Impacts of Hypoxia on Reproductive Function in the Gulf Killifish, Fundulus grandis

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Impacts of Hypoxia on Reproductive Function in
the Gulf Killifish, Fundulus grandis

• Ann Oliver Cheek

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GOALS HYPOTHESIS

• Develop indicators of hypoxic effects in a common
  marsh resident Fundulus grandis
• Advance understanding of how hypoxia regulates
  reproduction in fish
• Hypoxia impairs reproduction

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Gulf killifish
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REPRODUCTIVE LIFE HISTORY
Batch Spawner
Reproductive Parameters
J F M A M J J A S O N D
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INDICATORS of EFFECT

• Fultons condition factor (100,000W/L3)
• Gonadosomatic index (100Wgonad/Wbody)
• Estradiol (females)
• Testosterone (males females)
• 11-Ketotestosterone (males)
• Vitellogenin (females)

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Reproductive Hormone Function
brain
liver
pituitary
ovary
estrogen
testosterone
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Reproductive Hormone Function
brain
liver
pituitary
testis
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Laboratory ExposureChronic Hypoxia
15 ppt salinity 27C
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Chronic HypoxiaFemales
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Chronic HypoxiaEgg Production
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Chronic HypoxiaMales
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How do indicators respond in GOM estuaries?
Pensacola Bay, FL
Weeks Bay, AL
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Weeks Bay Mouth
Weeks Bay Creek
Mobile Bay
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WBM 4.03 mg/L 82 mmHg 0.79 hr 3/18
WBC 0.93 mg/L 19 mmHg 3.40 hr 18/19
2 mg/L ? 41 mmHg _at_ 31C
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Severe Hypoxia reduces Sex Steroid Concentrations
WBS Mild hypoxia WBC Severe
hypoxia, PO2 82 mmHg
PO2 19 mmHg
p lt 0.001
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WBM 4.65 mg/L 91 mmHg 0 0/6
WBC 2.61 mg/L 51 mmHg 0.63 3/6
2 mg/L ? 41 mmHg
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Moderate Hypoxia reduces GSI 11KT
WBS Normoxic, PO2 91 mmHg WBC Hypoxic,
PO2 51 mmHg
p lt 0.01, P lt 0.001
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Indian Bayou
Garcon Point
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GP1 4.39 mg/L 89 mmHg 0 0/9
IB 2.41 mg/L 49 mmHg 1.53 4/8
2 mg/L ? 41 mmHg
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Moderate Hypoxia reduces GSI 11KT
GP Normoxic, PO2 89 mmHg IB Hypoxic,
PO2 49 mmHg
p lt 0.01, P lt 0.001
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REPRODUCTIVE IMPACT
Hypoxia Setting M GSI M T M 11KT F GSI F T F E2 F VTG
Cyclic 49/1.5/50 Field PB ? ? ? ? ? ? ?
Cyclic 51/0.6/50 Field WB ? ? ? ? ? ? ?
Cyclic 19/3.4/95 Field WB ? ? ? ? ? ? ?
Cyclic 27/3.0/100 Lab ? ? ? ? ? ?
Chronic 25/24/100 Lab ? ? ? ? ? ? ?
Not changed by hypoxia
Reduced by hypoxia
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Reproductive Impacts of Diel Hypoxia

• In the field
• Male steroid hormones GSI are reduced
• Female GSI can be reduced
• In the lab
• Male steroid hormones are reduced
• Female steroid hormones GSI are reduced
• Fecundity is reduced

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Acknowledgments

• Christie Landry, Amy Sutton, Stacy Steele, Brett
  Henry, Sarah Temple, Lisa Cohen, Bern Wood, Ross
  Turlington SLU
• Dick Snyder lab UWF
• Steve Manning, Thea Hoexum-Brouwer USM
• Scott Phipps, Eric Brunden Weeks Bay NERR
• Shaye Sable, LSU
• Chad Ellington, UNO

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Cyclic Hypoxia
Cyclic Hypoxia Normoxia
DOmin 1.4 mg/L 26.6 mmHg 6.5 mg/L 123 mmHg
Period 2 mg/L 3.0 hr 0 hr
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Cyclic Hypoxia Steroids GSI
Males
Females
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Cyclic Hypoxia Egg Production
6.48 mg/L
1.4 mg/L
Daily Eggs/Female
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Cyclic Hypoxia Fertilization