The panel formed by the southern bench of the National Green Tribunal (NGT) to probe the cause of the sea turning red in Puducherry in October and November 2023 has attributed the phenomenon to plankton crash.
Ruling out algal bloom and contamination due to effluents from a paper manufacturing unit adjacent to a canal leading to the sea, the panel said the dates of operation of soaking and beating process by the unit in October - November 2023 did not coincide with the incidences of discoloration at Promenade Beach.
Instead, the panel comprising Member Secretary, Central Pollution Control Board, Member Secretary, Puducherry Pollution Control Committee, an expert from the Marine Biology Department of University of Puducherry, and a scientist from Centre of Advanced Study in Marine Biology, Parangipettai has said that there was high iron concentration, which may have favoured plankton bloom.
As per a study by Annamalai University, the majority of a particular unicellular species of phytoplankton — Noctiluca scintillans — in the sea were found ruptured, leading to the release of red pigment into the sea.
“The environmental parameters such as sea surface temperature (31°C), salinity(41psu), pH (6.5), and dissolved oxygen (5.8ppm) were assessed and related to the phytoplankton proliferation. The parameters were found to be conducive to the development of this species,” the panel report says.
The panel recommends strict vigilance on quality of sewage carried in the canal which confluences at Kuruchikuppam and to take long term measures on untreated sewage presently being let into the sea.
