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Sunday, April 5, 2020
Antarctic : beyond the dream
A video of our 2018 expedition to Antarctica on Sailing Vessel Spirit of Sydney, an aluminium 60-footer built in 1986 for Australian Ian Kiernan's BOC Challenge.
Filmed and edited by Captain Leo Tabourel and first mate Isaac Chambers, mixing Sound & Nature footages.
Saturday, April 4, 2020
Rare sea angel spotted off Russian Coast
Sea angels mating
credit : Alexander Semenov
From National Geographic by Heather Brady
Two mating sea angels flutter through the deep waters of the Arctic Ocean off the coast of Novaya Zemlya, an archipelago near northern Russia, in recently captured footage.
In the video, which was filmed by marine biologist Alexander Semenov, a single clearly visible sea angel is joined by a second one.
The pair of sea slugs then swims through the water side-by-side in a flowing mating ritual that resembles a dance.
When two sea angels find each other, they turn out their reproductive organs and attach themselves to their partner’s body with a sucker to stay together during the mating process.
This attachment leaves scars on their bodies, and some adult sea angels have up to four scars, which can indicate frequent mating rituals.
The fertilization process can last up to four hours, and while it happens, the sea angels stay connected to each other, swimming gracefully through the water with the help of all four of their wings.
Semenov says their mating ritual doesn’t affect their appetite, and sea angels can hunt for prey while they are attached to each other.
Once the mating ritual is complete, the sea angels move in a spiral shape in order to disconnect.
“This miniature creature is an incredibly graceful swimmer; watching it is a complete pleasure,” says Semenov. "They seem to float in the air, slowly waving their wings.”
Sea angels, so named because their shape resembles a snow angel, have translucent white bodies that are long, with a wing-like structure on both sides of their bodies.
Because they are semi-transparent, it is easy to see the coral-pink and yellow coloring of their internal structures.
Sea angels’ lovely outward appearance and name belie their status as a kind of sea slug, related to other forms of snails in the gastropod class.
They inhabit the frigid waters of the Arctic, subarctic Atlantic, and Pacific oceans, and prey on sea butterflies—specifically a small type of sea snail called Limacina helicina.
Some sea snails have even developed small tentacles with which they can catch their prey and hold it while they eat.
Scientifically named Clione limacina, they are protandrous hermaphrodites, which means they are both male and female during their life cycles, according to Semenov.
Young sea angels start out as males, developing eggs as they grow into adults.
Mature sea angels have both eggs and spermatozoa in their bodies.
Links :
- GeoGarage blog : Arctic biologist shares astonishing sea ...
Friday, April 3, 2020
The Ocean gets Big Data
A new array of cameras, vehicles, and sensors promises to change ocean science
Credit: bestdesigns/iStock/Getty Images Plus
Credit: bestdesigns/iStock/Getty Images Plus
From Nautilus Magazine by Claudia Geib
“Ithink that for some people,” says Peter Girguis, a deep-sea microbial physiologist at Harvard University, “the ocean seems passé — that the days of Jacques Cousteau are behind us.”
He begs to differ.
Even though space exploration, he says, “seems like the ultimate adventure, every time we do a deep sea dive and discover something new and exciting, there’s this huge flurry of activity and interest on social media.”
But the buzz soon fizzles out, perhaps because of ineffective media campaigns, he says.
But “we’re also not doing a good job of explaining how important and frankly exciting ocean exploration is.”
That might change with the launch, this month, of the Ocean Observatories Initiative, an unprecedented network of oceanographic instruments in seven sites around the world.
Each site features a suite of technologies at the surface, in the water column, and on the seafloor.
Buoys, underwater cameras, autonomous vehicles, and hundreds of sensors per site will collect data on ocean temperature, salinity, chlorophyll levels, volcanic activity, and much more.
Using this set of systems, oceanographers hope to address the limitations imposed by working on a ship or a single site for a limited period of time.
OCEAN EXPLORER: Peter Girguis thinks there is still much to be learned in the deep sea.
