However, novel organisms moving into a new habitat could disturb the ecological balance which has been established over a long period. Plants and herbivores are characterised by long-term co-evolution, shaping both their geographic distribution and the characteristics that they display in their occupied sites.

At higher elevations, this is seen in insect herbivores being generally less abundant and plants in turn being less well defended against herbivores, as a result of lower energy and shorter growing seasons. In contrast, low-elevation plant species defend themselves against more abundant and diverse herbivores, whether by means of spikes, thorns or hair, or by toxic substances. Climate change could disturb this ecological organisation.

Grasshoppers translocated to high elevations

In an experiment, researchers from ETH Zurich, the Swiss Federal Institute for Forest, Snow and Landscape Research (WSL) and the University of Neuchâtel investigated what could happen if herbivores — in this case various grasshoppers from middle elevations — settled in alpine meadows at higher elevations and encountered new plant communities there. The study has just been published in the journal Science.

The researchers translocated various grasshopper species from medium altitudes (1,400 metres above sea level) to three alpine grassland sites at elevations of 1,800, 2,070 and 2,270 metres above sea level, where the ecologists placed the grasshoppers in cages. The local grasshoppers had previously been removed from the experimental areas. The experiment was carried out in the Anzeindaz region in the Vaud Alps, Switzerland.

In their study, the researchers measured things like how the biomass, structure and composition of the alpine plant communities changed under the influence of the herbivorous insects. The researchers also investigated whether some plant species were more susceptible to herbivory, for instance plants with tougher leaves, or those containing more silica or other constituents such as phenols or tannins.

Lowland grasshoppers influence alpine community

The ecologists discovered that the grasshoppers’ feeding behaviour had a clear influence on the vegetation structure and composition of the alpine flora. Alpine communities display clear structure in the organisation of the canopy, with plants with tough leaves at the top, and more shade-tolerant plants with softer leaves at the bottom. But this natural organisation was disturbed, because the translocated grasshoppers preferred to feed on taller and tough alpine plants, which exhibited functional characteristics such as leaf structure, nutrient content, chemical defence, or growth form similar to those of their previous, lower-elevation food plants. As a result, the insects reduced the biomass of dominant tough alpine plants, which in turn favoured the growth of small-stature plant species that herbivores avoid. The overall plant diversity thus increased in the short term.

“Immigrant herbivores consume specific plants in their new location and this changes and reorganises the competitive interaction between those alpine plant species,” says the study’s first author, Patrice Descombes. Global warming, for example, could disrupt the ecological balance because mobile animals, including many herbivorous insects, can expand their habitat to higher elevations more rapidly than sedentary plants. Herbivorous insects from lower altitudes could therefore have an easy time in alpine habitats with resident plants that are insufficiently or not at all prepared to defend themselves against those new herbivores. This could change the current structure and functioning of alpine plant communities as a whole. Climate change would thus have an indirect impact on ecosystems, in addition to the direct consequences of rising temperatures.

Important drivers of changed ecosystems

For Loïc Pellisier, Professor of Landscape Ecology at ETH Zurich and WSL, this indirect effect of climate change on ecosystems is one of the most important things to emerge from the study: “Climate impact research has largely investigated the direct effects of temperature on ecosystems, but these novel interactions that arise between species moving into new habitats could generate important structural modifications. They are important drivers of changed ecosystems in an increasingly warm climate.”

With their results, the researchers also want to improve models that have so far only inadequately integrated such processes. They also hope that this will improve the prognosis of how climate change will influence the functioning of ecosystems and the services they provide.

Story Source:

Materials provided by ETH Zurich. Original written by Peter Rüegg. Note: Content may be edited for style and length.

And researchers are discovering why. The SARS-CoV-2 virus, like many viruses before it, is bad news for the brain. In a study published Dec.16 in Nature Neuroscience, researchers found that the spike protein, often depicted as the red arms of the virus, can cross the blood-brain barrier in mice.

This strongly suggests that SARS-CoV-2, the cause of COVID-19, can enter the brain.

The spike protein, often called the S1 protein, dictates which cells the virus can enter. Usually, the virus does the same thing as its binding protein, said lead author William A. Banks, a professor of medicine at the University of Washington School of Medicine and a Puget Sound Veterans Affairs Healthcare System physician and researcher. Banks said binding proteins like S1 usually by themselves cause damage as they detach from the virus and cause inflammation.

“The S1 protein likely causes the brain to release cytokines and inflammatory products,” he said.

In science circles, the intense inflammation caused by the COVID-19 infection is called a cytokine storm. The immune system, upon seeing the virus and its proteins, overreacts in its attempt to kill the invading virus. The infected person is left with brain fog, fatigue and other cognitive issues.

Banks and his team saw this reaction with the HIV virus and wanted to see if the same was happening with SARS CoV-2.

Banks said the S1 protein in SARS-CoV2 and the gp 120 protein in HIV-1 function similarly. They are glycoproteins — proteins that have a lot of sugars on them, hallmarks of proteins that bind to other receptors. Both these proteins function as the arms and hand for their viruses by grabbing onto other receptors. Both cross the blood-brain barrier and S1, like gp120, is likely toxic to brain tissues.

“It was like déjà vu,” said Banks, who has done extensive work on HIV-1, gp120, and the blood-brain barrier.

The Banks’ lab studies the blood-brain barrier in Alzheimer’s, obesity, diabetes, and HIV. But they put their work on hold and all 15 people in the lab started their experiments on the S1 protein in April. They enlisted long-time collaborator Jacob Raber, a professor in the departments of Behavioral Neuroscience, Neurology, and Radiation Medicine, and his teams at Oregon Health & Science University.

