International
Naresh M. Gohil out on his fishing boat. Image by Malavika Vyawahare/Mongabay.

Arabian Sea - A Single-Celled Organism Threatens the Vast Arabian Sea and the Millions That Depend on It

A single-celled organism that acts both as a plant and an animal has come to dominate wintertime algal blooms in the northern Arabian Sea. Winter blooms of Noctiluca scintillans, also known as the sea sparkle, have displaced microscopic algae called diatoms that form the basis of the marine food chain, a paper in Nature says.

  • Scientists at Columbia University fear the outbreaks could herald massive declines in fisheries in the region, potentially impacting millions of fishers in India, Pakistan, Iran, Oman and Yemen.
  • They have linked the emergence of N. scintillans blooms with the loss of ice cover in the Himalayan-Tibetan Plateau driven by climate change.

On February 26, 2003, a group of scientists set out to sea from Goa in the Arabian Sea, India, on a routine mission. They called it “sea truthing,” verifying data gathered by satellites eyeing the earth from hundreds of kilometers above. What the team encountered there, in the middle of the Arabian Sea, was far from routine. About 970 kilometers northwest of Mumbai on India’s western coast, they found themselves sailing on a green swirl that spread out as far as the eye could see. At night, the waters glowed neon blue.

The light was emitted by millions upon millions of a single-celled organism: Noctiluca scintillans, or the sea sparkle. It had never been found in these waters in such abundance before. Despite its luminescence, the N. scintillans blooms are a harbinger of darker tidings, a paper published in Nature earlier last year warns.

A map produced using satellite data on chlorophyll concentration. The red swirls indicate the presence of Noctiluca blooms in the Arabian Sea in February 2009. Image courtesy of Joaquim I. Goes.

The outbreaks occur every winter in the northern Arabian Sea, stretching from India’s western coast to the edges of the boot-shaped Arabian Peninsula. Scientists at Columbia University say they fear the rise of these blooms could herald massive declines in fisheries in the region.

“We are seeing an ecosystem shift in the Arabian Sea,” said Helga do Rosario Gomes, one of the study’s authors. “That can cause massive declines in fisheries and ultimately lead to the emergence of a dead zone.”

If the team is right, it would jeopardise the livelihoods of more than a million fishers living in settlements sprinkled along the coasts of India, Pakistan, Iran, Oman and Yemen.

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