Benthos

Abstract

Benthic organisms are sessile and sedentary in nature. True benthos can be divided into two groups - epifauna and infauna. They comprise major invertebrate phyla. Benthic organisms are separated into micro, meio, macro and mega-benthos based on size. The distribution of benthic faun in space and time showed wide variation in density and biomass. At some places the density may be as poor as 1 individual/m sup(2), while on the other hand it may be as high as 3000 individual/m sup(2). The benthic biomass also showed similar variation in distribution intertidal and subtidal areas. Spatially the faunal abundance inversely related to depth of the water. The magnitude of spatial and temporal variation depends on several factors like salinity, temperature, dissolved oxygen, sediment properties and productivity of the overlying water. The intertidal fauna show striking zonation pattern. Similarly the benthic fauna of estuaries show response to salinity gradient and the subtidal benthos are more related to availability of food. Benthic diversity in the intertidal and shallow seas is generally lower than the deep-sea. Benthos from the main food for the bottom dwellers and hence benthos have direct relevance to potential fishery resources. Benthic animals have reported to show great variations in quality and quantity as consequent to environmental disturbances and hence are ideally suited in the assessment of pollution.