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Alaska’s salmon are getting smaller

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Aug. 19 (UPI) — New research suggests Alaska’s salmon are spending fewer years in the ocean and returning early to spawn.

As a result, Alaska’s salmon are smaller than they were 30 years ago, according to an analysis published Wednesday in the journal Nature Communications.

In addition to feeding local communities and putting money in the pockets of commercial fishers, salmon help bring ocean nutrients inland and fertilize terrestrial ecosystems. Smaller salmon leave ecosystems starved for nutrients and local communities with less to eat.

To find out why Alaska’s salmon are shrinking, researchers analyzed the measurements of 12.5 million fish collected between 1957 and 2018 by the Alaska Department of Fish and Game.

The analysis showed salmon aren’t spending as much time cruising the open waters of the Pacific.

“There are two ways they could be getting smaller — they could be growing less and be the same age but smaller, or they could be younger,” corresponding author Eric Palkovacs said in a news release.

“We saw a strong and consistent pattern that the salmon are returning to the rivers younger than they did historically,” said Palkovacs, a professor of ecology and evolutionary biology at the University of California, Santa Cruz.

The research revealed a range of possible factors responsible for driving the shift in salmon size.

“There’s not a single smoking gun,” said first author Krista Oke, a postdoctoral scientist initially at University of Alaska Fairbanks. “Small contributions from a lot of factors are adding up to drive these changes.”

The data suggests climate change and increased competition among wild and hatchery salmon in the ocean are two of the main contributing factors.

Surprisingly, the influence of commercial fishing on salmon size has been varied and mostly minimal, according to the new analysis. Likewise, rebounding salmon predator populations have had a negligible effect.

“We know that climate drives changes in ocean productivity, and we see a consistent signal of climate factors associated with decreasing salmon size,” Palkovacs said. “Another consistent association is with the abundance of salmon in the ocean, especially pink salmon. Their abundance in the North Pacific is at historic highs due in part to hatchery production in Alaska and Asia, and they compete with other salmon for food.”

Palkovacs and his research partners suggest the ocean is becoming an increasingly risky place for bigger, older salmon. Scientists hope followup studies well help them understand exactly why that is.

“That’s the next hard step I hope we can get to soon,” Oke said. “It could be that they’re having to spend more time feeding, which is putting them in risky places. Lots of things could be happening to increase the overall risk of mortality in the ocean, but we weren’t able to pin that down.”

Smaller salmon are obviously bad for commercial fishers. Smaller salmon fetch lower prices, as they often can’t be converted into high-value products. But humans aren’t the only organisms dependent on salmon for their wellbeing.

Bears, insects, birds, trees and juvenile salmon themselves all count on the nutrients provided by salmon returning to spawn.

“Salmon go up into these small streams, and whether they are caught by predators or die after spawning, their nutrients are transferred into the forests and freshwater ecosystems,” Palkovacs said. “It’s a classic salmon ecosystem service, and the amount of nutrients they deliver depends on their body size.”



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Different type of photosynthesis may save temperate crops from climate change

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Oct. 23 (UPI) — In many places, climate change is expected to bring hotter, drier weather. In a new study, published Friday in the journal The Plant Cell, scientists considered whether an alternative mode of photosynthesis, might yield more heat-tolerant and drought-resistant plants.

Most plants in arid and semi-arid environs use a photosynthesis method called Crassulacean acid metabolism, or CAM. Alternatively, plants in temperate environs, including crops, rely on a photosynthesis method called C3 carbon fixation.

Plants using C3 carbon fixation absorb CO2 through their leaves’ stomatal pores. The daytime process allows C3 plants to immediately convert sunlight into food. When conditions are especially hot and dry, C3 metabolism causes plants to lose too much water.

Conversely, CAM plants absorb CO2 through their stomatal pores at the night. The carbon gets stored in cells until daytime, when it is converted into food via photosynthesis. This alternative carbon fixation technique allows CAM plants to close their stomatal pores during the day to prevent excess water loss.

For the new study, researchers developed sophisticated biological models to determine whether C3 plants genetically engineered to perform CAM photosynthesis would fare better as hotter, drier weather becomes the norm.

Researchers tested their genetic engineering simulations across a variety of temperature and relative humidity conditions. The data showed that the benefits provided by a switch to CAM metabolism are influenced by the vacuolar storage capacity of a plant’s leaves, which is dictated by climate conditions.

“Moreover, our model identified an alternative CAM cycle involving mitochondrial isocitrate dehydrogenase as a potential contributor to initial carbon fixation at night,” researchers wrote in their paper. “Simulations across a range of environmental conditions show that the water-saving potential of CAM strongly depends on the daytime weather conditions.”

