Coral bleaching grips Indian coasts; Lakshadweep, Andamans are most affected

Subject: Geography

Sec: Oceanography

Tag: Coral bleaching , Lakshadweep, Andamans

Coral Bleaching in India:

Coral reefs in India, found in regions such as Lakshadweep, Gulf of Kutch, Goa, Maharashtra, and along the eastern coast including the Gulf of Mannar and Tamil Nadu, are experiencing instances of coral bleaching.
Notably, Lakshadweep has reported widespread bleaching, especially around Kavaratti Island.
The bleaching affects both hard and soft coral species, extending down to depths of 30 meters.
While some islands like Agatti report lesser severity, areas like Goa and the Andaman islands are witnessing the onset of bleaching, which could escalate if high temperatures persist.

What is Coral Bleaching?

When corals face stress by changes in conditions such as temperature, light, or nutrients, they expel the symbiotic algae zooxanthellae living in their tissues, causing them to turn completely white. This phenomenon is called coral bleaching.
The pale white colour is of the translucent tissues of calcium carbonate which are visible due to the loss of pigment-producing zooxanthellae.
Bleached corals can survive depending on the levels of bleaching and the recovery of sea temperatures to normal levels.
If heat pollutions subside in time, over a few weeks, the zooxanthellae can come back to the corals and restart the partnership but severe bleaching and prolonged stress in the external environment can lead to coral death.
Over the last couple of decades, climate change and increased global warming owing to rising carbon emissions and other greenhouse gases have made seas warmer than usual.
Coral bleaching has occurred in the Caribbean, Indian, and Pacific oceans regularly.

Mass Coral Bleaching:

To officially declare a global mass bleaching event, widespread bleaching must be observed in three major ocean basins: the Atlantic, Pacific, and Indian Oceans.

Fourth Mass Coral Bleaching Event:

The current coral bleaching event is part of a global trend, identified as the fourth mass coral bleaching event, which has affected over 50 regions worldwide since 2023.
Triggered by elevated sea surface temperatures due to an ongoing El Niño event, this phenomenon threatens marine biodiversity, as corals act as crucial ecosystems for various marine species.
Historical data from global events in 1998, 2010, 2014, and 2017 highlight the recurring and severe nature of these bleaching events, emphasizing the urgent need for effective marine environmental management.

Previous Mass Coral Bleaching:

First Mass Bleaching: It occurred in 1998 when the El Niño weather pattern caused sea surfaces in the Pacific Ocean to heat up; this event caused 8% of the world’s coral to die.
Second Mass Bleaching: This event took place in 2002. In the past decade, however, mass bleaching occurrences have become more closely spaced in time, with the longest and most damaging bleaching event taking place from 2014 to 2017.
Third Mass Bleaching: The event that took place between 2014-17 affected reefs in Guam in the Western Pacific region, the North, South-Pacific, and the Indian Ocean.

Coral reef:

Corals are invertebrate animals belonging to a large group of colourful and fascinating animals called Cnidaria.
Each coral animal is called a polyp, and most live in groups of hundreds to thousands of genetically identical polyps that form a ‘colony’.
Coral polyps host a microscopic symbiotic alga called zooxanthella that photosynthesizes just like plants, providing food to the coral.
Coral is generally classified as either hard coral or soft coral.

Importance of Coral Reefs:

Coral reefs, often described as the “rainforests of the sea,” play a vital role in marine life by providing essential habitat, food, and breeding grounds for numerous marine organisms.
The health of coral reefs is directly linked to the broader ecological balance and biodiversity of the oceans.

Source: DTE