CONTRIBUTION TO THE STUDY OF CYANOBACTERIAL HARMFUL ALGAL BLOOMS (CYANOHAB) BASED ON THE THRESHOLD INDEX FOR FRESHWATER LAKES

Abstract

The worldwide phenomenon Cyanobacterial Harmful Algal Blooms (cyanoHAB) occurs with a worrisome frequency in Atlantic Canada in summer-fall periods, especially in Nova Scotia (NS) and Moncton waterbodies (NB). This work shows the dominance of cyanobacterial species associated with their potentially produced toxins in the NS and Moncton lakes and an approach to determine the thresholds of cyanoHAB. Threshold Index (TRINDEX), a combination of nutrients (absolute deviation of oxygen from 100%, phosphate, nitrate) and pigments (chlorophyll-a and phycocyanin), is proposed to detect the onset of cyanoHAB based on the independent datasets of Mattatall (2015- 2017) and Torment (2016-2018) lakes in Nova Scotia, Canada. The threshold ranges were detected by using the receiver operator curve analyses. The phycocyanin-based TRINDEX was found as a more appropriate indicator to predict cyanobacterial blooms. The research work can contribute to the monitoring and management plan for public health and freshwater resources of these provinces and globally.