Living in the desert might seem like a peculiar strategy for a fish. But 10,000 years ago, the southwestern US was a much wetter place than it is now, covered by water as deep as 100 m that was home to many creatures including pupfish. As the water receded, pupfish became isolated to warm springs, where they remain today. Water temperatures can reach 95 °C in the springs, exposing the small fish to a large amount of environmental stress. Research by Frank van Breukelen and Stanley Hillyard (University of Nevada, Las Vegas) suggests that pupfish use another peculiar strategy to survive these harsh conditions: they hold their breath.
Hillyard presented the research at the American Physiological Society Annual Meeting, part of Experimental Biology 2015 (31 March 2015; Boston, MA). Experiments showed that pupfish alternate between periods of oxygen consumption and anaerobic respiration that last as long as 5 hours. The scientists speculate that this strategy might help to avoid cell damage from reactive oxygen species. Reactive oxygen species are produced by oxygen consumption, especially during environmental stress, and cause cellular injury when present in large amounts. Minimizing oxygen consumption might therefore be a necessary adaptation for desert pupfish to survive in their harsh environment. MH
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