Postexposure metabolic effects of sulfide and evidence of sulfide-based ATP production in callianassid ghost shrimp (Crustacea:Decapoda:Thalassinidea)

Abstract

Lepidophthalmus louisianensis and Callichirus islagrande were exposed to simple anoxia and to sulfide under normoxia and anoxia, after which pleopodal ventilation and oxygen consumption were monitored in closed respirometers over declining oxygen tensions. C. islagrande exhibited the overall higher rate of ventilation at almost all time intervals and oxygen tensions, regardless of the pretreatment. Only in L. louisianensis was ventilatory rate significantly elevated immediately following anoxia. At time intervals ≥90–120 min, ventilatory patterns for the two species diverged in terms of how anoxic, normoxic sulfide, and anoxic sulfide pretreatments compared to controls. Only in L. louisianensis did rates of controls decrease over time. Ventilatory responses of this species may conserve energy as an adaptation to the stresses imposed. In both species, pretreatment with either normoxic sulfide or anoxic sulfide increased metabolic rates over those following pretreatment under normoxia in the absence of sulfide. C. islagrande maintained higher ventilatory and oxygen consumption rates overall than did L. louisianensis throughout the 3-h duration of experiments, both for controls and for animals prestressed with anoxia and/or sulfide. This suggests its greater dependence on aerobic metabolism than in L. lousianensis. Analysis of selected metabolically active tissues in a coupled enzyme procedure revealed that mitochondrial isolates of both species could produce ATP from sulfide. In 100 μmol l −1 sulfide, L. louisianensis produced more ATP than did C. islagrande. Ecological significance of this ability remains in question.