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Without otters, Alaskan reefs more vulnerable to climate change, urchins

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Sept. 10 (UPI) — Keystone predators provide ecological equilibrium, a kind of stability that allows ecosystems withstand sudden changes. Without them, the effects of climate change are more severe.

That’s the case off the coast of Alaska’s Aleutian Islands, where coral reefs and kelp forests have been left vulnerable to climate change and sea urchin predation in the absence of the Aleutian sea otter, according to a study published Thursday in the journal Science.

Since the 1990s, the Aleutian sea otter has been “functionally extinct,” researchers said.

“A ‘functional extinction’ indicates that, although the sea otter has not gone extinct as a species, its abundance is so low that it no longer has a meaningful ecological impact in the ecosystem,” Douglas Rasher, senior research scientist at Bigelow Laboratory for Ocean Sciences, told UPI in an email.

Without sea otters around, local sea urchin populations have exploded. Having thinned the region’s once-dense kelp forests, these voracious herbivores have begun gnawing their way through the coralline algae that forms the reef on which kelp grows.

Uranium-thorium dating suggests that some of the reefs, formed by the red alga Clathromorphum nereostratum, are more than 800 years old.

To better understand the resiliency of these unique reefs, researchers examined the layers of calcified skeleton formed by the algae. Each year, the algae builds new layers, cementing a record of their growth.

By examining the thickness of the different algal layers, researchers were able to identify previous sea urchin grazing events.

The layers showed earlier grazing events corresponded with the decline of otters during the height of the fur trade, but that the region’s coralline algae was able to withstand previous surges in local sea urchin populations.

Today, the coral-like reefs aren’t fairing so well.

To figure out why sea urchins are proving more deadly than they were more than a century ago, researchers paired algae and sea urchins in tanks of seawater back in the lab. Some tanks featured cooler, less acidic conditions, comparable to preindustrial seawater, while other tanks featured temperature and acidity levels comparable to modern ocean conditions.

The experiments proved warmer, more acidic ocean conditions, caused by anthropogenic climate change, have made Clathromorphum nereostratum algae more vulnerable to lethal sea urchin grazing.

“Although sea urchins likely abounded in the Aleutian Islands during and after the fur trade, our experiments indicate that the alga’s skeleton was stronger, and rates of sea urchin grazing were much lower, during those past centuries,” Rasher said.

The findings serve as a reminder that climate change doesn’t alter ecosystems in isolation.

“Our study shows that species interactions and climate change interact in complex ways, highlighting that we must study the processes of predator loss and climate change together,” Rasher said.

Sea urchins have proliferated in a variety of ecosystems beyond Alaska’s reefs. From the coast of Kenya to the Caribbean islands to the Gulf of Maine, the loss of large fish and other marine predators have led to the explosion of local sea urchin populations, decimating kelp forests and algal reefs.

Reefs and kelp forests often serve as an anchor for diverse marine ecosystems, providing both food and shelter to variety of species. When they become overgrazed, biodiversity declines.

“New consumers are also showing up in many marine ecosystems,” Rasher said. “Tropicalization of kelp forests of western Australia has caused the arrival of new herbivorous fishes, who are now preventing the recovery of kelp forests after marine heat waves occur. Moreover, new carnivores are shifting poleward in the Gulf of Maine where red hake and black sea bass have arrived for the first time in recorded history.”



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Male lions form coalitions to protect territory, increase mating opportunities

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Oct. 16 (UPI) — Male animals must compete with one another for food, territory and mates. Despite this, male lions prefer to work with one or more partners.

To better understand the how’s and why’s of coalition-building among lions, biologists from the Wildlife Institute of India and the University of Minnesota turned to the Asian lion, a single lion population confined to the forests of India’s Gir National Park.

In a previous study, researchers were able to show that lion pairs had greater access to mating opportunities and were better able protect their territories than solitary lions.

“However, a lack of genetic data from the population at this stage had prevented us from determining if such cooperation extended to relatives only, or whether non-kin were included as well,” Stotra Chakrabarti, a postdoctoral research associate at the University of Minnesota, said in a news release.

