Funding Program: Fisheries: Aquatic and Endangered Resources

Statement of Problem:
Many factors are cited in the decline of freshwater mussel (Family Unionidae) populations in North America and for the listing of greater than 70% of native unionid species as endangered, threatened, or of special concern. Habitat alteration, introduction of exotic species, over-utilization, disease, predation and pollution are considered causal or contributing factors in many areas of the United States. Almost all of the nearly 70 species of federally-listed endangered or threatened freshwater mussels in the United States occur in Service regions 3, 4, and 5, and this proposal is a joint submission from these regions' Environmental Contaminants and Endangered Species Programs aimed at remedying water quality threats to imperiled unionids. Impaired water quality is a very reasonable hypothesis to test as a limiting factor in the recovery of our listed aquatic species. Toxic substances were one of the top five stressors cited as limiting freshwater mussels in a recent survey of experts for these taxa. A separate review identified industrial, municipal, and agricultural pollution as significant threats to listed mussels (Wegner et al. 2001).
The Service's Environmental Contaminants Program can and should work on identifying the extent of this problem on three fronts:
1) The extent to which water quality is a limiting factor cannot be known without collection of site-specific water quality data. We need to answer the question, "What are the concentrations of hazardous chemicals in our mussel habitats?", and one aspect of this investigation will be collection of water chemistry data in the best remaining habitats for these species. Limited information indicates mussel exposure to copper, chlorine and ammonia is significant and in some cases in excess of concentrations thought to be harmful. We need to more completely document ambient exposure conditions of mussels to these and other common pollutants. Environmental concentrations will provide the numerator in hazard quotients developed for each chemical.
2) Interpreting the chemical data can be difficult due to the paucity of reference toxicity data for unionids. The toxicity database for freshwater mussels is sparse, particularly for long-term exposures that come closest to mimicking real-world exposures. We need to answer the question, "What is the sensitivity of freshwater mussels from chronic exposure to common pollutants in their habitats?" A second aspect of this study involves toxicity testing with these taxa. Limited data from acute (< 96 hours) exposures indicates mussels are quite sensitive to copper, ammonia and chlorine; we need to document chronic no effect concentrations for these chemicals. These tests will allow development of toxicity reference values (such as No Observed Adverse Effects Concentrations) for the denominator in hazard quotients.
3) Lack of standard toxicity testing methods for these taxa contributes to the lack of robust toxicity data and the under-use of existing information. There is a need to work toward standardizing the bioassays for sensitive life stages of freshwater mussels in order to overcome these problems. Work funded through this proposal will demonstrate the utility and reliability of mussels toxicity tests.
 
Objectives:
1. Assess the acute toxicity of chlorine, ammonia and copper to glochidia and juvenile lifestages of five species of freshwater mussel including endangered and non-endangered mussels from the central and eastern United States. In addition, assess the chronic toxicity of chlorine, copper and, if possible, ammonia to one of the species used in the acute toxicity assessments.
2. Document water quality conditions (particularly for copper, ammonia and chlorine) in the best remaining habitat for these species.
3. Employ captive propagation to supply test organisms and reap a number of ancillary benefits. Data to foster direct management actions expected from this part of the project include those related to elucidation of various life-history attributes (fish hosts, culture methods, rearing methods, etc.)
4. Evaluate the use of glochidia in acute toxicity assessments and refine methodology for conducting acute and chronic toxicity tests with juvenile mussels.

Partners:

• Chris Mebane, NAWQA, U.S. Geological Survey
• Cynthia Kane, U.S. Fish and Wildlife Service, Gloucester, VA  Conserving the Nature of America
• F. James Dwyer and Andy Roberts, U.S. Fish and Wildlife Service, Columbia, MO  Conserving the Nature of America
• Gregory Cope, Department of Environmental and Molecular Toxicology, North Carolina State University, Raleigh, NC
• Joseph Bidwell, Zoology Department, Oklahoma State University, Stillwater, OK
• Joseph Gorsuch, Copper Development Association
• M. Chris Barnhart, Biology Department, Missouri State University, Springfield, MO
• Richard Neves, Department of Fisheries and Wildlife Sciences, Virginia Polytechnic Institute and State University, Blacksburg, VA
• Robert Bringolf, Warnell School of Forestry and Natural Resources, University of Georgia
• Robert Santore, HydroQual, Inc.
• Russell Erickson and Charles Stephan, National Health and Environmental Effects Research Laboratory, U.S. EPA, Duluth, MN
• Steven Geis, Wisconsin State Laboratory of Hygiene, Madison, WI
• Teresa Newton, Upper Midwest Environmental Sciences Center, U.S.  Geological Survey, LaCrosse, WI
• Tom Augspurger, U.S. Fish and Wildlife Service, Raleigh, NC  Conserving the Nature of America