Studies on quantitative abundance of Euphausiacea (Crustacea) with special reference to distribution in space and time along the southwest coast of India

Abstract

The quantitative abundance and seasonal and spatial distribution of Euphausiaoea within the oontinental shelf waters between Calicut and Karwar along the southwest coast of India has been studied in detail for the first time. The abundance of total euphausiids in the study area has been numerically estimated to be 1980 per 1000 m' of water. A study of the seasonal variations of total euphausiids showed that the maximum abundance was in October followed by August. An examination of the spatial variation of total euphausiids revealed that the northern parts were richer with the maximum concentration in the deep neritio areas. The distribution of total euphausiids in space and time has also been investigated. When the seasonal and spatial distribution of the various species was considered, it was found that six species were particularly abundant in certain months; those species being Pseudeuphausia latifrons (December-February), Euphmsia diomedae (February), E. sibogae (August-October), Nermtoscelis gracilis (February), Stylocheiron armatum (October-April) and S. a/fine (October-February)