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Model contradicts scientists, predicts future phytoplankton boom in tropics

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Jan. 27 (UPI) — Contrary to the expectations of many environmental scientists, a new model has predicted a likely boom in tropical phytoplankton abundance as the century progresses.

Phytoplankton anchor the aquatic food web. Most scientists assumed this community of photosynthesizing bacteria and plant-like diatoms would struggle in the tropics as the oceans become increasingly stratified, with heavier cold water situated deep beneath the surface and lighter warm water isolated on top.

Phytoplankton relies on ocean mixing to bring nutrients to the surface where they live. But in a stratified ocean, there is likely to be less mixing, and thus, smaller phytoplankton populations.

“All the climate models have this mechanism built into them, and it has led to these well-established predictions that phytoplankton productivity, biomass and export into the deep ocean will all decline with climate change,” lead researcher Adam Martiny, professor of oceanography at the University of California, Irvine, said in a news release. “Earth system models are largely based upon laboratory studies of phytoplankton, but of course laboratory studies of plankton are not the real ocean.”

Traditionally, scientists measure phytoplankton abundance by measuring the concentration of chlorophyll in the water. Previous studies have revealed lower levels of chlorophyll in warmer, tropical waters and higher concentrations in ocean water collected farther away from the equator.

“The problem is that chlorophyll is not everything that’s in a cell, and actually in low latitudes, many plankton are characterized by having a very small amount of it; there’s so much sunlight, plankton only need a few chlorophyll molecules to get enough energy to grow,” Martiny said. “In reality, we have had so far very little data to actually demonstrate whether or not there is more or less biomass in regions undergoing stratification. As a result, the empirical basis for less biomass in warmer regions is not that strong.”

To build a more accurate ocean systems model, Martiny and his colleagues sampled phytoplankton communities at thousands of locations all over the globe. Their efforts revealed surprising levels of phyotplankton abundance in tropical waters.

Most of the phytoplankton living in the tropics are tiny cells called picophytoplankton. Though tiny compared the the phytoplankton living in cooler climates, picophytoplankton are abundant in warm water.

When scientists provided ocean models with their new phytoplankton survey data, the simulations showed increases in ocean temperature are likely to boost phytoplankton abundance.

“In many regions there would be an increase of 10 to 20 percent of plankton biomass, rather than a decline,” Martiny said. “Machine learning is not biased by the human mind. We just give the model tons and tons of data, but they can help us challenge existing paradigms.”

Scientists described the results of their new model in a new paper published Monday in the journal Nature Geoscience.

Though ocean warming is likely diminishing the levels of ocean mixing that bring nutrients to the surface, scientists suspect warm water phytoplankton will find new ways to get the nutrients they need to proliferate.

“When plankton die — especially these small species — they sit around for a while longer, and maybe at high temperature other plankton can more easily degrade them and recycle the nutrients back to build new biomass,” Martiny said.

Researchers said their findings aren’t proof that climate change won’t negatively impact marine ecosystems, only that phytoplankton communities are more resilient than previously suggested.

And if climate change continues unabated, scientists warned that the results could be catastrophic for all kinds of marine organisms.

“We could obviously let climate change get out of hand and go into completely uncharted territory, and then all bets are off,” Martiny said. “But at least for a while, I think the adaptive capabilities in these diverse plankton communities will help them maintain high biomass despite these environmental changes.”



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Astronomers measure spin-orbit alignment of a distant super-Jupiter

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June 29 (UPI) — For the first time, astronomers have measured the spin-orbit alignment of a faraway super-Jupiter exoplanet, located 63 light-years from the Earth in the Pictor constellation.

The super-Jupiter exoplanet, Beta Pictoris b, has a mass 11 times that of Jupiter and enjoys an orbit around its host star similar to the trajectory Jupiter takes around our own sun.

The detailed observations of Beta Pictoris b — shared Monday in the Astrophysical Journal Letters — could help scientists better understand the formation and evolution of planetary systems.

