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

Lepidophthalmus louisianensis and Callichirus islagrande were exposed to si mple 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, regar dless of the pretreatment. Only in L. louisianensis was ventilatory rate si gnificantly elevated immediately following anoxia. At time intervals greate r than or equal to 90-120 min, ventilatory patterns for the two species div erged in terms of how anoxic, normoxic sulfide, and anoxic sulfide pretreat ments compared to controls. Only in L. louisianensis did rates of controls decrease over time. Ventilatory responses of this species may conserve ener gy as an adaptation to the stresses imposed. In both species, pretreatment with either normoxic sulfide or anoxic sulfide increased metabolic rates ov er those following pretreatment under normoxia in the absence of sulfide. C . islagrande maintained higher ventilatory and oxygen consumption rates ove rall than did L. louisianensis throughout the 3-h duration of experiments, both for controls and for animals prestressed with anoxia and/or sulfide. T his suggests its greater dependence on aerobic metabolism than in L. lousia nensis. Analysis of selected metabolically active tissues in a coupled enzy me procedure revealed that mitochondrial isolates of both species could pro duce ATP from sulfide. In 100 mu mol l(-1) sulfide, L. louisianensis produc ed more ATP than did C. islagrande. Ecological significance of this ability remains in question. (C) 2001 Elsevier Science B.V. All rights reserved.