Satellites unveil the size and nature of the world’s coral reefs

A satellite photo from the Allen Coral Atlas showing shallow coral reefs off Fiji
Image Credit: Courtesy of Allen Coral Atlas

University of Queensland-led research has shown there is more coral reef area across the globe than previously thought, with detailed satellite mapping helping to conserve these vital ecosystems.

Dr Mitchell Lyons from UQ’s School of the Environment, working as part of the Allen Coral Atlas project, said scientists have now identified 348,000 square kilometers of shallow coral reefs, up to 20-30 meters deep.

“This revises up our previous estimate of shallow reefs in the world’s oceans,” Dr Lyons said.

“Importantly, the high-resolution, up-to-date mapping satellite technology also allows us to see what these habitats are made from.

“We’ve found 80,000 square kilometers of reef have a hard bottom, where coral tends to grow, as opposed to soft bottom like sand, rubble or seagrass.

Concordia researchers identify a decline in microbial genetic richness in the western Arctic Ocean

With the warming and freshening of the Arctic Ocean comes a decrease of nutrients that are important for photosynthesis
Photo Credit: Davide Cantelli

The Arctic region is experiencing climate change at a much faster rate than the rest of the world. Melting ice sheets, runoff from thawing permafrost and other factors are rapidly changing the composition of the Arctic Ocean’s water. And that change is being experienced all the way down to the microbial level.

In a Concordia-led study published in the journal ISME Communications, researchers analyzed archival samples of bacteria and archaea populations taken from the Beaufort Sea, bordering northwest Canada and Alaska. The samples were collected between 2004 and 2012, a period that included two years — 2007 and 2012 — in which the sea ice coverage was historically low. The researchers looked at samples taken from three levels of water: the summer mixed layer, the upper Arctic water below it and the Pacific-origin water at the deepest level.

The study examined the microbes’ genetic composition using bioinformatics and statistical analysis across the nine-year time span. Using this data, the researchers were able to see how changing environmental conditions were influencing the organisms’ structure and function.

The researchers found subtle but statistically significant changes in the communities they studied.

Octopus DNA solves mystery of ice sheet’s past

Octopus, probably Pareledone species, from 500m depth on the Bellingshausen Sea continental shelf.
Photo Credit: British Antarctic Survey

Scientists, including from British Antarctic Survey, have used octopus DNA to discover that the West Antarctic Ice Sheet (WAIS) likely collapsed during the Last Interglacial period around 120,000 years ago – when the global temperatures were similar to today.

This provides the first empirical evidence that the tipping point of this ice sheet could be reached even under the Paris Agreement targets of limiting warming to 1.5-2oC.

The study, published in the journal Science, was led by Professor Jan Strugnell, Chief Investigator, and Dr Sally Lau, Postdoctoral Research Fellow from ARC Securing Antarctica’s Environmental Future at James Cook University.

Octopus, probably Pareledone species, from 500m depth on the Bellingshausen Sea continental shelf. BAS.

Toxic chemicals found in oil spills and wildfire smoke detected in killer whales

Orcas (killer whales)
Photo Credit: Bart van Meele

Toxic chemicals produced from oil emissions and wildfire smoke have been found in muscle and liver samples from Southern Resident killer whales and Bigg’s killer whales.

A study published in Scientific Reports is the first to find polycyclic aromatic hydrocarbons (PAHs) in orcas off the coast of B.C., as well as in utero transfer of the chemicals from mother to fetus.

“Killer whales are iconic in the Pacific Northwest—important culturally, economically, ecologically and more. Because they are able to metabolically process PAHs, these are most likely recent exposures. Orcas are our canary in the coal mine for oceans, telling us how healthy our waters are,” said senior author Dr. Juan José Alava, principal investigator of the UBC Ocean Pollution Research Unit and adjunct professor at Simon Fraser University.

PAHs are a type of chemical found in coal, oil and gasoline which research suggests are carcinogenic, mutagenic, and have toxic effects on mammals. Their presence in the ocean comes from several sources, including oil spills, burning coal and forest fire smoke particles.

Researchers analyzed muscle and liver samples from six Bigg’s, or transient, killer whales and six Southern Resident killer whales (SRKWs) stranded in the northeastern Pacific Ocean between 2006 and 2018. They tested for 76 PAHs and found some in all samples, with half the PAHs appearing in at least 50 per cent of the samples. One compound, a PAH derivative called C3-phenanthrenes/anthracenes, accounted for 33 per cent of total contamination across all samples. These forms of PAHs, known as alkylated PAHs, are known to be more persistent, toxic, and to accumulate more in the bodies of organisms or animals than parental PAHs.

