2003 Progress Report: Effects of Multiple Stressors on Aquatic Communities in the Prairie Pothole RegionEPA Grant Number: R830879
Title: Effects of Multiple Stressors on Aquatic Communities in the Prairie Pothole Region
Investigators: Schoff, Pat , Guntenspergen, Glenn R. , Johnson, Carter , Johnson, Lucinda
Current Investigators: Schoff, Pat , Guntenspergen, Glenn R. , Johnson, Carter , Johnson, Lucinda , Olker, Jennifer H.
Institution: University of Minnesota - Duluth , South Dakota State University , United States Geological Survey [USGS]
Current Institution: University of Minnesota - Duluth
EPA Project Officer: Packard, Benjamin H
Project Period: April 7, 2003 through April 6, 2007
Project Period Covered by this Report: April 7, 2003 through April 6, 2004
Project Amount: $746,433
RFA: Developing Regional-Scale Stressor-Response Models for Use in Environmental Decision-making (2002) RFA Text | Recipients Lists
Research Category: Ecological Indicators/Assessment/Restoration , Ecosystems
This project has four major interrelated objectives involving the effects of global climate change and anthropomorphic impacts on amphibians in the Prairie Pothole Region (PPR) of the United States. The objectives of this research project are to:
• Quantify relationships among factors directly affected by climate change, such as hydroperiod (i.e., the amount of time that water stays in a wetland), differing land use (e.g., row crop or pasture grasslands), and the numbers and types of amphibians.
• Quantify the relationships among the physical and chemical attributes of individual wetlands (e.g., hydroperiod, temperature changes over time, pH, dissolved organic matter, solar UV-B radiation, which is increasing in the northern latitudes, and land use), and examine their effects on individual amphibians and amphibian communities.
• Quantify the effects of multiple stressors on the health and organismal responses of the leopard frog (Rana pipiens) by applying two stressors (i.e., shortened hydroperiod and the herbicide atrazine), at the same time and examining their separate and combined effects on frog development.
• Use the data we have gathered in the field and mesocosms, along with regional climate models and models of how water responds to climate changes in Prairie Pothole wetlands, to predict potential effects of multiple stressors on the amphibians and their associated amphibian communities.
The objectives of our study will be met by investigating wetlands and amphibian communities of the PPR on three spatial scales: (1) the landscape scale, in which a survey of wetlands of varying hydrology and in differing land use regimes over the entire U.S. portion of the PPR will be performed; (2) the wetland scale, in which a smaller number of wetlands in east-central South Dakota will be intensively surveyed for an entire amphibian breeding and metamorphic season; and (3) the mesocosm scale, in which frogs will be raised under controlled conditions and exposed to combinations of stressors (accelerated hydroperiod and atrazine). The wetland scale surveys were performed in full in 2003, and the mesocosm experiments were performed on a pilot level.
Data collected from the intensive sites included wetland morphology (hydrological regime and depth profile), physical and chemical conditions (pH, continuous temperature, conductance, salinity, UV radiation attenuation, color, and drying schedule), and amphibian community characteristics (frog calling surveys, amphibian larvae collection, visual encounter surveys, and malformation assessment).
Northern leopard frogs (R. pipiens) were found in 23 of the 27 sites and were found to breed (as evidenced by egg masses, larvae, or metamorphs) in 17 of these sites. Due to the late project start, calling surveys were not successful in identifying breeding amphibian sites in 2003; the only species heard during surveys was the chorus frog. Additional amphibians observed were the chorus frog (Pseudacris triseriata), tiger salamander (Ambystoma tigrinium), American toad (Bufo americanus), and other toad species (unidentifiable but likely Canadian toad, Woodhouses' toad, and Great Plains toad).
Water level and water quality were measured in conjunction with the amphibian surveys. Wetland depths were measured weekly along with measurements of water quality (pH, salinity, temperature, and conductivity). Water samples also were collected twice for chlorophyll-a, total suspended solids, true color, and dissolved organic carbon. Additionally, water temperature was recorded every 2 hours throughout the season for all sites.
All wetlands were surveyed for malformed metamorphs. A total of 1,475 metamorphs were collected, and of these, 45 had at least 1 identifiable skeletal or craniofacial malformation, resulting in a malformation prevalence of 3.1 percent.
The extensive landscape scale portion of our study will be conducted in 2004. In addition, a full complement of mesocosm experiments using combinations of stressors (accelerated hydroperiod and atrazine) will be performed.