Is Occurrence of Harmful Algal Blooms in the Exclusive Economic Zone of India on the Rise?

Abstract

Occurrence, increase in frequency, intensity and spatial coverage of harmful algal blooms during the past decade in the EEZ of India are documented here. Eighty algal blooms were recorded during the period 1998–2010. Of the eighty algal blooms, 31 blooms were formed by dinoflagellates, 27 by cyanobacteria, and 18 by diatoms. Three raphidophyte and one haptophyte blooms were also observed. Potentially toxic microalgae recorded from the Indian waters were Alexandrium spp., Gymnodinium spp. Dinophysis spp., Coolia monotis, Prorocentrum lima, and Pseudo-nitzschia spp. Examination of available data from the literature during the last hundred years and in situ observations during 1998–2010 indicates clear-cut increase in the occurrence of HABs in the Indian EEZ.

Distribution and abundance of dinoflagellates from the coastal waters of Karachi, Pakistan, northern part of the Arabian Sea

“…The current study reports 179 taxa, 154 species in 41 genera of dinoflagellates as oppose to worldwide distribution of 2377 species (259 genera) (Gómez, 2012). Similar dinoflagellate species have been reported from other regional waters, for example, India (179 spp; Padmakumar et al, 2012), Arabian Gulf and Sea of Oman (194 spp) (Polikarpov et al, 2016), Kuwait waters in the Persian Gulf (105 spp) (Al-Kandari et al, 2009). Only six genera (Tripos, Protoperidinium, Prorocentrum, Alexandrium, Diniphysis and Gonyaulax) that represent high species numbers (seven or more) are recorded in this study.…”

Marine Heatwaves in the Arabian Sea

“…One such possible impact is the recent increase in the harmful algal bloom in the Arabian Sea. Recent studies suggest that there is a manyfold increase in the harmful phytoplankton blooms in the northern Arabian Sea and along the west coast of India attributed primarily to the increased stratification, weaker winds and warming of the Arabian Sea (Padmakumar et al, 2012;Al Shehhi et al, 2014;Goes et al, 2020). Considering that the region of increased toxic blooms are collocated with the regions where the heatwave days observed, the possibility that the relation between these heatwave events and triggering of harmful blooms can not be negated.…”

Reactive Nitrogen in Coastal and Marine Waters of India and Its Relationship With Marine Aquaculture

“…Along the east coast, diatom blooms were reported to prevail. The Centre for Marine Living Resources and Ecology (CMLRE) worked on algal blooms formation, their spread and ecological consequences on marine ecosystems (Padmakumar et al, 2012) and documented the records of 80 algal blooms (of which 27 were by Cyanobacteria) in the Indian EEZ during 1998-2010, A compre hensive overview of historical harmful algal blooms in the AS, their causes and impact, and seasonal variability was presented by Al Shehhi et al (2014), Blooms mostly occurred during withdrawal of south-west monsoon and/or in pre-monsoon period (D'Silva et al, 2012;Raghukumar and Anil, 2003;Patil and Anil. 2008), Enhanced phytoplankton growth and blooms usually occur just after the south-west to north-east monsoon transition in the BOB (Prasarmakumar et al, 2007).…”