Revisiting harmful algal blooms in India through a global lens: An integrated framework for enhanced research and monitoring

Abstract

Harmful algal bloom (HAB) events substantially impact human and aquatic ecosystem health and the global blue economy; hence, a concerted effort is required to advance our understanding of HAB ecology to better inform monitoring and mitigation measures. Here, we highlight the current state of HAB research and monitoring in India, where ∼17% of the human population resides in the vicinity of its long coastline and is dependent on the sustainable blue economy. Through the lens of established programs from countries across the globe, we identify existing gaps and highlight four broad areas for focusing future efforts: (1) the development/employment of novel technologies for HAB research and monitoring; (2) the need for integrated observation networks and a coordinated effort across different central/state agencies and research institutes; (3) clinical studies on human health effects; and (4) public outreach and citizen science initiatives to increase awareness on this topic, including policy level interventions.

Keywords: Aquatic biology; Aquatic science; Environmental management; Environmental monitoring.

Graphical abstract

Figure 1

A depiction of three commonly occurring HAB-forming species in Indian waters (A) The dinoflagellate, Noctiluca scintillans. (B) The freshwater colonial cyanobacteria, Microcystis aeruginosa, which is also sometimes found in coastal estuarine waters. (C) The filamentous marine cyanobacteria, Trichodesmium erythraeum. The top row shows the blooms for each case as seen from satellite imagery; the second panel shows the blooms as observed from a vessel; and the bottom two panels depict individual organisms as observed through traditional and holographic microscopy. (License information: first row: left, middle, and right: Authors of this article made these subfigures. Second row: left: CC-BY license, middle: CC-BY 4.0, right: CC-BY. Third row: left: CC-BY, middle: CC-BY-NC, right: CC-BY, Fourth row: all images are from the lead author’s lab.).

Figure 2

A geographical map of the Indian coastline, showing the location of historical HAB events Geographically, data are grouped into 8 distinct regions for the West and East coasts respectively: (i) The states of Gujarat (GJ), Maharashtra (MH), Goa (GA) and the Union Territory of Daman and Diu (DD); (ii) Karnataka state (KA); (iii) Kerala (KL); (iv) Offshore waters of the Arabian Sea (AS); (v) The Lakshadweep archipelago (LD); (vi) The state of Tamil Nadu (TN) and the Union Territory of Puducherry (PY); (vii) the states of Andhra Pradesh (AP), Odisha (OD), West Bengal (WB), offshore waters of the Bay of Bengal (BoB) and (viii) Andaman and Nicobar Islands (AN). The number of HAB events in each grouping is represented by N. The colors in the bar charts represent different algal groupings: Dinoflagellates, Cyanobacteria, Haptophytes, Raphidophytes, and Diatoms. The seasons are broken down into pre-monsoon (PrM, Feb–May), southwest monsoon (Mon, Jun–Sep), post-monsoon (PoM, Oct–Jan for West coast and Oct–Nov for East coast), and northeast monsoon (NEM, Dec–Jan, for East coast only). See also the dataset by Kolluru and Nayak for comprehensive details of all known HAB incidents in coastal and estuarine Indian waters. Two of these records are not included in the above figure as either their location or the exact month of the occurrence was not reported.

Figure 3

A schematic depicting a potential HAB observation network that utilizes a holistic approach by combining different complementary technologies that enable synoptic observations of a bloom across different temporal and spatial scales