Temperature - Aquatic Habitats
The water temperature changes less rapidly than the temperature of air because water has a considerably higher specific heat than air, that is larger amounts of heat energy must be added to or taken away from water to raise or lower its temperature. Since water temperatures are less subject to change, it follows that aquatic organisms have narrow temperature tolerance.
As a result, even small changes in water temperatures are a great threat to the survival of aquatic organisms than comparable changes in air temperatures are in terrestrial organisms.