Heavy Metals in Marine Mammals Das et al 2003 & O’Hara et al 2003

MM Context Long lived – ? bowheads >100y Predators Bioaccumulators Epizootics in relatively polluted regions such as Baltic, N. Sea and Med. Possibly associated with immunosuppression

Problems Complex inorganic and organic mixtures Multiple stressors – foraging, reproducing, fasting, moulting, migrating, predators, disease, habitat degradation. Limited experimental opportunity Most samples from dead stranded animals de Swart 1996 seal pcb/ immuno study did not examine metal concentrations, only HAH’s. Hard to distinguish natural from anthropogenic Hg naturally high in Med, Cd in Arctic Experiments mimic levels in wild? Are high levels bio-available?

Metals Can be immunotoxic, although no clear indication in MM yet Essential: Zn, Cu, Cr, Ni, Se, Al Non-essential Hg, Cd, Pb Cr, Ni and Pb usually low in MM (few µg/g dw) Ringed seal stillbirth correlates with [Ni] in air in Finland Zn, Cu, Cd and Hg are bigger concerns

Das et al 2003

Arctic Higher in Greenland Arctic 15 th century Inuit and seal hair than in N Sea today. Natural source. Same for porpoises. May reflect lack of organic binders in Arctic water. Hg, CD, Zn and Cu levels vary across Arctic with natural sediment levels. ? Exposed for millenia and well adapted

Routes Lungs Skin Placenta Milk Mouth

Diet Cephalopods concentrate Cd in viscera – Holsbeek saw high Cd in Sperm whale (Physeter) – see osteomalacia in humans – not seen in Pm Bivalves transfer Cd and Pb to walrus. Dugongs – High Cd and Zn. ? Results from low seagrass Cu augmenting intake Minke whale: Hg Greenland >>>>Antarctic (fish vs krill)

Organ distribution Hg – Liver > Kidney > Muscle Beluga slough 20% of Hg burden annually in skin Cd – Kidney

Hg Me-Hg most lipid soluble and toxic form, so [ΣHg] poor indicator of Hg toxicity. Se demthylates Hg and reduces intake. Ratio important Biomagnifies up chain from zooplankters Easy placental transfer Sensory and motor deficits, anorexia and lethargy Hg in Tt hepatic lipofuchsin Hi Hg in N Sea Pp ? Assoc with incr. parasitism

Hg detoxification Hg/Se mutual antagonism Hg is demthylated – see mercuric selenide in hepatic macrophages – in Ziphius, striped dolphin, Tursiops and G mac also in lung assoc w C particles in latter 2 spp. – leads to high but non-toxic concentrations

Hg in Faroes G melas Faroese eat µg Hg/week Health advisory – no viscera and meat & blubber only once per week High Se may protect human consumer, but Weihe, Grandjean et al showed Hg associated cognitive deficits in human offspring Beluga – hepatic Hg levels high but may not be a major human diet item

Cd Kidney, lung, cardiovascular, hemopoietic Carcinogenic, mutagenic, teratogenic Osteomalacia ‘itai-itai’ Arctic ringed seals < 2000 µg/g dw (800 µg/g dw induces renal damage in humans), but no effects documented in seals: implies efficient detoxification and tolerance to high levels High in baleen whales – no effects seen Bowhead renal Cd levels of possible concern to human subsistence consumers

Metalothioneins High cysteine content – mainly in liver and kidney High affinity for divalent cations such as Cu 2+ and Zn 2+ as well as Cd 2+, Ag +, Hg 2+ and Pb 2+ Lowest levels in stranded sperm whales - ? Cd tox part of the syndrome

Organotins Higher in coastal water animals Higher in cetaceans than pinnipeds ( hair excretion) High in liver and hair of Steller’s sea lion TBT and DBT immunotoxic in vitro – Nakata et al 2002 – in Tt, Zc and humans Little loss to offspring from mothers – adult M and F levels compare – cf. HAH Nakata et al 2002 Environmental Pollution Volume 120, Issue 2, December 2002, Pages Environmental Pollution Volume 120, Issue 2

Fig. 2. Proliferation response of peripheral blood mononuclear cells (PBMCs) in two bottlenose dolphins following the treatment with non-ortho coplanar PCB congeners and butyltins. #: P<0.01.

Fig. 5. Proliferation response of peripheral blood mononuclear cells (PBMCs) in bottlenose dolphins following the treatment with the mixture of butyltins and non-ortho coplanar PCB congeners and butyltins. #: P<0.01.

Elevated accumulation of tributyltin and its breakdown products in bottlenose dolphins (Tursiops truncatus) found stranded along the U.S. Atlantic and Gulf coasts ? Immunosupression enhanced morbillivirus die- offs Kannan, et al 1997 Environmental Science & Technology vol. 31, no. 1, pp

Fluoride Fluoride concentration in fin whales higher than that normally occurring in any mammalian species, ranging from 4,340 to 18,570 ppm. – Significantly above the levels causing bony exostoses in sheep and cattle. Krill are high in Fl. Assume resistant – Landy et al 1991

Issues Many MM were over-exploited – some not recovering: vessel collision, gear entanglement, ? heavy metal impact, organic contaminants. Some species directly compete with commercial fisheries, others do not May have important community structure role as predators Do metals impact immune function?