Impact of Heavy Metals in Eggs and Tissues of C. caretta along the Sicilian Coast (Mediterranean Sea)

Abstract

In this study we compared the heavy metal concentration found in different tissues and eggs of the loggerhead sea turtle and evaluated the potential ecotoxicological risk for this important species. Eighteen heavy metal elements were determined in different tissues (liver, gonads, fat, kidney, heart, brain, and spleen) of nine individuals of Caretta caretta found stranded along the coasts of Messina (Sicily, Italy) and in the shell and yolk of six eggs from the island of Linosa (Sicily, Italy). For the analysis of the heavy metals, we used the analytical procedures in accordance with the EPA 200.8 method supplemented by EPA 6020b with three replicates for each measurement. The elements analysed showed different organotropism even if the liver showed higher levels of bioaccumulation. Turtles’ tissues showed the highest values of iron in the liver, followed by zinc in the heart and arsenic in the kidney. Regarding eggs, zinc, iron, and barium were dominant in the yolk and iron, boron, and copper in the eggshell. From the analyses carried out the worrying levels of arsenic and cadmium in the kidneys and liver of C. caretta raise questions about the risk related to exposure to these non-essential elements. This study highlights the importance of multi-element biomonitoring by increasing knowledge on the biodistribution of 18 heavy metals and the related potential risks for C. caretta. We also exploring for the first time the presence of several heavy metals in the eggs and their possible implication for the survival of the species.

Trace Elements and Persistent Organic Pollutants in Unhatched Loggerhead Turtle Eggs from an Emerging Nesting Site along the Southwestern Coasts of Italy, Western Mediterranean Sea

“…Selenium concentrations (median value = 1.2 mg kg -1 w.w.) were comparable to results obtained from the yolk of loggerhead turtle eggs from Linosa Island in the eastern Mediterranean Sea (mean value 4.61 mg kg −1 dry weight) [ 51 ] and in the egg content of loggerhead turtles from northwest Florida, USA (5.46 mg kg −1 dry weight corresponding to approximately 1.36 mg kg −1 w.w.) [ 58 ] but lower than levels measured in the yolk of green turtle eggs from Hong Kong (mean value 3.5 mg kg −1 w.w.) [ 63 ].…”

“…Despite this, Cd concentrations in the composite egg samples (median value = 0.005 mg kg −1 w.w.) were the lowest among the analyzed trace elements. Previous studies that have quantified cadmium in loggerhead turtle egg samples reported concentrations at least 2 × higher than those found here [ 17 , 48 , 49 , 51 , 59 ].…”

“…Unlike Pb and Hg, cadmium has been shown to accumulate in the renal tissue of Mediterranean loggerhead turtles, probably as a result of chronic exposure to this contaminant via food [ 19 , 21 , 44 , 51 ]. Despite this, Cd concentrations in the composite egg samples (median value = 0.005 mg kg −1 w.w.) were the lowest among the analyzed trace elements.…”

“…Trace elements, namely iron, zinc, copper, cadmium, lead, and mercury, have also been analyzed in 22 samples of eggshells and remaining yolks collected at four nesting beaches in Turkey, with mercury being the only toxic element always below the detection limit [ 48 ]. More recently, the occurrence of 18 heavy metals was investigated in six eggs from three different nests laid on Linosa Island, an Italian minor nesting site located in the eastern Mediterranean, and five elements (tin, nickel, barium, antimony, lead, and chromium) were below the detection limit [ 51 ].…”

Chlorinated Persistent Organic Pollutants (PCDD/Fs and PCBs) in Loggerhead Sea Turtles Stranded along the Central Adriatic Coast

“…Some papers reported that the levels of chlorobisphenyls (CBs) and organochlorine pesticides (OCPs) are higher in tissues of loggerhead sea turtles than in tissues of green and leatherback turtles, and this may be due to the different dietary habits [ 25 , 26 , 27 ]. As they are widely distributed from oceanic to neritic habitats, and they are opportunistic predators feeding mostly on benthic organisms [ 28 ], loggerhead sea turtles can be also considered bioindicators of chemical pollution in marine ecosystems [ 29 , 30 , 31 , 32 ]. The C. caretta is the most common species of sea turtle in the Mediterranean Sea, a semi-closed basin, with highly anthropized coasts [ 33 ].…”