“The degree to that a star and a planetary orbit are aligned with each other tells us a lot about how a planet formed and whether multiple planets in the system interacted dynamically after their formation,” lead study author Stefan Kraus said in a news release.

During the 18th century, scientists Immanuel Kant and Pierre-Simon Laplace noticed that the orbital planes of the solar system’s planets were largely aligned. They estimated that Earth and its planetary neighbors formed from a rotating and flattened protoplanetary disc.

“It was a major surprise when it was found that more than a third of all close-in exoplanets orbit their host star on orbits that are misaligned with respect to the stellar equator,” said Kraus, professor of astronomy and physics at the University of Exeter in Britain.

“A few exoplanets were even found to orbit in the opposite direction than the rotation direction of the star,” Kraus said. “These observations challenge the perception of planet formation as a neat and well-ordered process taking place in a geometrically thin and co-planar disc.”

Using the GRAVITY instrument on the Very Large Telescope in Chile, scientists measured the minuscule spatial displacement caused by the stellar rotation of Beta Pictoris. The data revealed an alignment between the star’s rotational axis and the orbital axis of the planet Beta Pictoris b and its surrounding debris disk.

“Gas absorption in the stellar atmosphere causes a tiny spatial displacement in spectral lines that can be used to determine the orientation of the stellar rotation axis,” said study co-author Jean-Baptiste LeBouquin, an astronomer at the University of Grenoble in France. “The challenge is that this spatial displacement is extremely small: about 1/100th of the apparent diameter of the star, or the equivalent to the size of a human footstep on the moon as seen from Earth.”

The latest findings showed the Beta Pictoris system is just as aligned as our own solar system, but authors of the new study suggest a wider sample size is needed to confirm how common spin orbit alignment is throughout the cosmos.

“A dedicated high-spectral resolution instrument at VLTI could measure the spin-orbit alignment for hundreds of planets, including those on long-period orbits,” said Kraus. “This will help us to answer the question what dynamical processes shape the architecture of planetary systems.”



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Gold mining stunts Amazon rainforest recovery

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June 29 (UPI) — The effects of gold mining on forest health are long lasting. According to new research, gold mining stunts the regrowth of Amazon forests, limiting their ability to store carbon.

“Historically gold mining was often overlooked in deforestation analysis as it occupies relatively small areas when compared to pastures or large-scale agriculture,” lead study author Michelle Kalamandeen told UPI in an email.

Kalamandeen started the research as a postgraduate researcher at the University of Leeds but is now a postdoctoral researcher at Cambridge University.

“Yet, given recent proliferation in mining activities since 2007-2008 and again in 2012, the potential areas may be underestimated and the impact on biodiversity and forest recovery unquantified,” she said.

For the study, Kalamandeen and her colleagues sampled soil and measured trees at 18 test plots in two main gold mining areas in Guyana. Researchers also established two control sites in old-growth forests.

“We measured trees/saplings/seedlings within each plot and took soil samples from abandoned gold mining sites, active sites and control ‘old-growth’ sites,” Kalamandeen said.

The data — published Monday in the Journal of Applied Ecology — showed trees in forests damaged by gold mining activity struggled to reestablish themselves. Where as forest harmed by other kinds of activities, such as logging and agriculture, were able to rebound, the negative effects of mining on growth and carbon storage persisted.

“Our analysis showed that the lack of nitrogen was the primary driving force for the lack of recovery occurring on the tailing ponds and mining pits,” Kalamandeen said. “On the overburden, where there was an abundance of nitrogen, regrowth of trees were similar to other Neotropical secondary, recovery forests.”

Researchers were surprised to find that a lack of nitrogen, instead of an excess of mercury, was to blame for the stunted regrowth.

“Our research showed that active mines had on average 250 times more mercury than abandoned mining sites, suggesting that this mercury leaches into neighboring forests and rivers,” Kalamandeen said.

