COMPARISON OF CIRCULATING AND HEPATIC VITAMIN AND MINERAL CONCENTRATIONS IN ELASMOBRANCHS UNDER MANAGED CARE

Both blood and liver samples can be used to evaluate vitamin, mineral, and heavy metal concentrations clinically. In elasmobranchs, it is unknown whether circulating concentrations of these analytes reflect concentrations in storage organs such as the liver. The purpose of this study was to report hepatic concentrations of select heavy metals and to compare concentrations of select vitamins and minerals in paired blood and liver samples in captive elasmobranchs. Blood (serum or lithium heparinized plasma) samples collected perimortem and hepatic tissue samples collected during necropsy from 27 elasmobranchs were included. Taxa (order, species), sex (male, female), and age class (immature, mature) were recorded. Vitamin A, vitamin E, cobalt, copper, iron, manganese, molybdenum, selenium, and zinc were measured in both blood and liver. Arsenic, cadmium, lead, mercury, and thallium concentrations were reported for liver only. Descriptive statistics were calculated for each analyte. Statistical analysis was performed with scatter plots with fitted regression lines, box plots, and a multiple linear regression model for multivariate analysis. Only the correlation between blood and liver concentrations of molybdenum (P < 0.001), cobalt (P = 0.001), iron (P = 0.014), and vitamin A (P = 0.020) were statistically significant. Significant differences in blood manganese and molybdenum, and hepatic vitamin A, manganese, molybdenum, and zinc were found between taxonomic orders. However, no differences based on sex or age class were detected. Future research is needed to elucidate the clinical significance of circulating versus tissue vitamin and mineral concentrations in elasmobranchs.