Mysids in toxicity testing - a review D. R. Nimmo & T. L. Hamaker Environmental Research & Technology, Inc., 1716 Heath Parkway, Fort Collins, CO 80522, U.S.A. Keywords: Mysidacea, Mysidopsis bahia, Mysidopsis almYra, toxicity Abstract The use of mysid shrimp, particularly the genus Mysidopsis, along with specific testing procedures, has become accepted in aquatic toxicology. Investigators have developed methodologies for both culture and testing of these organisms. Acute and chronic (life cycle) toxicity tests in addition to dredge spoil and effluent tests with mysids are now becoming common. Attempts have been made to use mysids as test organisms in behavioral, physiological, nutritional, and food-chain studies. In general, Mysidopsis spp. have been shown to be as sensitive or more sensitive to toxic substances than other marine species tested. The ease of handling and culture, relative sensitivity to toxicants, short life cycle, small size and direct larval development make these organisms desirable for research purposes. Continued research using mysid species will probably demonstrate even greater usefulness of these organisms in assessment of pollutant impacts on estuarine or marine communities. Introduction Most water-borne pollutants have the ocean as their ultimate repository, with the estuary as the corridor; therefore, organisms in estuaries and near-shore waters can be chronically exposed to various pollutants. But it was not until the mid 1970s that few, if any, chronic or life cycle toxicity tests were routinely employed using estuarine spe- cies. Schimmel & Hansen (1974) reported delete- rious effects of polychlorinated biphenyl (PCB) using the sheepshead minnow, Cyprinodon varie- gatus, throughout a life cycle, and this research stimulated interest in life cycle studies utilizing oth- er estuarine species. The life cycles of many estua- rine species, particularly invertebrates, are complex and require specific and often restrictive tempera- ture and salinity regimes. Often, food requirements of larval stages are not known and in addition, good quality salt water for laboratory culture of estua- rine species is difficult to obtain and expensive to maintain. For the above reasons many marine and estuarine species have not been utilized as research organisms. In 1975, we began using an estuarine mysid shrimp, Mysidopsis bahia, in the laboratory with the purpose of conducting entire life cycle tests. Life cycle tests using a species of palaemonid shrimp, Palaemonetes pugio, had been completed success- fully(Tyler-Schroeder 1977) but the test was lengthy due to the life history of the shrimp. In the late 1970s we reported the successful use of M. bahia in life cycle studies using a variety of toxicants, per- haps the most notable being Kepone (Nimmo et al. 1977, 1978a, 1980). At the time of our initial research little was known of the biology or ecology of this crustacean; the only publication of any scientific consequence was the original species description of M. bahia (Molenock 1969). Although M. bahia had not been used in acute testing, Anderson et al. (1974) had shown that Mysidopsis almyra was very susceptible Hydrobiologia 93, 171-178(1982). 0018-8158/82/0932-0171/$01.60. © Dr W. Junk Publishers, The Hague. Printed in the Netherlands.