Methylmercury and total mercury distribution in tissues of gray whales (Eschrichtius robustus) and spinner dolphins (Stenella longirostris) stranded along the lower Gulf of California, Mexico

Abstract

Four gray whales Eschrichtius robustus and eleven spinner dolphins Stenella longirostris were found stranded along the coasts of the lower Gulf of California, Mexico. Muscle, kidney and liver samples from all the specimens were used for mercury (Hg) analysis. Mean concentrations of total Hg (THg) were significantly different (P kidney>muscle. Mean values of THg in the three tissues of gray whales were not statistically different. Similarly, methylmercury (MeHg) levels in the analyzed tissues of dolphins and whales were not statistically different. Considering species-related differences, it seems that THg and MeHg levels in the studied marine mammals did not play a key role in the stranding of the specimens, though more studies about the implications of Hg compounds in stranding events are necessary.

Keywords

• mercury
• methylmercury
• Stenella longirostris
• Eschrichtius robustus
• Gulf of California (Mexico)