A Method for Conducting Acute Toxicity Tests with the Early Life Stages of Freshwater Mussels

Abstract

Testing techniques to assess the acute effects of pesticides to sensitive life stages of freshwater mussels have been developed for the Ecological Effects Branch (EEB), Office of Pesticide Programs (OPP), U.S. Environmental Protection Agency (EPA). The objective of this research was to define techniques for testing freshwater mussels, and not to promote or endorse the mussel species used. The techniques developed include testing of the following early life stages: mature glochidia, recently transformed juveniles, and older juveniles. Anodonta imbecilis was amenable to acute testing methods development for the following reasons: it is reproductively active throughout most of the year; it is easily collected in the field and maintained in the laboratory; it adapts well to artificial conditions; and the transformed juveniles do not require feeding or special conditions for short-term laboratory maintenance and testing. The acute sensitivity of these young mussels was evaluated using three pesticides. The A. imbecillis acute toxicity data obtained through these 48-h exposures show that the life stages tested are less sensitive to Cyhalothrin,® Carbaryl,® and Atrazine® than the commonly used freshwater cladoceran Daphnia magna.