'Glowing sea' phenomenon due to the swarming of Noctiluca miliaris on the southeast coast

Abstract

A phenomenon of 'glowing sea' was observed in the night hours in the inshore area off Tuticorin and nearshore areas of Kayalpatnam, Thiruchendur, Manapad, Idinthakarai and upto Kanyakumari. On examination of the water samples, it was found that the dominance of the plankton, Noctiluca miliaris (a toxic dinoflagellate which is microscopic, baloon-like and green in colour) was responsible for the 'glowing sea' condition of the sea water. Since Noctiluca has the ability of producing phosphorescence or bioluminescence, the whole area became illuminated and this caused anxiety among the local people. The blooming of Noctiluca is common along the coasts of India and they cause the 'red tide' in the inshore waters. However, the present observations of Noctiluca showed no 'red tide' since the organisms were green in colour due to the harbouring of green flagellates on Noctiluca.