Vitamin A and E Tissue Distribution and Stratification in Comparison with Organochlorine Concentrations of the Bowhead Whale (Balaena mysticetus)
Vitamin A and E concentrations were determined in the liver (n=51), blubber (n=23) and serum (n=53) of bowhead whales (Balaena mysticetus) collected over a four-year period (1998-2001). Samples were collected during the Inupiat subsistence bowhead whale hunt in Barrow and Kaktovik, Alaska as part of a larger health assessment effort. Retinol and alpha-tocopherol were the major forms of vitamin A and E detected, respectively. Liver contained the highest concentrations of vitamin A (4599 ± 3216.9 ug/g) followed by epidermis > blubber > serum. Liver contained the highest concentration of vitamin E (620.72 ± 485.59 ug/g) followed by serum > epidermis > blubber. Stratification of retinol and tocopherol was examined throughout the blubber cores collected. Retinol concentration was significantly higher in the epidermis than in the deeper blubber layers. Tocopherol was significantly higher in epidermis and the intermediate layer of blubber than in the innermost and outermost blubber layers. Serum retinol and tocopherol concentrations were 0.09 (± 0.03) ug/ml and 18.45 (± 11.45) ug/ml, respectively. Males were found to have significantly higher average levels of liver retinol than females. Liver retinol concentration was also found to be significantly higher in the spring versus the fall. Nonpregnant/lactating adults were found to have the highest levels of liver retinol, with the subadults, pregnant and juvenile whales following in decreasing order. The liver retinol concentration differed significantly over the three age groupings (adult > subadult > juvenile). Blubber retinol concentration in the outermost blubber layers was significantly higher in adults than in subadult and juvenile whales. Finally, tocopherol concentration in the intermediate blubber layers was found to be significantly higher in adults than in subadult or juvenile animals. Certain persistent organic contaminants have been shown to have a negative effect on retinol concentration in the serum of pinnipeds and cetaceans. Bowhead whales are known to have relatively low concentrations of organochlorines (OCs) in comparison to other mysticete species. As an adjunct study, the relationships between serum, liver and blubber retinol and serum and blubber OC concentrations were examined with no significant correlations noted. The authors thank Teri Rowles (NOAA) for financial support and for her role as permit holder (permit #932-1489-0000 for the MMHSRP program) as well as Gina Ylitalo (NOAA) and Paul Hoekstra for providing the lipid and OC data used in this study.