Temperature- Temperature is one of the main factor that has a profound effect on 'the growth of microorganisms. Microorganisms which require very low temperature for their growth are known as psychrophiles and which require a high temperature are known as thermophiles. The group which falls between these two are known as mesophiles. The temperature of natural waters varies from about 0 C in polar regions to even upto 75 to 80oe in hot springs.
Since the specific thermal capacity of water is very high, large water bodies are able to either absorb or lose great amount of heat energy without any change in their temperature. As a result of this many aquatic organisms including microbes experience very stable climatic conditions. For instance, about 90% of the marine habitats maintain more or less a constant temperature of about 4°C which favours Psychrophilic microorganisms.