Photo: Rose Lincoln/Harvard News Office
“What that means is, in general, we’re very good at doing one of two things: studying the ocean spatially, such as studying the same process as you cross an ocean, or temporally, studying one point over time,” says Girguis, “But going back to about 20 years ago, scientists began to say, maybe there’s a way to do both of these better.”
Getting the Initiative off the ground (or, rather, in the water) has taken 10 years and $386 million, and the launch is only the beginning: Operational costs will comprise about a sixth of the National Science Foundation’s annual ocean sciences budget, and the ocean’s tendency to rust metals and fry wiring could lead to higher maintenance costs over time.
With data now flowing, the questions that have followed the Initiative’s development are once again bobbing to the surface: Will it work? Will it be useful? And will the millions of dollars that taxpayers have provided be worth their investment?
We sat down with Girguis to talk about the worth of the Ocean Observatories Initiative and its place in modern marine science.
Why haven’t there been many large-scale commitments to ocean science, like this initiative, in recent years?
When they landed a spacecraft on the moon, all they had to do to keep the astronauts at one atmosphere was design a spacecraft that could tolerate one atmosphere of pressure.
Outside of the ship it’s simply zero atmospheres — that’s a difference of one.
When we dive in the submersible Alvin, routinely, to go to our study sights, Alvin has to withstand 250–300 atmospheres.
And the ocean is a harsh environment.
Alvin has to battle corrosion, electrical shorts; we have to keep from getting stuck on deep sea corals; and around vents, we have to keep from having the plastic windows — which, yes, they are plastic — from melting in water coming out that’s 300 degrees Celsius.
The fact that this seems routine to us scientists is a tribute to the engineers that make it happen.
But the fact that the public thinks it is routine means we scientists should be doing a better job of explaining the adventure of it, and also the deep and profound importance that our ocean has in keeping our planet healthy.
Does having the Ocean Observatories Initiative arrays in only seven places limit what they can tell us about the ocean?
This project is by no means comprehensive.
I don’t think anybody would say we are comprehensively studying the ocean.
That does not mean that it is meaningless.
We have, as a community, tried to judiciously pick sites that could tell us something about the other areas of the ocean.
Think of them as good representatives of wider-spread environments.
Additionally, those arrays are, to a degree, moveable assets.
They are essentially giant moorings, which in some point in the future could be picked up and moved to another locale.
But these seven sites are chosen because they’re good representations of important regions of the ocean — not only for natural scientists but also for applied scientists, like those trying to understand fisheries and fish stocks, and how the ocean responds to humans.
SECRETS OF THE DEEP: A deep-sea Ocean Observatories Initiative camera trained on a sea floor chimney located 5,000 feet down off the coast of Oregon.
Photo: NSF-OOI/UW/CSSF; Dive R1730; V14
How can researchers use the Initiative’s data in their work?
One example: By co-localizing these sensors, researchers can help monitor when phytoplankton — which make, by the way, half the oxygen you breathe — bloom, and grow to huge numbers.
When they do that, it’s not always clear what causes it.
By having sensors and samplers co-located, you can start to make correlations that help you identify a cause.
And I chose that phrase carefully: Correlations are easy to come by, but it’s only when you have a really good data set that you can really move from a correlation to a cause.
How will the array aid in your research?
I work primarily in the deep sea, at the hydrothermal vents in the Northeastern Pacific off the coast of Oregon, Washington, and Vancouver.
By deep sea, I mean the part of the ocean that is perpetually dark, which is 80 percent of our planet’s habitable space.
What happens in the deep sea is very much influenced by what happens in the surface waters, because that’s where most of the food in the deep sea comes from.
Conversely, we now finally have the data to support some long-standing questions and ideas we had about how processes in the deep sea influence what happens on the surface.
Hydrothermal vents, for example, are a major ocean source of iron and trace minerals.
They’re kind of like the ocean’s multivitamin.
You don’t need a lot of this stuff, in the same way were not guzzling pounds of iron, but you need just enough to stay healthy.
And that’s what hydrothermal vents provide.
By studying the processes on the surface, and concurrently studying processes in the deep sea, we can start understanding the ocean as a system, and not as a bunch of compartmentalized ecosystems.
I’m excited about using the observatories to look at the linkages among all of these processes — biological, chemical, and physical.
