Tag Archives: survey

Reef.

Researchers unveil the most comprehensive atlas of coral reefs to date

A new research effort from the Khaled bin Sultan Living Oceans Foundation and the University of Miami (UM) Rosenstiel School of Marine and Atmospheric Science created an atlas of the world’s coral reef — the body of data contains maps of over 65,000 square kilometers (25,097 square miles) of coral reefs and their surrounding habitats.

Reef.

Image via Pixabay.

Scientists now have a new tool at their disposal to accurately map large areas of coral reefs — much cheaper and faster than any time before. Traditionally, coral reef surveys are expensive, slow, and limited in scope. The main problem was that they relied on highly-trained divers swimming through the reefs, gathering data. Using the new model, however, researchers can now create detailed coral reef habitat maps at a regional scale without having to survey the entire reef in person.

Mapped reef

“In order to conserve something, it’s imperative to know where it is located and how much of it you have,” said Sam Purkis, professor and chair of the UM Rosenstiel School Department of Marine Geosciences, and the study’s lead author.

“Developing such an understanding for coral reefs is especially challenging because they are submerged underwater and therefore obscured from casual view. With this study, we demonstrate the potential to use satellite images to make coral reef maps at global scale.”

The atlas is the product of the 10-year long Global Reef Expedition by researchers from the Khaled bin Sultan Living Oceans Foundation, who traveled to over 1,000 coral reefs in 15 countries. They surveyed the reefs down to a one-square meter scale in a bid to help us better understand coral health and resilience. Many of the reefs they surveyed had never been studied before, the team notes.

The survey gathered data on shallow marine habitats such as fore and back reefs as well as associated habitats such as seagrass beds and mangrove forests for key reefs. These associated habitats are key components of tropical coastal ecosystems, the authors explain, which filter water, protect coasts from storms, and support fish populations. Coastal development, overfishing, and climate change impact these associated habitats as they do reefs.

Mapping extent.

The location of sites visited by the Khaled bin Sultan Living Oceans Foundation Global Reef Expedition. Red polygons show the extent of mapping activity and encompass a total area of 65,000 sq. km of habitat situated shallower than 25 m water depth. Accompanying site names in red also.
Image credits Sam J. Purkis et al., (2019), Coral Reefs.

Data collected by divers of the Global Reef Expedition was analyzed and — using ultra-high-resolution satellite imagery –extrapolated across entire reef structures. The team used video footage taken with cameras dropped at precise coordinates along the reef to validate the accuracy of their mapping method. The resulting maps are publicly available on the World Reef Map, an interactive coral reef atlas that anyone can use to explore all of the coral reefs and shallow water marine habitats mapped by the Global Reef Expedition.

“Benthic habitat maps are an essential tool in coral reef conservation as they provide a snapshot of where reefs are located and the status of their health,” said Alexandra Dempsey, the director of science management for the Khaled bin Sultan Living Oceans Foundation and a co-author of the paper.

“Scientists will use these habitat maps as baseline data to help track changes in reef composition and structure over time.”

Although the maps do not cover every reef in the world, they do include a meaningful portion of global reefs, the team says. As it was constructed with data recorded over the last 10 years, it also offers a unique baseline of coral reef health prior to the massive 2017 bleaching event. The team hopes that the publicly-available atlas will help governments, as well as conservation organizations, to protect and restore reefs. It is estimated that 50% of the world’s reefs have been lost in the past 40 years due to climate change and human activity, the paper also writes, underscoring the need for conservation and restoration efforts.

The paper “High-resolution habitat and bathymetry maps for 65,000 sq. km of Earth’s remotest coral reefs” has been published in the journal Coral Reefs.

Hubble completes the most complete ultraviolet-light survey of nearby galaxies — and the photos are mind blowing

Galaxies are amazing things, and we can now see some of them in unprecedented detail.

The spiral galaxy Messier 96 lies some 35 million light-years away. Image credits: NASA, ESA, and the LEGUS TEAM.

“There has never before been a star cluster and a stellar catalog that included observations in ultraviolet light,” explained survey leader Daniela Calzetti of the University of Massachusetts, Amherst. “Ultraviolet light is a major tracer of the youngest and hottest star populations, which astronomers need to derive the ages of stars and get a complete stellar history. The synergy of the two catalogs combined offers an unprecedented potential for understanding star formation.”

Light comes in different wavelengths. Ultraviolet light (UV) has a shorter wavelength than that of visible light, but longer than X-rays, and UV constitutes about 10% of the total light output of stars like the Sun. When you “look” at something in different wavelengths, you can infer different things about its physical properties. In this case, astronomers were trying to learn more about star formation, a process that still holds many secrets.

Astronomers combined new and old Hubble observations, looking for detailed information on young, massive stars and star clusters, as well as their evolution. It’s ironic, really — almost all we know about the universe, we know thanks to light from stars, and yet we don’t know how the stars themselves form.

The spiral galaxy Messier 66. Image credits: NASA, ESA, AND THE LEGUS TEAM.

As far as we know, stars form inside relatively dense concentrations of interstellar gas and dust known as molecular clouds. These areas are extremely cold (just ten degrees K above absolute zero), and at those temperatures, gases become molecular, meaning they’re much more likely to bind together. Oftentimes, gases clump up to higher and higher densities, and once a specific point is passed, stars can form. But here’s the thing: before the star is actually formed, the region is very dense and dark, virtually opaque to visible light (something called a dark nebula). Astronomers can still investigate them to an extent, but they use infrared and radio telescopes. So, instead, researchers try to find very young stars.