Some coral species might be more resilient to climate change than previously thought

OSU coral researcher Alex Vompe off the north shore of Mo'orea
Photo Credit: Mackenzie Kawahara

Some coral species can be resilient to marine heat waves by “remembering” how they lived through previous ones, research by Oregon State University scientists suggests.

The study also contains evidence that the ecological memory response is likely linked to the microbial communities that dwell among the corals.

The findings, published today in Global Change Biology, are important because coral reefs, crucial to the functioning of planet Earth, are in decline from a range of human pressures including climate change, said the study’s lead author, Alex Vompe.

“It is vital to understand how quickly reefs can adapt to ever more frequent, repeated disturbances such as marine heat waves,” said Vompe, a doctoral student who works in the lab of microbiology professor Rebecca Vega Thurber. “The microbiomes living within their coral hosts might be a key component of rapid adaptation.”

Heat waves are likely to increase in frequency and severity because of climate change, he added. Slowing down the rate of coral cover and species loss is a major conservation goal, and predicting and engineering heat tolerance are two important tools.

30-foot whale shark spotted off Kāneʻohe Bay by UH researchers

University of Hawaiʻi at Mānoa researchers spotted the world’s largest fish species, a 30-foot whale shark, a mile off Kāneʻohe Bay near Kualoa Ranch on November 2.

Researchers from the Hawaiʻi Institute of Marine Biology (HIMB) Shark Research Lab were returning from conducting field work when they spotted seabirds flying over what they suspected was a bait ball, where small fish swarm in a tightly packed spherical formation near the surface while being pursued and herded by predators below.

Mark Royer, a HIMB shark researcher, went into the water to see what sealife had gathered to feed and was surprised to see the whale shark.

“It is surprising,” said Royer. “[Whale sharks] are here more often than we think, however they are probably hard to come across, because I didn’t see this animal until I hopped in the water.”

The Unraveling of a Protist Genome Could Unlock the Mystery of Marine Viruses

Light-microscopy image of clusters of Aurantiochytrium limacinum cells. The marine protist is prevalent in the world’s oceans.
Image Credits: Laura Halligan, Joshua Rest and Jackie Collier

Viruses are the most prevalent biological entities in the world’s oceans and play essential roles in its ecological and biogeochemical balance. Yet, they are the least understood elements of marine life. By unraveling the entire genome of a certain marine protist that may act as a host for many viruses, an international research team led by scientists from Stony Brook University sets the stage for future investigations of marine protist genomes, marine microbial dynamics and the evolutionary interplay between host organisms and their viruses — work that may open doors to a better understanding of the “invisible” world of marine viruses and offers a key to the ecology and health of oceans worldwide. The research is published early online in Current Biology.

Food webs of the oceans provide humanity with essential food sources as well as the wonderment of sea creatures from polar bears to penguins. This wellspring of life is supported mainly by microscopic organisms, including the wide presence of viruses. Learning more about the viruses through DNA research and other forms of investigation is essential to scientists’ understanding of the sea. Novel groups of viruses are still being discovered, such as the recently discovered “mirusvirues” featured in a Nature paper earlier this year.

Study reveals location of starfish’s head

Postdoctoral scholar Laurent Formery (left) and biology Professor Christopher Lowe with starfish on the shore of Stanford’s Hopkins Marine Station, in Monterey, California.
Photo Credit: LiPo Ching / Stanford University

A new study that combines genetic and molecular techniques helps solve the riddle of starfish body plans, and how starfish start life with bilateral body symmetry – just like humans – but grow up to be adults with fivefold “pentaradial” symmetry.

If you put a hat on a starfish, where would you put it? On the center of the starfish? Or on the point of an arm and, if so, which one? The question is silly, but it gets at serious questions in the fields of zoology and developmental biology that have perplexed veteran scientists and schoolchildren in introductory biology classes alike: Where is the head on a starfish? And how does their body layout relate to ours?

Now, a new Stanford study that used genetic and molecular tools to map out the body regions of starfish – by creating a 3D atlas of their gene expression – helps answer this longstanding mystery. The “head” of a starfish, the researchers found, is not in any one place. Instead, the headlike regions are distributed with some in the center of the sea star as well as in the center of each limb of its body.

New study: Deep-sea pressure preserves food for microbes in the abyss

A flake of marine snow from the experiment.
Photo Credit: © Peter Stief/SDU

A new study from the Danish Center for Hadal Research reports on a series of experiments with exposing marine snow to increasing pressure - up to 1000 bar, which corresponds to the pressure at the bottom of some of the world's deep-sea trenches, 10 km below the sea surface.

