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Sargassum algae off Big Pine Key in the lower Florida Keys

The ‘great Atlantic Sargassum belt’ is a monstrous seaweed patch that stretches from the Gulf of Mexico (above, near the Florida Keys) to West Africa. Credit: Brian Lapointe/Florida Atlantic University


Huge algal mat spanning an ocean is visible from space

Deforestation in the Amazon has helped to fuel the growth of a seaweed blanket that exceeded 20 million tonnes in 2018.

The world’s largest seaweed bloom stretches from West Africa to the Gulf of Mexico, an analysis of satellite data has found.

Two species of brown seaweed, Sargassum fluitans and Sargassum natans, are common in the Gulf of Mexico and the Sargasso Sea, which takes its name from the algae. But in 2011, a giant Sargassum bloom was spotted blanketing the central Atlantic Ocean.

Chuanmin Hu at the University of South Florida St. Petersburg and his colleagues scrutinized satellite data to track Sargassum blooms. They found a recurring belt of seaweed that, at its maximum in 2018, extended over a distance of more than 8,850 kilometres and had a biomass of more than 20 million tonnes.

The seasonal blooms seemed to be linked to two key factors: the upward surge of water from deep levels of the ocean off the coast of West Africa in winter, and a spring and summer influx of nutrients from the Amazon River — fuelled, in part, by deforestation and fertilization.

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Ember and thick smoke from bushfires reach Braemar Bay in New South Wales

Vast bush fires that swept across Australia at the end of 2019 and the start of 2020 filled the skies with enough smoke to warm a portion of the atmosphere. Credit: Saeed Khan/AFP/Getty

Atmospheric science

Smoke from Australian fires turned up the heat in the southern sky

The catastrophic wildfires of late 2019 and early 2020 triggered a lingering temperature rise in a section of Earth’s lower atmosphere.
Visible and infrared images of the device in fully discharged and charged states

A display screen in its uncharged (top left) and charged (top right) state in visible light. The screen reflects one range of infrared wavelengths when uncharged (bottom left) and another range when charged (bottom right). Credit: M. S. Ergoktas et al./Nature Photon.

Optics and photonics

One screen, three images — some invisible in ordinary light

A graphene-based device can display several images simultaneously using a range of wavelengths.
Woman harvesting teff, Ethiopia

A farmer in Ethiopia harvests teff, a cereal. Small farms tend to have more-diverse landscapes than do sprawling industrial operations. Credit: Andia/Universal Images Group/Getty

Environmental sciences

Small farms outdo big ones on biodiversity — and crop yields

Large-scale farms account for most of the global food supply, but smallholdings protect species and are just as profitable.
Diagram of the nuclear composition and electron configuration of an atom of xenon-132.

A xenon atom’s electrons (grey circles; illustration) have been observed and even manipulated as they shifted their position. Credit: Carlos Clarivan/Science Photo Library

Atomic and molecular physics

An atom shuffles its electrons at ultrahigh speed — and is caught in the act

Scientists capture the movement of electrons in a xenon atom, a phenomenon that lasts for a fraction of one-billionth of a second.
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