Coral reefs in western Indian Ocean at risk of collapse
Researchers warn that all coral reefs of the western Indian Ocean are at high risk of collapse within the next five decades, due to ocean warming and overfishing.
Coral reefs in 10 countries in the western Indian Ocean were split into 11 sub-regions, and assessed. Reefs in all sub-regions were found to be at high risk of complete ecosystem collapse and irreversible damage.
Reefs in island nations in the western Indian Ocean were found to be under particularly high threat. In four of the subregions of East and South Madagascar, the Comoros, and Mascarene Islands, reefs were assessed as ‘Critically Endangered’, while they were found to be ‘Endangered’ in West and North Madagascar and the Outer Seychelles.
Rising seawater temperatures as a result of climate change were identified as the greatest threat to coral reefs in these island nations. In the remaining four sub-regions, in North Seychelles, and along the entire mainland East African coast from South Africa to Kenya, reefs were classified as ‘Vulnerable’ to collapse.
Overfishing, by altering the ecology of reefs and promoting algal takeover, was found to pose the greatest overall threat in continental African countries.
The study authors analysed data ranging as far back as 35 years as well as sea surface temperature projections 50 years into the future. Their study area included the east coast of continental Africa from Kenya to South Africa and east to the island states of Seychelles and Mauritius. In total, it comprised around 5 per cent of the world’s coral reefs. Read more here
Scientists find ‘best preserved’ example of Roman-era crucifixion
Archaeologists investigating a Roman settlement in the UK have discovered the remains of a man with a nail through his heel. The team from the University of Cambridge believes this may be the “best preserved” example of a Roman-era crucifixion anywhere in the world.
The remains were unearthed during the 2017 excavation of five small Roman cemeteries holding the remains of 40 adults and five children. The graves are mainly from the fourth century AD.
Most of the remains showed signs of poor health including dental disease, malaria and physical injuries such as fractures. One male skeleton, laid out in his grave like the others, was found with a 5cm iron nail driven horizontally through his right heel bone.
Dental analysis suggests that the man was aged between 25 and 35, and around 5 foot 7 inches in height. Radiocarbon dating indicates he died between 130 AD and 360 AD.
The man was buried surrounded by twelve iron nails and alongside a timber structure thought to be wooden board on which his body may have been laid once removed from the cross.
His remains showed signs of injuries prior to death, including fractures on six ribs that were just starting to heal, and evidence of infection on his legs including thinning of the shin bones: indicative of having been bound or shackled.
Although crucifixion was common in the Roman world, evidence for the practice is extremely rare, as nails were not always used – the victim was normally just tied to a crossbar – and bodies were not typically given formal burials.
Crucifixion was the main form of capital punishment in Roman times until Constantine the Great outlawed the practice during his reign in AD 306-337. Read more here
NASA launches mission to study high energy cosmic bodies
NASA has launched its Imaging X-ray Polarimetry Explorer (IXPE) from its Kennedy Space Center in Florida.
The IXPE observatory is NASA’s first mission dedicated to measuring the polarization of X-rays from the most extreme and mysterious objects in the universe, such as supernova remnants, supermassive black holes, and other high-energy objects.
About 33 minutes into flight, the spacecraft entered its orbit around Earth’s equator at an altitude of approximately 600 kilometers. About 40 minutes after launch, mission operators received the first spacecraft telemetry data.
IXPE carries three state-of-the-art space telescopes with special polarization-sensitive detectors. Polarization — in which the vibrations of the light wave occur in a single plane — is a property of light that holds clues to the environment from which the light originates. More about it here
Scientists solve mystery of helical jet from black hole
Using the Very Large Array (VLA), researchers have found out why a jet of material propelled from the core of a giant galaxy is shaped like DNA.
The giant elliptical galaxy, called M87, is about 55 million light-years from Earth. A supermassive black hole some 6.5 billion times more massive than the Sun at the center of M87 was the first one ever to be imaged.
The team found that the jet of material is channeled by a corkscrew-shaped magnetic field out to nearly 3,300 light-years from the galaxy’s central supermassive black hole. That is much farther than such a magnetic field previously had been detected in a galactic jet.
Helical magnetic fields are expected close to the black hole, and are thought to play a highly important role in channeling the material into a narrow jet.
However, the magnetic field is expected to weaken with its distance from the black hole. But in this case, a strong helical field extends far outward.
Scientists suggest that instabilities in the flow of material within the jet could make the magnetic field more ordered at the distances seen in the new images. The instabilities produce regions of higher pressure which also compress the magnetic field lines.
The astronomers think that this interaction between instabilities in the flow and the magnetic field is what produces the double-helix structure. If this is happening in the M87 jet, it likely also is happening in similar jets from galaxies throughout the Universe, according to the team. Read more about it here
Iron may have shaped evolution of complex life
While carbon and hydrogen are considered to be the key elements that give rise to all life forms, a study from University of Oxford this week suggests that iron influenced the development of complex life forms.
Their findings may also be used to understand how likely or unlikely advanced life forms might be on other planets.
Iron is an essential nutrient for almost all life forms on Earth. The amount of iron in the Earth’s rocky mantle was determined by the conditions under which the planet formed, and subsequently the metal had major ramifications for how life developed.
Too little iron in the rocky portion of the planet, like the planet Mercury, and life is unlikely. Too much, like Mars, and water may be difficult to keep on the surface long enough for complex life forms to evolve.
Initially, iron conditions on Earth would have been optimal to ensure surface retention of water. Iron would have also been soluble in sea water, making it easily available to give simple life forms a jumpstart in development.
However, oxygen levels on Earth began to rise approximately 2.4 billion years ago. An increase in oxygen created a reaction with iron, which led to it becoming insoluble. Gigatons of iron dropped out of sea water, where it was much less available to developing life forms.
The need to acquire poorly available iron as nutrient may have then driven the evolution of complex life forms.
Knowing now about how important iron is in the development of life may aid in the search for suitable planets that could develop life forms. By assessing the amount of iron in the mantle of exo-planets, it may now be possible to narrow the search for exo-planets capable of supporting life. Read more here