In other words, engineering CAM metabolism in temperature plants isn’t a cure-all. Still, authors of the new study suggest their findings will help plant scientists developed new strategies for engineering greater resiliency among C3 crops.

“Modelling is a powerful tool for exploring complex systems and it provides insights that can guide lab and field-based work,” lead study author Nadine Töpfer said in a news release.

“I believe that our results will provide encouragement and ideas for the researchers who aim to transfer the water-conserving trait of CAM plants into other species,” said Töpfer, a postdoctoral researcher at the Leibniz Institute of Plant Genetics and Crop Plant Research in Germany.



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The arrival of seabirds transformed the Falkland Islands 5,000 years ago

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Oct. 23 (UPI) — Roughly 5,000 years ago, seabirds colonized the Falkland Islands in record numbers. New research — published Friday in the journal Science Advances — suggests the seabirds arrived around the same time that the South Atlantic cooled, and their arrival shifted the ecosystems on the Falkland Islands.

Today, the remote South Atlantic islands remain a refuge for several important seabird species, including great shearwaters, black-browed albatrosses, white-chinned petrels and five species of penguins.

For a few thousand years, these burrowing and ground nesting seabirds had the islands mostly to themselves, but over the last few centuries, the birds have lost ground to sheep grazing and erosion.

In addition, sea and air temperatures in the South Atlantic have been steadily rising as a result of climate change.

To better understand how Falkland Island seabirds might cope in a warmer climate, scientists set out to study the history of climate change and ecological changes on the Falkland Islands.

By sampling peat core layers, researchers were able to reconstruct a 14,000-year record of climate and ecological shifts on the island. The data confirmed that seabirds began migrating to the islands in large numbers around the time the South Atlantic began to cool.

“Our 14,000-year record shows that seabirds established at Surf Bay during cooler climates,” lead study author Dulcinea Groff said in a news release.

“Seabird conservation efforts in the South Atlantic should be prepared for these species to move to new breeding grounds in a warmer world, and those locations may not be protected,” said Groff, who led the research while she was a doctoral student in ecology and environmental sciences at the University of Maine.

The peat layers also revealed a dramatic ecological transformation following the arrival of seabirds. Marine-derived nutrients from guano rejuvenated the island’s poor soil, allowing the establishment of tussock grasses, or bunch grasses. Ash in the peat layers showed the proliferation of grasslands across the islands led to an increase in seasonal wildfires.

Researchers suggest their work is a reminder of the important connections between disparate ecosystems, as well as an example of how quickly ecosystems can be transformed.

“Our study is unique because it documents a direct linkage across ocean and land ecosystems between top predators of the oceans — the seabirds — and island plant communities,” said Groff, now a postdoctoral researcher at the University of Wyoming. “The abrupt ecosystem shift happened within a matter of a few decades and suggests that as the climate continues to warm, it’s critical to think about where seabirds will go in the future and plan to protect those places.”

It’s not just rising temperatures that conservationists are worried about, she said.

Grasslands on the Falkland Islands have been degraded by a couple centuries of livestock grazing. The islands’ wildlife species depend on the health of the grasslands. And because the island’s tussock grass depend on bird droppings, a decline in the abundance of seabirds could have broad ecological repercussions.

“As the climate warms, seabirds may find and occupy more suitable environments elsewhere, and we should expect that the coastal grasslands will respond to the loss in nutrients from seabird guano,” said Groff.



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SpaceX launches cluster of Starlink satellites

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Oct. 24 (UPI) — SpaceX launched its Falcon 9 rocket into space Saturday morning, carrying 60 Internet satellites into orbit to help establish connections to remote areas.

The launch, which was originally scheduled for Wednesday, took off from Cape Canaveral Air Force Station. It went off without a hitch with the booster rocket safely landing on SpaceX’s drone ship in the Atlantic Ocean.

The upper stage of the Falcon 9 deployed the satellites into orbit 63 minutes after takeoff, allowing SpaceX to build on its previous successes.

SpaceX had put 180 Starlink satellites into space before Saturday’s launch. The launch was the mission’s 15th, but only the 14th with operational broadband satellites. The Starlink constellation currently boasts in excess of 800 mini satellites.

“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.

SpaceX was originally scheduled to launch Starlink-14 on Wednesday, but bad weather forced officials to scrub the launch. Liftoff was rescheduled for Thursday, but when a camera on the rocket’s upper stage failed, officials decided to nix the launch again.

SpaceX fans and media members have taken to referring to October as “Scrubtober” on social media, as SpaceX has been continually frustrated by poor weather and launch delays.

Despite the delays, SpaceX is inching closer to being able to offer everyday Internet users the chance to surf the web using Starlink.

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

Earlier this week, SpaceX announced that it would offer Starlink’s broadband services free of charge to families in Texas’ Ector County Independent School District. More than a third of children and their families in the district are without Internet access.



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