Metal contamination of the macrobenthic fauna of the Dakhla Bay (South of Morocco): An ecotoxicological diagnostic and environmental perspective

Abstract

This ecotoxicological research has focused on the metal contamination study of wild and livestock macrobenthic fauna in the Bay of Dakhla city. During the last decade, this coastal town in the extreme south-west of Morocco has known a considerable and accelerated socio-economic development. This latter could induce negative repercussions on the bay ecological state and its environment. Therefore, samples of mussels (Perna perna), hollow oysters (Crassostrea gigas) and knives (Solen marginatus) were collected in various locations in the Dakhla Bay during June and December 2011 in order to determine their trace metals levels: Lead, Cadmium, Zinc and Copper. The stud-ied species showed different behavior with respect to metal contamination: i) oysters tend to accumulate on average more than 2 mg/Kg dw. of Cd, and 400 mg/Kg dw. of Zn, ii) mussels assimilate Cu better with grades up to 29 mg/Kg dw., iii) knives have the lowest levels of trace metals, iv) Pb assayed showed a levels below the threshold of detection at different sites and for all samples. The difference in storage capacity would be allocated to multiple biological and environmental factors governing the spatial and temporal var-iation, more or less significant (p <0.05). Through the correlation between contaminated sites and urban and industrial activities points, it may be possi-ble to conclude that the multiple discharges related to the different human activities in Dakhla city are the main source of metal contamination observed in Dakhla bay bivalves. So ecological management of these discharges is needed to curb this pollution and avoid the associated health risks.