Salinity responses in brackish water populations of the freshwater shrimp Palaemonetes antennarius—I. Oxygen consumption

Abstract

1. 1. Rapid increases in salinity result in a mean increase in oxygen consumption of 54% which returns again to the initial level after 8–10 hr. Decreases in salinity produce an increase in the metabolic rate of only 20% which returns to the initial level again after 4–8 hr. 2. 2. In steady-state experiments, the shrimps display the lowest oxygen consumption rates at low salinities. The lowest metabolic rates occur at a salinity of 2‰ and 5‰. At 20‰ the shrimps exhibit up to 30% higher metabolism. 3. 3. A comparison of three brackish water populations shows that the metabolic response to an acute change of salinity depends on the salinity to which the animals had been acclimated before. 4. On the basis of measured metabolic rates productivity estimations were undertaken and discussed in connection with earlier ecological finclings. In 19‰ brackish water Palaemonetes antennarius lives at its physiological limit. There it does not grow, loses biomass, and probably only enters this area from autumn to spring.