For the latest study, published Friday in the journal Scientific Reports, researchers combined behavioral and genetic records of known mothers, offspring and siblings to better estimate the level of relatedness between cooperating lions.

The lions of Gita don’t just form pairs. Some lions form coalitions of three or four males. Researchers found lion trios and quartets were consistently composed of brothers and cousins. Their analysis also showed more than 70 percent of pairs were formed by unrelated lions.

“Forgoing mating opportunities is generally a severe evolutionary cost, unless in doing so you help related individuals,” said study co-author Joseph Bump, associate professor at the University of Minnesota. “As a consequence, this evidence supports a conclusion that large male lion coalitions are feasible only when all partners are brothers and/or cousins.”

Researchers found larger coalitions fared best, but the fitness of individual lions, the number of possibly sired offspring, was greater among pairs.

“The results of our study show that male coalitions prosper better than loners in established lion societies and this can have crucial implications for their conservation, especially when establishing new populations through reintroductions,” said YV Jhala, principal investigator of the Gir lion project and the dean of the Wildlife Institute of India.

The integration of field observations and genetic data allowed scientists to identify new forms of coalition building, including one team of lions feature a father and sun duo.

Because siblings rarely reach maturity, researchers found larger coalitions are uncommon among Gir lions, making up just 12 to 13 percent of male teams.

Scientists also determined that among pairs, related lions weren’t more likely to support one another during fights than unrelated lions.

“This shows that kin support is not the only reason why males cooperate with each other, but kin support makes the cooperation even more beneficial,” Bump said.

Overall, the findings suggest cooperation among lions is quite complex — a topic ripe for further investigation.

“We have quantified the ultimate reasons why unrelated males team up, but it would be worthwhile to investigate other aspects of male cooperation, including how their bonds are forged in the first place, how they find compatible partners, what breaks the ice between them when they first meet and how they decide who will lead and who will follow,” lead study author Chakrabarti said.



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Ancient societies collapsed when leaders ignored the social contract

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Oct. 16 (UPI) — When ancient societies formerly ruled by principles of good governance failed, they failed hard.

According to a new study published in the journal Frontiers in Political Science, ancient autocracies were less likely to last, but suffered less dramatic failures.

To better understand the role of government on the success and longevity of ancient societies, researchers took an in-depth look at principles that guided the governments of four societies: the Roman Empire, China’s Ming Dynasty, India’s Mughal Empire and the Venetian Republic.

Because free and fair elections were rare or nonexistent during ancient times, researchers had to come up with an alternative for gauging good governance.

“You can’t really measure it by the role of elections, so important in contemporary democracies,” study co-author Gary Feinman, the MacArthur curator of anthropology at Chicago’s Field Museum, said in a news release. “You have to come up with some other yardsticks, and the core features of the good governance concept serve as a suitable measure of that.”

“They didn’t have elections, but they had other checks and balances on the concentration of personal power and wealth by a few individuals,” Feinman said. “They all had means to enhance social well-being, provision goods and services beyond just a narrow few, and means for commoners to express their voices.”

For the ruling elite, good governance was a sensible choice. Most successful empires depended on taxes and resources from local economies, and thus their leaders had to meet the basic needs of their citizens.

“There are often checks on both the power and the economic selfishness of leaders, so they can’t hoard all the wealth,” Feinman said.

Researchers found societies with governments that were reasonably responsive to their people — governments that met the definition of good governance — tended to last a bit longer than autocratic governments.

However, researchers found that when good governments turned rotten, the breakup was often uglier than the collapse of autocratic governments.

According to the study, good governments fail more dramatically because the bureaucracy is more intimately integrated with society at large.

“Social networks and institutions become highly connected, economically, socially, and politically,” Feinman said. “Whereas if an autocratic regime collapses, you might see a different leader or you might see a different capital, but it doesn’t permeate all the way down into people’s lives, as such rulers generally monopolize resources and fund their regimes in ways less dependent on local production or broad-based taxation.”

