Hypoxia tolerance in two juvenile estuary-dependent fishes

Our results indicate that direct mortality due to hypoxia will vary with species, size, and temperature, but will likely only be substantial when these species are exposed to oxygen concentrations less than about 1 ppm O2. Given the severity of hypoxia necessary to cause mortality and the ability of fish to behaviorally avoid hypoxia, direct mortality due to hypoxia may have limited impacts on fish population dynamics. Therefore, the greatest effects due to hypoxia may be caused by the stress imposed by sublethal hypoxic conditions alone or in concert with other stressors, or by indirect effects incurred by avoiding hypoxic areas.