Are you concerned that the high price of the project will lead to fewer exploratory projects?
That is a really big question now.
I think scientists owe it to the taxpayers to make best use of these assets, and best use of the money, and to provide an explanation for the value of our work.
But the Ocean Observatories Initiative has the potential to bring together different federal and non-government agencies to look at the relationships that we have not previously considered.
So, a hypothetical example — as the ocean’s multivitamin, hydrothermal vents could stimulate phytoplankton in the Northeast Pacific.
How does that influence commercial fisheries, like salmon or tuna?
That’s a question nobody really knows the answer to.
And it could bring interest from agencies outside of the National Science Foundation, like the National Oceanic and Atmospheric Administration, the U.S. Geologic Survey, the Environmental Protection Agency, even commercial fisheries.
Expand it even further — Google is always interested in providing real-time information on traffic.
It’s not unreasonable that commercial entities could make use of some of these systems, to provide information for commercial operations.
The question should not be limited to what we can do with our current sensors, but rather:
What is it that we’re not doing yet that would change the way we think about our oceans?
And, how do we develop the tools and methods to change that?
So it’s my hope that the observatories expand well beyond the scope of the National Science Foundation, and well beyond their sole dependence for support.
Links :
- GIM : Big data rising tides
Thursday, April 2, 2020
Satellite sleuthing detects underwater eruptions
On 21 August 2019, a pumice raft close to the Exclusive Economic Zone border between Fiji and Tonga was visible from space.
Satellite data, combined with seismic readings, helped locate the undersea volcano that was the source of the pumice.
Credit: European Space Agency, Copernicus Sentinel-2, CC BY-SA 3.0 IGO
From EOS by Philipp A. Brandl
Satellite data helped scientists locate the volcanic source of a pumice raft floating in the South Pacific Ocean, illustrating their promise in locating and monitoring undersea eruptions.
In August 2019, news media reported a new pumice raft floating in the territorial waters of the South Pacific island kingdom of Tonga.
This visible evidence of an underwater volcanic eruption was borne out by seismic measurements, but conditions were less than ideal for using seismic sensors to precisely locate the source of the eruption.
My colleagues and I eventually traced the source of the pumice raft to a submarine volcano referred to as “Volcano F” using a combination of satellite and seismic data (Figure 1), demonstrating remote sensing’s potential for locating and monitoring underwater volcanoes [Brandl et al., 2020].
Fig. 1 The drift of the pumice raft between 8 and 14 August 2019 following the 6–8 August eruption at Volcano F.
Dots represent locations of pumice on the sea surface and other observations reported by the ROAM catamaran.
Volcanoes that breach the sea surface often provide clues to impending eruptions, and the events during and after eruptions demonstrate the hazards that marine volcanoes can pose to communities nearby.
For example, after several months of growth, a large sector of the south flank of Anak Krakatau, a volcanic island situated in the Sunda Strait of Indonesia, suddenly collapsed into the sea on 22 December 2018.
The resulting tsunami killed more than 430 people in nearby coastal areas of Java and Sumatra; it also injured 14,000 people and displaced 33,000.
This cascade of events was not totally unexpected because the part of the island above water was clearly visible and was being monitored [Walter et al., 2019].
Unlike events above the sea surface, landslides, earthquakes, volcanic eruptions, and other geological events below sea level are seldom observed as they are happening, but they can also wreak havoc on vulnerable coastal communities.
Despite the hazards they pose, assessing the natural hazard risk and mitigating the aftereffects of submarine events remain major challenges.
In many cases, the events themselves are hidden beneath the water, and only their direct aftermaths are visible.
Recent advances, especially in remote sensing techniques, may enable scientists to identify potential underwater hazards and areas at risk in the near future.
The Challenge of Underwater Eruptions
Landslides and earthquakes are particularly hazardous when they occur not as isolated events but as parts of cascading natural disasters.
When these events occur underwater, the disaster might not be evident until it is well under way.
Landslides can be directly located only if they are associated with seismicity or are not exclusively submarine.
And although global seismic networks can precisely locate earthquakes, determining the details of fault motion, which can influence whether quakes trigger subsequent hazards like tsunamis, requires knowledge of the local seafloor geology and tectonic structure.
