Metal Bioaccumulation and Biochemical Responses in Loggerhead Turtles (Caretta caretta) from the Gulf of Gabès (Tunisia)

Caretta caretta (Cheloniidae, Cryptodira) is a species of turtle considered a ‘flagship species’ in the Mediterranean Sea. Unfortunately, the circular marine currents and semi-enclosed configuration of the Mediterranean Sea encourage the accumulation of pollutants (metals, pesticides, etc.) emitted by human activities. Tunisia suffers particularly from coastal urbanisation and industrial development. Metal concentrations (Ag, Al, As, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, Zn) were measured in distinct tissues (heart, kidney, liver, lung, muscle) of loggerhead turtles stranded in the Gulf of Gabès (Tunisia) to estimate the pollution levels in this emblematic species. High concentrations of arsenic and cadmium were found in marine turtles. Therefore, the differential accumulation of metals was measured in the tissues. For example, the liver appears to be a preferential organ for the accumulation of copper, iron, silver and zinc. In contrast, cobalt and cadmium were more concentrated in the kidneys, while arsenic, chromium and nickel were mainly found in the muscles. Antioxidant enzyme responses (catalase, GPx and SOD) and lipid peroxidation were more expressed in the liver and kidneys than in the muscles.