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Sri Lanka probes diatom algal blooms in the Indian Ocean

ECONOMYNEXT – Algal blooms found off the coast of Sri Lanka are not toxic to other marine life, a researcher at the National Aquatic Resources Research and Development Agency (NARA) which is probing the cause of the phenomenon said.

The algal blooms were found in Dehiwala, Moratuwa-Angulana, Kalutara-Payagala areas and some cases in Chilaw areas about 4-17 kilometres off the coast of Sri Lanka in the Indian Ocean

NARA has identified the cause of the blooms a species of diatom microalgae. Diatoms are photosynthetic and produce oxygen.

“It was identified as a Navicula Diatom alga which is not a poisonous species, but we found it in high densities than before,” Shyamalika Weerasekara, Head of Environmental Studies Division at (NARA) said.

“They are a single cell alga but it can create mucus and they can bind together. There are 1200 species in the world, and we have found it in Sri Lanka too. But what is suspicious is that we are recording it in high density in the water.

“Earlier we suspected it to be a blue-green algae when we found it in fishnets and we saw fishermen’s legs and hands covered with some kind of a yellow residue”.

A blue-green algae, although referred to as algae is a bacteria called cyanobacteria, which can be toxic to other life in the water. Such Harmful Algal Blooms (HAB) include the so-called Red Tide.

Researchers are trying to find the trigger for the latest algal blooms.

“The algae that we have found is volatile and highly sensitive for the nutrients in the water,” Weerasekara said.

“Therefore, we are testing the seawater samples to check whether there are any changes in the nutrients in the water. We are testing to see the reason for these algae to grow is the nutrients level or not.”





Though algal blooms in freshwater bodies, in particular, are associated with fertilizer run-off researchers suspect it could due to an upwelling in the Ocean.

Upwelling occurs when the wind blows across the ocean, pushing away surface water, and colder waters well up from beneath the surface carrying nutrients to the surface.

This process happens both in the coastline and in the open ocean.

Sri Lanka has also seen high temperatures in late August with the sun shining directly across the island. (Colombo/Sept06/2020-sb)

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