Grantee Research Project Results

2001 Progress Report: Effects of Interacting Stressors in Agricultural Ecosystems: Mesocosm and Field Evaluation of Multi-level Indicators of Wetland Responses

EPA Grant Number: R826595
Title: 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 , University of California - Davis
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, 2000 through September 30, 2001
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 were chosen to represent a selection of mechanism-based and system-level integrative characteristics that might be amenable to cost-effective routine monitoring. Our null hypothesis is that indicators that effectively characterize ecosystem responses to single stressors are also 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 examined first in a set of 72 wetland mesocosms where individual and multiple, interacting stressors are used as treatments in a controlled outdoor experiment. Postexperiment analysis will focus on the efficacy of each indicator to discriminate among different stressors or combinations of stressors. Successful indicators will then 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:

In the past project year, our efforts have focused on three areas: (1) intensive sampling of randomly selected wetlands within the Little Tallahatchie River Basin; (2) continuation of mapping and GIS development incorporating data collected from the field; and (3) analysis of data collected during the experimental, mesocosm phase of the previous project year. We discuss particulars of each effort and details of future activities below. During the past year we requested, and were granted, a no-cost extension for the project to allow more time for data analysis and report preparation. As such, the present document is an annual, rather than final, report.

Field Sampling Effort: Our research efforts in the field have been focused on: (1) contacting
landowners requesting access to their property; (2) assessing suitability of potential sampling sites once access has been granted; and (3) sampling a suite of endpoints from several levels of biological organization at acceptable sites. Data from field sampling will be incorporated in a multivariate analysis that includes data from our previous year's mesocosm experiment to examine scale dependency?both spatially and temporally?across the levels of biological organization.

Information packets were sent to each landowner of an agricultural (pesticide-impacted) or nonagricultural pond that met selection criteria. A brief review of selection criteria is as follows: selection of ponds within agricultural sections (by township, range, and section according to the Public Land Survey [PLS] system) was done by assigning a random number to each pond and then selecting the first five ponds per section for which there was ownership data (as obtained through county Farm Services Agency offices). Selection of ponds from sections not impacted by agriculture began with the random selection of up to 25 sections from each of the seven major geologic units across the basin. A random number previously assigned to all ponds was then used to select the first five ponds from each of these sections. Ownership information for nonagricultural ponds was obtained through county tax assessor records.

Information packets included a letter of introduction, personalized color-maps that indicated both location and pond(s) for which we were requesting access, and statements of authorization. Access was granted when the landowner signed the authorization statements and returned a copy to us. Information packets were sent to owners of 103 agricultural and 408 nonagricultural ponds across the study basin. Replies were received for 76 of the agricultural ponds and 230 on the nonagricultural ponds. Positive responses (permission granted) were received for 75 percent (57 of 76) of the agricultural ponds and 84 percent (194 of 230) of the nonagricultural ponds. Agricultural ponds were coded according to the potential pesticide load for the four pesticides of interest: chlorpyrifos, methyl parathion, atrazine, and MSMA (monosodium methanearsonate). Eight of the 17 combinations of these pesticides can physically occur in the real world as determined by crop and pest types for which the pesticide(s) were produced. Of those eight, our randomly selected ponds represented five of the combinations. There were no ponds existing on properties with the other three combinations. Access was granted for ponds from the five combinations.

