Lucina pectinata Gmelin, the mud clam, as a resource in the monitoring of ecosystem responses to environmental changes

The feasibility of using Lucina pectinata, the mud clam, as a sentinel organism to monitor environmental changes due to contaminants was studied. Histopathological effects and induction of cytochrorne P-450 were selected as biological responses. The contaminants employed were pyrene and the herbicide 2,4-dichlorophenoxyacetic acid (2,4-D). The effects of contaminants in clams were assessed following 30 and 60 days periods of continuous exposure in seawater with concentrations of 0.1, 1.0 and 10.0 mug/L for pyrene and 1.0, 10.0 and 100.0 mug/L for 2,4-D, respectively. Following each period of exposure the effects of contaminant depuration were assessed during 30 and 60 day periods. Field studies of bioaccumulation were conducted for comparison with laboratory results. Clam transplantations from uncontaminated to contaminated areas were made in order to measure differences in uptake, accumulation and biological responses to pollutants. Concentrations were measured in whole tissue and determined by gas chromatography-mass spectrometer (GC-MS).;Histopathological examination did not reveal any pyrene or 2,4-D related increases of pathology. There were just a few minor changes. In the gonads, clusters of brown cells and resorption of gonads were observed with high frequency. These frequencies were not significantly correlated with contaminant concentrations. There was no spectral evidence for the presence of cytochrome P-450 in whole clam microsomal preparations because the interference of hemoglobin spectra matching those corresponding to P-450 region. On the other hand, enzymatic activity of cytochrome P-450 was observed in clams of all pyrene and 2,4-D treatments except controls. Average results were low. Several factors were suggested as possible causes for the low activity observed.;The ability of L. pectinata to bioconcentrate contaminants in the laboratory suggests that it is a good potential candidate to be employed in biomonitoring when pollutant bioavailability under controlled conditions is needed. However, the effectiveness of L. pectinata as a deployed sentinel organism for measuring the bioaccumulation of contaminants present in the field was unsatisfactory. Histopathological results were considered non successful since no significant changes were observed. (Abstract shortened by UMI.).