Trace elements in loggerhead turtles (Caretta caretta) stranded in mainland Portugal: Bioaccumulation and tissue distribution

Abstract

Pollution is among the most significant threats that endanger sea turtles worldwide. Waters off the Portuguese mainland are acknowledged as important feeding grounds for juvenile loggerheads. However, there is no data on trace element concentrations in marine turtles occurring in these waters. We present the first assessment of trace element concentrations in loggerhead turtles (Caretta caretta) occurring off the coast of mainland Portugal. Also, we compare our results with those from other areas and discuss parameters that may affect element concentrations. Trace element concentrations (As, Cd, Cu, Pb, Mn, Hg, Ni, Se, Zn) were determined in kidney, liver and muscle samples from 38 loggerheads stranded between 2011 and 2013. As was the only element with higher concentrations in muscle (14.78 μg g ww) than in liver or kidney. Considering non-essential elements, Cd presented the highest concentrations in kidney (34.67 μg g) and liver (5.03 μg g). Only a weak positive link was found between renal Cd and turtle size. Inter-elemental correlations were observed in both liver and kidney tissues. Hepatic Hg values (0.30 ± 0.03 μg g) were higher than values reported in loggerheads in the Canary Islands but lower than in Mediterranean loggerheads. Cd concentrations in the present study were only exceeded by values found in turtles from the Pacific. Although many endogenous and exogenous parameters related with complex life cycle changes and wide geographic range may influence trace element accumulation, the concentrations of Cd are probably related to the importance of crustaceans in loggerhead diet in the Portuguese coast.

Trace metal accumulation in decapods and its use in monitoring the marine environment

“…Bioaccumulation distribution patterns vary with species, but the tissue type results of this work generally align with previous trace element research (Beeram et al, 2012;Soedarini et al, 2012;Mazlum et al, 2016;Nicolau et al, 2017). As copper is a bioessential element, it is expected to be taken up preferentially in the organs for use.…”

“…The animals in the 20µg/L copper treatment had higher concentrations of copper than the controls in all of their tissues, including the muscle, indicating accumulation of the contaminant. Most studies, on decapods and on other organisms, have found the accumulation is highest in the organ, then the exoskeleton (in the case of crustaceans), with muscle containing the least amount of copper (Guner 2007;Beeram et al, 2012;Soedarini et al, 2012;Mazlum et al, 2016;Nicolau et al, 2017). The results of this experiment showed the highest rate of accumulation of copper was in the organs, but in contrast, this study found that even the undoped animals had more copper in their muscle tissue than in their shells.…”

Toxic metals in Loggerhead sea turtles ( Caretta caretta ) stranded freshly dead along Sicilian coasts

“… 1998 ; Storelli and Marcotrigiano 2000 ), Portugal (14.7 ± 1.47 mg/kg w.w.) (Nicolau et al. 2017 ) and Canarias (7.35 ± 1.37 mg/kg w.w.) (Torrent et al. 2004 ), even though the diet of southeast Mediterranean Loggerhead sea turtles is primarily based on small crustaceans which usually show high concentrations of total As (Norin et al.…”

“… 2004 ; Nicolau et al. 2017 ). No significant correlation was found between cadmium concentration and the morphometric parameters of the specimens examined, in contrast to what was reported by Storelli et al.…”

Biogenic Elements and Heavy Metals in Hermann’s Tortoises—Testudo hermanni: Effect on Serum Biochemistry and Oxidative Status Parameters

“…Studies on the issue of the toxicological potential of Cd have shown that it can increase the levels of reactive forms of oxygen (ROS), leading to much structural and functional damage, such as peroxidation of cellular lipids, destruction of proteins, and DNA mutations [ 13 , 14 , 15 , 16 , 17 , 18 ]. Influence of heavy metals (mercury—Hg, lead—Pb) has a severe impact on turtles [ 19 , 20 , 21 , 22 ]. Anthropogenic influences such as mining, burning of fossil fuels, factory liquidation of waste, usage of agricultural pesticides, and release of waste from water treatment plants may lead to excessive accumulation of trace elements in the environment [ 23 , 24 , 25 ].…”