Mapping the seafloor for potential hazards will remain challenging because water rapidly absorbs the electromagnetic waves used in satellite remote sensing methods used to map land surfaces.
In most cases, submarine volcanic activity thus stays obscured from our eyes.
This is especially true if an eruption is effusive rather than explosive or if an eruption does not breach the sea surface to produce a detectable volcanic gas plume in the atmosphere.
Visible eruptions from submerged volcanoes are the exceptions.These include silicic eruptions at island arcs, which are often explosive and eventually eject matter into the air.
They also include eruptions of pumice, a highly porous, low-density abrasive volcanic rock that can float on the sea surface [Carey et al., 2018].
Large volumes of pumice can aggregate into rafts that drift with the wind, waves, and currents and that present hazards for ships.
But these rafts also provide clues to recent submarine eruptions.
Scientists currently rely on in situ methods to track floating pumice rafts, but improved Earth observation from space, coupled with automated image analysis and artificial intelligence, could further enable tracking, ultimately allowing us to trace them back to their volcanic sources if weather permits.
Sourcing the Tonga Pumice Raft
During the August 2019 eruption that produced the pumice raft near Tonga, two stations of the global seismic network located far out in the Pacific Ocean on the islands of Niue and Rarotonga recorded T phases, low-frequency sound waves related to submarine volcanic eruptions.
Under ideal conditions, such seismoacoustic signals can be transmitted over very long distances because they couple into a specific layer of the ocean water column, the sound fixing and ranging (SOFAR) channel, which acts as a guide for sound waves.
Sound waves reach their minimum speed within the SOFAR channel, and these low-frequency sound waves may travel thousands of kilometers before dissipating.
T phases from the 2011 submarine eruption of the Monowai volcanic system, for example, were transmitted in the SOFAR channel over more than 15,000 kilometers.
However, under less favorable conditions, seismoacoustic signal transmission may be more limited.
The Tonga Ridge is one example of where such unfavorable conditions prevail because the ridge sits in shallow water and breaches the surface in some places, thus blocking seismoacoustic signal transmissions in some directions.
During the August 2019 eruption, it was not possible to use triangulation to define the precise location of the source because only two stations recorded the relevant T phases.
This difficulty clearly emphasizes the need for increased sensitivity of the global seismic network in this part of the world, which is particularly important with respect to submarine natural hazards.
Seismoacoustic signals may be directly linked to an active submarine eruption, but seismic precursor events may also hint at increasing activity within a volcanic system.
In the case of the 6–8 August eruption of Volcano F, eight earthquakes of magnitude 3.9–4.7 were detected in the vicinity of the volcano in the days and hours prior to the eruption.
However, given the tremendous amount of seismic activity in this area and the related mass of data under normal conditions, events of this scale usually trigger interest only when followed by a larger and more significant geohazard.
Thus, submarine volcanic eruptions may go unnoticed unless boats and ships report encountering pumice rafts or surveillance flights report visual observations of eruption plumes.
In this respect, recent advances in the quality, quantity (e.g., daily coverage), and availability (e.g., the open-source data of the European Union’s Copernicus program) of satellite observations have greatly improved our ability to visually detect ongoing volcanic eruptions and their immediate aftermaths, thus representing an important addition to monitoring capabilities.
Satellite data may include, among other things, visual observation of the sea surface and spectral detection of volcanic gases or temperature variations in the atmosphere.
This satellite imagery shows the sea surface on 6 August 2019 following the eruption of Volcano F.
Abbreviations are UTC, coordinated universal time; Bft 5, Beaufort scale category 5 winds, corresponding to 29–38 kilometers per hour.
Credit: European Space Agency, Copernicus Sentinel-2, modified by Philipp Brandl
The European Space Agency’s (ESA) Sentinel-2 satellite, for example, captured a plume of discolored convecting water, volcanic gas, and vapor about 1.2 kilometers wide coming from the shallow submarine eruption of Volcano F.
By combining data from Sentinel-2, available through Copernicus, and from NASA’s Moderate Resolution Imaging Spectroradiometer (MODIS) system, we tracked the daily dispersal and drift of the related pumice raft.
