A toxic algae patch is expanding in the oceans

A study conducted by researchers at the Southern University of Science and Technology in China found that the total area affected by phytoplankton growth has increased by 13.2% since 2003.

When nutrients from fertilizer, sewage, air pollution, and livestock dung find their way into water sources, phytoplankton will feed on their nutrients and grow.

The researchers also found that rising sea temperatures have increased algal blooms over the past two decades, as warmer waters have increased the length of the blooming season.

They write: “Many algal blooms are beneficial, fixing carbon at the base of the food chain and supporting fisheries and ecosystems around the world. However, harmful algal blooms, called harmful algal blooms, have become a major environmental problem worldwide. the world".

An algal bloom is a rapid increase in the number of algae in an aquatic system, and can occur in freshwater as well as marine environments.

Bloom can cause surface-level water to change color, turning yellow, red or bright green, as evidenced by new satellite imagery.

It is often the result of eutrophication (water eutrophication or eutrophication), when water bodies are enriched with nutrients such as phosphates and nitrates, which provide food for algae and other green plants, allowing their growth.

Phytoplankton become harmful when they use up all the dissolved oxygen in the water, suffocating fish and aquatic insects, which in turn become nutrients themselves.

Some algae species also produce biotoxins that can have severe effects on wildlife, and contribute to these "dead zones" where aquatic life cannot survive.

In the study, published in the journal Nature , researchers used 760,000 images taken by NASA satellites from 2003 to 2020 to calculate the area of ​​the global oceans covered by algae each year and the frequency of blooms.

They then compared this data to sea surface temperatures (SST) as well as the amount of temperature change per meter, or the "spatial gradient of sea surface temperature".

A large temperature difference between two adjacent regions of the ocean, or a large spatial gradient in sea surface temperature, could indicate poor water circulation.

This is because hotter water is less dense than cooler water and less drowned in the natural "conveyor belt" motion of the currents.

As a result, nutrients are distributed less evenly through the water column, and phytoplankton are able to thrive in areas where they are most concentrated, generally those closest to the surface.

Large differences in temperature between adjacent ocean regions can cause disturbances and cause more nutrients from deeper waters to further encourage algae growth.

The maps showed that coastal phytoplankton blooms increased by 1.53 million square miles (3.97 million square kilometers) during the observed period.

In 2020, it covered 8.6% of the total global ocean area.

It was also found that the average annual number of blooms observed increased by 59.2% between 2003 and 2020, which equates to 2.19% each year.

The higher flowering frequency was significantly associated with ocean temperature, suggesting that "the favorable seasons in these temperate seas extended under warmer temperatures."

Flowering frequency also increased with the spatial gradient of sea surface temperature in several regions, including California, Steam Bay and the Canary Stream.

This indicates that weak ocean currents caused by rising sea temperatures contribute to the growth of algae.

Across China, Iran, Vietnam and the Philippines, the researchers also observed an increase in fertilizer use during the study period, which likely contributed to the phytoplankton blooms.

The same can be said of intensive aquaculture in Finland, China, Algeria, Guinea, Vietnam, Argentina, Russia and Uruguay.

The researchers hope that their maps and data will help increase understanding of the mechanisms that drive and dissipate coastal phytoplankton blooms.

An amazing video reveals how our planet's surface has changed over the past 100 million years

The surface of our planet is constantly changing, although we may not notice it. To prove this, scientists from the University of Sydney in Australia modeled how the Earth's landscape has changed over the past 100 million years.

The model takes into account how climate affects the movement of sediments through rivers and seas, as well as the movement of tectonic plates.

Scientists hope that their model will enable accurate testing of theories about future effects of climate change on Earth's surface.

Coronal topography on Venus may solve one of the biggest mysteries of Earth's twin

Lead author Dr Tristan Sales from the University of Sydney explained: “To predict the future, we must understand the past. But our geological models have provided only a fragmentary understanding of how the modern physical features of our planet formed. If you are looking for a continuous model of the interaction between river basins, global-scale erosion and sediment deposition, "With high precision over the past 100 million years, it hasn't existed. So this is a huge advance. It's not only a tool to help us investigate the past but it will also help scientists understand and predict the future."

The landscape of the planet today is the result of millions of years of climate change and the movement of tectonic plates.

These plates are made up of the Earth's crust and the upper part of the mantle, which is a rocky layer, and float on top of a layer of sticky, hot rock called the asthenosphere, located between about 80 km (50 miles) and 200 km (200 miles) 124 miles) below Earth's surface.

The asenosphere causes tectonic plates to collide, changing the landscape with the formation of mountains, volcanoes and earthquakes.

On the other hand, climate can affect the weathering of sediments, causing them to break up and flow into water bodies.

It can also cause rivers to form or flood, and change their flow rates, processes that affect sediment movement.

In the model, detailed in the journal Science, the scientists wanted to show how geophysical landscapes have evolved today at the highest resolution yet.

They used geological records to simulate how the land's elevation changed over time, and then factored in ancient climate data from a separate computer model.

Their final model was calibrated and tested by comparing its predictions to natural, real-world examples of sediment formations and water flow processes.

The resulting timelapse clip shows the scene in high resolution, revealing erosion up to 5 km (3 miles) deep and sediments up to 5 km high.

Each frame shows the evolution of another million years on Earth.

Second author Dr Laurent Huson of the Institute of Geosciences in France explained: "This unprecedented, high-resolution model of Earth's recent past will provide geoscientists with a more complete understanding of the dynamics of the Earth's surface. Crucially, it captures the dynamics of sediment transport from land to ocean in a way we have never been able to." before".

Man-made climate change is known to alter the chemical composition of the oceans, and the processes within them.

The team hopes that the model will allow for a better understanding of the impact on current and future sedimentary processes.

"Our results will provide a dynamic and detailed background for scientists in other areas to prepare and test hypotheses, such as biochemical cycles or biological evolution," said Dr. Sales.

Source: Daily Mail