Marine snow is millimeter-sized flakes, created when sticky, dead cells at the sea surface clump together with other dead or dying cells, particles and bacteria and sink to the bottom. The organic material can be dead algae, dead small animals, or their feces. Together, it is called marine snow because the flakes look like snow as they sink through the water column. There can be hundreds of different bacteria in one flake in addition to particles of organic matter.

"Not much is known about how marine snow responds to the increasing pressure when it sinks. But it is known that marine snow is food for an enormous number of microbes and small animals on the seabed. In fact, there are more microbes in the part of the ocean that lies at or below 1000 meters depth than anywhere else on Earth. This habitat is extremely large, and there can be a long distance between the microbes down there, but nevertheless a huge number of Earth's organisms thrive under high pressure, and we don't know how", says biologist Peter Stief, who is the lead author of the study.

Endangered whales live in area earmarked for gas exploration

Risso's dolphins.
Photo Credit Leonidas Karantzas/Greenpeace

Endangered whales and dolphins live year-round in an area of the Mediterranean earmarked for oil and gas exploration, new research shows.

Various cetacean species are known to inhabit the Hellenic Trench off Greece in the summer, but until now little has been known about their winter whereabouts.

This lack of information has been used to justify seismic surveys (which may harm whales and dolphins) in winter.

The new study found that at least four species – including the regionally endangered sperm whale – live in the deep waters of the Hellenic Trench in both summer and winter.

The research was carried out in 2021-22 by the Greenpeace Research Laboratories, University of Exeter, Greenpeace Greece and the Pelagos Cetacean Research Institute.

“The Mediterranean is one of the busiest seas on the planet, and whales and dolphins are already threatened by ship strikes, overfishing, bycatch (accidental catching), pollution with chemicals and plastics, and climate change,” said Dr Kirsten Thompson.

Killer whales’ diet more important than location for pollutant exposure

Photo Credit: Thomas Lipke

Both elegant and fierce, killer whales are some of the oceans’ top predators, but even they can be exposed to environmental pollution. Now, in the largest study to date on North Atlantic killer whales, researchers in the American Chemical Society’ Environmental Science & Technology report the levels of legacy and emerging pollutants in 162 individuals’ blubber. The animals’ diet, rather than location, greatly impacted contaminant levels and potential health risks — information that’s helpful to conservation efforts.

As the largest member of the dolphin family, killer whales, also known as orcas, are found worldwide. Marine vessel traffic can disturb the hunting and communication of these black-and-white marine mammals. But they face another type of human threat — legacy and emerging persistent organic pollutants (POPs) in their environments. POPs include chlorinated hydrocarbons and flame retardants, and can accumulate in animals’ fat stores as the contaminants move up the food chain though a process called biomagnification.

Scientists from UNSW Sydney reveal biases in the field of coral reef research

Photo Credit: Vincent Rivaud

Analysis of the literature revealed authors from countries with large coral reef systems, such as The Maldives, Papua New Guinea and Indonesia, are underrepresented. 

Coral reefs support approximately 25 per cent of marine species, and are essential to coastal economies, such as the fishing and tourism industries, to name a few. But coral reefs worldwide are at risk due to climate change and are on the brink of collapse. 

The global decline of coral reefs has encouraged extensive research. Now, scientists from UNSW Sydney have assessed the current landscape of coral health research to reveal biases in the field.  

The team discovered that most papers on coral reef research are published from within the US and Australia, while researchers from countries with large coral reefs, such as The Maldives and Papua New Guinea, are underrepresented. As these reefs are also on the brink of collapse, the UNSW research team emphasizes the importance of local experts to be included. 

They also identified key topic areas that are underrepresented within the existing literature, including coral bioerosion and the microbiome, both of which are important to paint a more complete picture of the state of our reefs.  

Genomic Stability: A Double-Edged Sword for Sharks

The adult pair of epaulette sharks from the study.
Photo Credit: Frank J. Tulenko

Sharks have existed for millions of years, rarely develop cancer, and react sensitively to ecological changes. An international study led by Würzburg scientists shows that one explanation lies in the fish's genes.

Sharks have been populating the oceans for about 400 to 500 million years. While our planet and many of its inhabitants have undergone massive changes several times during this period, this basal group of vertebrates has remained somewhat constant. Their body shape and biology has hardly changed since then.

