Red tide

Red tide

Subject :Environment

Section: Pollution

Context: Beach-goers in Puducherry were shell-shocked on Tuesday, October 17, 2023 after they witnessed the strange phenomenon of the sea turning red.

What is the news?

The entire stretch of coastal waters from Vaithikuppam on the northern side of the Promenade, up until Gandhi statue has become red, reportedly due to algal bloom

Why beach has become red?

“Industrial pollution or ‘Red Tide’ can be factors behind the sea turning red. This phenomenon has been observed in Vaithikuppam and a few other patches on the coastline over the past one week. Red Tide is a toxic algal bloom and is known to be harmful to marine life.

What is a red tide?

Harmful algal blooms, or HABs, occur when colonies of algae—plant-like organisms that live in the sea and freshwater—grow out of control while producing toxic or harmful effects on people, fish, shellfish, marine mammals, and birds. The human illnesses caused by HABs, though rare, can be debilitating or even fatal.

While many people call these blooms ‘red tides,’ scientists prefer the term harmful algal bloom. One of the best known HABs in the nation occurs nearly every summer along Florida’s Gulf Coast. This bloom, like many HABs, is caused by microscopic algae that produce toxins that kill fish and make shellfish dangerous to eat. The toxins may also make the surrounding air difficult to breathe. As the name suggests, the bloom of algae often turns the water red.

HABs are a national concern because they affect not only the health of people and marine ecosystems, but also the ‘health’ of local and regional economies.

Are all Algal blooms harmful?

But not all algal blooms are harmful?

Most blooms, in fact, are beneficial because the tiny plants are food for animals in the ocean. In fact, they are the major source of energy that fuels the ocean food web.

A small percentage of algae, however, produce powerful toxins that can kill fish, shellfish, mammals, and birds, and may directly or indirectly cause illness in people. HABs also include blooms of non-toxic species that have harmful effects on marine ecosystems. For example, when masses of algae die and decompose, the decaying process can deplete oxygen in the water, causing the water to become so low in oxygen that animals either leave the area or die.