Enhanced biological production in the southeastern Arabian Sea during spring intermonsoon

Abstract

Hydrographic observations in the southeastern Arabian Sea (SEAS) have identified a warm (over 30 degrees C) and stratified water mass (stability more than 5x10 sup(-5) m sup(-1)) along the near shore area between 10 degrees N and 15 degrees N during spring intermonsoon This water mass was relatively low saline (34.2) and nitrate-rich (0.5 mu M), favoring moderate primary production (6.7 mg C m sup(-3) d sup(-1) Since the mixing of the Arabian Sea and the Bay of Bengal waters is an important process during this period, the enhanced primary production in the SEAS is attributed to the entrainment of unconsumed nitrate left over during the previous season from the northern Arabian Sea The season was further characterized by the presence of a deep chlorophyll-a maximum (0.5 mg.m sup(-3)) in the outer shelf below (greater than 50 m) the subducted Arabian Sea High Saline waters, which was photosynthetically less active (less than 1.5 mg C m sup(-3) d sup(-1)) due to light limitation