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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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NASA’s OSIRIS-REx touches down on asteroid Bennu to nab sample

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Oct. 20 (UPI) — NASA’s OSIRIS-REx touched down on asteroid Bennu on Tuesday evening in a mission to scoop a sample of rocks and dirt.

The spacecraft — the Origins, Spectral Interpretation, Resource Identification, Security, Regolith Explorer — made soft contact with the asteroid at 6:12 p.m. EDT.

The historic “touch and go” event featured animation displaying OSIRIS-REx’s sample collection activities in real time. It takes time for real images of the touchdown to travel back to the Earth, so they won’t be released to the public until Wednesday.

The craft executed a series of maneuvers over the course of several hours before making soft contact with the surface of the asteroid to collect regolith, or rocks and dirt.

“It will be four and a half hours of anxiousness,” Beth Buck, OSIRIS-REx mission operations manager at Lockheed Martin Space, said in a news conference ahead of the event.

Buck made a comparison to the descent of a spacecraft on Mars, when there is typically “seven minutes of terror.”

The goal is to learn more about the solar system’s history and help “planetary defense” engineers with missions to protect earth from rogue asteroids. Bennu is believed to be a window into the solar system’s past since it’s a pristine, carbon-rich body carrying building blocks of both planets and life.

At around 1:50 p.m. EDT, the spacecraft left orbit around the asteroid before executing a series of burns to position itself over a sampling area nicknamed Nightingale.

Once in position, the craft began its approach to the asteroid at 5:50 p.m. EDT. It then spent about 15 seconds attempting to collect the regolith sample before backing away again.

The area, which is 52 feet in diameter, will make for a more demanding landing than expected, Kenneth Getzandanner, OSIRIS-REx flight dynamics manager at the NASA Goddard Space Flight Center in Maryland, said in the news conference.

The original mission called for a landing “zone” about 150% larger than Nightingale, at 82 feet, but that changed because Bennu was more rocky than expected.

The goal was to collect at least 1.7 ounces of fine-grained material, but the spacecraft can carry up to 4.4 pounds, Heather Enos, OSIRIS-REx deputy principal investigator at the University of Arizona said.

“I would love for that capsule to be completely full,” Enos said.

Though early images from the asteroid should hint at whether the mission succeeded, it will take engineers roughly 10 days to compare and analyze the mass before and after the maneuver to actually know how much dirt is inside the OSIRIS-REx.

If it failed, the spacecraft has enough fuel to attempt two more touch downs to collect material.

The spacecraft is expected to return to Earth, with the regolith sample from Bennu, in 2023.



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SpaceX scrubs Starlink launch until Thursday, if weather cooperates

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Oct. 21 (UPI) — Just three days after sending 60 more Starlink satellites into orbit, SpaceX is aiming to launch another batch of broadband satellites into space from Florida.

If the weather cooperates, Thursday’s launch will be SpaceX’s 15th Starlink mission.

Liftoff had been scheduled for 12:29 p.m. EDT Wednesday aboard a Falcon 9 rocket at Launch Complex 40 at Cape Canaveral Air Force Station, but controllers scrubbed the launch due to weather and rescheduled for 12:14 p.m. on Thursday.

With a launch Sunday, SpaceX increased the size of their Starlink constellation to nearly 800 satellites. The 15th mission will see another 60-odd satellites join the network.

“The goal of Starlink is to create a network that will help provide Internet services to those who are not yet connected, and to provide reliable and affordable Internet across the globe,” according to the Kennedy Space Center.

Weather for Wednesday’s planned launch had looked so-so and the Space Force’s 45th Weather Squadron predicted a 60 percent chance of favorable conditions.

“A mid-level inverted trough and associated easterly wave currently across the Bahamas will meander into the state over the next few days, bringing enhanced moisture, cloud cover, and instability with a higher coverage of showers and storms,” Space Force forecasters wrote.

They said Thursday’s forecast looks quite similar to Wednesday’s.

Earlier this month, SpaceX founder and CEO Elon Musk tweeted that Starlink’s constellation was big enough to begin beta-testing the Internet service system in both the United States and southern Canada.

SpaceX has already offered Starlink Internet services to emergency responders in wildfire-stricken areas of Washington State.

Washington’s Hoh tribe is also using the Internet service to provide their members online education and telehealth services.



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Chernobyl-level radiation harms bumblebee reproduction

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Oct. 21 (UPI) — Bees are more sensitive to radiation than scientists thought. Scientists found the reproduction rates of bumblebees declined significantly when exposed to Chernobyl-level radiation.

The research, published Wednesday in the journal Proceedings of the Royal Society B: Biological Sciences, suggests radiation in Ukraine’s Chernobyl Exclusion Zone could impair pollination services, triggering wider ecological consequences than previously estimated.

Humans are not allowed to live in the Chernobyl Exclusion Zone, the disaster area more directly impacted by the 1986 nuclear accident, the worst in history. However, the destroyed nuclear reactors are surrounded by forests that are populated by robust populations of birds, bears, bison, lynx, moose, wolves and more.

Efforts to gauge the effects of radiation contamination on insects have yielded mixed results in the past. While some studies have suggested insects are relatively radiation-resistant, others have demonstrated significant impairment.

When researchers exposed bumblebees in the lab to radiation dose of 100 µGyh-1, an amount approximating exposure inside the Chernobyl Exclusion Zone, reproduction rates among the bees dropped between 30 and 45 percent.

Researchers found a direct correlation between the size of the radiation dose and reproduction rate declines. Lower levels of radiation had a smaller effect, while larger doses yielded greater declines.

Scientists were surprised to find they were able to detect reproductive rate declines at very small levels of radiation exposure.

“Our research provides much needed understanding as to the effects of radiation in highly contaminated areas and this is the first research to underpin the international recommendation for the effects of radiation on bees,” lead study author Katherine Raines, environmental scientist at the University of Stirling in Scotland, said in a news release.



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