links between mercury and liver damage in wild fish populations a.k. gevertz 1, p.e. drevnick 2, and...
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Links Between Mercury and Liver Links Between Mercury and Liver Damage in Wild Fish Populations Damage in Wild Fish Populations
A.K. GevertzA.K. Gevertz11, P.E. Drevnick, P.E. Drevnick22, and A.P. Roberts, and A.P. Roberts11
11University of North Texas, Denton, TXUniversity of North Texas, Denton, TX22Woods Hole Oceanographic Institute, Boston, MAWoods Hole Oceanographic Institute, Boston, MA
BackgroundBackground
Sources of Mercury: Sources of Mercury: atmospheric depositionatmospheric deposition metal miningmetal mining power plantspower plants natural sources natural sources
Mercury is Mercury is methylatedmethylated in aquatic systems in aquatic systemsHg Hg MeHg MeHg
Biomagnification occurs as methylmercury is passed through food web
Environment Canada
Effects of MercuryEffects of Mercury
Neurotoxic to humans Neurotoxic to humans
Laboratory studies have demonstrated effects Laboratory studies have demonstrated effects on fish survival, fertility, development, and on fish survival, fertility, development, and behavior.behavior.
No studies have demonstrated impacts of No studies have demonstrated impacts of atmospherically-deposited Hg on wild fish at atmospherically-deposited Hg on wild fish at ecologically-relevant levels.ecologically-relevant levels.
Isle Royale National ParkIsle Royale National Park Located in Lake SuperiorLocated in Lake Superior
Unusually high levels of methylmercury due to Unusually high levels of methylmercury due to atmospheric deposition atmospheric deposition
Question: Does Hg pose a threat to fish health on IRNP?Question: Does Hg pose a threat to fish health on IRNP?
124 northern pike were collected from 8 lakes124 northern pike were collected from 8 lakes
Fillets and livers were tested for mercury with cold-vapor A.A. Fillets and livers were tested for mercury with cold-vapor A.A. spectroscopyspectroscopy
Subsamples of liver from each fish were embedded in paraffin Subsamples of liver from each fish were embedded in paraffin for histologyfor histology
State of Alaska
What was found…What was found…
…a correlation between liver color and fish mercury content
Question: Why was the liver color different?
LipofuscionLipofuscion• Pigmentation change that occurs as a result of accumulation of cellular-breakdown products
• Can indicate increased cellular damage as a result of toxicant exposure
Question: Does LF correlate with [Hg] in fish?
Dark livers from IRNP contained large numbers of LF bodies
Small samples of liver were embedded in paraffin and Small samples of liver were embedded in paraffin and sectioned on a microtomesectioned on a microtome
Each sample was photographed at 200XEach sample was photographed at 200X
A grid (squares 25 X 25A grid (squares 25 X 25m) was overlaid on each imagem) was overlaid on each image
50 squares were randomly selected and evaluated for 50 squares were randomly selected and evaluated for the presence of LF. the presence of LF.
The proportion of squares containing LF were used to The proportion of squares containing LF were used to quantify the amount of liver damagequantify the amount of liver damage
Lipofuscion Quantification
r2= 0.81P= 0.006
Lipofuscion content was correlated with liver color
Liver color was correlated with Hg content
ConclusionsConclusions1)1) LF levels are higher in the dark liver samplesLF levels are higher in the dark liver samples
2)2) Darker samples have higher mercury Darker samples have higher mercury contentcontent
3)3) Lipofuscion quantification might provide an Lipofuscion quantification might provide an accurate method to determine mercury accurate method to determine mercury concentration and as well as damageconcentration and as well as damage
Future DirectionsFuture Directions Caddo LakeCaddo Lake Lab studiesLab studies
AcknowledgementsAcknowledgements
Coauthors: Dr. Paul Drevnick, Dr. Aaron RobertsCoauthors: Dr. Paul Drevnick, Dr. Aaron Roberts Funding Source: U.S. EPA STAR ProgramFunding Source: U.S. EPA STAR Program Dr. Kevin Stevens, Dr. Ed Dzialowski, Dao Ho, Dr. Kevin Stevens, Dr. Ed Dzialowski, Dao Ho,
Matt KovachMatt Kovach
Questions?Questions?
Amanda K. GevertzAmanda K. Gevertz
akg0034@unt.eduakg0034@unt.edu
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