740 VERNBERG 



peaks during low tides, or (3) no detectable rhythm (Azariah, Ismail, 

 and Najib, 1975). 



Metabolic responses of excised gills of the crab Hemigrapsus 

 nudus to temperature and salinity adaptation were reported by 

 Hulbert, Schneider, and Moon (1976a). These workers also investi- 

 gated the effects of temperature and salinity on the intermediary 

 metabolism of excised gill homogenates of this species (Hulbert, 

 Schneider, and Moon, 1976b). At the subcellular level Thomson, 

 Sargent, and Owen (1977) reported on the influence of acclimatiza- 

 tion temperature and salinity on Na/K-dependent adenosine triphos- 

 phate and fatty acid composition in the gills of the eel Anguilla 

 anguilla. They concluded that temperature and not salinity deter- 

 mines the degree of unsaturation of gill lipids. The Arrhenius plot 

 showed a different discontinuity for microsomal Na/K-ATPase from 

 gills of freshwater eels than that for preparations from gills of 

 seawater eels. In another study, temperature and thermal acclimation 

 influenced the osmotic properties and the nonelectrolyte perme- 

 ability of liver and gill mitochondria from the rainbow trout, Salmo 

 gairdneri (Hazel and Schuster, 1976). 



Osmoregulation 



Temperature and salinity effects have been studied on ion levels 

 in the hemolymph of the blue crab Callinectes sapidus (Engel et al., 

 1974) and on the intracellular osmoregulation and muscle-free amino 

 acids in the fish Fundulus diaphanus (Ahokas and Sorg, 1977). 



The relative effects of temperature and salinity on the osmoreg- 

 ulatory ability of marine organisms also have been investigated. Two 

 species of shrimp (genus Crangon) common to the North Sea vary in 

 their migratory behavior (Spaargaren, 1971). Crangon crangon 

 migrates to coastal and inland waters in the spring and returns to the 

 North Sea with the approach of winter; in contrast, C. allmanni 

 typically remains in deeper waters throughout the year. The rate of 

 accommodation of the blood concentration to a new salinity is 

 temperature dependent, i.e., the rate increases as the temperature 

 increases, and Spaargaren generalized that marine species show a 

 quicker adaptation rate than estuarine species. The salinity at which 

 maximal regulation in C. crangon occurs decreases with increasing 

 temperature as was also shown by Weber and Spaargaren (1970). 

 This shifting of the regulation range to reduced salinities at elevated 

 temperatures appeared to be correlated with the summer migration 

 of this species to brackish water. Spaargaren (1971) reported that, in 



