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Scientists study Salish Sea’s endangered orcas amid quietest ocean in ‘3 or 4 decades’ – Globalnews.ca

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A significant drop in sea traffic brought on by the COVID-19 pandemic has created what scientists call a rare opportunity to study how quieter waters affect southern resident killer whales off the British Columbia coast.

Ocean Networks Canada, which has been monitoring noise from ships and sounds made by marine mammals such as orcas, said it believes the change will be a boon for the animals.

“The anticipation is that the quieter environment will help the killer whales in communicating, in socializing, in navigating and most importantly, in finding food,” said Richard Dewey, the organization’s associate director of science.

Read more:
‘Quieter ocean’ from COVID-19 could be a boon to endangered orcas, say researchers

A paper published last month in the Journal of the Acoustical Society of America said there has been about a 30 per cent decrease commercial shipping traffic into the Port of Vancouver from China due to COVID-19 in just the first four months of the year.

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Dewey said it’s not just commercial traffic that’s gone down — there’s also been a pause in whale watching boats, cruise ships, recreational vessels and tankers. That’s led to a noise reduction of
about 75 per cent, he said.

“What we are seeing in the Salish Sea is levels of shipping noise that haven’t been present for three or four decades,” he said.

“So we would have to go back to the 1980s before we would have heard such a quiet environment.”






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Quieter oceans a boon to whale researchers and orcas


Quieter oceans a boon to whale researchers and orcas

One of the major concerns for the endangered southern resident killer whales is that shipping noises have been increasing and almost doubling every decade, he said.

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These mammals have a hearing that is similar to that of humans, and they communicate in a frequency band similar to ours, Dewey said.

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They use vocalizations to communicate within the pod, to navigate and most importantly to find their prey, he said.

“They echo-locate to find their salmon. It’s a very sophisticated sort of acoustic capability and the quieter the environment, they would have more success in finding prey.”

In the ocean, Dewey said whales use sound “continuously and all the time.”

READ MORE: Coronavirus: Less boat traffic is good news for Canada’s marine life

Their eyesight helps them see up to a distance of about five to 10 metres while using sounds helps them scope out kilometres, he said, adding that the Salish Sea is a “very murky environment.”

Scientists believe the loud noises caused by humans increase stress hormones in orcas because they have to shout and cannot communicate over large distances, Dewey said.

He compared it to someone going into a loud club and having to pause until noise passes, to speak more loudly or give up.

He noted that unlike people in a club, orcas can’t just leave for a quieter space.






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New restrictions on boating around orcas off B.C. coast


New restrictions on boating around orcas off B.C. coast

Scientists will be using 30 hydrophones to record sounds made by the killer whales when they come into the Salish Sea, which should be any time now, Dewey said.

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Hydrophones are underwater recording devices that record how loudly the whales talk when it’s noisy or if just give up.

The team is hoping this study will yield much-needed data to make policy and regulation changes to help the animals survive, he said.

“If we see them returning and staying in their critical habitat for longer periods … if we have evidence of successful feeding on the salmon, then those are all good signs and in some sense the quieter environments can only have helped their survival,” he said.

READ MORE: Coronavirus: Canadians report increased wildlife sightings amid COVID-19 pandemic

The director of the University of British Columbia’s marine mammal research unit said that in the past, killer whales would be seen in the Salish Sea in May and June, but for the past four years they have been coming in much later, sometimes as late as September.

Andrew Trites said one of the reasons could be that there is not enough salmon, although mathematically there is enough fish for the 72 remaining southern resident killer whales.

This has left scientists wondering whether the trouble is that the whales cannot hunt because of disruption from vessels, he said.

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“And there is an opportunity to see whether or not the behaviour of whales is different with fewer boats on the water and less noise.”

© 2020 The Canadian Press

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First direct evidence of ocean mixing across the Gulf Stream – Phys.org

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The “Triaxus” towing platform breaks through the choppy surface of the ocean during a storm. By towing such a platform with monitoring instruments through the water, changing its depth in a ‘yo-yo’ pattern as it traveled, scientists created high-resolution snapshots of how a dye released upstream evolved across the Gulf Stream front. Credit: Craig M. Lee, UW APL

New research provides the first direct evidence for the Gulf Stream blender effect, identifying a new mechanism of mixing water across the swift-moving current. The results have important implications for weather, climate and fisheries because ocean mixing plays a critical role in these processes. The Gulf Stream is one of the largest drivers of climate and biological productivity from Florida to Newfoundland and along the western coast of Europe.

The multi-institutional study led by a University of Maryland researcher revealed that churning along the edges of the Gulf Stream across areas as small as a kilometer could be a leading source of mixing between the waters on either side of the current. The study was published in the Proceedings of the National Academy of Sciences on July 6, 2020.

“This long-standing debate about whether the Gulf Stream acts as a blender or a barrier to ocean mixing has mainly considered big ocean eddies, tens of kilometers to a hundred kilometers across,” said Jacob Wenegrat, an assistant professor in UMD’s Department of Atmospheric and Oceanic Science and the lead author of the study. “What we’re adding to this debate is this new evidence that variability at the kilometer scale seems to be doing a lot of mixing. And those scales are really hard to monitor and model.”

As the Gulf Stream courses its way up the east coast of the U.S. and Canada, it brings warm salty from the tropics into the north Atlantic. But the current also creates an invisible wall of water that divides two distinct ocean regions: the colder, fresher waters along the northern edge of the Gulf Stream that swirl in a counterclockwise direction, and the warmer, saltier waters on the southern edge of the current that circulate in a clockwise direction.

