Jellyfish Blooms in Kerala’s Backwaters – UPSC 2025 Environment Notes

Description

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Context

In India, particularly along the Kerala coast, blooms have intensified post monsoon, driven by warming seas, pollution, habitat modification, and depleted fish stocks.

What are jellyfish blooms?

Jellyfish, ancient and resilient gelatinous zooplankton from the phylum Cnidaria, are highly adaptable marine organisms with simple anatomy, stinging tentacles, and effective jet propulsion.
While they play important roles in marine food webs as both predators and prey, under the right conditions, their populations can explode into dense "blooms" — events that are increasingly being driven by human-induced and environmental stresses.
These blooms devastate marine ecosystems by reducing biodiversity, outcompeting native species, and destroying fish and invertebrate populations.

About Kochi's bioluminescent backwaters

When the water is disturbed, Kochi's backwaters come alive with a dazzling blue glow every year from March to May.
This natural phenomenon is known as "kavaru" in Malayalam.
The phenomenon received widespread attention following its stunning portrayal in the 2019 Malayalam film Kumbalangi Nights.

The Science of Bioluminescence

Bioluminescence is the production of light by certain microorganisms when water is disturbed.
The primary contributor to Kerala's waters is Noctiluca scintillans, also known as'sea sparkle.'
This phenomenon is caused by chemical reactions within the organisms' specialized structures, which create the glowing effect.
While fascinating, these plankton blooms are a sign of eutrophication, which is often caused by excess nutrients from industrial and agricultural runoff.

Source: Downtoearth

Practice Question:

Q. With reference to Jellyfish blooms observed in the backwaters of Kerala, consider the following statements:

Jellyfish blooms are often triggered by rising sea surface temperatures and eutrophication.

Their sudden appearance in Kerala's backwaters is considered a sign of healthy marine ecosystems.

Jellyfish blooms can disrupt local fisheries and tourism activities.

Jellyfish are classified as marine mammals under the Wildlife Protection Act of 1972.

Which of the statements given above is/are correct?

A) 1 and 3 only

B) 2 and 4 only

C) 1, 2 and 3 only

D) 1, 3 and 4 only

Answer:

A) 1 and 3 only

Explanation:

Statement 1: Correct. Jellyfish blooms are linked to environmental changes such as increased sea temperatures, nutrient pollution (eutrophication), and reduced predation.

Statement 2: Incorrect. Their presence in large numbers can indicate ecological imbalance, not health.

Statement 3: Correct. Jellyfish blooms can clog fishing nets, sting swimmers, and negatively impact tourism and fisheries.

Statement 4: Incorrect. Jellyfish are marine invertebrates, not mammals, and they are not classified under mammals in any wildlife protection framework.