Researchers found that in the few mining sites where topsoil was replaced and fertilized with nitrogen — an often mandated, but rarely enforced, restoration step — regrowth was comparable to plots where trees were cleared for other types of activity.

Scientists hope their findings will inspire politicians and policy makers in the Amazon to strengthen environmental regulations for gold mining.

“It’s important the current environmental policies are enforced. Most Amazonian countries have reasonable monitoring and enforcement policies but weakening of such policies or reduced funding to regulatory agencies as we’ve seen in Brazil and Venezuela, means that enforcement isn’t occurring,” Kalamandeen said.

“Addressing corruption in mining agencies is also another issue that needs addressing at the national scale,” Kalamandeen said. “For restoration, many Amazonian countries don’t have a forest restoration policy when it comes to gold mining and this needs to be tested and developed for tropical forests at the landscape-scale.”

Gold prices often rise in the wake of economic crises, and when they do, small-scale gold mining activity ramps up in the Amazon.

Though under new leadership, Brazil has recently been weakening environmental regulations. But in the years that followed the financial crisis, strong rainforest protections forced miners to pursue gold in neighboring countries, especially the dense forests of Guyana and the French Guiana.

With the COVID-19 pandemic putting a significant dent in global economic growth, researchers worry gold mining activity will once again proliferate across a large stretch of forest known as the Guiana Shield. In the future, scientists hope to test new technologies designed to curb the threat of gold mining.

“We hope to use remote sensing to help detect gold mining especially illegal mining within the Amazon,” Kalamandeen said.



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Ancient Japanese birds looked a lot like New Zealand’s monster penguins

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June 29 (UPI) — New analysis suggests New Zealand’s giant penguins and a much younger group of Northern Hemisphere birds, the plotopterids, were physically quite similar.

The research, published Monday in the Journal of Zoological Systematics and Evolutionary Research, could help scientists figure out how birds evolved wings better suited for swimming than flying.

Fossil remains suggest as many as nine different species once swam the tropical seas that washed over most of what’s now New Zealand, some 62 million years ago. While some species were the size of modern penguins, others grew to heights of more than five feet.

Plotopterids don’t appear in the Northern Hemisphere fossil record until 30 million years later. Their remains have been recovered from several sites in Japan and North America. Like penguins, plotopterids used flipper-like wings to navigate coastal seas. But while the relatives of New Zealand’s ancient penguins can still be found today, plotopterids went extinct around 25 million years ago.

For the new study, scientists compared the fossilized remains of plotopterids recovered from Japan with the fossils of three giant penguin species. In addition to boasting similar wings, the analysis showed both groups of birds possessed long beaks with slit-like nostrils, as well as chest and shoulder bones conducive to swimming. Like the giant penguins, some plotopterid species were oversized, growing to heights of more than six feet.

Despite their physical similarities, plotopterids and penguins aren’t particularly close relatives. Plotopterids are more closely related to other seaworthy birds like boobies, gannets and cormorants.

“What’s remarkable about all this is that plotopterids and ancient penguins evolved these shared features independently,” study co-author Vanesa De Pietri, curator at the Canterbury Museum in New Zealand, said in a news release. “This is an example of what we call convergent evolution, when distantly related organisms develop similar morphological traits under similar environmental conditions.”

Though plotopterids and giant penguins were separated by several thousand miles and nearly 30 million years, had they lived side-by-side, they would have been hard to distinguish.

“Plotopterids looked like penguins, they swam like penguins, they probably ate like penguins — but they weren’t penguins,” said Paul Scofield, study co-author and Canterbury curator.

The newly published comparison of the two ancient bird groups has helped scientists begin to develop an explanation for why some birds developed wings for swimming.

“Wing-propelled diving is quite rare among birds; most swimming birds use their feet,” said study co-author Gerald Mayr, scientist at the Senckenberg Research Institute and Natural History Museum in Germany.

“We think both penguins and plotodopterids had flying ancestors that would plunge from the air into the water in search of food,” Mayr said. “Over time these ancestor species got better at swimming and worse at flying.”



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