First direct evidence of ocean mixing across the gulf stream
A research crew deployed a float from the R/V Knorr before releasing a fluorescent dye into the water. Scientists then tracked the drift of both dye and float through the Gulf Stream revealing significant mixing of waters across the swift current. Credit: Craig M. Lee, UW APL

How much ocean mixing occurs across the Gulf Stream has been a matter of scientific debate. As a result, ocean models that predict climate, weather and biological productivity have not fully accounted for the contribution of mixing between the two very different types of water on either side of the current.

To conduct the study, the researchers had to take their instruments to the source: the edge of the Gulf Stream. Two teams of scientists aboard two global-class research vessels braved winter storms on the Atlantic Ocean to release a along the northern front of the Gulf Stream and trace its path over the following days.

The first team released the dye along with a float containing an acoustic beacon. Downstream, the second team tracked the float and monitored the concentration of dye along with , salinity, chemistry and other features.

Back on shore, Wenegrat and his coauthors developed high-resolution simulations of the physical processes that could cause the dye to disperse through the water in the manner the field teams recorded. Their results showed that turbulence across areas as small as a kilometer exerted an important influence on the dye’s path and resulted in significant mixing of water properties such as salinity and temperature.

First direct evidence of ocean mixing across the gulf stream
Fluorescent dye provides a unique way to track the evolution and mixing of water across the Gulf Stream. In a recent study fluorescein dye (as pictured here) was released along the north wall of the Gulf Stream, and tracked by ship as it mixed horizontally across the current. Credit: Lance Wills, WHOI

“These results emphasize the role of variability at very small scales that are currently hard to observe using standard methods, such as satellite observations,” Wenegrat said. “Variability at this scale is not currently resolved in global climate models and won’t be for decades to come, so it leads us to wonder, what have we been missing?”

By showing that small-scale mixing across the Gulf Stream may have a significant impact, the new study reveals an important, under-recognized contributor to ocean circulation, biology and potentially climate.

For example, the Gulf Stream plays an important role in what’s known as the ocean biological pump—a system that traps excess carbon dioxide, buffering the planet from global warming. In the surface waters of the Gulf Stream region, ocean mixing influences the growth of phytoplankton—the base of the ocean food web. These phytoplankton absorb carbon dioxide near the surface and later sink to the bottom, taking carbon with them and trapping it in the deep ocean. Current models of the ocean biological pump don’t account for the large effect small-scale mixing across the Gulf Stream could have on phytoplankton growth.

“To make progress on this we need to find ways to quantify these processes on a finer scale using theory, state-of-the-art numerical models and new observational techniques,” Wenegrat said. “We need to be able to understand their impact on large-scale circulation and biogeochemistry of the ocean.”

The research paper, “Enhanced mixing across the gyre boundary at the Gulf Stream front,” Jacob O. Wenegrat, Leif N. Thomas, Miles A. Sundermeyer, John R. Taylor, Eric A. D’Asaro, Jody M. Klymak, R. Kipp Shearman, and Craig M. Lee, was published in the July 6, 2020 issue of the Proceedings of the National Academy of Sciences.


Explore further

New opportunities for ocean and climate modelling


More information:
Jacob O. Wenegrat el al., “Enhanced mixing across the gyre boundary at the Gulf Stream front,” PNAS (2020). www.pnas.org/cgi/doi/10.1073/pnas.2005558117

Citation:
First direct evidence of ocean mixing across the Gulf Stream (2020, July 6)
retrieved 6 July 2020
from https://phys.org/news/2020-07-evidence-ocean-gulf-stream.html

This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no
part may be reproduced without the written permission. The content is provided for information purposes only.

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Strange pink snow in the Italian Alps might be a red flag – CNET

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Pink Snow as seen in the Presena glacier.


Miguel Medina/Getty Images

Pink snow, also called “watermelon snow,” has appeared at the Presena glacier in northern Italy, according to researcher Biagio Di Mauro of the Institute of Polar Sciences at Italy’s National Research Council. While it’s not uncommon for the Italian alps to be “pretty in pink” in spring and summer, scientists become cautious when the phenomenon, which is caused by algae, starts happening more frequently. 

Di Mauro told CNN that 2020’s lack of snowfall and higher temperatures have nurtured the algae’s growth. More algae could lead to ice melting faster.

When Di Mauro tweeted clarification for an article from The Guardian, he said the algae was probably Chlamydomonas nivalis, a snow algae. He also said the algae’s relationship with climate change hasn’t been proven yet. 

Di Mauro tweeted photos of the pink snow on Monday.

Across the ocean, in late May, Antarctica reported green snow, caused by microscopic algae. Though microscopic, the green blooms could be spotted by satellites. The color might also have connections with the impact of warming climates, researchers said.


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Canadarm3 will help pave way for Canadian boots on moon, and maybe Mars, Space Agency says – National Post

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When humankind makes its long-awaited return to our nearest celestial neighbour, Canada will lend a hand. Literally.

The Canadian Space Agency has recently announced that our nation and the Brampton, Ontario-based company MacDonald, Dettwiler and Associates, will design and build Canadarm3, a new robotic arm for use aboard the U.S.-led Lunar Gateway. In 1999 the company purchased Spar Aerospace, which developed the first two arms, also known as remote manipulator systems or RMS.

“We will be the masters of robotics on Gateway,” says Gilles Leclerc, whose enthusiasm for the project is matched only by his out-of-this-world job title of Director General, Space Exploration, Canadian Space Agency.

The Lunar Gateway, slated to begin construction in 2023, is a small space station that will remain in lunar orbit, providing a rendezvous location for ships travelling from the Earth to the moon, as well as landers on their way to the lunar surface. It could also be used as a staging area for future crewed flights to Mars.

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