Fish Microbiology and Quality Assurance (2+2)

Unit 1 - Role and significance of microorganisms in food

1.3 Microorganisms in aquatic environment
All surface waters such as ponds, lakes, rivers and oceans differ in their physical, chemical and biological characters. Depending on the nutrient status of water body, the microbial load varies with higher numbers encountering in eutrophic waters. Ground waters or subterranean waters generally have very low microbial load because of filtration effect of soil layers.

Categories of microorganisms in natural waters
The natural waters contain a variety of microorganisms. These include,

• Natural flora : Microorganisms natural to the water body and
• Transient flora : Microorganisms entering the water body from outside environment like from soil, air and through pollutants.

Microorganisms in natural aquatic environment play an important role in nutrient recycling, and as primary producers and decomposers of organic matter. All the microorganisms present in a water body can be seen as surface flora of inhabiting organisms. These not only include spoilage organisms but also human pathogenic microorganisms especially in sewage contaminated waters.