The adverse effects of HABs include toxin production, fish gill clogging, oxygen depletion and unpleasant water quality. Molecular approaches to species identification and quantification may be broadly categorized as “whole cell” (eg. FISH) or “lysed cell” methods (e.g. sandwich hybridization, microarray hybridization, real-time qPCR). DNA-based methods are more rapid, sensitive and specific at the species and population level, amenable to high throughput, and requiring a minor level of expertise in the routine laboratory procedures.