Algal Blooms: Basic Concepts

Abstract

An algal bloom is a rapid and prolific increase in phytoplankton biomass in freshwater, brackish water or marine water systems and is recognized by the discolouration in the water based on the phytopigments in the algal cells (either innocuous or toxic). Algae can be considered to be blooming at widely varied concentrations, reaching millions of cells per millilitre, or tens of thousands of cells per litre. Occurrence of bloom and its persistence are a complex environmental process involving multiple factors such as anthropogenic nutrient (eutrophication), solar radiation, temperature, current patterns and other associated factors. This natural but stochastic event leads to severe ecological health hazards, degradation of water quality and productivity and pelagic community structure. Proliferations of toxic microalgae in aquatic systems can cause massive fish kills, contaminate seafood with toxins and alter ecosystems in ways that humans perceive as harmful. The chapter addresses a comprehensive account regarding basic features related to algal bloom, such as Redfield ratios, eutrophication and hypoxia (deoxygenation). This is followed by detailed account of the major bloom causative agents (diatoms, dinoflagellates and cyanobacteria) and the remote sensors usually in practice for water quality monitoring. Finally a comprehensive account of the analytical instruments has been discussed generally used for microalgal studies for taxonomic and chemical component analyses.