Gathering Data from Many Sources
Because these satellite techniques are restricted to studying the sea surface, we may still miss many volcanic eruptions in the deep sea.
Only hydroacoustic techniques deployed from ships or autonomous underwater vehicles (AUVs) are capable of surveying the ocean floor at needed resolutions, so increased marine research focused on rapid response to submarine eruptions and landslides could strengthen our ability to predict potential natural hazards in the deep sea.
Ship-based multibeam mapping (which can achieve resolutions down to about 15 meters) of submarine volcanoes can help constrain eruption dynamics and volume and monitor morphological changes of volcanic edifices during or after an eruption.
And developments in robotic technology for seafloor mapping, such as unmanned surface vehicles and improved AUVs, which could extend resolution to less than 1 meter, may soon lead to significant advancements in our marine remote sensing capabilities.
But currently, the limited coverage of these techniques—less than about 30% of the ocean floor has been mapped by ship-based multibeam sonar—means that only a few areas exist where repeated multibeam surveys allow us to analyze changes in bathymetry over time.
Several segments of the East Pacific Rise, of the Galápagos Spreading Center, and of the Juan de Fuca Rise are examples of areas where detailed bathymetric maps have been used to monitor volcanic activity.
In the southwestern Pacific, well-mapped areas include arc volcanoes such as those in the Tofua-Kermadec Arc, the Monowai Volcanic Center, the Havre and Brothers volcanoes, and West Mata.
Repeated phases of growth and partial collapse of the edifice of the Monowai arc volcano have been well monitored [Watts et al., 2012].
However, this level of monitoring has been possible only through repeated bathymetric surveys (1978, 1986, 1998, 2004, 2007, and 2011) that together integrate to an important time series.
During a cruise in 2018, my colleagues and I “accidentally” mapped the flanks of Volcano F (it was not the focus of our cruise).
By combining our data with preexisting data from an Australian cruise, we created a combined bathymetric map (Figure 2) that could serve as a basis for future changes in bathymetry due to volcanic activity [Brandl et al., 2020].
Fig. 2. Composite bathymetry of Volcano F from ship-based multibeam data collected by R/V Sonne cruise SO267 and R/V Southern Surveyor cruise SS2004/11.
At present, the risk potential of cascading events in the submarine realm is poorly understood, mainly because of the lack of data and monitoring.
Studies like those described above would be of great value in assessing the risks of cascading natural disasters elsewhere—for example, at the many arc volcanoes whose edifices are composed of poorly consolidated volcaniclastic material rather than of solid masses of rock.
Volcanic growth can lead to a buildup of material that if followed by partial sector collapse, can trigger a tsunami—this was the case at Anak Krakatau in 2018.
Emerging technologies such as artificial intelligence and machine learning could fill an important gap.
Proactive automated processing of data from global seismic networks could help to identify clusters of increased seismicity that could be precursors to volcanic eruptions.
The locations and timing of these clusters could then be used to pick out features in hydrophone data from the same times and places that correlate with submarine eruptions.
Earth and computer scientists are currently developing techniques for automated image analysis and data processing as well as the use of artificial intelligence for pattern recognition and the proper identification of submarine volcanic eruptions.
Moving Beyond Accidental Discovery
Currently, submarine eruptions from island arc volcanoes and mid-ocean ridges are observed mainly by accident or when their eruption products breach the sea surface.
Thus, we likely never see a significant proportion of submarine volcanic eruptions.
And we lack the ability to monitor submarine volcanic activity on a global scale, which limits our ability to assess risks related to underwater volcanic eruptions, sector collapses, and cascading events.
Remote sensing techniques that collect data from space and at sea may provide us with more powerful tools to detect and monitor this volcanic activity and to project associated risks in remote areas.
Recent advances in data processing may also greatly improve capabilities in this field.
And compiling existing data and collecting new data related to submarine volcanic activity in a dedicated open-access database should help researchers estimate risk potentials as the first step toward forecasting natural hazards.
The experience with the 2019 eruption of Volcano F shows how important the integration of open-source and interdisciplinary remote sensing data is for the monitoring and management of natural hazards.
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