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

Chl a Grass shrimp Benthic consumers N cycle BacteriaAerobic Bacteria Land Use decomposition N nutrients N, P nutrients Gulf killifish Blue crabsAtlantic croaker 1° producers 3° consumers 1° consumers 2° consumers larval juvenile

GOALS & HYPOTHESIS 1.Develop indicators of hypoxic effects in a common marsh resident – Fundulus grandis 2.Advance understanding of how hypoxia regulates reproduction in fish  Hypoxia impairs reproduction

Gulf killifish

REPRODUCTIVE LIFE HISTORY J F M A M J J A S O N D Batch Spawner Reproductive Parameters

INDICATORS of EFFECT  Fulton’s condition factor (100,000*W/L 3 )  Gonadosomatic index (100*W gonad /W body )  Estradiol (females)  Testosterone (males & females)  11-Ketotestosterone (males)  Vitellogenin (females)

Reproductive Hormone Function liver ovary pituitary estrogen brain FSH testosteroneVITELLOGENIN

liver testis pituitary brain FSH, LH T, 11KT

Laboratory Exposure Chronic Hypoxia 15 ppt salinity 27°C

Chronic Hypoxia Females

Chronic Hypoxia Egg Production

Chronic Hypoxia Males

How do indicators respond in GOM estuaries? Weeks Bay, AL Pensacola Bay, FL

Weeks Bay Creek Weeks Bay Mouth Mobile Bay

2 mg/L  41 31C WBM4.03 mg/L = 82 mmHg0.79 hr3/18 WBC0.93 mg/L = 19 mmHg3.40 hr18/19

Severe Hypoxia reduces Sex Steroid Concentrations ***p < WBS = Mild hypoxia WBC = Severe hypoxia, PO2 ~ 82 mmHg PO2 ~ 19 mmHg

2 mg/L  41 mmHg WBM4.65 mg/L = 91 mmHg00/6 WBC2.61 mg/L = 51 mmHg0.633/6

Moderate Hypoxia reduces GSI & 11KT **p < 0.01, ***P < WBS = Normoxic, PO2 ~ 91 mmHg WBC = Hypoxic, PO2 ~ 51 mmHg

Garcon Point Indian Bayou

2 mg/L  41 mmHg GP14.39 mg/L = 89 mmHg00/9 IB2.41 mg/L = 49 mmHg1.534/8

Moderate Hypoxia reduces GSI & 11KT **p < 0.01, ***P < GP = Normoxic, PO2 ~ 89 mmHg IB = Hypoxic, PO2 ~ 49 mmHg

REPRODUCTIVE IMPACT HypoxiaSettingM GSI MTMT M 11KT F GSI FTFT 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

Reproductive Impacts of Diel Hypoxia In the fieldIn the field –Male steroid hormones & GSI are reduced –Female GSI can be reduced In the labIn 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 Normoxia DOmin1.4 mg/L ≈ 26.6 mmHg6.5 mg/L ≈ 123 mmHg Period ≤ 2 mg/L3.0 hr0 hr

Cyclic Hypoxia Steroids & GSI MalesFemales

Cyclic Hypoxia Egg Production Daily Eggs/Female 6.48 mg/L 1.4 mg/L

Cyclic Hypoxia Fertilization