Microorganisms in Sustainable Aquaculture Development

Abstract

Microbes found in aquaculture are usually from source water, feeds including augmented live foods. These microbes are found in the gills, intestine, muscles and on the surface of fish, shrimps, crustaceans and other aquatic organisms. Microorganisms in aquaculture play several roles including their use as live food, food supplements, probiotics, in pond aeration and in the purification of aquarium. As food, microbes provide the essential nutrients such as vitamins, enzymes, polyunsaturated fatty acids, amino acids, pigments and steroids. They also serve as carbon and nitrogen sources. Microbial diversity in aquaculture depends largely on the quality (physicochemical properties) of the farm water and this has greatly influenced the growth of every aquaculture. Fungi, Bacteria, Protozoa, Helminthes and Microalgae are present in aquaculture, each performing its unique role in the ecosystem. While some are beneficial, others are not. To minimize the use of antibiotics in aquaculture treatment, probiotics are used. These probiotics antagonizes some existing pathogenic species by competing with them for attachment, substrate utilization, lowering the environmental pH (characteristics of lactic acid bacteria) and by production of antimicrobial substances like bacteriocins. Microbial live foods include Bacteria, Fungi, Microalgae and Protozoa. Microbes used as live food include lactic acid bacteria, Bacillus, Chlorella vulgaris, Saccharomyces, Aspergellus, Artemia, Copepods, Infusoria and Rotifers. These live foods have the advantage of small size, ease of digestion and ability to stimulate enzyme synthesis. Besides, microbes function in pond purification (biofilters) as well as its bioenergetic cycle. Microalgae, specifically aerate ponds through the release of oxygen during photosynthesis. The beneficial roles of microbes contribute to the growth, development and quality of fish, shrimps and crustaceans in an aquaculture by way of better growth rate, survival and disease resistance