Sporadic occurrence of harmful cyanobacteria Woronichinia naegeliana and its bloom dynamics from the aquatic ecosystem of South India

The present study reports a potentially toxic cyanobacterial species, Woronichinia naegeliana , which was observed along with a continuous bloom of Microcystis from a freshwater pond while monitoring cyanobacterial blooms along central Kerala, south India. Woronichinia is a toxic cyanobacterium usually found in freshwater ecosystems associated with other harmful cyanobacterial blooms. The monitoring was carried out from 2019 to 2020, and the high cell density of Woronichinia was observed in March 2020 (8.4 × 10 4 cells L −1 ). Hydrographic parameters studied revealed that the abundance of Woronichinia species was favoured by higher temperature (29 °C) with comparatively low nutrient values (NO 3 : 10.5 μmol L −1 ; PO 4 : 2.3 μmol L −1 ) while Microcystis desired a higher temperature (31 °C) with increased nutrient values (NO 3 : 96.78 μmol L −1 ; PO 4 : 5.88 μmol L −1 ).