Climate change has led to abundant blooms of toxic phytoplankton in the seas

(ORDO NEWS) — Microalgal blooms generally benefit fisheries by increasing the food supply for fish and whales.

But not only beneficial phytoplankton blooms – toxic algae poison marine life, deprive the ocean of oxygen and lead to the formation of dead zones.

A new scientific study found that climate change has led to more frequent and abundant microalgae blooms off the coast of the seas and oceans.

Phytoplankton blooms microscopic algae that float on the surface of the ocean have become more frequent and more abundant along coastlines in different parts of the world.

This benefits fisheries, but potentially poses a threat to the inhabitants of the oceans.

The study of the state of the marine flora was carried out by Chinese, American and Canadian specialists with the support of NASA, the Intergovernmental Oceanographic Commission of UNESCO and the National Natural Science Foundation of China.

According to experts, from 2003 to 2020, coastal phytoplankton blooms increased by about 13%, covering an additional 4 million square meters. km of the oceans.

Flowering frequency jumped by 59% over the same period. Toxic microalgae in large numbers create the so-called dead zones, where there is no oxygen and all life is killed.

They wreak havoc on marine food chains and damage industrial fisheries. For example, an algal bloom near Chile cost salmon farms $800 million in 2016.

According to Don Anderson, head of the US National Office for the Control of Harmful Algal Blooms at the Woods Hole Oceanographic Institute, researchers suggest that the increase in phytoplankton masses is triggered by climate change.

“Fisheries are largely dependent on phytoplankton blooms. It is important to understand why it happens so abundantly,” he said.

The researchers tried to use satellite images to determine the extent of the increase in the mass of phytoplankton and its quality.

So far, they have not been able to distinguish between beneficial and harmful blooms.

Although they managed to record that it has intensified in the northern part of the Gulf of Mexico, as well as in the East China and South China Seas.

According to scientists, the reasons most likely lie in the increase in sea surface temperatures. Climate change has disrupted water circulation and affected the mixing of nutrients.

Anthropogenic activity has added pollution: fertilizers from agricultural fields flow into water bodies, which also enhances flowering.

“I was also interested in the relationship between the increase in population in coastal areas and the growth of phytoplankton.

This is especially true for some countries in the southern hemisphere, where most household waste is not recycled and dumped into the ocean,” explained Canadian scientist Nandita Basu, an expert in global water sustainability and ecohydrology.


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