Published today, AIMS’ Annual Summary Report on Coral Reef Condition for 2021/22 shows another year of increased coral cover across much of the Reef.

In the 87 representative reefs surveyed between August 2021 and May 2022 under the AIMS Long-Term Monitoring Program (LTMP), average hard coral cover in the region north of Cooktown increased to 36% (from 27% in 2021) and to 33% in the central Great Barrier Reef (from 26% in 2021).

However, average coral cover in the southern region (from Proserpine to Gladstone) decreased from 38% in 2021 to 34%.

AIMS CEO Dr Paul Hardisty said the results in the north and central regions were a sign the Reef could still recover, but the loss of coral cover in the southern region showed how dynamic the Reef was.

“A third of the gain in coral cover we recorded in the south in 2020/21 was lost last year due to ongoing crown-of-thorns starfish outbreaks,” he said.

“This shows how vulnerable the Reef is to the continued acute and severe disturbances that are occurring more often and are longer-lasting.”

Dr Hardisty said the increased frequency of mass coral bleaching events was “uncharted territory” for the Reef, with this year’s bleaching event the fourth in seven years and the first to occur during a La Niña.

“In our 36 years of monitoring the condition of the Great Barrier Reef we have not seen bleaching events so close together,” he said.

“Every summer the Reef is at risk of temperature stress, bleaching and potentially mortality and our understanding of how the ecosystem responds to that is still developing.

“The 2020 and 2022 bleaching events, while extensive, didn’t reach the intensity of the 2016 and 2017 events and, as a result, we have seen less mortality. These latest results demonstrate the Reef can still recover in periods free of intense disturbances.”

AIMS monitoring program team leader Dr Mike Emslie said the 2022 results built on the increases in coral cover reported for 2021, with most of the increase continuing to be driven by fast-growing Acropora corals.

“These corals are particularly vulnerable to wave damage, like that generated by strong winds and tropical cyclones,” he said.

“They are also highly susceptible to coral bleaching, when water temperatures reach elevated levels, and are the preferred prey for crown-of-thorns starfish. This means that large increases in hard coral cover can quickly be negated by disturbances on reefs where Acropora corals predominate.”

Dr Emslie said climate change was driving increasingly frequent and longer-lasting marine heatwaves.

“The peak of the most recent bleaching event in March occurred when the accumulated heat stress caused widespread bleaching but not extensive mortality,” he said.

“The increasing frequency of warming ocean temperatures and the extent of mass bleaching events highlights the critical threat climate change poses to all reefs, particularly while crown-of-thorns starfish outbreaks and tropical cyclones are also occurring. Future disturbance can reverse the observed recovery in a short amount of time.”

Background

The 36-year-long dataset of AIMS’ Long-Term Monitoring Program (LTMP) is the largest, longest, and most comprehensive information source on the health of the Great Barrier Reef. It helps determine long-term trends in the condition of coral communities across the Reef.

Percent hard coral cover describes the proportion of the reef that is covered in living hard coral. In 2021-22, most reefs surveyed had between 10 and 50 percent.

Bleaching is a coral’s response to stressful conditions such as heat. During bleaching, the coral animal loses its symbiotic algae and pigments, causing it to turn white and potentially die. Corals can survive a bleaching event, but they are under more stress.

Report; https://www.aims.gov.au/monitoring-great-barrier-reef/gbr-condition-summary-2021-22

Xiaoping Bao, a Purdue University assistant professor from the Davidson School of Chemical Engineering, said CAR-neutrophils, or chimeric antigen receptor neutrophils, and engraftable HSCs, or hematopoietic stem cells, are effective types of therapies for blood diseases and cancer. Neutrophils are the most abundant white cell blood type and effectively cross physiological barriers to infiltrate solid tumors. HSCs are specific progenitor cells that will replenish all blood lineages, including neutrophils, throughout life.

“These cells are not readily available for broad clinical or research use because of the difficulty to expand ex vivo to a sufficient number required for infusion after isolation from donors,” Bao said. “Primary neutrophils especially are resistant to genetic modification and have a short half-life.”

Bao has developed a patent-pending method to mass-produce CAR-neutrophils from human pluripotent stem cells (hPSCs), that is, cells that self-renew and are able to become any type of human cell. The chimeric antigen receptor constructs were engineered to express on the surface of the hPSCs, which were directed into functional CAR-neutrophils through a novel, chemically defined protocol.

The method was created in collaboration with Qing Deng at Purdue’s Department of Biological Sciences, Hal E. Broxmeyer, now deceased, at Indiana University School of Medicine, and Xiaojun Lian at the Pennsylvania State University.

“We developed a robust protocol for massive production of de novo neutrophils from human pluripotent stem cells,” Bao said. “These hPSC-derived neutrophils displayed superior and specific antitumor activities against glioblastoma after engineering with chimeric antigen receptors.”

Bao disclosed the innovation to the Purdue Research Foundation Office of Technology Commercialization, which has applied for an international patent under the Patent Cooperation Treaty system of the World Intellectual Property Organization. The innovation has been optioned to an Indiana-headquartered life sciences company.

