The effect of salinity on the development ofLoxothylacus panopaei larvae (Crustacea: Cirripedia: Rhizocephala)

The rhizocephalan barnacleLoxothylacus panopaei, which parasitizes the mud crabRhithropanopeus harrisii, releases its larvae as nauplii. The nauplii develop through four stages to the cypris stage; both larval forms are lecithotrophs. Parasitized crabs were acclimated in 10‰, 15‰, and 20‰ water during August and the development of releasedL. panopaei larvae was monitored in a range of salinities. After 48–60 h, the nauplii and cyprids in each experimental salinity were counted and the numbers used to calculate a developmental index. The range of salinities in which successful development to cyprids occurred (developmental index >70%) could be shifted as a consequence of the acclimating salinity.L. panopaei larvae can develop successfully over a 10–30‰ salinity range, indicating that settlement onto host crabs and virgin externae is likely to take place in nature within this range.