Deep parts of Great Barrier Reef ‘insulated’ from global warming – for now

Mesophotic corals on the Great Barrier Reef.
Photo Credit Prof Peter Mumby

Some deeper areas of the Great Barrier Reef are insulated from harmful heatwaves – but that protection will be lost if global warming continues, according to new research.

High surface temperatures have caused mass “bleaching” of the Great Barrier Reef in five of the last eight years, with the latest happening now.

Climate change projections for coral reefs are usually based on sea surface temperatures, but this overlooks the fact that deeper water does not necessarily experience the same warming as that at the surface.

The new study – led by the universities of Exeter and Queensland – examined how changing temperatures will affect mesophotic corals (depth 30-50 meters).

It found that separation between warm buoyant surface water and cooler deeper water can insulate reefs from surface heatwaves, but this protection will be lost if global warming exceeds 3°C above pre-industrial levels.

The researchers say similar patterns could occur on other reefs worldwide, but local conditions affecting how the water moves and mixes will mean the degree to which deeper water coral refuges exist and remain insulated from surface heatwaves will vary.

“Coral reefs are the canary in the coalmine, warning us of the many species and ecosystems affected by climate change,” said Dr Jennifer McWhorter, who led the research during a QUEX PhD studentship at the universities of Exeter and Queensland.

Tomorrow's reefs – the importance of environmental awareness in coral restoration

Restoration nursery in the northern Red Sea of smooth cauliflower coral (Stylophora pistillata), almost ready for reef transplantation. Classified as near-threatened, S. pistillata is native to the wider Indo-Pacific region. This nursery is at 5 metres depth, close to the Inter University Institute of Marine Science, Eilat.
Photo Credit: H Nativ/Morris Kahn Marine Research

Around the world, projects are underway to save or rebuild damaged coral reefs. However, many restoration projects fail within just a few years. Giving more consideration to current and future environmental conditions would, in many cases, improve long-term restoration success, say the researchers behind a new article published in Plos Biology.

Coral reefs are extremely valuable. An estimated 25 percent of all plants and animals in the ocean, and 1 billion people worldwide depend on them – for food, income, coastal protection or cultural traditions. But their existence is also threatened by multiple factors, such as climate change, pollution, overfishing and coastal development.

Relying on climate change mitigation alone to ensure the future viability of coral reefs is no longer realistic. Targeted efforts are now needed, and restoration of damaged coral reefs has today become a multimillion-dollar business. Nevertheless, the long-term outcome of many coral restoration projects is highly uncertain.

Shy sea anemones are more likely to survive heatwaves

Photo Credit: Praveen Kenderla

Even in nature, pride can prevail. A study with researchers from the University of Gothenburg shows that sea anemones that react more slowly to change can survive a heatwave better than individuals that change their behavior quickly.

Along the Atlantic coasts of Europe, many species are exposed to abrupt shifts in habitat. Tides, storms and rapid temperature changes are commonplace for the marine species that live there. With climate change, heatwaves are expected to become more frequent, and researchers wanted to find out how coastal marine species cope with extreme water temperatures. They chose to study the sea anemone species Actinia equina, a species that exhibits individual behaviors.

Bold or shy

“We call them animal personalities. They are different behavioral life strategies found in the same species. The anemones we studied have two personality traits, bold and shy, and in extreme heat waves the shy anemones do better,” says Lynne Sneddon, a zoophysiologist at the University of Gothenburg and co-author of the study published in the Journal of Experimental Biology.

AI breakthrough: UH researchers help uncover climate impact on whales

Underside of a humpback whale’s tail fluke which can serve as a “finger-print” for identification.
Photo Credit: Adam Pack

More than 10,000 images of humpback whale tail flukes collected by University of Hawaiʻi researchers have played a pivotal role in revealing both positive and negative impacts on North Pacific humpback whales, positive trends in the historical annual abundance of North Pacific humpback whales, and how a major climate event negatively impacted the population. Adam Pack, who heads the UH Hilo Marine Mammal Laboratory, Lars Bejder, director of the UH Mānoa Marine Mammal Research Program (MMRP) and graduate students Martin van Aswegen and Jens Currie, co-authored a study on humpback whales in the North Pacific Ocean, and the images—along with artificial intelligence (AI)-driven image recognition—were instrumental in tracking individuals and offering insights into their 20% population decline observed in 2012–21.

“The underside of a humpback whales tail fluke has a unique pigmentation pattern and trailing edge that can serve as the ‘finger-print’ for identifying individuals,” said Pack.

