Why might a change in temperature threaten life in the water?
Every organism has certain temperatures that are better for certain stages of life (laying eggs, migrating, for example). Temperature changes the water chemistry. Warm water holds less oxygen and some species need more oxygen. Here are two different kinds of salmon responding to slightly different temperature conditions. Max for growth Best for Embryos Best for Spawning ATLANTIC SALMON 23 deg C /73 deg F 5 deg C/41 deg F 7 deg C, 45 deg F Coho SALMON 24/75 10/50 13/55 Water temperature is like a clock for aquatic organisms. It clues organisms about the time to reproduce, grow, and move to a new location. Some organisms are adapted to colder water (trout, salmon, and most stonefly nymphs), some are adapted to warmer water (carp, and most dragonfly nymphs). Most organisms become stressed in extremely hot or cold water and when water temperatures suddenly change (for instance, due to thermal pollution).” (Imagiworks) Extremes of temperature in their natural range can stress them. Species
