New record of a bloom forming, genotoxic strain Nodularia strain (KT447209) from Andaman and Nicobar Islands, India

- First report of Nodularia sp. blooms along coastal waters of Andaman Nicobar Islands.
- Molecular studies revealed the Nodularia sp. (KT447209) to be a novel strain.
- Crude extract exhibited slight genotoxicity against human lymphocytes.
- Population of Nodularia crashed at low salinities of ∼12-18‰ during monsoon.
- It flourished in summers attaining blooms at salinity >30‰ & SST of 29.5-30.5 °C.

Cyanobacteria blooms in marine waters are limited to only a few taxa; with the genus Nodularia (Nostocales) being one among the most commonly observed and widely studied species. A bloom of Nodularia sp. was observed across a vast area along the coast of the Andaman and Nicobar Islands. The bloom occurred during the summer when salinity was >30‰. This differed to previous reports where blooms have crashed at such high salinities. The molecular phylogeny revealed the Nodularia species to be a novel one. A crude extract from the bloom demonstrated lowed toxicity with an LC50 of 5 mg/ml at 48 h towards Artemia salina and slight genotoxicity when tested against human lymphocytes.