Effects of long-term exposure to pentachlorophenol on the free amino acid pool and energy reserves of the freshwater amphipod Gammarus pseudolimnaeus Bousfield (Crustacea, Amphipoda).

The freshwater amphipod Gammarus pseudolimnaeus was exposed for 45 days to pentachlorophenol (PCP). The total concentration of free amino acids (FAA) decreased significantly after 5 days exposure to 0.77 or 1.25 mg PCP/liter. Exposure to PCP had no effect on the relative concentrations of individual amino acids exposed to 0.77, 1.06, or 1.25 mg PCP/liter. Whole body concentrations of glycogen, protein, and caloric content were significantly decreased after 15 days and lipid content after 30 days exposure to 0.77 mg PCP/liter. Since energy reserves and caloric content were not measured on the 5th day of PCP exposure, the relative sensitivity of FAA as a biochemical indicator of toxicant-induced stress cannot be compared directly. However, since reductions in growth and/or energy reserves can significantly influence the fecundity of amphipods, alterations in the FAA pool are indicative of future adverse effects on the organism. The use of alterations in the concentration of FAA is discussed with respect to its application as a biochemical indicator of toxicant exposure in freshwater invertebrates.