Interactive Effects of Climate Change, Wetlands, and Dissolved Organic Matter on UV Damage to Aquatic FoodwebsEPA Grant Number: R829643
Title: Interactive Effects of Climate Change, Wetlands, and Dissolved Organic Matter on UV Damage to Aquatic Foodwebs
Investigators: Bridgham, Scott D. , Johnston, Carol A. , Lamberti, Gary A. , Lodge, David M. , Maurice, Patricia A. , Shmagin, Boris A.
Current Investigators: Bridgham, Scott D. , Frost, Paul C , Johnston, Carol A. , Lamberti, Gary A. , Lodge, David M. , Maurice, Patricia A. , Shmagin, Boris A.
Institution: University of Oregon , University of Minnesota - Duluth
Current Institution: University of Oregon , Natural Resources Research Institute , Trent University , University of Notre Dame
EPA Project Officer: Hiscock, Michael
Project Period: June 24, 2002 through June 23, 2005 (Extended to June 23, 2006)
Project Amount: $897,307
RFA: Assessing the Consequences of Global Change for Aquatic Ecosystems: Climate, Land Use, and UV Radiation (2001) RFA Text | Recipients Lists
Research Category: Global Climate Change , Ecological Indicators/Assessment/Restoration , Water , Ecosystems , Climate Change
Attenuation of ultraviolet (UV) radiation is an exponential function of dissolved organic matter (DOM) concentration, such that UV-B penetration in darkly stained waters is limited to only a few centimeters. At the landscape scale, the strongest correlate of DOM concentrations in aquatic ecosystems is the percentage of wetlands in the watershed. Climate change may reduce DOM concentrations in aquatic ecosystems, thereby exacerbating UV effects, by changing the amount and flowpaths of DOM from upland and wetland ecosystems. We hypothesize that the linkages among wetland area and type, DOM, and climate will be the most important factors determining the amount of UV damage to aquatic ecosystems at the landscape scale. Our objectives are to (1) relate DOM concentration and chemistry in various tributaries of a relatively pristine watershed in the Lake Superior drainage basin (Ontonagon River in northern Michigan) to discharge, wetland and upland landscape characteristics, and stream order via multivariate analysis, (2) determine interactions among UVR intensity and DOM chemistry, photodegradation, photoaggregation, and biodegradation, and (3) determine the response of stream foodwebs to the interactions among UVR intensity and DOM concentration and type.
These objectives will be addressed through a combination of landscape and hydrological analyses, extensive sampling of water chemistry throughout the watershed for two years, analysis of the chemistry, photodegradation, and biodegradation of DOM, and experiments quantifying the effects of DOM concentration and source on UV damage to three stream trophic levels.
This research will greatly improve risk assessment of global change to aquatic foodwebs through knowledge of the interactive effects of climate change, landscape watershed attributes, and DOM in controlling damage by UV radiation to aquatic ecosystems. We hypothesize that watersheds with substantial wetland area will be much less susceptible to drought-induced reductions in DOM due to climate change, thereby buffering the aquatic biota from UV damage. This knowledge will allow appropriate risk management strategies to reduce the threat of future damage to aquatic ecosystems from global change.