Benzo(a)pyrene mono-oxygenase activity in the shore CRAB, Carcinus maenas, in response to salinity stress

Abstract

1. The cytochrome P-450 mono-oxygenase system is involved in the detoxification of xenobiotic compounds and, as such, has been suggested as a possible indicator of certain hydrocarbon pollutants. Microsomal benzo(a)pyrene mono-oxygenase (BPM) activity was assayed in the antennary gland, eyestalk, testes and heart of Carcinus maenas exposed to constant and “cycling” salinity regimes over a range of 5–36% 0. 2. In all tissues examined, an inverse relationship between BPM activities and hypo-salinity stress was noted, with lower BPM levels monitored at salinities between 25 and 36% 0, approximately 75–110% seawater. The enzyme activity-salinity pattern was not considered quantifiable, however, as there was significant variation in assays of BPM activity. 3. Of the tissues examined, BPM activities were highest in the antennary gland and the BPM differential between salinity extremes was also greatest in this tissue. 4. A seasonal pattern, associated with ambient temperature, was superimposed at all salinities, with higher BPM activities recorded during the winter. 5. In view of the significant and inconsistant variations in BPM activity during exposure to salinity levels normally associated with the habitat of Carcinus, the usefulness of BPM as an indicator of organic pollution is questionable.