An international research team from Germany, Australia, Sweden, and the USA has now discovered the reason for this. They found that sharks have the lowest mutation rate between generations ever recorded in vertebrates.

The study was led and coordinated by the research group of Senior Professor Manfred Schartl at the Department of Developmental Biochemistry of the Julius-Maximilians-Universität Würzburg (JMU).

It has now been published in the journal Nature Communications.

New mollusk and crustacean species in symbiosis with worms in dead coral rocks

Bonellia sp. aff. minor (green) and its burrow associates -- Basterotia bonelliphila (right) and Leucothoe bonelliae (left) -- in dead coral rock. The inside of the burrows is partly occupied by sandy sediments collected by Bo. sp. aff. minor.
Image Credit: KyotoU/Ryutaro Goto

Good real estate is not easy to find, even for sea creatures. Sometimes, push comes to shove, and species resort to competition or conquering before weighing the benefits of sharing an ecosystem like housemates.

There is abundant research on live-in symbionts, which share the burrows of other organisms in sand and mud on the seabed. However, studies on burrow niches in rigid substrates, such as rocks on the seabed, have been scarce.

Now, a research team led by Kyoto University has discovered the symbiotic communities of invertebrates in dead coral gravel on the shallow, warm-temperate coast of the Kii Peninsula in western Japan. New bivalve species and sideswimmers have been found to live communally with the greenish Bonellia spoonworm.

Biodegradable plastics still damaging to fish

Professor Indrawati Oey, of the Department of Food Science, and Dr Bridie Allan, of the Department of Marine Science, hold the biodegradable plastic used in the study and a photo of the mottled triplefin, the species analyzed.
Photo Credit: University of Otago

Biodegradable plastics may not be the solution to plastic pollution many hoped for, with a University of Otago study showing they are still harmful to fish.

Petroleum-derived microplastics are known to impact marine life, but little is known about the impact of biodegradable alternatives.

The study, published in Science of the Total Environment and funded by a University of Otago Research Grant, is the first to assess the impact petroleum-derived plastic and biodegradable plastic have on wild fish.

Lead author Ashleigh Hawke, who completed a Master of Science in Otago’s Department of Marine Science, says petroleum-derived plastic exposure negatively affected the fish’s escape performance, routine swimming, and aerobic metabolism.

New insights into the genetics of the common octopus: genome at the chromosome level decoded

Octopus vulgaris
Photo Credit: ©Antonio, Valerio Cirillo (BEOM SZN), 2023

Octopuses are fascinating animals – and serve as important model organisms in neuroscience, cognition research and developmental biology. To gain a deeper understanding of their biology and evolutionary history, validated data on the composition of their genome is needed, which has been lacking until now. Scientists from the University of Vienna together with an international research team have now been able to close this gap and, in a study, determined impressive figures: 2.8 billion base pairs - organized in 30 chromosomes. What sounds so simple is the result of complex, computer-assisted genome analyses and comparisons with the genomes of other cephalopod species. This groundbreaking research has just been published in the renowned journal G3: Genes / Genomes / Genetics.

Octopuses, together with squid and cuttlefish, belong to a group of coleoid cephalopods consisting of several hundreds of species that are characterized by highly diversified lifestyles, body structure and adaptations to their environment. The study of these animals looks back on a long tradition, especially since the neuronal plasticity of the octopus brain – meaning the brain's ability to change and adapt as you learn and experience new things – provides evidence for the existence of functionally analogous structures to the brains of mammals. This is making them a comparative model group for neurophysiological studies. Also, their ability to regenerate parts of their bodies as well as the rapid changes of their body patterns, which are important for camouflage and communication, make octopuses a popular research subject for studying how these innovative traits arose – and how they have changed – during evolution.

FSU scientists find oxygen levels increased during boom in ancient marine life

Postdoctoral fellow Anders Lindskog examined limestone samples from modern-day Scandinavia to unravel why marine life boomed during the Ordovician Period roughly 487 to 443 million years ago.
 Photo Credit: Seth Young

Florida State University scientists have uncovered answers to a conundrum in Earth’s history: Why did marine life experience an extraordinary boom millions of years ago?

Scientists have long been puzzled about what triggered this explosion of life and a remarkable increase in the diversity of marine species during the Ordovician Period roughly 487 to 443 million years ago. A new study led by FSU Associate Professor of Geology Seth Young and postdoctoral fellow Anders Lindskog has provided insights into this ancient ecological transformation and the role oxygen played in it. Their study was published in Nature Geoscience.