Onsite visits were conducted at each pond for which access was granted. Site visits took place from November 2000, through March 2001, and allowed us to determine suitability of each site for sampling. Pond location (latitude and longitude) was verified with a hand-held global positioning system. Positive verification was necessary, as we were visiting only a small fraction of the available ponds in the study basin (251 out of more than 8,700). Once location was verified, the following information was collected: present condition of the pond (i.e., ability to retain water); upstream and downstream land use (i.e., crops, active/inactive livestock pasture, timber, etc.); proximity to residential houses (i.e., septic systems), proximity to illegal garbage dumps; proximity to other selected ponds (e.g., two or more ponds on the same property may be located in the same drainage pattern); and ease of access (i.e., distance from nearest navigable road, hiking conditions to pond, etc.). Ponds were removed from consideration if they received residential waste, drained directly into another selected pond, were more than a 30-minute hike from a road or path, or did not hold water. Of the ponds for which access was granted, 41 agricultural ponds and 103 nonagricultural ponds were determined to be suitable for sampling.
Sampling of ponds took place from March to August 2001. Postcards were sent to landowners 1 week prior to the scheduled sampling date for their pond(s). This form of communication significantly enhanced our rapport with the landowners. Ponds were scheduled for sampling so as to achieve a diverse group of ponds for each week (i.e., agricultural and nonagricultural ponds across varying geologic formations). Ponds were visited by a team of project personnel (e.g., C.A. Britson and 1-2 student technicians) on each of 2 consecutive days. On the first day, ambient and water conditions were recorded, and all water, sediment, zooplankton, vegetation, and seine/dipnet samples were collected. Text descriptions and digital photos also were recorded on the first day. Minnow, crawfish, and a variety of turtle traps were baited and set on the first day to passively sample macroinvertebrate, fish, amphibian, and reptile communities. Additional financial support for turtle trapping (i.e., cost of nets, bait, mileage, etc.) was provided by the Mississippi Wildlife Heritage Fund as part of their efforts to locate alligator snapping turtles (Macroclemys temminckii) in selected river basins in the state. Data loggers also were deployed on the first day to obtain a 24-hour water temperature cycle at 5-minute intervals. On the second day, all traps and data loggers were removed.

A total of 101 ponds were visited during the sampling season. Samples and endpoints (Table 1) correlated with the endpoints measured from our previous year's mesocosm experiment. This correlation is critical to the testing of our null hypothesis, which states 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). Analysis of field data and multivariate statistical analyses of all data taken across the various spatial and temporal scales will begin in October 2001. Pond-specific reports of data collected will be sent to all landowners in December 2001.

Mapping and GIS Effort: Current mapping activities consist of detailing local conditions in the area surrounding each of the 101 ponds that were sampled. Activities include evaluating factors that influence water flow and quality into each pond as well as natural conditions that may affect species migration to and from each pond. The up-gradient extent of analysis consists of the pond's watershed. Watershed characterization includes factors such as agricultural occurrence (crop type and acreage), general land use (grass, trees, roads, gravel, bare soil, etc.), residential or urban land use, and industrial land use. The down-gradient area, which does not contribute to the watershed, also is being characterized for evaluation of factors not restricted by the movement of surface water such as animal migration. Data sets used for this activity include: (1) digital elevation models of the study basin, USGS 30 meter DEM data; (2) Landsat 7 imagery
collected from multiple dates in the 1999 growing season; and (3) 1998 and 1999 Farm Service Agency crop data. Upon completion of the characterization of the watershed area affecting each pond, biological sampling data will be combined with this information and analyzed for interactions. These interactions will be used in the development of a conceptual model of interaction in agricultural ecosystems.

