CS15 Fish
Date: Tuesday, June 11, 2002
Location: Poster Session - VCC
 
AguilarNM, White Mountain Research Station, La Jolla, USA, nmaguilar@ucsd.edu
 
EFFECT OF DIURNAL HYPOXIA ON THE ESTUARINE TELEOST, GILLICHTHYS MIRABILIS
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The hypothesis of this study was that daily exposure to moderate hypoxia pre-adapts teleosts for more severe hypoxic events. Heart rate (HR), an indicator of physiological fitness, was measured in the estuarine teleost, Gillichthys mirabilis under three experimental conditions: (1) 7 days of normoxia, (2) 7 days of chronic moderate hypoxia; and (3) 7 days of moderate intermittent hypoxia. Each condition was followed by 12hr of acute severe hypoxia, and 2hr normoxia. In the intermittently hypoxic group, HR decreased by approximately 30% during moderate hypoxia, relative to normoxia each day, even though the resting normoxic HR was variable from day to day. During severe hypoxia in all three groups, HR decreased by approximately 50%, relative to resting HR. These data suggest that the magnitude of the heart rate response to a change in oxygen tension is not very plastic, even though the set-point can vary. During the normoxic period following severe hypoxia, the chronically hypoxic group had the fastest recovery. In conclusion, physiological changes that occur during hypoxic exposure may be of greater importance for recovery than for acclimatization.