The objectives of this study were to evaluate existing techniques for culturing three species of the genus Mysidopsis that are routinely used as toxicity test organisms. A comparison of the life history, ecology and distribution of M. bahia, M. bigelowi and M. almyra is presented. Culture systems are described, supplemental foods are suggested, and guidelines are given for salinity, temperature, dissolved oxygen and nitrogen levels that will maintain optimum laboratory culture conditions. Methods are outlined for harvesting juveniles and controlling contaminant organisms, and general feeding procedures are described. Culture management is stressed as the most significant factor in maintaining productive mysid cultures. Specific recommendations are made regarding culture density, harvesting frequency, sex ratio and introduction of feral animals.

Abstract-para-Nonylphenol (PNP), a mixture of alkylphenols used in producing nonionic surfactants, is distributed widely in surface waters and aquatic sediments, where it can affect saltwater species. This article describes a database for acute toxicity of PNP derived for calculating a national saltwater quality criterion. Using a flow-through exposure system with measured concentrations, we tested early life stages of four species of saltwater invertebrates and two species of fish. Static 96-h tests were also conducted on zoeal Homarus americanus, embryo-larval Mulinia lateralis, and larval Pleuronectes americanus. The number of organisms surviving the flow-through test was measured at 2, 4, 8, and 12 h and daily through day 7. Mortality for most species plateaued by 96 h. The ranked sensitivities (96-h 50% lethal concentrations, measured in micrograms per liter) for the species tested were 17 for Pleuronectes americanus, 37.9 (48-h 50% effective concentration) for Mulinia lateralis, 59.4 for Paleomonetes vulgaris, 60.6 for Americamysis bahia (formerly Mysidopsis bahia), 61.6 for Leptocheirus plumulosos, 70 for Menidia beryllina, 71 for Homarus americanus, 142 for Cyprinodon variegatus, and Ͼ195 for Dyspanopius sayii. Values for the seven most sensitive of these species ranged over a factor of only 4.2. The narrow range of responses for PNP implies that exceeding a threshold concentration would endanger a large proportion of the aquatic community.

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Abstract-Acute and chronic bioassay statistics are used to evaluate the toxicity and risks of chemical stressors to the mysid shrimp Americamysis bahia (formerly Mysidopsis bahia). These include LC50 values from acute tests, chronic values (the geometric mean of the no-observed-effect concentration and the lowest-observed-effect concentration from 7-d and life-cycle tests), and U.S. Environmental Protection Agency water quality criterion continuous concentration (CCC). Because these statistics are generated from responses of individual organisms, the relationships of these statistics to significant effects at higher levels of ecological organization are unknown. This study was conducted to evaluate the quantitative relationships between toxicity test statistics and a concentration-based statistic derived from exposure-response models relating projected population growth rate to stressor concentration. This statistic, C*, describes the concentration above which mysid populations are projected to decline in abundance as determined using population modeling techniques. An analysis of responses of A. bahia to 10 metals, nine organic compounds, and ammonia surprisingly indicated the acute LC50 to be the best predictor of C*, followed by the chronic value from life-cycle tests, which predicted population-level response almost equally as well. The chronic value for the 7-d test was less predictive of population-level effects. The CCC was lower than C* for 94% of the compounds evaluated, indicating the criterion value to be protective of population-level effects for A. bahia, as intended.