The osmorespiratory compromise in the euryhaline killifish: Water regulation during hypoxia

Chris M. Wood, Ilan M. Ruhr, Kevin L. Schauer, Yadong Wang, Edward M. Mager, M. Danielle McDonald, Bruce Stanton, Martin Grosell

Research output: Contribution to journalArticlepeer-review

7 Scopus citations


Freshwater- and seawater-acclimated Fundulus heteroclitus were exposed to acute hypoxia (10% air saturation, 3 h), followed by normoxic recovery (3 h). In both salinities, ventilation increased and heart rate fell in the classic manner, while M_ O2 initially declined by ∼50%, with partial restoration by 3 h of hypoxia, and no O2 debt repayment during recovery. Gill paracellular permeability (measured with [14C] PEG-4000) was 1.4-fold higher in seawater, and declined by 50% during hypoxia with post-exposure overshoot to 188%. A similar pattern with smaller changes occurred in freshwater. Drinking rate (also measured with [14C] PEG-4000) was 8-fold higher in seawater fish, but declined by ∼90% during hypoxia in both groups, with post-exposure overshoots to ∼270%. Gill diffusive water flux (measured with 3H2O) was 1.9-fold higher in freshwater fish, and exhibited a ∼35% decrease during hypoxia, which persisted throughout recovery, but was unchanged during hypoxia in seawater fish. Nevertheless, freshwater killifish gained mass while seawater fish lost mass during hypoxia, and these changes were not corrected during normoxic recovery. We conclude that this hypoxia-tolerant teleost beneficially reduces gill water permeability in a salinity-dependent fashion during hypoxia, despite attempting to simultaneously improve M_ O2 , but nevertheless incurs a net water balance penalty in both freshwater and seawater.

Original languageEnglish (US)
Article numberjeb204818
JournalJournal of Experimental Biology
Issue number18
StatePublished - 2019
Externally publishedYes


  • Diffusive water flux
  • Drinking
  • Freshwater
  • Fundulus heteroclitus
  • Gills
  • PEG-4000
  • Seawater
  • Transcellular permeability
  • Tritiated water
  • Ventilation

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Physiology
  • Aquatic Science
  • Animal Science and Zoology
  • Molecular Biology
  • Insect Science


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