Alternate Title

Effects of Salinity on Development in the Ghost Shrimp Callichirus islagrande and Two Populations of C. major (Crustacea: Decapoda: Thalassinidea)

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Salinity (S) was abruptly decreased from 35‰ to 25‰ at either the 4th zoeal (ZIV) or decapodid stage (D) in Callichirus islagrande (Schmitt) and 2 populations of C. major (Say). Other larvae were maintained at stable 35‰ or 25‰ S throughout development. In C. islagrande, duration of ZIV did not vary among the stable salinities. However, a decrease of salinity at ZIV reduced the duration of this stage, suggesting that the S decrease could be a possible cue for acceleration of larval development. In the Gulf population of C. major duration of ZIV was significantly longer at stable 35‰ S than at stable 25‰ S; the latter equaled duration for larvae transferred from 35 to 25‰ S at ZIV. Development in the Florida Atlantic population of C. major was variable but similar at stable 35 and 25‰ S. In 2 of 3 such comparisons, larvae reared at a stable 35‰ S more often molted to a 5th zoeal stage and became deformed at D than those reared at a stable 25‰ S. Callichirus islagrande and the Gulf population of C. major, both of which inhabit lower salinity waters on the Louisiana coast, were more similar in larval responses to salinity than were the 2 populations of C. major. Adult habitat was a better indicator of larval response to salinity than was phylogenetic proximity.

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