A whale of a tale: A One Environmental Health approach to study metal pollution in the Sea of Cortez.

Marine metal pollution is an emerging concern for human, animal, and ecosystem health. We considered metal pollution in the Sea of Cortez, which is a relatively isolated sea rich in biodiversity. Here there are potentially significant anthropogenic inputs of pollution from agriculture and metal mining. We considered the levels of 23 heavy metals and selenium in seven distinct cetacean species found in the area. Our efforts considered two different periods of time: 1999 and 2016/17. We considered the metal levels in relation to (1) all species together across years, (2) differences between suborders Odontoceti and Mysticeti, (3) each species individually across years, and (4) gender differences for each of these comparisons. We further compared metal levels found in sperm whale skin samples collected during these voyages to a previous voyage in 1999, to assess changes in metal levels over a longer timescale. The metals Mg, Fe, Al, and Zn were found at the highest concentrations across all species and all years. For sperm whales, we observed decreased metal levels from 1999 to 2016/2017, except for iron (Fe), nickel (Ni), and chromium (Cr), which either increased or did not change during this time period. These results indicate a recent change in the metal input to the Sea of Cortez, which may indicate a decreased concern for human, animal, and ecosystem health for some metals, but raises concern for the genotoxic metals Cr and Ni. This work was supported by NIEHS grant ES016893 (J.P.W.) and numerous donors to the Wise Laboratory.

Absorption and ocular deposition of dietary lutein in marine mammals.

Cataracts and ocular disease are common lesions of marine mammals in zoological collections. Lutein, an oxygenated carotenoid, may have therapeutic or prophylactic effects on ocular disorder. Therefore, this study examined the ability of marine mammals to absorb dietary lutein. Two preliminary trials examined lutein in two forms (beadlet or ester) in a small sample size of marine mammals representing pinnipeds and cetaceans. Lutein was fed daily in tablets providing 0.89-3.6 mg lutein/kg body weight(0.75) per day for 15 days to 2 years. A third study was conducted using lutein beadlet fed at 3.6 mg lutein/kg body weight(0.75) per day for 15-21 days. Blood was analyzed for lutein pre- and postsupplementation. In the preliminary trials, lutein beadlet was observed to result in greater blood lutein levels than lutein esters, and cetaceans had more noticeable responses than pinnipeds. In Study 3, serum lutein and zeaxanthin increased postsupplementation in beluga whales (P < 0.05), and serum lutein tended to increase postsupplementation in dolphins (P < 0.10), but little change was seen in serum lutein in pinnipeds or manatee. Opportunistic retinal samples demonstrated some detectable lutein in the retina of a dolphin and several harp seals. The lutein levels in dolphins after supplementation are similar to those reported in free-ranging animals. Ocular lutein in harp seals demonstrates that ocular deposition occurs despite low circulating lutein levels.

Trace elements intake in the Faroe Islands. I. Element levels in edible parts of pilot whales (Globicephalus meleanus).

We examined the distribution of copper, zinc, selenium, arsenic, cadmium and mercury (total and methyl mercury) in samples of muscle, liver, kidney and blubber from pilot whales (Globicephalus meleanus) caught off the Faroe Islands in 1977 and 1978. The very high total mercury level in the mature pilot whale exhibited differences among tissues and was highest in the liver. The total mercury concentration increased with body size. With increasing body size the ratio of methyl mercury to total mercury was relatively constant in muscle and kidney, but it decreased in liver. The concentrations of total mercury in the tissues of immature whales were much lower than those of mature whales. Selenium levels increased with body size. Significant correlation coefficients were found between the total mercury and selenium in liver and kidney. Selenium was present in the kidney in molar excess relative to mercury, whereas the opposite was the case in the muscle tissue. High cadmium contents were found in kidney and liver. In muscle and liver no significant correlations were found between cadmium and selenium, but a weak correlation between these elements was recorded in the kidney.

Occurrence and fate of organic and inorganic contaminants in marine animals.

Most chemical contaminants occur in highest concentrations in coastal waters, often maximized in very localized areas. In general, this situation represents the exposure pattern for marine animals. However, the availability of contaminant to an organism depends not only on its concentration but also on its chemical nature, its physical state, and whether the source of exposure is the surrounding seawater or the diet. Depending on the type of exposure, uptake occurs across absorptive surfaces, such as those of the respiratory apparatus or gastrointestinal tract, where selectivity may occur, even among neighboring homologs. Deposition in tissues, accumulation, degradation, or depuration depends on tissue type, metabolic processes, detoxification mechanisms, and the adaptive status of a particular animal. This hypothesis is examined briefly for hydrocarbons, pesticides, other miscellaneous organic contaminants, heavy metals, and radionuclides. It is concluded that most data relate to occurrence and distribution. Considerably less information is available on the underlying biochemical processes.

Heavy metals in tissues of stranded short-finned pilot whales.

Selected tissues from four short-finned pilot whales that stranded at Cumberland Island National Seashore were analyzed for total cadmium, mercury and selenium by neutron activation. Cadmium reached a maximum mean wet weight concentration of 31.4 ppm in the kidney tissues. Maximum mean wet weight concentrations of mercury, 230.0 ppm, and selenium, 44.2 ppm, were found in the liver tissues. The lowest concentration of each metal was found in the blubber. Postmortem examination showed that the whales had no food in their stomachs. The whales must have been utilizing metabolic reserves, contaminated with residual concentrations of heavy metals, prior to beaching. This utilization of reserves probably resulted in the high concentrations of cadmium, mercury and selenium found in the liver and kidney tissues. Since the heavy metal concentrations were three to four times greater in the stranded whales, as compared to apparently healthy whales of the same species, it is suggested that heavy metal toxicosis may have been a factor contributing to this particular stranding.

Mercury and selenium in marine mammals and birds.

Information is provided concerning the concentrations of mercury and selenium in tissues of marine animals. In marine mammals a 1:1 Hg/Se molecular increment ratio was found and an almost perfect linear correlation between mercury and selenium. It is suggested that marine mammals are able to detoxify methylmercury by a specific chemical mechanism in which selenium is involved. The results also indicate that the fate of methylmercury in fish-eating marine birds differs fundamentally from that in marine mammals.