Influence of the monsoon climate on the distribution of neuston copepods in the Northeastern Indian ocean

Abstract

The horizontal distribution of the near-surface (neuston) copepods of the family Pontellidae was studied on the meridional transects through the central part of the Indian ocean between 12°N and 12°S and in the Bay of Bengal in the summer monsoon period. Eleven species of neuston pontellids were found. The common species Labidocera detruncate and Pontellopsis villosa have the sane high frequencies in the central part of the ocean and in the Bay of Bengal. Some species are rarer in the Bay of Bengal than in the central part of the ocean. In contrast, other species are more frequent in the Bay of Bengal. The special traits of the distribution in the Bay of Bengal coincide with the lower salinity in the bay than in the central ocean. The distribution of some neritic species from the Bay of Bengal to the south is dependent on the intensification of the water translocation to the south in the summer. In the central part of the Indian Ocean, the distribution of the common neustonic pontellids is similar in the periods of the summer and winter monsoons. It is the result of the occupation of the region by the same equatorial water masses.