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Links Between Mercury and Liver Damage in Wild Fish Populations

Links Between Mercury and Liver Damage in Wild Fish Populations. A.K. Gevertz 1 , P.E. Drevnick 2 , and A.P. Roberts 1 1 University of North Texas, Denton, TX 2 Woods Hole Oceanographic Institute , Boston, MA. Background. Sources of Mercury: atmospheric deposition metal mining

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Links Between Mercury and Liver Damage in Wild Fish Populations

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  1. Links Between Mercury and LiverDamage in Wild FishPopulations A.K. Gevertz1, P.E. Drevnick2, and A.P. Roberts1 1University of North Texas, Denton, TX2Woods HoleOceanographicInstitute, Boston, MA

  2. Background Sources of Mercury: • atmospheric deposition • metal mining • power plants • natural sources Mercury is methylated in aquatic systems Hg  MeHg

  3. Biomagnification occurs as methylmercury is passed through food web Environment Canada

  4. Effects of Mercury • Neurotoxic to humans • Laboratory studies have demonstrated effects on fish survival, fertility, development, and behavior. • No studies have demonstrated impacts of atmospherically-deposited Hg on wild fish at ecologically-relevant levels.

  5. Isle RoyaleNational Park • Located in Lake Superior • Unusually high levels of methylmercury due to atmospheric deposition

  6. Question: Does Hg pose a threattofishhealthon IRNP? • 124 northernpikewerecollectedfrom 8 lakes • Fillets and liversweretestedformercurywithcold-vapor A.A. spectroscopy • Subsamples of liverfromeachfishwereembedded in paraffinforhistology State of Alaska

  7. What was found… …a correlation between liver color and fish mercury content Question: Why was the liver color different?

  8. Lipofuscion • Pigmentation change that occurs as a result of accumulation of cellular-breakdown products • Can indicate increased cellular damage as a result of toxicant exposure Dark livers from IRNP contained large numbers of LF bodies Question: Does LF correlate with [Hg] in fish?

  9. Lipofuscion Quantification • Small samples of liverwereembedded in paraffin and sectionedon a microtome • Eachsamplewasphotographed at 200X • A grid (squares 25 X 25mm) wasoverlaidoneachimage • 50 squareswererandomlyselected and evaluatedforthepresence of LF. • Theproportion of squarescontaining LF wereusedtoquantifytheamount of liverdamage

  10. r2= 0.81 P= 0.006 Lipofuscion content was correlated with liver color Liver color was correlated with Hg content

  11. Conclusions • LF levels are higher in the dark liver samples • Darker samples have higher mercury content • Lipofuscion quantification might provide an accurate method to determine mercury concentration and as well as damage • Future Directions • Caddo Lake • Lab studies

  12. Acknowledgements • Coauthors: Dr. Paul Drevnick, Dr. Aaron Roberts • Funding Source: U.S. EPA STAR Program • Dr. Kevin Stevens, Dr. Ed Dzialowski, Dao Ho, Matt Kovach

  13. Questions? Amanda K. Gevertz akg0034@unt.edu

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