THE EFFECTS OF SEASON, TEMPERATURE, AND SALINITY ON STANDARD AND ACTIVE OXYGEN CONSUMPTION OF THE GRASS SHRIMP, PALAEMONETES VULGARIS (SAY)

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Abstract
The effects of season, temperature, and salinity on the standard and active oxygen consumption of Palaemonetes vulgaris (Say) from Texas bays were determined by manometry. Chronic exposure to salinities from 3.5 to 32 p.p.t. produced no change in standard oxygen metabolism. Nor were circadian or tidally induced metabolic rhythms evident. Except for summer or warm-adapted shrimps measured at 10 °C, neither season nor prolonged exposure of shrimps to 10°, 20°, or 30 °C produced shifts in the standard or active oxygen rate – temperature curves obtained between 10° and 30 °C. Rather the effect of treatment or of season was reflected primarily by adaptation to temperature extremes. Thus, warm-adapted and summer shrimps lost equilibrium at 10 °C, whereas cold-acclimated shrimps showed metabolic depressions at high temperatures (35 °C). In general, Q10 values were low (< 2.0) for both standard and active oxygen rates. Also an adaptive adjustment in the availability of energy for activity appears to occur with warm and cold adaptation. Thus, although metabolic rates do not change markedly, when exposed to warm temperatures, warm-adapted grass shrimps swim faster per unit of active oxygen consumption than do intermediate or cold-acclimated shrimps. The reverse condition prevails for cold-acclimated shrimps.