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Impacts of Hypoxia on Reproductive Function in the Gulf Killifish, Fundulus grandis. Ann Oliver Cheek. juvenile. Blue crabs. Atlantic croaker. 3 ° consumers. juvenile. larval. Gulf killifish. 2 ° consumers. 1 ° consumers. Grass shrimp. Benthic consumers. Chl a. 1 ° producers.
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Impacts of Hypoxia on Reproductive Function in the Gulf Killifish, Fundulus grandis Ann Oliver Cheek
juvenile Blue crabs Atlantic croaker 3° consumers juvenile larval Gulf killifish 2° consumers 1° consumers Grass shrimp Benthic consumers Chl a 1° producers N, P nutrients decomposition N nutrients Land Use N cycle Bacteria Aerobic Bacteria
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
REPRODUCTIVE LIFE HISTORY Batch Spawner Reproductive Parameters J F M A M J J A S O N D
INDICATORS of EFFECT • Fulton’s condition factor (100,000*W/L3) • Gonadosomatic index (100*Wgonad/Wbody) • Estradiol (females) • Testosterone (males & females) • 11-Ketotestosterone (males) • Vitellogenin (females)
VITELLOGENIN FSH Reproductive Hormone Function brain liver pituitary ovary estrogen testosterone
T, 11KT FSH, LH Reproductive Hormone Function brain liver pituitary testis
Laboratory ExposureChronic Hypoxia 15 ppt salinity 27°C
How do indicators respond in GOM estuaries? Pensacola Bay, FL Weeks Bay, AL
Weeks Bay Mouth Weeks Bay Creek Mobile Bay
2 mg/L 41 mmHg @ 31C
Severe Hypoxia reduces Sex Steroid Concentrations WBS = Mild hypoxia WBC = Severe hypoxia, PO2 ~ 82 mmHg PO2 ~ 19 mmHg ***p < 0.001
Moderate Hypoxia reduces GSI & 11KT WBS = Normoxic, PO2 ~ 91 mmHg WBC = Hypoxic, PO2 ~ 51 mmHg **p < 0.01, ***P < 0.001
Indian Bayou Garcon Point
Moderate Hypoxia reduces GSI & 11KT GP = Normoxic, PO2 ~ 89 mmHg IB = Hypoxic, PO2 ~ 49 mmHg **p < 0.01, ***P < 0.001
REPRODUCTIVE IMPACT Not changed by hypoxia Reduced by hypoxia
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
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
Cyclic Hypoxia Steroids & GSI Males Females
50 40 30 20 10 0 8/3/06 8/10/06 8/17/06 8/24/06 8/31/06 Cyclic Hypoxia Egg Production 6.48 mg/L 1.4 mg/L Daily Eggs/Female