‘Back to the Future’ to Forecast the Fate of a Dead Florida Coral Reef

Alex Modys, Ph.D., diving at the coral death assemblage in Pompano Ridge and digging up a subfossil coral, Orbicella annularis.
Photo Credit: Anton Olenik, Ph.D., Florida Atlantic University

Rising temperatures and disease outbreaks are decimating coral reefs throughout the tropics. Evidence suggests that higher latitude marine environments may provide crucial refuges for many at-risk, temperature-sensitive coral species. However, how coral populations expand into new areas and sustain themselves over time is constrained by the limited scope of modern observations. 

What can thousands of years of history tell us about what lies ahead for coral reef communities? A lot. In a new study, Florida Atlantic University researchers and collaborators provide geological insights into coral range expansions by reconstructing the composition of a Late Holocene-aged subfossil coral death assemblage in an unusual location in Southeast Florida and comparing it to modern reefs throughout the region. 

Located off one of the most densely populated and urbanized coastlines in the continental United States, the Late Holocene coral death assemblage known as “Pompano Ridge,” records a northward range expansion of tropical coral communities that occurred during a period of regional climate warming more than 2,000 years ago.

Could this happen again in the face of climate change? Going “back to the future,” this study offers a unique glimpse into what was once a vibrant coral reef assemblage and explores if history can repeat itself.

Hypoxia is widespread and increasing in the ocean off the Pacific Northwest coast

In late August, OSU's Jack Barth and his colleagues deployed a glider that traversed Oregon’s near-shore waters from Astoria to Coos Bay and measured the oxygen levels through the water column, and beamed the data back to OSU computers.
Photo Credit: Courtesy of Jack Barth.

Low oxygen conditions that pose a significant threat to marine life are widespread and increasing in coastal Pacific Northwest ocean waters as the climate warms, a new study shows.

Researchers found that in 2021, more than half the continental shelf off the Pacific Northwest coast experienced the low-oxygen condition known as hypoxia, said the study’s lead author, Jack Barth of Oregon State University.

“We’ve known that low oxygen conditions are increasing based on single points of study in the past, but this confirms that these conditions are occurring across Pacific Northwest coastal waters,” said Barth, an oceanography professor in the College of Earth, Ocean, and Atmospheric Sciences. “The 2021 season was unusually strong compared to past years but with climate change, we are headed in a direction where this may be the norm.”

The new study, published recently in Nature Scientific Reports, is based on data collected by an unprecedented number of research vessels and autonomous underwater gliders that were collecting measurements in the ocean during summer 2021.

Menopause explains why some female whales live so long

Orcas
Photo Credit: NOAA

Females of some whale species have evolved to live drastically longer lives so they can care for their families, new research shows.

The study focused on five whale species that – along with humans – are the only mammals known to go through menopause.

The findings show that females of these whale species that experience menopause live around 40 years longer than other female whales of a similar size.

By living longer without extending their “reproductive lifespan” (the years in which they breed), these females have more years to help their children and grandchildren, without increasing the “overlap” period when they compete with their daughters by breeding and raising calves at the same time.

This new research shows that – despite being separated by 90 million years of evolution – whales and humans show remarkably similar life histories, which have evolved independently.

The study was carried out by the universities of Exeter and York, and the Center for Whale Research.

“The process of evolution favors traits and behaviors by which an animal passes its genes to future generations,” said lead author Dr Sam Ellis, from the University of Exeter.

Marine heat waves disrupt the ocean food web in the northeast Pacific Ocean

Pyrosomes.
Photo Credit: Mark Farley, Hatfield Marine Science Center, Oregon State University.

Marine heat waves in the northeast Pacific Ocean create ongoing and complex disruptions of the ocean food web that may benefit some species but threaten the future of many others, a new study has shown.

The study, just published in the journal Nature Communications, is the first of its kind to examine the impacts of marine heat waves on the entire ocean ecosystem in the northern California Current, the span of waters along the West Coast from Washington to Northern California.

The researchers found that the biggest beneficiary of marine heat waves is gelatinous zooplankton – predominantly cylindrical-shaped pyrosomes that explode in numbers following a marine heat wave and shift how energy moves throughout the food web, said lead author Dylan Gomes, who worked on the study as a postdoctoral scholar with Oregon State University’s Marine Mammal Institute.

“If you look at single species interactions, you’re likely to miss a lot,” Gomes said. “The natural effects of a disturbance are not necessarily going to be straightforward and linear. What this showed us is that these heat waves impact every predator and prey in the ecosystem through direct and indirect pathways.”

The project was a collaboration by Oregon State University and the National Oceanic and Atmospheric Administration. Joshua Stewart, an assistant professor with the Marine Mammal Institute, mentored Gomes and co-authored the paper.

