. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. TOLERANCE IN HERMIT CRAB POPULATIONS 97 than their Hereford counterparts. \Yhen acclimated to the same salinity, varia- tion in temperature tolerance hetween Cape Shore and Hereford crahs decreased, but Cape Shore crabs still survived wider extremes of temperature than did iden- tically acclimated Hereford crabs. Differential temperature tolerance is more pro- nounced at 22%c acclimation (Figs. 1 and 4) than at 30'{6 (Figs. 2 and 3). In interpreting temperature tolerance, one must keep in mind that a popula- tion acclimated
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. TOLERANCE IN HERMIT CRAB POPULATIONS 97 than their Hereford counterparts. \Yhen acclimated to the same salinity, varia- tion in temperature tolerance hetween Cape Shore and Hereford crahs decreased, but Cape Shore crabs still survived wider extremes of temperature than did iden- tically acclimated Hereford crabs. Differential temperature tolerance is more pro- nounced at 22%c acclimation (Figs. 1 and 4) than at 30'{6 (Figs. 2 and 3). In interpreting temperature tolerance, one must keep in mind that a popula- tion acclimated to higher salinity will survive better at high salinity extremes, regardless of the temperature. Conversely, at any combination of temperature and low salinity, a low salinity acclimated group should have a survival advantage. Interaction of temperature and salinity is minimal and independent of acclimation salinity. 45- 40— 35— H 30— a.' a: 25^ 10- 5—. r^r\ ' ' ' T ' ' I ' ' 'I 5 10 15 20 25 30 TEMPERATURE °C FIGURE 4. Estimation of per cent mortality of Hereford hermits acclimated to a lower than normal salinity of 22%c based on fitted response surface to observed mortality at 96 hours under twenty conditions of temperature and salinity (Y = - , - , + ° + ,- + ,X,). Finally, independent of changes in acclimation salinity, low temperatures near 4° C represented more favorable conditions for P. longicarpus than high temperatures near 31° C. Additional factors and their effects Seasonal variation in time to reach LD-50 was negligible in both optimum and extreme temperature-salinity combinations, and seldom varied by more than 12 hours when populations collected at different times during 1971-72 were subjected to any of the temperature-salinity combinations. Cape Shore crabs with only one week acclimation to higher than normal salinity showed tolerance intermediate between that of a normal-acclimated popula-. Please n
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