Perrault Justin R, Lehner Andreas F, Buchweitz John P, Page-Karjian Annie
Loggerhead Marinelife Center, 14200 U.S. Highway 1, Juno Beach, FL 33408, USA.
Veterinary Diagnostic Laboratory, Toxicology Section, Michigan State University, 4125 Beaumont Road, East Lansing, MI 48910, USA.
Chemosphere. 2019 Feb;217:59-67. doi: 10.1016/j.chemosphere.2018.10.206. Epub 2018 Oct 30.
Plasma osmolalities of marine vertebrates are generally lower than the surrounding medium; therefore, marine organisms must cope with the osmoregulatory challenges of life in a salty environment. The salt glands serve to maintain osmotic and ionic homeostasis in a number of lower marine vertebrates. One marine reptile, the leatherback sea turtle (Dermochelys coriacea), ingests excessive amounts of salts due to their diet of gelatinous zooplankton. Outside of the normal osmoregulatory function of the salt gland, little research has been conducted on contaminant accumulation and excretion in this organ. Here, we established arsenic, cadmium, lead, mercury, and selenium concentrations in red blood cells (RBCs) and salt gland secretions (SGSs) of nesting leatherbacks. We also collected salt glands from different life stage classes of dead stranded leatherbacks from the western Atlantic Ocean to determine if inorganic contaminants accumulate in this organ. Using non-metric multidimensional scaling and regression analyses, we determined that RBC and SGS inorganic contaminant concentrations were not correlated. Additionally, RBCs showed significantly higher concentrations of these contaminants in comparison to SGSs, likely due to the affinity of inorganic contaminants for the heme group of RBCs. Lastly, we found that salt gland cadmium and mercury concentrations tended to increase with increasing curved carapace length (CCL) in stranded leatherbacks. Our results indicate that different physiological mechanisms determine the distribution of inorganic contaminants in blood and SGSs. Increases in salt gland contaminant concentrations with increasing CCL suggest this organ as a potential target for accumulation.
海洋脊椎动物的血浆渗透压通常低于周围介质；因此，海洋生物必须应对在咸水环境中生活的渗透调节挑战。盐腺有助于维持一些低等海洋脊椎动物的渗透和离子平衡。一种海洋爬行动物，棱皮龟（Dermochelys coriacea），由于其以胶状浮游动物为食，会摄入过量的盐分。除了盐腺的正常渗透调节功能外，关于该器官中污染物的积累和排泄的研究很少。在这里，我们测定了筑巢棱皮龟红细胞（RBC）和盐腺分泌物（SGS）中的砷、镉、铅、汞和硒浓度。我们还从西大西洋搁浅死亡的不同生活阶段的棱皮龟身上收集了盐腺，以确定无机污染物是否在这个器官中积累。通过非度量多维尺度分析和回归分析，我们确定红细胞和盐腺分泌物中的无机污染物浓度没有相关性。此外，与盐腺分泌物相比，红细胞中这些污染物的浓度显著更高，这可能是由于无机污染物对红细胞血红素基团的亲和力。最后，我们发现搁浅棱皮龟的盐腺镉和汞浓度往往随着弯曲背甲长度（CCL）的增加而增加。我们的结果表明，不同的生理机制决定了无机污染物在血液和盐腺分泌物中的分布。随着弯曲背甲长度增加，盐腺污染物浓度升高，表明这个器官是污染物积累的潜在目标。
