Marine Biology

, Volume 35, Issue 1, pp 91-104

First online:

Mercury-selenium-bromine imbalance in premature parturient California sea lions

  • J. H. MartinAffiliated withCalifornia State UniversityMoss Landing Marine Laboratories
  • , P. D. ElliottAffiliated withCalifornia State UniversityMoss Landing Marine Laboratories
  • , V. C. AnderliniAffiliated withLawrence Berkeley Laboratory, University of California
  • , D. GirvinAffiliated withLawrence Berkeley Laboratory, University of California
  • , S. A. JacobsAffiliated withLawrence Berkeley Laboratory, University of California
  • , R. W. RisebroughAffiliated withBodega Marine Laboratory, University of California
  • , R. L. DelongAffiliated withMarine Mammal Division, National Marine Fisheries Service, Naval Support Activity
  • , W. G. GilmartinAffiliated withBio-Systems Program, Naval Undersea Center

Rent the article at a discount

Rent now

* Final gross prices may vary according to local VAT.

Get Access


High premature birth rates have been observed in the rookeries of the California sea lion Zalophus californianus since 1968. The reasons for the premature pupping are complex and, hence, not well understood, although leptospirosis infection and elevated PCB and DDT residues have been implicated. We were interested in determining what role trace and major elements played in these events. Livers and kidneys from 10 normal parturient and 10 premature parturient mothers and their pups were analyzed for Hg, Se, Br, Cd, Ag, Cu, Fe, Zn, Mn, K, Na, Ca, and Mg in order to detect differences that might exist between the two groups. A further objective was to establish how these elements varied in relation to each other in the normal and abnormal sea lions. Our results revealed that Hg, Se, Cd, and Br levels were significantly higher in the livers of the normal mothers and that these elements were all in balance (highly correlated) with each other. This was especially true for Hg, Se, and Br. In mothers with high concentrations of these elements (e.g. Hg greater than 800 μg/g dry weight), atomic ratios of approximately 1Hg:1Se:1Br were observed. Atomic Se:Hg ratios were also near unity in the abnormal mothers; however, Br concentrations were always severely depressed in these individuals. Normal full-term pups had higher hepatic levels of Hg and Se, and near-perfect 1:1 Se:Hg atomic ratios were almost always observed. In contrast, the livers of the premature pups appeared to be deficient in Hg, and, consequently, elevated Se:Hg ratios were always found. In almost all cases, the premature pups had increased concentrations of Na, Ca, and Br. Levels of these elements were correlated with their Se:Hg ratios. Amounts of Mn and Cu were reduced in the premature pups and negatively correlated with Se:Hg ratios. The results suggest that balance between elements is of more importance than absolute concentration when the possible effects of toxic elements are considered. It also appears that bromine may be important in the detoxification process involving Se and Hg and perhaps Cd as well; i.e., every mother that had Br in balance with Hg, Cd, and Se had a normal pup, while every mother that lacked sufficient Br had a premature pup. The question of whether Hg detoxifies Se is also raised. All the normal pups had Se:Hg atomic ratios of less than 2.2, while all the premature pups had reduced Hg amounts and Se:Hg ratios above 3.4.