Assessing the Interactive Effects of Landscape, Climate, and UV Radiation on River Ecosystems: Modeling Transparency to UVR and the Response of BiotaEPA Grant Number: R829642
Title: Assessing the Interactive Effects of Landscape, Climate, and UV Radiation on River Ecosystems: Modeling Transparency to UVR and the Response of Biota
Investigators: Morris, Donald P. , Hargreaves, Bruce R. , Pazzaglia, Frank J. , Weisman, Richard N. , Williamson, Craig E.
Institution: Lehigh University
EPA Project Officer: Hiscock, Michael
Project Period: July 30, 2002 through July 29, 2006
Project Amount: $825,850
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
Climate currently affects the transparency of aquatic ecosystems through rain mediated transfer of UV-attenuating substances from watershed to water, and solar radiation mediated photochemical reactions of some of these substances. Land cover also affects the transfer of water along with UV-attenuating substances into streams and rivers: Forests control erosion of sediments; wetlands release dissolved organic matter; human development of land for agriculture, roads, and buildings tends to increase storm runoff at the expense of groundwater recharge. Two factors control the biotic effects of UV radiation (UVR) in aquatic ecosystems: exposure to UVR, and physiological resistance mechanisms. Our objective is to determine how current watershed and river properties (including land use and land cover) interact with climate and solar radiation to determine current UV exposure, and how living organisms have adapted in order to survive this UV exposure. We will also establish how temperature affects UV resistance of organisms, and how dissolved oxygen is affected by UVR exposure. Only by understanding present interactions under a range of conditions can we hope to predict the response of aquatic ecosystems to future change, including anticipated increases in extreme weather conditions and increases in UV-B associated with ozone destruction in the stratosphere.
The Lehigh River watershed in northeastern Pennsylvania will be the site of intensive manual and automated field measurements of water quality relevant to UV transparency. We will use a hierarchically-scaled set of matched stream catchments to tease apart the influences of different watershed properties as well as processes within streams and the Lehigh River. Benthic macroinvertebrates from selected sites within these catchments will be tested for their resistance to UVR using a laboratory solar simulator instrument (the UV Phototron). The interactive effects of water temperature (with screening for potential stressors in the river water) will be examined by comparing an organism's response to UV at several temperatures, testing in both high quality spring water as well as water from the natural habitat.
We expect to improve predictions of the future response of aquatic ecosystems to the combined effects of changing climate and increasing UV-B radiation. Especially useful to environmental managers will be what we learn about the impact of land use on stream and river ecosystems, both in terms of storm runoff and UV transparency.