Temperature tolerances of some closely related tropical atlantic and pacific fish species.

Species of Pacific shallow-water fish are more tolerant of low temperatures than Atlantic species are. At high temperatures Atlantic species are more tolerant than Pacific species. For species pairs of Bathygobius differences in the tolerance of low temperatures are small and can be removed by acclimation to 23 degrees C. Differences in the tolerance to low temperature in transisthmian species of Apogon, however, are large and persist after acclimation to 23 degrees C. Some Pacific species adapt to the cooler temperatures of their habitat through increasing their rates of oxygen consumption at ambient temperatures or decreasing the dependence of oxygen uptake rate on temperature, or both.