Formatted Title:

Recent Developments in the Use of Freshwater Mussels for Water and Sediment Toxicity Testing

Background/Objectives:

Freshwater mussels are among North America’s most imperiled aquatic species, with over 70% considered at risk, threatened, or endangered. Numerous stressors can affect native freshwater mussels such as changes in water quality, degraded habitat, and contaminants. Freshwater mussels are frequently identified as potential receptors with intact exposure pathways in aquatic risk assessments. In order to assess the effects of contaminants, there is a need to develop and standardize methods that can be used to derive high-quality reliable toxicity data that can be used to support decisions on the conservation of freshwater mussels.

The objectives of this research were to 1) develop standard methods for the culturing of freshwater mussels for routine toxicity testing and 2) optimize and demonstrate standard toxicity test methods for analysis of waters and sediment.

Approach/Activities:

To develop culturing methods we have evaluated the unique lifecycle of freshwater mussels – which includes a parasitic life stage on the gills of a fish host. We have evaluated these methods for over 20 different test species from across North America and included four different fish hosts including Largemouth Bass, Smallmouth Bass, Channel Catfish, and Freshwater Drum. To rear juvenile mussels, we explored different methods including the use of commercially available diets, using automated feeding systems, and using natural surface waters. Toxicity test method development has focused on adapting and optimizing standard methods for acute and chronic water-only tests, short-term effluent tests, and whole sediment toxicity tests.

Results/Lessons Learned:

Culturing methods have been optimized using a pulse-flow feeding system to produce high-quality test organisms. We are currently using a pulse-flow system for delivering scheduled commercially available algae. This approach provides high quality organisms for toxicity testing. We have also developed test methods for water-only, effluent, and sediment toxicity testing that have been published in ASTM International standards. Studies following the standard methods have demonstrated that mussels are sensitive to numerous chemicals including major ions, metals, and nutrients. In addition, we are currently assisting the USEPA to update effluent test methods by including mussels as additional test species under USEPA’s water quality management programs. These methods have been routinely used worldwide, including at Natural Resource Damage Assessment and Restoration (NRDAR) and Superfund sites.

Ning Wang

Affiliation

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Recent Developments in the Use of Freshwater Mussels for Water and Sediment Toxicity Testing