Range-shifting fishes are climate-change losers, according to new research

Pouting (Trisopterus luscus)
Photo Credit: Diego Delso
(CC BY-SA 4.0 DEED)

The warming of the Earth’s oceans due to climate change is affecting where the world’s fishes live, eat and spawn — and often in ways that can negatively impact their populations. That’s according to a new paper in the journal Nature Ecology and Evolution.

The researchers write that populations that experience rapid-range shift decline noticeably, up to 50 per cent over a decade. The populations affected most are those living on the northern poleward edges of their species’ range.

“There is a conventional wisdom among many climate-change biologists that species that shift their ranges quickly by moving northward should provide a mechanism to sustain healthy populations — that shifting species should be climate-change winners. Our results show the exact opposite,” says paper co-author Jean-Philippe Lessard, a professor in the Department of Biology.

“Species that are shifting their range quickly experience little change in their population size in their core range. But some of them experience a major collapse in their populations at the northern edges.

“In fact, the population collapse is mostly driven by the northern poleward populations,” he adds. “We were expecting that many individuals from the core of the range would be moving up north due to climate change and maintain these northern populations. But the northern-edge populations are the ones most likely to collapse.”

Maternal obesity may promote liver cancer

Obese mice pass on an altered microbiome to their offspring, which has an impact on liver health in adulthood and increases the risk of liver cancer. Normalising the intestinal microbiome reduces the risk of cancer. Specific families of bacteria are linked to tumour burden and liver inflammation.
Image Credit: Toso, Moeckli et al. 2024
CC-by-nc-nd

A team from the UNIGE and the HUG has revealed the role of the microbiota in the increased risk of developing liver disease in the offspring of mothers suffering from obesity.

Obesity, which could reach 50% of the population in certain developed countries by 2030, is a major public health concern. It not only affects the health of those who suffer from it, but could also have serious consequences for their offspring. Scientists at the University of Geneva (UNIGE) and the Geneva University Hospitals (HUG) have studied the impact of maternal obesity on the risk of developing liver disease and liver cancer. Using an animal model, the team discovered that this risk was indeed much higher in the offspring of mothers suffering from obesity. One of the main causes was the transmission of a disturbed intestinal microbiota from the mother, resulting in a chronic liver disease whose effects became apparent in adulthood. These results, which have yet to be confirmed in humans, are a warning signal and a call for action to limit the deleterious effect of obesity on children. This research is published in the journal JHEP Reports.

History repeats as Coral Bay faces mass loss of coral and fish life

Photo Credit: Nico Smit

A perfect storm of environmental factors has seen a monumental loss of fish and coral life at a popular area of Ningaloo Reef in Western Australia’s Gascoyne region — however Curtin University research into the event shows there is hope it will recover.

In March 2022, during the annual coral spawning event, calm weather and limited tidal movement combined to trap the coral’s eggs within Bills Bay, at the town of Coral Bay.

This led to an excess of nutrients in the water which consumed more oxygen than usual — causing massive numbers of fish and corals to die from asphyxiation.

Study lead Associate Professor Zoe Richards, from Curtin’s School of Molecular and Life Sciences, said a lack of oxygen is a well-known risk for tropical coral reefs.

“Severely low oxygen levels in the ocean can create ‘dead zones’ where almost nothing can live, causing a lot of harm to nature and, in tourist areas such as Coral Bay, this can also impact the economy and community,” Associate Professor Richards said.

Unprecedented heatwaves revealed by marine lab’s historic data

Photo Credit: Courtesy of University of Auckland

A unique record at the University of Auckland's Leigh marine lab shows dramatic change in the Hauraki Gulf.

A thermometer dipped in a bucket of sea water on New Year’s Day in 1967 began a unique record which shows the dramatic intensification of warming in the Hauraki Gulf.

Sea-surface readings at the Leigh Marine Laboratory north of Auckland since that time indicate the “unprecedented nature of recent marine heatwaves,” according to Dr Nick Shears of the University of Auckland, Waipapa Taumata Rau.

The number of marine heatwave days and their cumulative intensity has increased sharply since 2012, Shears and his co-authors write in a paper published in the New Zealand Journal of Marine and Freshwater Research.

In past decades, some years had no heatwaves, but that hasn’t happened since 2012. Sponges `melting,’ becoming detached from rocks and dying, along with seaweed and kelp die-offs, are among temperature effects.

Especially warm autumns and winters have likely facilitated an increase in subtropical and tropical species such as the long-spined sea urchin Centrostephanus rodgersii, a voracious herbivore which can lay waste to deep reef environments.

