Temporal Evolution of Metals in the Two Most Industrialized and Densely Populated Gulfs of Greece, via Metal Accumulation by Mytilus galloprovincialis
The status and trend of chemical contamination of the coastal marine environment through the monitoring of sessile marine organisms is widely established (i.e., the mollusc bivalve Mytilus galloprovincialis often used in the “mussel-watch” programs). This paper aims to describe temporal trends of metals by the means of metal accumulation in Mytilus galloprovincialis at the most industrialized and densely populated gulfs in Greece. Municipal, industrial wastes, and naval activities are the three main pollution sources responsible for the decline of the Saronikos (Central Aegean Sea) and Thermaikos (North Aegean Sea) Gulfs’ water quality. In addition, three rivers flowing into Thermaikos contribute to the surcharge of its waters. Note that the coasts of the Thermaikos gulf and its adjacent area host the most extended and productive mussel aquacultures in Greece. Mussels were collected from selected stations frequently:—four times per year from Saronikos Gulf (1986–2006) and one to two times per year from Thermaikos Gulf (1993–2007). They were monitored for the metals Cu, Cr, Ni, Zn, Fe, and Mn, and occasionally for Cd and Pb. Data were treated statistically in order to calculate trends. Metal concentrations varied considerably during the studied period in both gulfs. Evolution patterns were not common for all metals. In Saronikos Gulf, metal values in mussels reached their high levels during the periods 1988–1990 and 1994–1998. The operation (since 1996) of the Athens waste treatment plant together with a certain deindustrialization of the area is the probable cause of a decreasing trend in Ni, Cd, and Cu; Cr and Mn presented no trend, while Zn was increasing. In the case of Thermaikos Gulf, metal values in mussels reached their high levels during the 2004–2007 period, while lower levels were noted during 1996–1998. An increasing trend was recorded for Cu, Cr, Ni, Zn, Fe, and Mn that for some metals were of 150% of magnitude, a fact that needs a special attention.
KeywordsMain Pollution Source Water Quality Decline Important Water Quality Mussel Aquaculture Bioindicator Organism
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