VARIATION IN TEMPERATURE-SALINITY TOLERANCE BETWEEN TWO ESTUARINE POPULATIONS OF PAGURUS LONGICARPUS SAY (CRUSTACEA:ANOMURA)

¹ Department of Biology, Franklin and Marshall College, Lancaster, Pennsylvania 17604

1. A hermit crab, Pagurus longicarpus Say, was collected from two sites in southern New Jersey at approximately the same latitude but on different sides of the Cape May peninsula. Those from Hereford Inlet lived in mean salinity of 30, and Delaware Bay Cape Shore hermits lived in 20.

2. Adults from both populations were acclimated for two weeks to 22 and 30 and were then subjected to 20-36 combinations of temperature and salinity. Cumulative mortality after 96 hours was used to fit response surfaces for estimating tolerance.

3. Hereford and Cape Shore populations differed in temperature-salinity tolerance. Cape Shore crabs showed wider temperature tolerance than identically-acclimated Hereford crabs, while the latter survived greater variation in salinity. Apparently, different acclimation salinities are not alone sufficient to explain differential tolerance.

4. Salinity tolerance of adults from New Jersey is compared with tolerance of zoeae and megalopae from previous studies in Virginia. At 20° C, zoeal salinity tolerance is identical from 18.0-30.5. At the same temperature, estimated optimal salinity range for adults is 15-36.