One day by the bank o f the rive r he no tic e d a pile o f e - - PowerPoint PPT Presentation

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One day by the bank o f the rive r he no tic e d a pile o f e - - PowerPoint PPT Presentation

Oct 05, 2022 614 likes •834 views

One day by the bank o f the rive r he no tic e d a pile o f e mpty she lls o f the fre sh-wate r Musse l, o r Clam. T he she lls we re c o mmo n e no ugh, but why all to ge the r and marke d in the same way? Aro und the pile o n

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SLIDE 1

Aro und the pile o n the mud we re c urio us trac ks and marks…. he saw a ro und, bro wn animal hunc he d o n the bank e ating a c lam. I t dive d into the wate r o n his appro ac h, but it re appe are d swimming farthe r o n. T he n, whe n it dive d again, Yan saw by its lo ng thin tail that it was a Muskrat…”

E rne st T ho mpso n Se to n, T wo L ittle Sa va g e s, 1903

“One day by the bank o f the rive r he no tic e d a pile o f e mpty she lls o f the fre sh-wate r Musse l, o r

  • Clam. T

he she lls we re c o mmo n e no ugh, but why all to ge the r and marke d in the same way?

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SLIDE 2

The mercury uptake and bioaccumulation by resident muskrats

  • f the South River, VA

JMU Graduate Student: Tiffany Tumer Thesis Advisor: Dr. Tom Benzing

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SLIDE 3

Muskrat Ecology

  • Semi-aquatic mammal
  • Inhabits large variety of

aquatic environments

  • Distributed across most
  • f North America
  • Very prolific species
  • Lifespan of 3-4 years
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SLIDE 4

Muskrat Ecology

  • Significant portion of diet in riverine muskrats is clams
  • Muskrat predation has inhibited recovery of endangered

mussel in Clinch River

  • Corbicula mollusk of choice
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SLIDE 5

Control Site: Middle River (Verona, VA)

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SLIDE 6

Middle River

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SLIDE 7

Study Site: South River (Dooms, VA)

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SLIDE 8

South River

Dooms Mill Pond

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SLIDE 9

Results: Animals Collected

Middle River South River N 12 13 Collection Dates December 7 – 14, 2005 January 6 – 8. 2006 Average age (months) 7.7 9.6 Sex 1 male, 11 females 10 males, 3 females

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SLIDE 10

Tissue Analysis

  • Tissue type
  • Kidney
  • Liver
  • Muscle (Biceps femoris)
  • Future analysis
  • Brain
  • Hair
  • Claw
  • Tail
  • Procedures
  • Acid tissue digestion
  • Cold Vapor Atomic Absorption Spectrometry

(CVAAS)

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SLIDE 11

0.000 0.200 0.400 0.600 0.800 1.000 1.200 1.400 Kidney Type of Tissue Mean Hg Concentration (ppm) Middle River South River

Results: Kidney

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SLIDE 12

0.000 0.050 0.100 0.150 0.200 0.250 Liver Type of Tissue Mean Hg Concentration (ppm) Middle River South River

Results: Liver

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SLIDE 13

0.00 0.05 0.10 0.15 0.20 0.25 Muscle Type of Tissue Mean Hg Concentration (ppm) Middle River South River

Results: Muscle

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SLIDE 14

Other Findings

  • Standard body measurements are similar

between MR and SR muskrats

  • SR muskrats had livers (9 of 13) infected

with multiple cestode cysts

  • SR muskrats had stomach contents that

included clam tissue (9% by weight)

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SLIDE 15

Conclusions

  • Significant differences exist in total Hg between

MR and SR muskrats (kidney, liver, and muscle)

  • Poor correlations between Hg in tissues and:
  • Animal age
  • Animal sex
  • Body weight
  • Total body length
  • Slight correlation between Hg in liver, kidney and

muskrat preference for clams

  • Kidneys contained significantly higher total Hg

than liver or muscle samples

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SLIDE 16

Thanks To….

  • Michael Hensley
  • William Cook
  • Dan Downey
  • Larry Mohn
  • Jason Hallacher
  • Carney Tumer
  • Mike Fees
  • Hunter Joseph
  • Whit Wall
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SLIDE 17

Questions?

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SLIDE 18

Discussion, cont…

  • Hg concentrations measured in South River muskrat

tissues, specifically the kidney, far exceeds any levels found in previous studies

* denotes control site

Study Tissue Type N Mean Hg Concentration (ppm) Halbrook et al. Kidney 30 0.019 Halbrook et al. Kidney 20 0.017 Halbrook et al. Kidney 26 0.011* Everett & Anthony Liver 14 0.029 Everett & Anthony Liver 18 0.039 Everett & Anthony Liver 20 0.053 Everett & Anthony Liver 11 0.070 Sheffy and St. Amant Liver 14 < 0.02 Sheffy and St. Amant Kidney 14 < 0.02 Sheffy and St. Amant Muscle 14 < 0.02

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SLIDE 19

y = 0.0282x + 0.7084 R2 = 0.2013 0.00 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 5 10 15 20 “Percent of stomach contents identified as clams” Concentration of mercury in kidney (ppm)

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SLIDE 20

y = 0.0037x + 0.1446 R2 = 0.1214 0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35 5 10 15 20 “Percent of stomach contents identified as clams” Concentration of mercury in muscle (ppm)