Comparative Sublethal Actions of 3-Trifluoromethyl-4-nitrophenol in Marine Molluscs as Measured by in Vivo31P NMR

The sublethal actions of the piscicide, 3-trifluoromethyl-4-nitrophenol, were characterized in two marine molluscs by in vivo31P nuclear magnetic resonance spectroscopy. This noninvasive technique is ideal for examination of cellular respiratory toxicity since inorganic phosphate, phosphoarginine, and adenosine 5ʹ-triphosphate levels, and the arginine kinase rate constant, can be measured. These parameters were characterized in both red abalone (Haliotis rufescens) and owl limpets (Lottia gigantea) during 5-h exposures to 3 mg L-1 (14.5 muM) 3-trifluoromethyl-4-nitrophenol, followed by 5-h recovery periods. In exposed abalone, phosphoarginine decreased by 50%, inorganic phosphate increased by 900%, and the arginine kinase rate constant quadrupled--all compared to controls and consistent with an uncoupling of oxidative phosphorylation. Limpets were less severely impacted, showing no change in phosphoarginine, an increase of only 200% in inorganic phosphate, and an approximate doubling of the arginine kinase rate constant. Adenosine 5ʹtriphosphate levels remained constant in all control and exposed molluscs. In addition, at the cessation of dosing, all biochemical parameters in abalone returned to preexposure levels within 3-4 h, consistent with rapid depuration, whereas the limpet recovery data were inconclusive. We suggest that the owl limpetʹs greater tolerance toward the pesticide could result from an increased capability for anaerobic glycolysis, which is required to survive the periodic anoxia associated with residing higher in the intertidal zone. Thus, the natural histories of nontarget organisms should be considered when the effects of pesticide exposure are determined.