Heavy Metals in Sediments and Lobster (Panulirus gracilis) from the Discharge Area of the Submarine Sewage Outfall in Mazatlán Bay (SE Gulf of California)

Abstract

Concentrations of selected heavy metals in lobster (Panulirus gracilis) tissues and sediments (bulk and bioavailable fractions) from an area influenced by sewage discharge in Mazatlán Bay were determined. Cd, Cu, Fe, Pb, and Zn in the sediments showed enrichment factors higher than one related to the discharge and were higher than the lower values of the sediment quality guidelines proposed by NOAA and CCME. In addition to the high levels, relatively high bioavailability in the sediments was estimated for Cd, Cu, Mn, Pb, and Zn, suggesting a possible adverse effect on the associated benthic organisms. A high concentration of Cr, Fe, Mn, and Ni was found in the exoskeleton of P. gracilis. The hemolymph, hepatopancreas, gills, and gonads concentrate Cu, Cd, and Zn to levels higher than the available concentration in the sediments (BCF > 1). However, most of the metals studied in the edible muscle tissue in P. gracilis ranged within the recommended limits for human consumption, except Pb, which was found to be above the acceptable level for shellfish and represents a health risk.