Effects of salinity on larval stages of the rhizocephalan barnacle Loxothylacus texanus:: survival and metamorphosis in response to the host, Callinectes sapidus

It is known that the rhizocephalan barnacle Loxothylacus texanus infects the greater blue crab, Callinectes sapidus, in the Gulf of Mexico and adjacent waters, however, factors that affect the prevalence and distribution of this parasite, particularly the dispersive larval stages of this organism, are not well understood. In the current study, the effects of salinity on larval survival and the metamorphosis of L. texanus in response to postmolt host exoskeleton were examined. Acute and acclimated responses were similar. Larval survival was highest in the 20-35 parts per thousand range, with 100% mortality of nauplii at all salinities <20parts per thousand and <50parts per thousand. L. texanus cyprids were able to metamorphose over a broad range of salinities (15-60parts per thousand). In several cases, metamorphosis was actually greatest at high salinities (40-50parts per thousand). These data predict that L. texanus larvae would be concentrated in portions of Gulf of Mexico waters with salinities >20parts per thousand such as the mouths of estuaries and bays. Conversely, upper regions of estuaries may be inhospitable to the dispersive (naupliar) stage of the parasite and may serve as a refuge from infection for host crabs. (C) 2003 Elsevier B.V. All rights reserved.