To unravel the ancient mystery, Lindskog and Young embarked on a mission with colleagues at FSU and Lund University in Sweden to understand the environmental conditions, particularly the oxygen levels in the ancient seas, of the Ordovician Period. Oxygen is essential for the development of higher organisms, so it’s a key player in the evolution of marine life.

“By better understanding the backdrop to these changes, we can better understand the mechanisms that drive large-scale and long-term evolution — basically, how life became what it is today,” said Lindskog, who is now at Lund University.

Whaling wiped out far more fin whales than previously thought

The study found current conservation efforts should be enough to help the Eastern North Pacific fin whale population rebound without becoming inbred.
Photo Credit: Aqqa Rosing-Asvid
(CC BY 4.0 DEED)

A new genomic study by UCLA biologists shows that whaling in the 20th century destroyed 99% of the Eastern North Pacific fin whale breeding, or “effective,” population — 29% more than previously thought.

But there is also some good news: Genes among members of this endangered species are still diverse enough that current conservation measures should be be enough to help the population rebound without becoming inbred. The study also found that the health of this group is essential for the survival of highly isolated, genetically distinct fin whales in the Gulf of California.

The study, published in Nature Communications, is among the first to use whole genome information to get a picture of the size and genetic diversity of today’s population. Previous studies had to rely on whaling records or mitochondrial DNA, which is inherited only from the mother, providing limited genetic information.

In the 19th century, whaling decimated most whale species around the world but left the largest ones — blue and fin whales — largely untouched. That changed with the advent of industrial whaling in the 20th century. By midcentury, close to a million fin whales worldwide had been slaughtered, at least 75,000 of these in the Eastern North Pacific.

Reducing fishing gear could save whales with low impacts to California’s crab fishermen

 Less gear in the water means fewer chances for Whales to become entangled.
Photo Credit E. Lyman/ NOAA Sanctuaries

Sometimes simple solutions are better. It all depends on the nature of the problem. For humpback whales, the problem is the rope connecting a crab trap on the seafloor to the buoy on the surface. And for fishermen, it’s fishery closures caused by whale entanglements.

Managing this issue is currently a major item on California’s agenda, and it appears less fishing gear may be the optimal solution. So says a team of researchers led by Christopher Free, at UC Santa Barbara, after modeling the benefits and impacts that several management strategies would have on whales and fishermen. Their results, published in the journal Biological Conservation, find that simply reducing the amount of gear in the water is more effective than dynamic approaches involving real-time monitoring of whale populations. There may even be solutions on the horizon that provide these benefits with fewer drawbacks.

“We were trying to figure out what types of management strategies would work best at reducing whale entanglements in the Dungeness crab fishery while also minimizing impacts to fishing,” said first author Free, a researcher at the university’s Marine Science Institute. “And what we found is that some of the simpler strategies, such as just reducing the amount of gear allocated to the fishermen, outperformed a lot of the more complex management strategies.”

Growth of coral reefs likely cannot keep pace with rising sea level

The upper panel shows a coral reef margin in Belize with living branched Acropora (elkhorn) and platy Millepora (fire) corals, which are both competitive and fast-growing. The lower panel shows broken branches of dead Acropora corals overgrown by weedy, fertile hill and finger corals (Porites) as well as fleshy algae.
Photo Credit: E. Gischler.

In identifying and dating coral remains in drill cores taken from Belize reefs, a team of experts from Goethe University Frankfurt and partners from Germany, the USA and Canada has shown the importance of specific types of coral for reef-building during the current Holocene geological epoch, dating back some 12,000 years. The scientists found that certain coral species disappeared for longer periods in the past due to climate changes, and identified another climate-related threat to coral reefs: In addition to warming and ocean acidification, among others, the rising sea level also threatens coral reefs, whose growth rates cannot keep up. 

Tropical coral reefs could end up being one of the first victims of climate change. The marine diversity hotspots are threatened by and declining as a result of global warming, ocean acidification, a deterioration of water quality, as well as diseases of reef-building organisms, and their growth is unable to keep up with the projected rise in sea levels. These are some of the conclusions drawn by an interdisciplinary team of scientists from Goethe University Frankfurt's Institute of Geosciences, the company ReefTech Inc., the GEOMAR Helmholtz Center of Ocean Research, the University of Ottawa's Department of Earth and Environmental Sciences, and the GSI Helmholtz Center of Heavy Ion Research. Their findings are based on an examination of 22 drill cores collected from the Belize barrier reef and atolls, the largest reef system in the Atlantic Ocean, which focused on identifying and dating coral growth and accretion rates over the past 9,000 years.