Table 1. Summary of samples taken, endpoints measured, and current data status at 101 wetland sites in the Little Tallahatchie River Basin, Mississippi. Researcher initials stand for those personnel (investigators and graduate stu-dents) responsible for the particular assay(s).
Sample	Endpoint and Units (where applicable)	Investigator	Sample Processed	Data Collected	Data Entry
ambient conditions	temperature (C)	CB	completed	completed	completed
	relative humidity (%)	CB	completed	completed	completed
water conditions (onsite)	dissolved oxygen (mg/l)	CB	completed	completed	completed
	temperature (C)	CB	completed	completed	completed
250 mL sediment	sediment pH ([H])	PS	completed	completed	completed
500 mL water	pH ([H])	CB	completed	completed	completed
	turbidity (NTU)	CB	completed	completed	completed
	Phenolphthalein-alkalinity (ppm CaCO3)	CB	completed	completed	completed
	Total-alkalinity (ppm CaCO3)	CB	completed	completed	completed
4 L water	primary productivity	CO,FO	completed	completed	in progress
	bacterial productivity	CO,FO	completed	completed	in progress
	DOC	CO,FO	completed	completed	in progress
	TP	CO,FO	completed	completed	in progress
	light extinction coefficient	CO,FO	completed	completed	in progress
	TN	CO,FO	completed	in progress	in progress
	CHNS	CO,FO	completed	in progress	in progress
	pigments	CO,FO	completed	in progress	in progress
	chlorophyll a	CO,FO	completed	in progress	in progress
	suspended sediments	CO,FO	completed	in progress	in progress
temperature logger	water temp at 5 min intervals (C)	CB	completed	87/101	completed
zooplankton sample	community description	ST	completed	in progress	in progress
vegetation transect	categorical vegetation description at -1, 0, 1, 5, and > 5 m from shore	CB	completed	completed	completed
50 m perimeter walk/site description	site description, owner info, frogs calling, etc.	CB	completed	completed	completed
seine/dipnet captures	count of fish, reptiles, amphibians, inverts	CB	completed	completed	completed
minnow trap captures (fish)	age category	CB	completed	completed	completed
	species	CB	completed	completed	completed
crawfish trap captures (fish)	age category	CB	completed	completed	completed
	species	CB	completed	completed	completed
crawfish trap captures (hatchling /juvenile turtles)	species	CB	completed	completed	completed
	gender (M/F/J)	CB	completed	completed	completed
	mass (g)	CB	completed	completed	completed
	length (mm)	CB	completed	completed	completed
turtle trapping (3' diameter hoop nets of varying mesh and opening sizes)	species	CB	completed	completed	completed
	gender (M/F/J)	CB	completed	completed	completed
	mass (g)	CB	completed	completed	completed
	length (mm)	CB	completed	completed	completed
Digital photos	digital photos	CB	completed	in CD format	NA
Trachemys scripta (male)	digestive efficiency of turtles	SS	completed	completed	completed
Gambusia affinis	DNA strand breakage	SD,PS	in progress	in progress	in progress
	apoptosis (presence/absence)	SD,PS	in progress	in progress	in progress
	RAPD	SD,PS	in progress	in progress	in progress
Rana sphenocephala eggs and tadpoles	DNA strand breakage	SD,PS	in progress	in progress	in progress
	apoptosis (presence/absence)	SD,PS	in progress	in progress	in progress
Lepomis macrochirus	DNA strand breakage	SD,PS	in progress	in progress	in progress
	apoptosis (presence/absence)	SD,PS	in progress	in progress	in progress
	RAPD	SD,PS	in progress	in progress	in progress

Mesocosm Experimental Effort: Univariate and multivariate analysis of data from our previous year's multiple stressor mesocosm experiment is underway. Rana sphenocephala metamorphs emerging from the mesocosms in 2000 were released into a drift-fence enclosed common pond. Surveys of pitfall trap captures revealed that these individuals have survived under enclosed conditions but had not reached reproductive maturity by spring of 2000. Assessment of survival and reproductive activity will continue through the spring of 2002.

Future Activities:

A conceptual model of interaction in agricultural systems will be developed based on characterization of the watershed area affecting each pond, biological sampling data, and interactions found when this information is combined and analyzed. Further investigation will be conducted to evaluate spatial or temporal scale dependencies of the model and how it can be used in both small watersheds and the overall study basin. This process may include the use of additional imagery most likely of a higher resolution than that available with Landsat 7.

Journal Articles on this Report : 1 Displayed | Download in RIS Format

Publications Views

Other project views:	All 33 publications	3 publications in selected types	All 2 journal articles

Publications

Type	Citation	Project	Document Sources
Journal Article	Easson GL, Robinson H. Using 30-meter resolution digital elevation data for basin analysis-a practical utilization of USGS 24K digital elevation data-complications and solutions. ArcUser 2001;4(3):26-28.	R826595 (2001) R826595 (Final)	not available

Supplemental Keywords:

water, watersheds, scaling, metals, organics, genetics, molecular biology, remote sensing, monitoring, ecology, limnology, agriculture, organism, cellular, population, enzymes, 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 ecosystems

Relevant Websites:

http://www.olemiss.edu/projects/epa-eig/

Progress and Final Reports:

Original Abstract

1999 Progress Report

2000 Progress Report

Final Report