Sea sparkle blues: What sparkly tides mean for India’s marine ecosystems

People living along India’s Arabian Sea coast witness beautiful sparkling blue tides at night every year in November and December. In 2020, for instance, such sightings were recorded in Mumbai’s Juhu and other places across Maharashtra such as Devgad and Murud, as well as along the coast of Goa, Karnataka and Kerala.

Such bioluminescence is produced by colonies of a kind of marine plankton — mostly microscopic organisms that drift with tides.

Plankton are the foundation of the marine ecosystem owing to their role as primary food producers (phytoplankton or plant plankton) and primary consumers (zooplankton or animal plankton) in the aquatic food chain. Phytoplankton are said to be responsible for up to 50 per cent of global primary food production, making their existence central to sustaining the global food chain, and therefore, life on Earth.

Any major shift in their population, in any specific region or globally, can cause a severe ripple effect across the entire food chain and affect the functioning of the world’s ecosystems.

And yet, many plankton species can be toxic to marine life, as is the case with the blue tides of the Arabian Sea. The glowing blue creatures spotted off the Mumbai and Karnataka coast are colonies of Noctiluca scintillans, commonly known as ‘Sea Sparkle’.

Blooms of Sea Sparkle devour fish larvae and diatoms (a kind of phytoplankton) and produce huge amounts of ammonia that is then spread across the surrounding waters. Their presence has been linked to a decline in dissolved oxygen levels as well as with mortality events of fish, coral, and other marine species.   

Implications for India’s marine ecosystems

Increased sightings of these sparkly blue tides across India’s west coast indicate a gradual and alarming shift in the ecosystem services in the region. A rise in blooms of Sea Sparkle may lead to more large-scale fish mortality events (and those of other marine species).

This could spell doom for part of India’s marine biodiversity and the livelihoods of millions of people dependent, directly or indirectly, on marine fisheries.

India’s 8,118-kilometres-long coastline has more than 3,200 fishing villages and 33 major and minor fishing harbours. Its 3.5 million marine fishers have a 1.1 per cent share in the country’s gross domestic product and a 3 per cent share in total exports.

The country produced 12.59 million tonnes (MMT) in 2017-18, with marine fisheries accounting for 3.69 MMT (29 per cent) and the rest coming from inland fisheries.

While marine fisheries used to have a larger share in the country’s total fish production till the 1990s, its share has been on a decline since the early 2000s with a stagnant production growth.

Trend in India’s fish production since 2005-06

Source: Department of Fisheries [DoF], Government of India (2019)

In 1950-51, marine fish production accounted for 71 per cent of total fish production while inland fisheries accounted for 29 per cent. In 2017-18, their respective shares were exactly opposite, with marine accounting for 29 per cent and inland accounting for 71 per cent.

While the declining share of marine fisheries is a point of concern already, the possible ramifications of increased Sea Sparkle bloom could exacerbate this decline as most of India’s marine fish production comes from states on the west coast.

State-wise share of marine fish production in India in 2017-18

Source: DoF (2019)

The climate connect

Between 1998 and 2010, at least 80 blooming events of various types of phytoplankton were reported in both the Arabian Sea and the Bay of Bengal. Many such blooms, including those of Noctiluca scintillans, were initially attributed to the expansion of low oxygen zones due to pollution caused by waste dumping along the coast. 

Later, a long-term study conducted by experts from Columbia University linked the increase in such blooms in the Arabian Sea to declining snow cover and melting glaciers in the Himalayas and their resulting impact on temperature dynamics between the Indian mainland and the Arabian Sea.

While some disputed this connection and credited the increasing blooming events to “natural long-term variability”, a review of major studies on the impact of climate change on marine plankton concluded that their populations have been severely affected in the last few decades due to rise in sea surface temperature and ocean acidification.

