This project represents a comparative study of larval release rhythms and the environmental factors that control egg hatching in caridean shrimp of the genus, Palaemonetes. Grass shrimp from estuaries exhibiting different tidal cycles and a freshwater pond/lake will be used as test organisms. Palaemontes pugio and Palaemonetes paludosus will represent the estuarine and freshwater habitats, respectively. The major objectives of this project are: 1. to determine the type of hatching rhythms shown by grass shrimp species from the two habitats; 2. to ascertain the presence of endogenous control of the hatching rhythm and the environmental parameters to which they are entrained; 3. to establish the site(s) of control of endogenous hatching rhythms in grass shrimp from the two habitats; 4. to ascertain the presence and nature of any chemical cue that synchronizes the hatching of eggs; and 5. to correlate hatching rhythms with the prevailing environmental parameters in the two habitats. The results of this investigation will represent the first comparative account of egg hatching rhythms of grass shrimp from diverse habitats and will provide a unique opportunity for testing previously proposed larval release models. The project will contribute to our understanding of the basic types of hatching rhythms and the interrelationship between the ecology of adult shrimp and hatching rhythms.
