Distribution of copper in the Atlantic and Pacific Oceans using green turtles (Chelonia mydas) as a bioindicator

Marine pollution by trace elements is a global concern due to potential toxicity to species and ecosystems. Copper is a fundamental trace element for many organisms; however, it becomes toxic at certain concentrations. The green turtle (Chelonia mydas) is a good sentinel species, due to its circumglobal distribution, long life cycle, coastal habits when juvenile, and is subject to environmental pollution. Quantifying and comparing copper levels makes it possible to understand the availability of this trace element in nature. During this research, comparisons were made between the levels of copper found in the liver, kidneys, and muscles of 35 turtles, from the United States (Hawaii and Texas), Brazil, and Japan. Copper was found in all specimens. In the liver, animals from Hawaii (91.08 µg g^-1), Texas (46.11 µg g^-1), and Japan (65.18 µg g^-1) had statistically equal means, while those from Brazil (16. 79 µg g^-1) had the lowest means. For the kidney, copper means were statistically equal for all Hawaii (3.71 µg g^-1), Texas (4.83 µg g^-1), Japan (2.47 µg g^-1), and Brazil (1.89 µg g^-1). In muscle, the means between Texas (0.75 µg g^-1) and Japan (0.75 µg g^-1) were the same, and the mean for Brazil (0.13 µg g^-1) was the lowest. Among the organs, the highest levels of copper were found in the liver (28.33 µg g^-1) followed by the kidney (2.25 µg g^-1) and with the lowest levels in the muscle (0.33 µg g^-1). This is the first study of copper levels among marine vertebrates in distant parts of the globe using similar comparative filters between different locations. Similar levels in turtles from such distant locations may indicate that there is a pantropical pattern of copper distribution in the biota, and that these animals are subject to the process of bioavailability of this metal in the environment and metabolic regulation.