“We will also work with Dr. Timothy Bentley, professor of neurology and neurosurgery,and his team at the Purdue College of Veterinary Medicine to run clinical trials in pet dogs with spontaneous glioma,” Bao said.

This research project was partially supported by the Davidson School of Chemical Engineering and College of Engineering Startup Funds, Purdue Center for Cancer Research, Showalter Research Trust and federal grants from the National Science Foundation and National Institute of General Medical Sciences.

Story Source:

Materials provided by Purdue University. Original written by Steve Martin. Note: Content may be edited for style and length.

With that in mind, a team of University of Arizona students and faculty completed a comprehensive study to track and characterize the brightness of satellites, using a ground-based sensor they developed to measure satellites’ brightness, speed and paths through the sky. Their work could be helpful for astronomers, who, if notified of incoming bright satellites, could close the shutters of their telescope-mounted cameras to prevent light trails from tainting their long-exposure astronomical images.

The research team was led by professor of planetary sciences Vishnu Reddy, who also co-leads — with professor of systems and industrial engineering Roberto Furfaro — the university’s Space Domain Awareness lab, which tracks and characterizes all kinds of objects orbiting Earth and the moon.

Grace Halferty, a senior graduating this summer with a bachelor’s degree in aerospace and mechanical engineering, is the lead author of the study, which is published in Monthly Notices of the Royal Astronomical Society. The study details how the team created a satellite tracking device to measure the brightness and position of SpaceX Starlink satellites and compared those observations to government satellite tracking data from the Space Track Catalog database.

“Until now, most photometric — or brightness — observations that were available were done by naked eye,” Halferty said. “This is one of the first comprehensive photometric studies out there to go through peer review. The satellites are challenging to track with traditional astronomical telescopes, because they are so bright and fast-moving, so we built what’s basically a small sensor with a camera lens ourselves because there was nothing off the shelf available.”

The team made 353 measurements of 61 satellites over two years and found that the position of Starlink satellites as recorded in the government’s Space Track Catalog only differed by an average of 0.3 arc seconds from the UArizona calculations. An arc second on the sky is about the size of a dime held 2.5 miles away. The tiny difference is probably due to natural lag times in the government data, Reddy said. Because that data is based on estimated orbits calculated days earlier, rather than on real-time observations, positioning errors can build up.

“This suggests that there is hope that astronomers can use these data to close the shutter of their telescopes in time amid the growing chaos in the skies above,” Reddy said.

A stellar traffic jam

Starlink is a large network of satellites, also called a mega constellation, operated by SpaceX with the goal of providing global internet coverage. SpaceX started launching Starlink satellites in 2019. Today, more than 2,700 Starlink satellites have launched — a fraction of the intended total of 42,000 satellites.

Other examples of satellite constellations include 31 GPS satellites and 75 iridium satellites for communication. Other entities have plans to launch more satellites into low and medium Earth orbit in the next few years. Amazon, for example, plans to launch 3,000 satellites, and the Chinese government plans to launch 13,000. These satellites will orbit no higher than 22,000 miles above Earth.

The problem with satellites is that they require power harvested from solar panels, which can reflect sunlight at ground-based telescopes and, in turn, impact astronomical observations from telescopes around the world. About 30% of all telescope images will be impacted by at least one satellite trail once the Starlink constellation is complete, said research team member Tanner Campbell, a graduate research assistant in the Department of Aerospace and Mechanical Engineering.

“As other constellations are added, the problem will only get worse for ground-based astronomical surveys,” he said.

These satellites are even more reflective right after launch, while they are still relatively low and tightly clustered before they spread throughout their orbit over time. They are often as bright as Saturn or Jupiter, two of the brightest objects in the night sky. As they maneuver into higher orbits, they become slightly fainter.

A moving target

SpaceX has deployed a few different methods to darken its Starlink satellites. For example, VisorSat satellites rely on a shade to block additional sunlight, making them 1.6 times fainter. DarkSat satellites, on the other hand, rely on an anti-reflective coating that makes them 4.8 times fainter. However, DarkSats got too hot, so SpaceX moved away from that specific method. Since August 2021, all Starlink satellites are VisorSats.

“While these modifications are steps in the right direction, they also don’t dim the satellites enough for astronomical surveys,” said research team member Adam Battle, a graduate student studying planetary science.

In July, SpaceX announced new strategies. One involves mirrors that reflect sunlight away from Earth and another involves using darker building materials. Reddy’s team plans to study how effective these methods are at reducing sunlight reflection back to Earth.

While knowing exactly where satellites are is helpful to astronomers, the act of shutting the cameras adds overhead costs for telescope operations. Surveys become less efficient when astronomers have to close the shutter or throw away contaminated images. For example, a survey that would take five years to complete could take 10% to 20% more time if survey efficiency is down. Costs will continue to increase as more satellites are launched, Reddy said.

The team plans to build upon its success by studying the brightness of the latest generation of Starlink satellites in four different colored filters — the same ones used in astronomical surveys of the sky to tease out different information from stars, planets and more. To achieve this, the team has worked with Tucson-based small business Starizona to build a sensor that can take pictures of satellites in four colors simultaneously.

“Working with local small businesses is a win for us as it provides our students an opportunity to rapidly prototype and bring a new system online,” Reddy said.