Researchers also looked at why exactly good governments fail. They found the collapse of good governments was often triggered by the rise to power of amoral leaders — leaders who ignored the social contract and abandoned their society’s ideals.

Such betrayals often precipitated or accompanied rising inequality, concentration of political power, tax evasion, crumbling infrastructure and the decline of bureaucratic institutions — a pattern researchers suggest can be observed in modern societies.

“What I see around me feels like what I’ve observed in studying the deep histories of other world regions, and now I’m living it in my own life,” said Feinman. “It’s sort of like Groundhog Day for archaeologists and historians.”

Researchers suggest their findings are a reminder that even previously successful governments and prosperous, stable societies can fail when leaders abandon a society’s core principles.

“In the cases we address, calamity could very likely have been avoided, yet, citizens and state-builders too willingly assumed that their leadership will feel an obligation to do as expected for the benefit of society,” said lead study author Richard Blanton.

“Given the failure to anticipate, the kinds of institutional guardrails required to minimize the consequences of moral failure were inadequate,” said Blanton, a professor emeritus of anthropology at Purdue University.



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Rain really does move mountains, study finds

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Oct. 16 (UPI) — Scientists have finally shown that precipitation and erosion rates influence the movement of mountains. Researchers detailed the breakthrough in a new paper, published Friday in the journal Science Advances.

The role that rain — and climate — plays in the evolution of mountain changes has been debated for decades. It seems intuitive that rain erodes mountains, altering a range’s topography, and even its tectonics, but the link has been difficult to prove.

“Previously, many papers have brought together large datasets and found relationships ranging from a strong correlation to no correlation between rainfall and erosion rate,” Byron Adams told UPI in an email.

“The problem with the studies that suggested there was a strong correlation was that they did not provide a physical mechanism for why rainfall would affect erosion,” said Adams, earth scientist and research fellow at the University of Bristol.

To establish a connection between climate patterns and erosion rates, researchers precisely dated and mapped quartz sand grains across the slopes of the central and eastern Himalaya in Bhutan and Nepal.

Researchers used a novel dating technique that relied on the precise measurement of a rare element, Berllyium-10, in quartz samples.

“Berllyium-10 is produced within quartz when cosmic radiation, mostly neutrons, from outer space travels through the atmosphere and strikes the nucleus of an Oxygen-16 or Silicon-28 atom in the mineral,” Adams said. “When this interaction occurs, the atom breaks apart, or spalls, and new elements are formed including Berllyium-10.”

Berllyium-10, or Be10, is a very rare form of Berllyium, so scientists can be confident that its presence in quartz is a measure of what’s called “cosmogenic spallation.”

“Because we know the flux of cosmic radiation and the production rate of 10Be in quartz, we can use this technique to keep track of time,” Adams said.

In other words, by counting Be10 atoms, scientists can measure how long quartz sands have been exposed to the heavens in any given place on mountain sides and in river valleys.

“To make our erosion rate measurements we need to extract very small amount of Berllyium-10 from river sands and measure it very precisely with mass spectrometers,” Adams told UPI.

For the study, researchers combined their precise erosion rate measurements with precipitation and elevation data, and then used sophisticated numerical models to make sense of it all.

The analysis allowed the research team to isolate the influence of rainfall on erosion rates. The breakthrough helped researchers improve the accuracy of simulations for mountain tectonics.

“We found that if we used our new understanding of how the rivers are responding to rainfall, we could more accurately constrain the geometry and velocity of the active faults in Bhutan,” Adams said.

While researchers were able to confirm the influence of precipitation on erosion and local tectonic activity in the Himalayas, Adams suggests there is more work to be done to understand the true scope of this phenomena.

“The question that remains is: Is this a big enough change to drive crustal flow?” he said.

Researchers are currently working to expand their analysis across the entirety of the Himalayas and to use their findings to update risk models for landslides, dam breaches and fault slips.



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