Spatiotemporal variation of alkaline phosphatase activity in coastal waters off Trivandrum

Phosphatase is an extracellular enzyme which releases inorganic phosphate (Pi) from dissolved organic phosphate and indirectly organic carbon as nutrients for aquatic communities. Here, we have examined spatiotemporal variation in total alkaline phosphatase activity (APA) over a short period off Trivandrum, SW India. Sampling was at 50 m water depth at 5, 15, 25 and 45 m for 5 consecutive days at 6 h intervals during post-monsoon season. Total APA and phosphatase producing bacteria (PPB) were estimated along with pertinent environmental parameters. APA increased with depth up to 3.98 µM P h−1 at 45 m. Increase in pigment concentration with depth is responsible for an increase in APA and Pi uptake. There is a marginal increase in APA towards 18–24 h suggesting feeding activities of secondary producers. On the whole, chlorophyll and phaeophytin were responsible for nearly 45 and 55% variation in APA (p