Dust from Africa sparked a massive phytoplankton bloom

Picture this for a moment – a wind that sweeps across southern Africa, picking up tiny particles of dust and hurling them across the vast expanse of the Indian Ocean.

This seemingly common act of nature had surprising and unexpected effects in 2019, causing the largest phytoplankton bloom in two decades, and at a time of year when these blooms are rarely seen.

Traveling nutrient buffet

Dust, though often regarded as nothing more than a household nuisance, has hidden virtues. Dust clouds can voyage great distances, even crossing oceans.

A significant example of this is the Sahara Desert’s dust which frequently voyages across the Atlantic Ocean to the Americas.

As these minute particles settle on land or water, they deliver essential nutrients which spur plant growth and enhance ocean productivity – a much-needed buffet for marine phytoplankton.

How dust, deserts, and oceans connect

Despite recognizing the voyages of dust and its potential effects, the intricate relationship between desertification, dust emissions, and ocean fertilisation still remains somewhat of a mystery.

A research paper recently published in the journal PNAS Nexus, however, marks notable progress in unlocking these complex links.

Rare and remarkable bloom

A team of scientists from ESA’s Living Planet Fellowships Poseidon and Pyroplankton traced an exceptional phytoplankton bloom off the eastern coast of southern Africa.

This proliferation, triggered by “dust wet deposition” (or rain), occurred in the nutrient-scarce waters southeast of Madagascar.

The study was led by Dr. John Gittings from the University of Athens. The research has contributed immensely in shedding light on this extraordinary event.

Trail of dust to the ocean

Dr. Gittings and his team employed an array of satellite data from multiple projects led by ESA, including the Climate Change Initiative Ocean Colour project, the Climate Change Initiative Soil Moisture project, and the Science for Society Biological Pump and Carbon Exchange Processes project.

Further contributing to the research were the Copernicus Atmosphere Monitoring Service and the Copernicus Marine Service.

This rich pool of satellite data enabled the team to accurately trace the expanse of this colossal bloom and identify the dust events that caused it.

Dust anomalies, oceans and climate change

Dr. Gittings noted that although this extensive phytoplankton bloom was highly unusual, recent trends of increasing air temperatures, aridity, and dust emissions in southern Africa could signify that such events may become more common in the future.

Together with recent discoveries of ocean fertilization caused by mega-fire induced droughts in Australia, these findings hint at a possible link between climate change, drought, aerosols, and ocean blooms.

Dual role of dust in ecosystems

While dust plays a pivotal role in natural fertilization processes, it also poses challenges to both terrestrial and marine ecosystems.

On the one hand, nutrient-rich dust contributes to plant growth on land and supports plankton blooms, which form the foundation of the marine food web.

On the other hand, excessive dust can lead to oppressive air pollution, impacting human health and reducing visibility.

Recognizing this dual role of dust is crucial in understanding its comprehensive impact on ecosystems and developing strategies to mitigate the adverse effects while leveraging its benefits.

Future directions in dust research

The study by Dr. Gittings and his team marks significant progress in understanding the complex interactions between dust, climate change, and oceanic ecosystems.

However, more research is needed to investigate the long-term implications of dust-related events and their potential to alter ecological and climatic dynamics.

Expanding international collaboration, enhancing satellite monitoring capabilities, and incorporating more sophisticated climate models will be vital to unraveling the intricacies of dust’s influence on our planet’s future.

Interconnectedness of our world

Marie-Helene Rio of ESA emphasized the critical role of our oceans. Covering two-thirds of our planet, oceans are integral to the health of our ecosystems.

Unraveling how climate change is altering their biological processes is not a mere scientific curiosity – it’s a matter of survival for life on Earth.

“Having access to such rich satellite datasets enabled us to clearly track the extent of this massive bloom and pinpoint the dust events responsible for it,” said Dr. Gittings.

This research highlights the interconnectedness of our world, reminding us that even the smallest of particles can have massive, surprising effects in the grand scheme of things.

The study is published in the journal PNAS Nexus.

Video Credit: ESA

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