Marine algae implants could boost crop yields

Discovery could lead to more sustainable food supply
Photo Credit: Oktavianus Mulyadi

Scientists have discovered the gene that enables marine algae to make a unique type of chlorophyll. They successfully implanted this gene in a land plant, paving the way for better crop yields on less land. 

Finding the gene solves a long-standing mystery amongst scientists about the molecular pathways that allow the algae to manufacture this chlorophyll and survive. 

“Marine algae produce half of all the oxygen we breathe, even more than plants on land. And they feed huge food webs, fish that get eaten by mammals and humans,” said UC Riverside assistant professor of bioengineering and lead study author Tingting Xiang. “Despite their global significance, we did not understand the genetic basis for the algae’s survival, until now.”

The study, published in Current Biology, also documents another first-of-its-kind achievement: demonstrating that a land plant could produce the marine chlorophyll. Tobacco plants were used for this experiment, but in theory, any land plant may be able to incorporate the marine algae gene, allowing them to absorb a fuller spectrum of light and achieve better growth. 

Aerial surveys reveal ample populations of rays in southeast Florida

The giant manta ray is designated as threatened under the U.S. Endangered Species Act and is protected in Florida waters.
Photo Credit: Steve Kajiura, Florida Atlantic University

The whitespotted eagle ray (Aetobatus narinari) and the giant manta ray (Mobula birostris) are rapidly declining globally. Both species are classified by the International Union for Conservation of Nature as endangered worldwide and the giant manta ray is designated as threatened under the United States Endangered Species Act.

In Florida waters, giant manta rays and whitespotted eagle rays are protected species. To provide effective management for these species, it is necessary to gather information on their distribution and abundance.

Using aerial surveys, Florida Atlantic University researchers conducted a unique long-term (2014 to 2021) study to quantify the spatial (latitude) and temporal (month, year) abundance of the whitespotted eagle rays and giant manta rays in Southeast Florida. The researchers conducted 120 survey flights between January 2014 and December 2021 along the Atlantic Coast from Miami north to the Jupiter Inlet. They reviewed the video footage from the flights to quantify the number of rays of each species.

New Fish Species Discovered at Remote Islands Off Mexico’s Pacific Coast

Two females of the newly discovered species, Halichoeres sanchezi or the tailspot wrasse. The males are larger and have different coloration.
Photo Credit: Allison & Carlos Estape

A team of scientists including Ben Frable of UC San Diego’s Scripps Institution of Oceanography have discovered a new species of tropical fish during an expedition to the remote islands of the Revillagigedo Archipelago off Mexico’s Pacific coast. The fish is likely endemic to these islands, meaning it is found no place else on Earth. The Revillagigedos are sometimes called the “Mexican Galapagos” for their trove of marine biodiversity and rugged beauty. 

The researchers describe the new species, dubbed Halichoeres sanchezi or the tailspot wrasse, in a paper published Feb. 28 in the journal PeerJ. Halichoeres sanchezi was named in honor of marine scientist Carlos Armando Sánchez Ortíz of the Universidad Autónoma de Baja California Sur (UABCS) who collected the first specimen and who organized the 2022 expedition that led to the fish’s discovery.

The eight specimens of the new species collected by the team range in size from around an inch long to nearly six inches. The smaller females of the species are mostly white with reddish horizontal stripes along their top half and black patches on their dorsal fin, behind their gills, and just ahead of their tail fin. Frable described the males as “orangy red up top fading to a yellow belly with a dark band at the base of the tail.” 

Halichoeres sanchezi is a member of the wrasse family, a highly diverse and colorful group of more than 600 species. Most wrasse are less than seven inches long, such as the bluestreak cleaner wrasse (Labroides dimidiatus), but some get much larger like the California sheephead (Semicossyphus pulcher) or the massive humphead wrasse (Cheilinus undulatus), which can reach seven feet in length.

Researchers encountered the new wrasse species inhabiting an underwater field of volcanic rubble at a depth of around 70 feet near San Benedicto Island.

‘Janitors’ of the Sea: Overharvested Sea Cucumbers Play Crucial Role in Protecting Coral

Photo Credit: Cody Clements

Corals are foundational for ocean life. Known as the rainforests of the sea, they create habitats for 25% of all marine organisms, despite only covering less than 1% of the ocean’s area. 

Coral patches the width and height of basketball arenas, used to be common throughout the world’s oceans. But due to numerous human-generated stresses and coral disease, which is known to be associated with ocean sediments, most of the world’s coral is gone.

