Grantee Research Project Results
2000 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
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, 1999 through September 30, 2000
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 indicators will be identified first in a set of 72 wetland mesocosms where individual and multiple, interacting, stressors are used as treatments in a controlled outdoor experiment. Post-experiment analysis will focus on the efficacy of each indicator to discriminate among different stressors or combinations of stressors. Successful indicators then will be evaluated in agricultural wetlands identified by analysis of northern Mississippi agricultural landscapes, based on remote imagery and other landscape data, to have the same stressors or combinations of stressors present that were included in the mesocosm experiment.Progress Summary:
Our efforts in the project's second year have been directed towards the mesocosm experiment, further development of GIS and field site selection, and a field survey to characterize the biota of the river basin and refine field sampling protocols. During March and April the mesocosms were cleaned, filled with spring water, stocked with zooplankton, and other sampling materials added (e.g., unglazed clay tiles for periphyton collection, sediment traps, etc.). During this time, organisms for the experiment also were collected and include southern leopard frog (Rana sphenocephala) egg masses, mosquitofish (Gambusia affinis), and freshwater snails (Lymnaea sp.). Egg masses were allowed to hatch in the laboratory and on March 25, 2000, 40 tadpoles were added to each mesocosm. On March 27, two snail egg masses with approximately 40-50 embryos each were added to each mesocosm. On May 15, 10 Gambusia were added to an enclosure within each mesocosm, which allowed water exchange while allowing easy retrieval of the fish. On May 21, our 27-1 center point enhanced experiment commenced. Seven treatment factors were applied to 64 mesocosms at one of two levels (high or low). Eight additional mesocosms were used as experimental center points where factors were applied at a 50 percent level (not all factors could be reduced to 50 percent). We examined three pesticides, nutrient fertilizers, ultraviolet radiation, suspended solids, and predation. Our pesticides were atrazine (192 ppb high, 0 ppb low), chlorpyrifos (32 ppb high, 0 ppb low), and monosodium methane arsonate (MSMA) (219 ppb high, 0 ppb low). The nutrient treatment consisted of a nitrogen (0.9 mg/L high, 0 mg/L low) and phosphorus (0.33 mg/L high, 0 mg/L low) mixture. OP-4 and OP-3 acrylite filters, which transmit or filter ambient UV radiation, respectively, were used for the high and low UV treatments. Kaolin was added (0, 80 mg/L) in a slurry to the mesocosms. Five fathead minnows (Pimephales promelas) were added to half of the mesocosms as a predator treatment.
Several endpoints (water quality; UV dosimetry; Rana and Pimephales behavior; DNA and biochemical responses of snails, tadpoles, and Gambusia; and amphibian metamorphosis) were measured from each mesocosm on days 2, 12, 24, and 48 after treatment application. Other variables (e.g., ambient conditions, water temperature) were measured at 10-minute intervals with data being stored in either a Li-Cor 1000 data logger or HOBO temperature loggers. Analysis of all endpoints has not yet been completed but will be finished in the project's third year. All Rana metamorphs emerging from the mesocosms were captured, weighed, toe-clipped for identification, and released into a drift-fence enclosed common pond. These individuals will be assessed for reproductive activity in the coming spring.
In our second year, we further developed our geographic information system (GIS) of potential field sites. Selected sites, from which samples will be taken for measurement of several endpoints as described above, need to be identified objectively to increase the reliability of data and analysis of scale dependence. With the completion of both agriculture and pesticide distribution data sets, analysis within each section (by township, range, and section according the Public Land Survey [PLS] system) with respect to combined loading from the selected pesticides was completed. There were two steps in this process. First, each pesticide was coded with a high/low/none value. High values were assigned where pesticide usage totals exceeding 25 percent of the maximum usage for an individual section. Calculation of maximum usage was determined by multiplying application rates (obtained from the Lafayette County Extension Service office) by the number of acres in a particular crop for each square mile. Low values were assigned sections with usage below 25 percent but above 0. None was the value given to sections with no recorded pesticide use. Second, we identified geographic areas where multiple pesticides were used and expression of biological effects to multiple, interacting stressors, was possible. By using the information obtained in the first step, pesticide loading combinations for each section was calculated. After review of the information, we decided to combine the data for methyl parathion and chlorpyrifos due to their nearly identical usage patterns. Only those agricultural sections with high loading values for one or more pesticides were selected for further investigation.
During the past 6 months, we have begun to characterize the habitat and biota
of wetlands in our study basin. We have been concentrating on publicly owned
areas such as U.S. Army Corps of Engineers and Mississippi Department of
Wildlife, Fisheries, and Parks lands. These site visits have allowed us to
optimize our field sampling techniques, develop safety plans for our personnel,
and evaluate sites with reference to potential residence of organisms of
interest. These activities will allow us to effectively conduct the varied
aspects associated with our upcoming, and intensive, field research.
Journal Articles:
No journal articles submitted with this report: View all 33 publications for this projectSupplemental Keywords:
water, watersheds, scaling, metals, organics, genetics, molecular biology, remote sensing, monitoring, ecology, limnology, agriculture, organism, cellular, population, enzymes, 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
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.