The study could explain many of the complications from COVID-19.

“We know that when you have the COVID infection you have trouble breathing and that’s because there’s infection in your lung, but an additional explanation is that the virus enters the respiratory centers of the brain and causes problems there as well,” said Banks.

Raber said in their experiments transport of S1 was faster in the olfactory bulb and kidney of males than females. This observation might relate to the increased susceptibility of men to more severe COVID-19 outcomes.

As for people taking the virus lightly, Banks has a message:

“You do not want to mess with this virus,” he said. “Many of the effects that the COVID virus has could be accentuated or perpetuated or even caused by virus getting in the brain and those effects could last for a very long time.”

This study was partially supported by a National Institute on Aging-funded COVID-19 supplement to a shared RF1 grant of Banks and Raber.?

“You don’t get big fish,” said UC Santa Barbara biogeochemist Morgan Raven. “You don’t even get charismatic zooplankton.” But although anoxic oceans may seem alien to organisms like ourselves that breathe oxygen, they’re full of life, she said.

These strange ecosystems are expanding, thanks to climate change — a development that is of concern for fisheries and anyone who relies on oxygen-rich oceans. But what piques Raven’s interest is the changing chemistry of the oceans — the Earth’s largest carbon sink — and how it could move carbon from the atmosphere to long-term reservoirs like rocks.

“What happens to our carbon cycle as we get these large areas of the ocean that are oxygen-free?” she said. This question was central to research conducted by Raven and colleagues Rick Keil (University of Washington) and Samuel Webb (Stanford Linear Accelerator Laboratory) in a paper published in the journal Science.

‘A spinning wheel’

In oxygen-rich oceans, carbon is moved around largely by food web processes that begin with carbon dioxide-fixing phytoplankton that photosynthesize at the water’s surface.

“Most of the time they just get eaten by zooplankton,” Raven said. But if they aren’t eaten by larger animals, they head to the depths where they respire carbon dioxide and excrete organic carbon.

“It’s like a spinning wheel — CO₂ goes to plankton, goes to CO₂,” Raven said.

In the absence of zooplankton and fish, however, more of the sinking organic carbon can survive and be deposited at depth, she said. In fact, sediments under these anoxic zones generally have more organic carbon deposits than their oxygen-rich counterparts. But, according to the researchers, we lack a “full mechanistic understanding” of how this occurs.

“It’s been a bit of a mystery,” Raven said.

The team did have a clue in the form of a hypothesis formed about a decade ago by University of Southern Denmark geologist Don Canfield and colleagues.

“They put out this idea that maybe inside of these zones, microbes are still eating organic carbon, but respiring sulfate,” Raven said. Called “cryptic sulfur cycling,” the idea was somewhat difficult to accept largely because the products of this microbial sulfate reduction (MSR) were difficult to detect, and because other compounds in the area, such as nitrates, were more energetically favorable to metabolize.

However, according to the study, “there is emerging molecular and geochemical evidence that suggests MSR may occur in (oxygen-deficient zones) despite plentiful dissolved nitrate.”

The researchers tested whether this enigmatic process might be hiding inside of large (>1mm), fast-sinking organic particles by collecting particles from the Eastern Tropical North Pacific oxygen-deficient zone, roughly located off the northwestern coast of Mexico.

“It really is just this polymeric, sticky stuff,” Raven said of the aggregations of mostly dead phytoplankton, fecal matter, other small organisms and bits of sand and clay that get glued together in a “fluffy” matrix. Collection of these particles is itself an accomplishment for researchers combing the vast oceans for relatively small, diffuse particles.

“My colleagues from the University of Washington had this collection device that was really the thing that made it possible to do this,” she said. The collected particles were sent to the Stanford Synchotron Radiation Lightsource for analysis.

Pickled phytoplankton

Results of the analysis, such as evidence of the production of organic sulfur within the samples, demonstrate what Raven calls a “pickling” of the dead phytoplankton, as they sink through the anoxic area.

“Phytoplankton grow in the surface ocean, but due to gravity, they sink,” she said. As they fall through the anoxic region, these organic aggregates undergo sulfurization, which has the effect of shielding the carbon at their core from enzymes or other substances that would otherwise wear them away.

“Even when it gets to the sediment, bacteria there can’t eat these organic particles,” noted Raven. And just like the pickles we know and love, the preservation process makes the organic particle resistant to bacteria, she said, which could explain why more organic carbon is found in the sediments below anoxic ocean zones.

Sulfurization of organic carbon particles in anoxic ocean zones, while newly confirmed in modern-day oceans, is actually an ancient process, Raven explained.

“It’s the same process that can also make petroleum,” she said, pointing out that where oilbeds are found, so, too, is sulfur. This process may have been widespread during the Cretaceous period (145.5 to 65.5 million years ago), when the Earth was consistently tropical and the ocean was subject to geologic and mass extinction events that resulted in the burial of massive amounts of carbon, and anoxic waters throughout the Atlantic.

“What we didn’t know is whether this was also going on in these less extreme modern environments,” Raven said.

What remains to be seen is how these growing oxygen depleted zones will interact with climate change.

“Potentially as these zones expand, there could be a negative feedback — more CO₂ in the atmosphere makes higher temperatures, which makes these zones bigger,” Raven said. “These bigger zones then trap more CO₂ and put it in the sediment and rocks.” This feedback might help the Earth balance its carbon cycle over time, she said, “but we need to know how this connects to everything else.”