When ships pass, whales eat less, says study

NATURE’S BEAUTY: A Humpback whale swimming on the surface of the Pacific Ocean at the Uramba Bahia Malaga natural park in Colombia. (AFP)
Updated 11 August 2016
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When ships pass, whales eat less, says study

PARIS: Noise from ships impedes humpback whales from foraging for food, and could have long-term impacts on the health of these majestic creatures, according to a study released Wednesday.
Shipping lanes overlapping with the coastal migratory paths of whales create a steady source of underwater noise pollution.
Earlier research has shown how this can interfere with the behavior of so-called toothed whales, a category that included dolphins, as well as killer and sperm whales, that emit sonar-like pings to locate prey and communicate.
But very little was known about how the constant, low-frequency drone of ocean vessels might affect baleen whales, the other major category.
These include blue, humpback, right and bowhead whales.
To find out, a team of scientists led by Hannah Blair of Syracuse University in New York attached non-intrusive sensors to 10 humpbacks in the western North Atlantic.
The devices not only picked up and recorded all the sounds heard by the whales, but also tracked their underwater movement.
Humpbacks have a wide array of foraging techniques used to consume a large number of small prey, including one maneuver scientists call the “bottom side-roll.”
To feed on sand lance, bottom-dwelling eel-like fish, “the whale dives and scrapes along the ocean floor,” explained Blair.
A humpback can deep-dive for up to 30 minutes.
“At the same time, it rolls regularly onto its side and opens its mouth, scooping up the fish hidden in the sand,” especially at night, she told AFP.
Every barrel roll is like a meal.
The study found that half of the whales, all of them adult females, failed to execute these important side-rolls in the presence of ship noise on at least one of their deep dives.
Researchers can only speculate as to why.
The humpback may have perceived the ships as a threat. It is also possible, they said, that the prey reacted to the noise too, scattering or digging more deeply into the sand.
Humpbacks have been dealing with chronic noise from ships for decades, and have shown some capacity to adapt.
The new findings, however, “suggest that the whales are unable to completely adjust to this disturbance,” the study concluded.
The paper appears in Biology Letters, a journal published by Britain’s de-facto academy of sciences, the Royal Society.


NASA probe detects likely ‘marsquake’ — an interplanetary first

A life-size model of the spaceship Insight, NASA's first robotic lander dedicated to studying the deep interior of Mars, is shown at Jet Propulsion Laboratory (JPL) in Pasadena, California, U.S. November 26, 2018. (REUTERS)
Updated 24 April 2019
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NASA probe detects likely ‘marsquake’ — an interplanetary first

  • A more distant quake would yield greater information about Mars’ interior because seismic waves would “penetrate deeper into the planet before they come back up to the seismometer,” he said

CALIFORNIA: NASA’s robotic probe InSight has detected and measured what scientists believe to be a “marsquake,” marking the first time a likely seismological tremor has been recorded on another planet, the Jet Propulsion Laboratory in California reported on Tuesday.
The breakthrough came nearly five months after InSight, the first spacecraft designed specifically to study the deep interior of a distant world, touched down on the surface of Mars to begin its two-year seismological mission on the red planet.
The faint rumble characterized by JPL scientists as a likely marsquake, roughly equal to a 2.5 magnitude earthquake, was recorded on April 6 — the lander’s 128th Martian day, or sol.
It was detected by InSight’s French-built seismometer, an instrument sensitive enough to measure a seismic wave just one-half the radius of a hydrogen atom.
“We’ve been collecting background noise up until now, but this first event officially kicks off a new field: Martian seismology,” InSight principal investigator Bruce Banerdt said in a news release.
Scientists are still examining the data to conclusively determine the precise cause of the signal, but the trembling appeared to have originated from inside the planet, as opposed to being caused by forces above the surface, such as wind.
“The high frequency level and broad band is very similar to what we get from a rupture process. So we are very confident that this is a marsquake,” Philippe Lognonné, a geophysics and planetary science professor at University Paris Diderot in France and lead researcher for InSight’s seismometer, said in an email.
Still, a tremor so faint in Southern California would be virtually lost among the dozens of small seismic crackles that occur there every day.
“Our informed guesswork is that this a very small event that’s relatively close, maybe from 50 to 100 kilometers away” from the lander, Banerdt told Reuters by telephone.
A more distant quake would yield greater information about Mars’ interior because seismic waves would “penetrate deeper into the planet before they come back up to the seismometer,” he said.
 
The size and duration of the marsquake also fit the profile of some of the thousands of moonquakes detected on the lunar surface between 1969 and 1977 by seismometers installed there by NASA’s Apollo missions, said Lori Glaze, planetary science division director at NASA headquarters in Washington.
The lunar and Martian surfaces are extremely quiet compared with Earth, which experiences constant low-level seismic noise from oceans and weather as well as quakes that occur along subterranean fault lines created by shifting tectonic plates in the planet’s crust.
Mars and the moon lack tectonic plates. Their seismic activity is instead driven by a cooling and contracting process that causes stress to build up and become strong enough to rupture the crust.
Three other apparent seismic signals were picked up by InSight on March 14, April 10 and April 11 but were even smaller and more ambiguous in origin, leaving scientists less certain they were actual marsquakes.
Lognonné said he expected InSight to eventually detect quakes 50 to 100 times larger than the April 6 tremor.