The research team carefully selected the LEGUS targets from among 500 galaxies, all of which lie between 11 million and 58 million light-years from Earth. Team members chose the galaxies based on their mass, star-formation rate, and abundances of metals –which, in this context, means elements that are heavier than hydrogen and helium.

Galaxies come in multiple shapes and sizes. We tend to think of galaxies as being spiral, Milky Way-like structures, but galaxies can be quite varied in terms of shape and size. Stars tend to be distributed quite regularly in galaxies, but while groups of stars tend to be more predictable, the same can’t be said about individual stars.

“When we look at a spiral galaxy, we usually don’t just see a random distribution of stars,” Calzetti said. “It’s a very orderly structure, whether it’s spiral arms or rings, and that’s particularly true with the youngest stellar populations. On the other hand, there are multiple competing theories to connect the individual stars in individual star clusters to these ordered structures.

These six images represent the variety of star-forming regions in nearby galaxies. The galaxies are part of the Hubble Space Telescope’s Legacy ExtraGalactic UV Survey (LEGUS), the sharpest, most comprehensive ultraviolet-light survey of star-forming galaxies in the nearby universe. The six images consist of two dwarf galaxies (UGC 5340 and UGCA 281) and four large spiral galaxies (NGC 3368, NGC 3627, NGC 6744, and NGC 4258). The images are a blend of ultraviolet light and visible light from Hubble’s Wide Field Camera 3 and Advanced Camera for Surveys. Image credits: NASA/ESA/LEGUS team.

This is where the new survey comes in, and why it’s so important. By imaging the galaxies in such detail, astronomers are able to zoom in on individual star populations, thus gaining more information about them. We can almost certainly expect a flurry of studies on star formation in the near future.

“By seeing galaxies in very fine detail — the star clusters — while also showing the connection to the larger structures, we are trying to identify the physical parameters underlying this ordering of stellar populations within galaxies. Getting the final link between gas and star formation is key for understanding galaxy evolution,” Calzetti concludes.

 

Brits expect to spend their holidays on the moon by 2020

I had some good laughs reading data from a survey published last week that outlined the blurred perspective between science and science fiction for some Britons (one in five believed light sabers were real). Today, I ran into another online survey that posed some laughs conducted by a British online travel agency in which people were asked where would they like to vacation in the forthcoming years.

Hilariously, more than one in ten people said that holidaying on the moon would be possible by 2020, according to sunshine.co.uk. In the same year, 16% of the over 2,000 interviewed correspondents in the survey  reckon that an undersea railway tunnel between the UK and the US will be built. A small fraction of travel aficionados, about 4%,  said there’s a good chance of being able to time travel in the near future – you know, so you can avert those bad holidays or the booking of that dirty, over-priced hotel.

“It seems that some people just aren’t content with the holidays of today,” sunshine.co.uk co-founder Chris Brown told the Associated Press.

“Some evidently quite like the idea of floating through space, as opposed to lounging by the pool or walking along a sunny beach. It’s interesting to see what some people think will be possible in the near future.”

Stunning variety of sea life found in Antarctica

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The British Antarctic Survey (BAS) published some quite awesome pictures showing that Antarctica isn’t the lifeless frozen wasteland most people believe it to be; ice fish, octopus, sea pigs, giant sea spiders, rare rays and gorgeous basket stars all thrive in the extreme temperatures in Antarctica’s waters. Well, thrive is perhaps a too strong word, but they’re doing just fine in what seemed to be an impossible habitat.

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An unknown coral that awaits identification from experts

“Few people realise just how rich in biodiversity the Southern Ocean is – even a single trawl can reveal a fascinating array of weird and wonderful creatures as would be seen on a coral reef. These animals are potentially very good indicators of environmental change as many occur in the shallows, which are changing fast, but also in deeper water which will warm much less quickly. We can now begin to get a better understanding of how the ecosystem will adapt to change.”, said Dr. David Barnes of BAS

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A young ocean

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Amazing basket star

“Our research on species living in the waters surrounding the BAS Rothera Research Station on the Antarctic Peninsula shows that some species are incredibly sensitive to temperature changes. Our new studies on the diverse range of marine creatures living in the deep waters of the Bellingshausen Sea will help us build a more complete picture of Antarctica’s marine biodiversity and give us an important baseline against which we can compare future impact on marine life.”, he added.

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BAS biologist Dr. Sophie Fielding concludes: “Changes at the Earth’s surface directly affect the surrounding ocean and the marine animals living there. For example accelerating glacier melt, collapse of ice shelves and shrinking winter sea-ice all seem to be impacting sea life. We want to understand that impact and what the implications for the food chain may be.”

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Feather star

Amphipod sandhopper

Amphipod sandhopper

I have to say, it’s exactly this kind of study that shows us exactly how little we know about the very world we live in and how we affect it in ways we don’t even understand. Hopefully, this will make people pay more attention to any environment and ecosystem, no matter how barren it appears to be. I take my hat off.

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A lovely comb jellyfish

A lovely comb jellyfish

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VIA Antarctica.ac.uk; go there for more pics in higher resolution and more explanations