Grantee Research Project Results
1999 Progress Report: Effects of Interacting Stressors in Agricultural Ecosystems: Mesocosm and Field Evaluation of Multi-level Indicators of Wetland Responses
EPA Grant Number: R826595Title: Effects of Interacting Stressors in Agricultural Ecosystems: Mesocosm and Field Evaluation of Multi-level Indicators of Wetland Responses
Investigators: Threlkeld, Stephen , Crain, Andrew , Ochs, Clifford , Schlenk, Daniel , Easson, Greg , Slattery, Marc , D'Surney, Stephen , Britson, Carol
Current Investigators: Threlkeld, Stephen , Benson, William H. , Crain, Andrew , D'Surney, Stephen , Easson, Greg , Ochs, Clifford , Schlenk, Daniel , Slattery, Marc
Institution: University of Mississippi , Maryville University of Saint Louis
Current Institution: University of Mississippi
EPA Project Officer: Packard, Benjamin H
Project Period: October 1, 1998 through September 30, 2001 (Extended to September 30, 2002)
Project Period Covered by this Report: October 1, 1998 through September 30, 1999
Project Amount: $897,634
RFA: Ecological Indicators (1998) RFA Text | Recipients Lists
Research Category: Ecological Indicators/Assessment/Restoration , Aquatic Ecosystems
Objective:
Our primary objective is to evaluate indicators of molecular, cellular, population, community, and ecosystem responses to multiple, potentially interacting, natural and anthropogenic stressors that vary at different spatial and temporal scales in agricultural wetlands. The indicators are chosen to represent a selection of mechanism-based and system-level integrative characteristics that might be more amenable to cost-effective routine monitoring. Our null hypothesis is that indicators that effectively characterize ecosystem responses to single stressors also are scale- and interaction-independent (i.e., useful even when there are multiple, interacting stressors with diverse operational scales). Our alternative hypothesis is that when multiple, interacting stressors are present, responses are not well characterized by indicators that are useful for monitoring the effects of single stressors. This outcome demands the use of either a different set of indicators or a different spatial or temporal scale of resolution for evaluating the indicators. The results of exposure of wetlands to single or multiple chemical stressors in outdoor mesocosms will be field tested in agricultural wetlands within the Little Tallahatchie River basin in northern Mississippi.
Progress Summary:
In the project's first year, we focused our attention on development of a geographic information system (GIS) for the watershed of the Little Tallahatchie River in northern Mississippi. We have characterized physical features, land use practices, and potential pesticide loads in the Little Tallahatchie River Basin in northern Mississippi. These data sets are being incorporated into a GIS database that will be used to randomly select approximately 150 field sites from about 18,000 potential sampling areas (ponds, oxbow lakes, impoundments, and intermittent stream segments) that have been identified. Physical features have been mapped from 1:100,000 and 1:24,000 U. S. Geological Survey (USGS) data. Features not visible on 1:100,000 data (already in digital form) were digitized from 1:24,000 maps (e.g., intermittent streams, small ponds, etc.). Land use practices have been characterized from data obtained through county Farm Services Agency (FSA) offices, which maintain separate records for each farm in their jurisdiction. For each square mile of our study area, we have crop data (in acres) for all major and minor crops planted in 1998. Potential pesticide loads for each square mile of our study area were calculated for the following chemicals: chlorpyrifos, atrazine, methyl parathion, and monosodium methane arsonate. Pesticide loads were calculated by multiplying the chemical application rate (amount of chemical per acre) by the number of acres in a square mile planted in a crop for which a particular chemical is used. Application rates were obtained from resource information from the Lafayette County (Mississippi) Extension Office. This information incorporates data from companies that produce the chemicals as well as data pertinent to Mississippi that may affect application (e.g., weather patterns, soil types, etc.). From these chemical distributions, we have identified map sections most likely to have wetlands with agrichemical loadings typical of the single or multiple stressor treatments in our mesocosm experiments. In the first year, we also further developed the analytical and sampling protocols to be used in the upcoming mesocosm experiment. Because the design of the mesocosm experiment would be refined and improved by our preliminary field sampling, we delayed starting the mesocosm experiment until April 2000.
Future Activities:
During the second project year, we will continue to develop and refine the GIS and watershed maps, so that they provide an excellent foundation for choice of study sites in the watershed that are typical of single and multiple stressor distributions. Spatial scale dependency will be evaluated using the GIS database as applied at different resolutions, beginning with 1-square mile resolution and progressively increasing grid size (to 9- and 25-square mile resolution). Spatial relationship of wetlands to upstream sources of agrichemicals also will be included in our evaluation of scale dependency, even though organism dispersal between wetlands (especially amphibians) does not appear to be under hydrological or topographical control. During the spring and summer of 2000, sampling of as many as 150 representative field sites in the study watershed will commence. In April, the mesocosm experiment, to be conducted at the University of Mississippi field station, will begin. Invited presentations highlighting our project will be made at the University of Kentucky in February 2000 and at the EPA Science to Achieve Results (STAR) Progress Review meeting in Las Vegas, NV, in May 2000.
Journal Articles:
No journal articles submitted with this report: View all 33 publications for this projectSupplemental Keywords:
landscape, factorial experiment, agriculture, pesticides, Mississippi, MS., RFA, Scientific Discipline, Water, Ecosystem Protection/Environmental Exposure & Risk, Water & Watershed, Ecology, Limnology, Ecosystem/Assessment/Indicators, Environmental Chemistry, Ecological Effects - Environmental Exposure & Risk, Agronomy, Watersheds, Ecological Indicators, anthropogenic stresses, ecological risk assessment, interactive stressors, remote sensing, UV effects, agricultural watershed, chlorpyrifos, enzymes, metal release, multiple spatial scales, multiple stressors, ecosystem indicators, field validation, mesocosm, aquatic ecosystems, environmental stress, water quality, stress responses, multiscale assessment, agriculture ecosystemsRelevant Websites:
http://www.olemiss.edu/projects/epa-eig Exit
Progress and Final Reports:
Original AbstractThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.