ecology and river paleolimnology to examine how landscape changes and dams influence the aquatic communities in river systems.
Historical landscape changes and fish habitat in the Namekagon River, Wisconsin
The Namekagon River is part of the St. Croix National Scenic Riverway in northern Wisconsin. The basins of the Namekagon River and St. Croix River were logged extensively in the 19th Century. Although these rivers have wild and scenic designations today, human modifications to the landscape have changed the aquatic habitat and species composition. The goal of this project is to describe historical conditions of the Namekagon River, which will help river managers restore cold water fish habitat, thereby protecting native species.
Because the Namekagon River has been altered by human activity, we will examine historical records to provide information on how habitat conditions have changed since widespread logging of northern Wisconsin. We will examine a series of time periods from first European exploration to the present day to test the following hypotheses: 1) the Namekagon River is wider, shallower, warmer, and has less big woody cover on banks and in the stream channel, due primarily to logging; 2) Namekagon River habitat conditions are no longer suitable for some native species, such as brook trout.
Our techniques will include examining historical documents, photographs, fishing records, agency reports, and existing fish habitat of the Namekagon River. We will also use museum collection records to examine historical fish communities since these provide a scientific record of the fish assemblage. Museum collection records can be used to determine species composition during specific time periods, permitting inference of habitat conditions. The information obtained from all of the techniques will be used to summarize fish habitat conditions and species composition of the Namekagon River for time periods from European exploration to present-day conditions.
Long-term impact of dams
The decline of fish populations in many of North America’s rivers has been associated with dam construction and flow regulation (Benke 1990). Dams alter habitat and reduce available floodplain habitat by restricting peak flows (Baxter 1977; Petts 1980; Ligon et al. 1995). The reservoirs impounded by dams also trap sediments and nutrients that benefit downstream habitats. Dam removal is considered by some to be the best solution for restoring natural flow regimes. However, in areas where dam removal is a controversial solution, flow regimes can be managed between dams to provide habitat for native fishes. If scientists can reference historic conditions to compare with contemporary conditions, then natural resource managers can be provided with information needed for restoring river ecosystems. The goal of this project is to examine the long-term effects that dams have on river ecosystems by sampling preserved fish specimens for gut content and stable isotopes.
Few paleolimnology studies have examined river systems because of the difficulty in examining past river conditions using traditional techniques (Amoros and Van Urk 1989; Van Dam and Mertens 1995). For example, examination of river sediment to obtain information on ecological response to hydrologic change can be a lengthy process (Reavie and Smol 1997; Sheldon et al. 2000) and is dependent on availability of sediments where long-term deposition has remained undisturbed (Reavie et al. 1998). A reliable alternative for examining historical conditions of river ecosystems is sampling preserved museum fish specimens for gut contents (particularly diatoms - Rosati et al. 2003; Shirey et al. In press) and stable isotopes (Vander Zanden et al. 2003). This is a viable method for examining the long-term impact of dams on river systems because precise sample dates and localities are known for archived museum specimens.
Amoros, C. and G. Van Urk. (1989) Palaeoecological analyses of large rivers: some principles and methods. In G.E. Petts, ed. Historical Change of Large Alluvial Rivers: Western Europe. John Wiley & Sons Ltd.
Baxter, R.M. (1977) Environmental effects of dams and impoundments. Annual Review of Ecology and Systematics 8:255-283.
Benke, A.C. (1990) A perspective on stream-catchment connections. Journal of the North American Benthological Society 12, 44-47.
Ligon, F.K., W.E. Dietrich, and W.J. Trush. (1995) Downstream ecological effects of dams. BioScience 45(3):183-192.
Petts, G.E. (1980) Long-term consequences of upstream impoundment. Environmental Conservation 7:325-332.
Reavie, E.D. and J.P. Smol (1997) Diatom-based model to infer past littoral habitat characteristics in the St. Lawrence River. Journal of Great Lakes Research 23(3):339-348.
Reavie, E.D., J.P. Smol, R. Carignan, and S. Lorrain. (1998) Diatom paleolimnology of two fluvial lakes in the St. Lawrence River: a reconstruction of environmental changes during the last century. Journal of Phycology 34(3):446-456.
Rosati T.C., J.R.Johansen, and M.M. Coburn (2003) Cyprinid fishes as samplers of benthic diatom communities in freshwater streams of varying water quality. Canadian Journal of Fisheries and Aquatic Sciences 60:117–125.
Sheldon F, M.C. Thoms, O. Berry, and J.P. Smol 2000. Using disaster to prevent catastrophe: referencing the impacts of flow changes in large dryland rivers. Regulated Rivers-Research & Management 16: 403–420.
Van Dam, H. and A. Mertens. (1995) Long-term changes of diatoms and chemistry in headwater streams polluted by atmospheric deposition of sulphur and nitrogen compounds. Freshwater Biology 34:579-600.
Vander Zanden M.J., S. Chandra, B.C. Allen, J.E. Reuter, and C.R. Goldman (2003) Historical food web structure and restoration of native aquatic communities in the Lake Tahoe (California–Nevada) basin. Ecosystems 6, 274-288.
Research Publications and Presentations
Shirey, P.D., D.E. Cowley, and R. Sallenave. In press. Diatoms from gut contents of museum specimens of an endangered minnow suggest long-term ecological changes in the Rio Grande (USA). Journal of Paleolimnology, early online DOI 10.1007/s10933-007-9156-4.