CHANGES IN TEMPERATURE, SALINITY, AND PH AFFECT GROWTH AND ECDYSONE LEVEL IN MARINE MYSID

The opossum shrimp, Neomysis awatschensis (Crustacea: Mysidae) is a small crustacean native to coastal regions of South Korea. In this study, we measured in vivo ecdysone (i.e. 20-hydroxyecdysone) levels by employing competitive Enzyme Immunoassay (EIA) method from 10 developmental stages which are comprised by embryo, nauplioid, postnauplioid, and adult stage. Furthermore we analyzed potential correlation between environmental fluctuations (i.e. changes in temperature, salinity, and pH) and subsequent modulations in ecdysone levels as well as morphological parameters. Briefly, the ecdysone contents were drastically increased from late nauplioid to postnauplioid stages. The highest temperature treated (25^oC) significantly increased growth parameters and ecdysone content, while mortality slightly increased compared to the 20^oC-exposed mysids. In the case of salinity, both growth parameters and ecdysone content showed high levels in the 30 psu-treated mysids. Significant low levels in survival, growth parameters, and ecdysone content were observed in the groups treated with relatively low salinity (e.g. 5, 10, and 15 psu). When mysids exposed to different pH conditions, low levels in survival, growth parameters, ecdysone contents were observed in pH 7.0-exposed mysids. Our results suggest that ecdysone level is crucial for mysid growth and the levels are strongly associated with culture conditions in N. awathchesis.