Elemental and Organochlorine Concentrations in Tissues of Stranded Marine Mammals on Maryland Shoreline from 2000 to 2015

This study evaluated toxic metallic and organochlorine concentrations in tissues of marine mammals that stranded in Maryland over a 15-year period (2000-2015). The sampled marine animals belonged to Delphinidae (dolphins and long finned pilot whales; n=61), Phocidae (Harp, Gray, Harbor and Hooded seals; n=20), Phocoenidae (Harbor porpoises, n=4), Ziphiidae (Gervais' beaked whale and True’s beaked whale, n=2) Balaenopteridae (humpback whales, n=2) and Kogiidae (pygmy sperm whales, n=2). Stranding location, age group, sex, date and season were recorded. Metallic elements in liver and kidney were analyzed using ICP-MS, while GC-MS was used for organochlorines in blubber. Data were analyzed by computing median concentrations followed by analysis with Mann Whitney U or Kruskal Wallis tests. All statistical comparisons were considered statistically significant at p< 0.05. Mercury and copper were significantly elevated in Delphinidae liver in comparison to Phocidae. Hg was elevated in adult strandings. Concentrations of trans-nonachlor and oxychlordane were significantly higher in blubber of adult Phocidae strandings while p_p_DDD and dieldrin were significantly elevated in adult Delphinidae. Total PCB and p_p_DDE were significantly higher in Delphinidae females. This data shows variability in accumulations of toxic elements and persistent organic pollutants among different marine mammals. While it cannot be concluded that these pollutants are a major cause of strandings of the marine mammals, factors leading to bioaccumulation and toxicity of the contaminants need to be elucidated.