Phytoplankton Ecology in Indian Coastal Lagoons: A Review

Abstract

AbstractPhytoplankton composition, diversity, and distribution pattern serve as efficient bioindicators in determining a lagoon’s health. In this regard, this review was carried out to understand the phytoplankton ecology vis-à-vis environmental factors (biotic and abiotic) that regulate phytoplankton biomass and diversity in Indian coastal lagoons. Indian subcontinent houses eight coastal lagoons on the eastern seaboard and nine on the western seaboard. Phytoplankton ecology in Indian lagoons is principally determined by nutrient availability and light penetration, that promote phytoplankton biomass gain and factors that contribute to biomass loss, such as tidal flushing and zooplankton grazing. The phytoplankton floral spectra of Indian lagoons are represented by diverse algal divisions such as Bacillariophyta, Dinophyta, Cyanophyta, Chlorophyta, Euglenophyta, Chrysophyta, Cryptophyta, and Xanthophyta. This review revealed that the phytoplankton ecology of Chilika Lagoon is relatively well investigated compared to the other Indian lagoons. A total of 739 phytoplankton species have been reported from Chilika, followed by 141 from Muthukadu, 101 from Muthupet, and 53 from Pulicat, on the eastern seaboard. While on the western seaboard, 181 genera from Vembanad, 53 genera from Veli, and 53 species of phytoplankton from Ashtamudi Lagoon have been documented. Bacillariophyta is the most diverse and abundant phytoplankton group in coastal lagoons of both Indian east and west coast, which may be attributed to their high growth rates and positive correlation with regulating environmental factors. Indian coastal lagoons, which are hubs of fisheries and tourist attractions, are undergoing rapid changes due to natural and anthropogenic forcing such as littoral drift, climate change, agricultural runoff, industrial waste discharge, and domestic sewage. Hence, long-term but rapid analysis of phytoplankton communities across the broad spatial scales of lagoons are needed to decipher how these factors potentially influence lagoon phytoplankton ecology. This review recommends adoption of rapid and more robust pigment chemotaxonomy and remote sensing techniques to study phytoplankton ecology in Indian coastal lagoons, in addition to conventional microscopy.KeywordsPhytoplanktonCoastal lagoonAnthropogenic influencePollution