The results of hydrobiological investigations oonducted in the inshore waters off Tuticorin during
1983-84 have been presented. The primary production estimated by oxygen technique indicated three
distinct peak periods, the first during January-March, the second during June-August and the third
during October-December. The trend of secondary production closely followed that of primary
production. Zooplankters were found to be abundant during May-September and again a
short secondary peak was noticed during November-January. The occurrence of different zooplankters
showed a definite seasonal fluctuation. The physico-chemical properties of the seawater showed
variations in space and time. A general picture of the environmental conditions of the inshore area,
based on the earlier observations along with the present observations of primary and secondary
production are discussed in this account
