Toxicity of Mexel 432 to Three Species of Freshwater Organisms

Abstract

Certain species of life are incompatible with mechanisms associated with industries using natural waters for cooling or manufacturing. Many industries have increasing concerns with the interference of water flows due to aquatic organism accumulations ultimately causing flows to decrease and interfering with the mechanical processes. One species of particular concern in the United States and Europe is the zebra mussel (Dreissena polymorpha). Many control methods for this species have been attempted with limited success. J\.new chemical product developed in France, Mexel 432, shows promise as a control agent. The Lake Superior Research Institute (LSRI) has conducted tests with this mixture with sensitive non-target species to determine the acute toxicity of Mexel.

The three animal species tested were a cladoceran, Daphnia magna, fathead minnow, Pimephales promelas, and the rainbow trout, Oncorhynchus mykiss. Daphnia magna was chosen because it represents sensitive invertebrate species that ,may inhabit lakes and large rivers where Mexel could potentially be discharged if used as control' agent for the zebra mussel. Organic matter was varied between acute tests with the cfadoceran because it has been shown in studies conducted in Europe that water quality has strong influence on the toxicity of Mexel to aquatic organisms. The cladoceran was tested in both short-term acute tests and a long-term chronic test. .The fathead minnow was chosen because it represents the warmwater group of fish. Rainbow trout represent .the coldwater fish species. Both fish species were tested as juveniles (very sensitive life stage) in seven-day exposures.