METAMORPHOSIS OF THE ESTUARINE CRAB RHITHROPANOPEUS-HARRISII - EFFECTOF WATER TYPE AND ADULT ODOR

Larvae of many estuarine crabs are transported to coastal/offshore are as where they develop and subsequently return to the estuary as postla rvae (megalopae), which settle and metamorphose. For these species, it is important for megalopae to be able to differentiate between offsho re and estuarine areas as sites for metamorphosis. In contrast, larvae of the crab Rhithropanopeus harrisii (Gould) are retained in estuarie s near the adult habitat throughout development. Although previous stu dies have demonstrated that the rate of metamorphosis of the megalopal stages of several estuarine crabs is accelerated when exposed to estu arine cues, it was hypothesized that metamorphosis of R, harrisii post larvae is not affected by exposure to offshore and estuarine waters bu t is accelerated by exposure to adult odor cues. Metamorphosis of R. h arrisii megalopae was accelerated upon exposure to estuarine water and delayed in offshore water at salinities ranging from 5 to 25 PSU. Tim e to metamorphosis in both water types increased as the salinity decre ased. Adult odor also accelerated metamorphosis. Thus, the test hypoth esis was only partially supported, and the results indicate that diffe rentiation between offshore and estuarine areas for metamorphosis is c ommon among estuarine crabs regardless of their patterns of larval dev elopment.