A 2018 joint study published by Hyderabad-based Indian National Centre for Ocean Information Services (INCOIS), an autonomous organisation under the Union Ministry of Earth Sciences and US-based National Oceanic and Atmospheric Administration (NOAA), also substantiated the findings of the review. The study concluded that blooming events, particularly those of Sea Sparkle, resulted from increasing sea surface temperature due to global warming, not coastal waste dumping.

The results of these studies revealed how sensitive marine plankton are to changes in local and global temperature regimes and how such changes can, in turn, drastically alter the normal functioning of marine ecosystems, affecting entire food chains, populations and economies.

From a policy perspective, thus, a gradual increase in Sea Sparkle bloom and other similar events presents a unique challenge as well as an opportunity for collective action towards climate adaptation. Continuous monitoring of changes in marine plankton populations across the Arabian Sea region is necessary to tackle its current impact on fishers as well as to study the localised effects of climate change.

To an extent, the latter is already happening in India through the Marine Observation System along Indian Coast (MOSAIC) and the more recent Algal Bloom Information Service (ABIS), both launched by INCOIS. While MOSAIC gathers data on India’s coastal water quality, ABIS provides almost real-time information on the presence and extent of phytoplankton bloom across the northern Indian Ocean through satellite mapping.

The service, which also feeds into the government’s Potential Fishing Zone Advisory programme, is particularly helpful as an early-warning system for fishers, resource managers, and ecologists, although it is difficult to gauge its on-ground impact.

If developed further, it could also aid in monitoring the status of biodiversity in marine protected areas and identifying zones that may require such designation in the future. According to India’s 2020 voluntary national review (VNR) of progress on the Sustainable Development Goals, it currently has “25 Marine-Protected Areas in the peninsular region and 106 in islands, collectively covering approximately 10,000 square km of the country’s geographical areas.”

Notably, the VNR emphasises maintaining the “ecological integrity of the marine environment” to avoid any negative impact on endangered species as a key aspect of the country’s efforts under SDG14 (life below water).

Similarly, India’s draft National Fisheries Policy 2020 also highlights an ecosystem-based approach to “ensure sound management and sustainable development of the resources and associated habitats, maintaining the ecosystem integrity, meeting the food and nutritional security of the growing population, protecting the rights of the fishing and farming communities and building their resilience.”

The NFP also separately delineates a potential upgradation of India’s monitoring capabilities and efforts to protect ecologically and biologically significant areas through species-specific and zone-specific management plans.

If implemented properly, this contextual and localised management approach for biodiversity conservation could propel India’s efforts under SDG14. Simultaneously, the policy recommends mariculture (salt-water farming of commercially important marine species) and alternative livelihood opportunities, given the sector is dominated by socio-economically weaker small-scale fishers.

Some of these recommendations have already been mainstreamed in the Pradhan Mantri Matsya Sampada Yojana (PMMSY) approved in May 2020 with an ambitious aim to increase India’s total fish production from 137.6 lakh MT in 2018-19 to 220 lakh MT in 2024-25. However, about 42 per cent of the scheme’s total investment of over Rs 20,000 crore has been earmarked for infrastructure building and upgradation for fisheries.

This not only indicates the singular emphasis on a production-centred approach to marine ecosystem management as against the ecosystem-centred approach highlighted in the NFP, but also lays bare the dissonance in the ideas and intent of policymakers when it comes to crucial decisions concerning the present and future impacts of climate change.

 While one can only speculate the potential benefits of the aforementioned plans, there is an identifiable need for higher investments to ensure coastal communities can better adapt to the vagaries of climate change.

Monitoring and early warning systems like ABIS are crucial to better adaptation, as are the promotion of sustainable forms of fishing and a gradual move towards alternative livelihood opportunities for small-scale fishers who will be most adversely impacted because of a possible decline in marine biodiversity.

However, such initiatives need to be undertaken almost in tandem across the Arabian Sea region. Given the impact of increasing blooming events on almost 150 million people living across several countries that share the waters of the Arabian Sea, a multilateral research and monitoring mechanism is key to understanding the future of marine ecosystem services in the region as well as ways to adapt to its rapidly changing nature. 

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