Diel changes in phytoplankton population in the Mandovi and Zuari estuaries of Goa

Abstract

Diel changes in surface phytoplankton were studied in Mandovi and Zuari estuaries during pre-and post-monsoon seasons at two stations in each estuary - one near the mouth and other in mid-reaches. Phytoplankton cell counts indicated an overall greater value in the Mandovi. Mean counts for the whole day (24 hours) at the mouth of Mandovi and at mid-reaches were 13,600 and 15,200 cells/l respectively in the premonsoon. In the post-monsoon period the counts were 55,800 and 37,600 cells/l. The corresponding figures for the Zuari were 10,100 and 17,200 cells/l in the premonsoon and 2,100 and 2,000 cells/l in the post-monsoon. In general, higher concentrations of phytoplankton were noticed in the morning hours during premonsoon in the Mandovi and during post-monsoon in the Zuari indicating seasonal changes in the two estuaries. The two estuaries, thus exhibit a contrasting picture during the two seasons