ARE ALGAL BLOOMS GOOD OR BAD?

ALGAL BLOOMS AND THEIR INFLUENCE ON THE ENVIRONMENT

Typically, algae are simple, non-flowering, aquatic, photosynthetic plants. They can be found in both salt and fresh water. Algae have eukaryotic cells. Their sizes range from single-celled, microscopic, to large structures of 20 to 30 meters.

The ocean supplies 50% to 80% of world oxygen production. Planktons and algae in the ocean are the primary sources of that oxygen. So, algae can be introduced as the world’s main oxygen source.

Also algae have other benefits as well. They are excellent biofuels and excellent wastewater filtering materials. They help to control pollution by consuming carbon dioxide gas. This purifies the air.

What are the algal blooms?

Algal blooms rapidly increase algae quantity in fresh or saltwater systems. Here, the algae density in the selected place shows rapid growth. Even the water in that area turns into the colour of the algae.

If any aquatic area bears optimum environmental conditions for algal growth at higher levels, that will cause an algal bloom. So, the factors such as nutrient level of water, temperature, and light are the main reasons for the formation of an algal bloom.

Sometimes marine areas have external nutrient sources such as wastewater disposal, fertiliser runoff from agricultural areas etc. For these reasons, phosphorus and nitrogen levels in the water can increase and make more suitable conditions for an algal bloom.

After the disaster of the Xpress pearl ship in 2021, there was a risk of algal blooms in Sri Lankan oceans.

Benefits of algal blooms

Algal blooms are large gatherings of algae. So, consuming carbon dioxide and releasing oxygen levels by photosynthesis is higher. Also, algal blooms increase the carbon sources of marine areas. So, the number of marine creatures increase.

Usually, the species of algae in an algal bloom can give a brief idea about the beneficial or toxic nature of the algal bloom.

Are all the algal blooms beneficial?

People have a great impression of algae. So, there is a misconception that algal blooms always benefit the environment and humans.

But is it always a good trend?

Harmful nature of algal blooms

As already mentioned, the harmfulness or beneficial nature of algae can be decided according to the species of algae. Algal blooms with algae like cyanobacteria and blue-green algae can be harmful.

These harmful algae release toxins that can be poisonous or fatal for aquatic animals. They form in water and are spread all through the aquatic source by water.

These toxins mobilise in the lower levels of the food chain and concentrate in the higher levels by consuming the primary consumers. So, this can even cause damage to human and other land animals’ health as well. They can form irritations, itching, swellings, difficulties in the alimentary canal and nervous system, and even damage to the liver.

Algal blooms cover the entrance of the light to the depth of water. This harms the growth and life of plants and animals in the depth of water.

When algae die, they mobilise at the bottom of the water. And it consumes a large amount of dissolved oxygen in the water to decompose.

Misconception

Algal blooms can not be confirmed as 100% harmful or beneficial. The species of algae in algal blooms are essential to predict their toxicity. Algae which can provide toxic substances, can prepare the most harmful algal blooms.

But because of the oxygen consumption of dead parts of algae in algal blooms, almost every algal bloom has a bad result.

So, controlling algal bloom formation is very important to the environment.

Algal blooms in Sri Lanka and their impact

There was a toxic algal bloom incident with cyanobacteria in 2006 at Nuwara wewa in Anuradhapura. More details about the research on its water standard can be read here Archived   

In 2020, there was nontoxic diatom algal bloom near the Indian ocean around Sri Lanka.

Xpress pearl incident in 2021 was the nearest and most memorable disaster, with the highest risk of giving rise to a very harmful algal bloom. This ship carried a considerable amount of chemicals which can lead to algal bloom spread.

Distribution of algal bloom in the world

The world’s most giant algal bloom formation was reported in the Mexican gulf in North Africa. Details about the most harmful algal blooms in the world can be found here Archived

Controlling and minimising the harm from algal blooms

Preparation before a disaster is the most suitable way to control algal colours. So, to avoid algal blooms, aeration of still water is essential. Controlling mixing of fertilisers, wastewater, and chemicals into water is necessary to avoid algal blooms. Biochemical additives and ultrasonic waves can stop and prevent the growth of algae.

Algal bloom formation from the Xpress pearl incident was controlled using these methods.