Effect of salinity and temperature on the intra-marsupial development of the brackish water mysid Neomysis integer (Crustacea: Mysidacea)

The brackish water mysid Neomysis integer has been proposed as a toxicological test species for the low saline reaches of Western European estuaries and brackish inland water bodies. The embryonic/larval development is a critical time window within the life history of an organism and has high potential to serve as a tool for assessing endocrine-disruptive effects. A protocol is developed to examine the intra-marsupial development of N. integer in vitro, and a morphological description of the embryonic and larval developmental stages was made. Daily survival percentage, percentage survival days, hatching success, total development time, duration of each developmental stage and the size increment of the embryos and larvae were evaluated as potential endpoints, and their response to temperature and salinity was investigated. The survival and hatching success are highly dependent on the salinity conditions, while the development time is strongly affected by temperature. High temperatures (21 degrees C) shorten the development time in comparison with low temperatures (11 degrees C) from 22 to 10 days, but have an opposite effect on survival. Optimal salinity for in vitro embryonic/larval development of N. integer is 14-17. Living in lower or higher salinities thus implies suboptimal conditions for the juvenile recruitment to the population, unless the species can actively regulate the concentration of its marsupial fluid. The developed in vitro technique may be used for testing the effect of both abiotic factors and (endocrine) disrupting chemicals on the intra-marsupial development of N. integer. Survival, hatching success and development time appeared to be adequate endpoints, while size and growth increment of the embryos/larvae seemed to be unsuitable