Since 1988, the waters of the Gulf of Oman and the Arabian Sea have been turning red and green in the months between January and May. The flourish of luminescent colour takes places due to algae blooms that spread in calm, nutrient-enriched waters.
These bioluminescent algae are known as ‘Sea Sparkles’ – because of the glowing trail ships leave in their wake after passing through a bloom. These might be pretty to look at, but they’re deadly for the local ecology. Since these algae thrive in conditions bad for all other aquatic life, these blooms serve as large glowing indicators of a water body’s health.
This year, a patch the size of Mexico appeared in the Gulf of Oman. The long-term implications of a bloom like this include the livelihoods of the more than 120 million people who live along the affected coastlines.
As scientists link the changing water temperature to melting glaciers, the bloom serves as yet another warning that climate change will be coming to your doorstep as the 21st century progresses.
Dr. K.B. Padmakumar is Assistant Professor at Cochin University – with years of experience studying algae blooms in the Arabian Sea. He says the phenomenon is an annual one – but that this year’s bloom was larger in size.
It’s unlikely that this bloom will cause human deaths just yet. Its real impact will be once the algae start to die – releasing noxious clouds of ammonia. Speaking to the Madras Courier he said:
“If the bloom persists for a long time, because of anoxic [absence of oxygen] conditions and [presence of] ammonia, the fishes will avoid the area. Like humans, fishes will [hide from] the odour,”
Not all algae blooms are bad – it’s the harmful algae blooms that one needs to look out for. They vary in effect, from asphyxiating fish through oxygen depletion to clogging their gills – or producing neurotoxins.
It’s the neurotoxins that pose the largest threat, thanks to a phenomenon known as biomagnification, where toxins accumulate as they travel up the food chain. The shellfish consumed by humans act as a filter species, that gets sustenance from eating whatever it finds on the seabed. They serve as the link between the glowing neurotoxins and humans.
Paralytic Shellfish Poisoning (PSP) is a condition where after eating contaminated shellfish, one’s lips start to tingle – soon followed by nausea, vomiting, muscle weakness and eventually a paralysis. Victims are often unable to breathe at all. In 1991, several cases of PSP from contaminated mussels resulted in seven dead and over 500 hospitalized from the town of Vizhinjam in Kerala.
Even blooms that kill fish can be harmful to humans. In 2004, a mass die-off of fish in Kerala led to hundreds of children being hospitalized for nausea from the stench. Up close, the blooms have a pungent aroma of ammonia – lethal at high doses.
A report by the National Institute of Oceanography estimates there to have been 109 cases of algal blooms since 1909, with most of them along India’s South-West coast. The reasons are both physical and chemical – the former caused by up-swells in ocean currents, the latter by a surge in nutrients in the water that allow algae to thrive. But a third explanation – of climate change – has been making the rounds.
Researchers from the Lamont-Doherty Earth Observatory of Columbia University have been observing Oman’s algae swells since 2003. The trouble started when large amounts of Noctiluca Scintillans started appearing amidst the algae – in winter.
Phytoplankton is the primary source of food for many species of fish. They also turn CO2 into Oxygen – producing half the world’s supply. When N. Scintillas blooms dominate the smaller plankton, many species of fish might end up without food in an oxygen-deprived environment. The effects are likely to travel up the food chain and disturb the ecological balance.
It’s a troubling question made even more so by the observation that climate change could be to blame. The same researchers found that the Himalaya’s melting snow-caps had made the subcontinent a warmer place – triggering stronger South-West winds before the monsoons. These, in turn, cause the upswellings that bring nutrient-rich water to the surface – the perfect recipe for an algae bloom.
It’s not the first time the Gulf of Oman has told us about climate change. In 2000, researchers from Columbia University drilled through deep-sea sediment to find out what killed the Akkadian Empire more than 4000 years ago. By observing the sediment, they concluded a recent theory – that a 300-year-long drought triggered by a sudden act of climate change had laid waste to what was once a glorious empire.
Of course, the Akkadians didn’t cause their climate to change – they were merely victims of it. What makes the modern scenario different is that we’re both victim and perpetrator. The number of dead-zones on the ocean floor – regions with not enough oxygen to sustain life other than the blooms – have increased by a third between 1995 and 2007.
It’s an irony that such a deadly phenomenon could be so fantastic to look at. The phytoplankton generate light when they sense a predator approaching – serving a sort of siren call to attract the predator’s predators to take care of the situation for them.
When bioluminescent algae swells showed up along the beaches of Mumbai in November 2016 – it excited photographers and tourists alike. People rushed to take photographs and videos of a phenomenon that looked magical in the nights.
Ecologically, the magic fades when you’re a species with neither food to eat nor oxygen to breathe. With country-sized algae-blooms increasingly becoming a new norm, could climate change be choking the life out of our oceans?
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