Research

Riparian and Aquatic Habitat Change

Freshwater streams, rivers, wetlands, and lakes provide society with many ecosystem goods and services, including water filtration, flood control, and habitat for fish, waterfowl, and plants.  While people do not often think in economic terms about these things that nature provides, the benefits are nevertheless highly valuable.  Healthy aquatic systems and the riparian areas that surround them are vital in controlling flooding and mitigating eutrophication by filtering polluted water as it runs off from surrounding land.  These systems also provide habitat for birds, fish, and other organisms that society harvests or enjoys recreationally. 

The Role of Large Woody Debris in Stream Ecosystems
What does a “healthy” aquatic system look like?  CAC researchers are investigating how streams work to answer this question.  Gary Lamberti, Jennifer Tank and others are investigating the role of large woody debris in maintaining stream ecosystem function.  In many parts of the country where logging has occurred, streams and rivers no longer contain natural quantities of logs and sticks.  Such large woody debris stabilizes stream channels, filters out leaves and other organic matter that many insect larvae consume, and provides habitat for invertebrates and fishes.  In general, large woody debris are one of the things that define a healthy stream. Lamberti and Tank are discovering just how important submerged wood is to stream productivity (plant and algal growth) and metabolism, nutrient cycling, and energy flow through food webs.  Fish, for instance, are attracted to areas of the streams with wood habitat but how much the production of fish is enhanced by wood in streams is not fully understood.  By conducting replicated wood additions (that mimic historical wood conditions) in three streams in the Ottawa National Forest (ONF) in the Upper Peninsula of Michigan, CAC researchers are determining the response of the streams and fish populations over a span of three years. Once researchers more fully understand the influence of wood on ecosystem processes, decisions by the Forest Service and other agencies can be made about how much and what type of wood could be added to best enhance the ecosystem goods and services provided by streams and rivers.

The Importance of Nutrient Input from Biota
An overlapping team of CAC researchers is investigating the importance of salmon in providing nutrients to otherwise nutrient-poor streams in the Pacific Northwest.  Migrating salmon in these streams die and their carcasses decompose in the stream creating seasonal influxes of ocean-derived nutrients into these streams. Led by Tank and Lamberti, in collaboration with USFS scientists in Alaska and at Michigan State, the researchers are investigating the response to nutrients from salmon by all levels of the stream food web, including salmon fry and the smaller animals that they eat.  These researchers believe that riparian ecosystems also benefit from salmon nutrients as terrestrial animals, including bears, scavenge the salmon, moving the nutrients into the riparian area alongside streams. The research team is also testing how forest management in these watersheds influences the nutrient contribution from salmon.  This research will inform forest management by the USFS and management of the salmon fishery by NOAA and state agencies.

Relevant Publications

Chaloner, D.T., Lamberti, G.A., Merritt, R.W., Mitchell, N.L., Ostrom, P.H., Wipfli, M.S. 2004. Variation in responses to spawning Pacific salmon among three south-eastern Alaska streams. Freshwater Biology 49 (5): 587-599.

Moerke, A.H., Lamberti, G.A. 2004. Restoring stream ecosystems: Lessons from a midwestern state. Restoration Ecology 12 (3): 327-334.

Moerke, A.H., and G.A. Lamberti. 2003. Responses in fish community structure to restoration of two Indiana streams. No. Am. J. Fish. Manage. 23: 748-759

Moerke, A.H., K.J. Gerard, J.A. Latimore, R.A. Hellenthal, and G.A. Lamberti. 2004. Restoration of an Indiana, USA, stream: Bridging the gap between basic and applied lotic ecology. J. No. Am. Benthol. Soc. 23: 647-660

Mitchell, N.L., and G.A. Lamberti. 2005. Responses in dissolved nutrients and epilithon abundance to spawning salmon in Southeast Alaska streams. Limnol. Oceanogr. 50: 217-227

Rosi-Marshall, E.J., A.H. Moerke, and G.A. Lamberti. 2006. Ecological responses to rehabilitation of a Northern Michigan trout stream. Environmental Management 38:99-107.