“It’s like if all the pine trees in Georgia disappeared over a period of 30 to 40 years,” said Mark Hay, Regents’ Chair and the Harry and Anna Teasley Chair in Environmental Biology in the School of Biological Sciences at the Georgia Institute of Technology. “Just imagine how that affects biodiversity and ecosystems of the ocean.”

In first-of-its-kind research, Hay, along with research scientist Cody Clements, discovered a crucial missing element that plays a profound role in keeping coral healthy — an animal of overlooked importance known as a sea cucumber.

New study uncovers the importance of deepwater ecosystems for endangered species

Hawksbills typically forage on coral reefs where their diet is predominantly sponges.
Photo Credit: Jeanne A Mortimer

Using tracking data, a new study has revealed for the first time that hawksbill turtles feed at reef sites much deeper than previously thought.

Critically endangered hawksbill turtles are found in every ocean and are the most tropical of sea turtles. Adult hawksbills have long been considered to have a close association with shallow (less than 15 meters depth) seas where coral reefs thrive.

Young hawksbills drift in currents during their open water phase of their development before they move to seabed habitats. Hawksbills are usually seen foraging in coral reefs where their diet is predominantly sponges.

To study their feeding habits in more detail, researchers at Swansea, Florida and Deakin universities used high-accuracy GPS satellite tags to track 22 adult female hawksbills from their nesting site on Diego Garcia in the Chagos archipelago in the Indian Ocean to their foraging grounds.

Research reveals new insights into marine plastic pollution

Photo Credit: Lucien Wanda

A groundbreaking study led by researchers at the University of Stirling has uncovered the crucial role of bacteria living on plastic debris.

The research also identifies rare and understudied bacteria that could assist in plastic biodegradation, offering new insights for tackling plastic pollution.

Plastic pollution is a worldwide problem, with up to two million tons estimated to enter oceans every year, damaging wildlife and ecosystems.

In a pioneering study, experts at the University of Stirling’s Faculty of Natural Sciences and the University of Mons (Belgium) analyzed the proteins in plastic samples taken from Gullane Beach in Scotland.

Unlike previous studies carried out in warmer climates that focus on the genetic potential of biofilms inhabiting plastics, this research led by Dr Sabine Matallana-Surget took a unique approach by analyzing the proteins expressed by active microorganisms.

Their findings have unveiled a remarkable discovery of enzymes actively engaged in degrading plastic. Moreover, the team has pioneered new methodologies for enhanced predictions in marine microbiology research.

Baleen whales evolved a unique larynx to communicate

humpback whales
Image Credit: Jeanette Atherton AI generated.

The new results also make it clear that human noise in the oceans severely restricts the animals

The iconic baleen whales, such as the blue, gray and humpback whale, depend on sound for communication in the vast marine environment where they live. However, ever since whale song were first discovered more than 50 years ago, it remained unknown how baleen whales produce their complex vocalizations – until now. A team led by the voice scientists Coen Elemans from the University of Southern Denmark and Tecumseh Fitch from the University of Vienna has now for the first time found that baleen whales evolved novel structures in their larynx to make their vast array of underwater songs. The study was published in the prestigious journal Nature. 

Baleen whales are the largest animals to have ever roamed our planet and as top predators play a vital role in marine ecosystems. To communicate across vast distances and find each other, baleen whales depend critically on the production of sounds that travels far in murky and dark oceans. 

A new study in the prestigious journal Nature reports that baleen whales evolved unique structures in their larynx that enable their low-frequency vocalizations, but also limit their communication range.

"The toothed and baleen whales evolved from land mammals that had a larynx serving two functions: protecting the airways and sound production. However, their transition to aquatic life placed new and strict demands on the larynx to prevent choking underwater.", says Tecumseh Fitch. 

Compounds released by bleaching coral reefs promote bacteria

Field site in Moʻorea, French Polynesia.
Photo Credit: Milou Arts of NIOZ

On healthy reefs, corals, algae, fishes and microbes live interconnected and in balance—exchanging nutrients, resources and chemical signals. New research led by the University of Hawaiʻi at Mānoa and the Royal Netherlands Institute for Sea Research (NIOZ) revealed that when coral bleaching occurs, corals release unique organic compounds into the surrounding water that not only promote bacterial growth overall, but also promote bacteria that may further stress reefs and pose the risk for more damage.

“Our results demonstrate how the impacts of both short-term thermal stress and long-term bleaching may extend beyond coral and into the water column,” said Wesley Sparagon, co-lead author, postdoctoral researcher in the UH Mānoa College of Tropical Agriculture and Human Resources and previous doctoral student with the UH Mānoa School of Ocean and Earth Science and Technology (SOEST).

The research team, which included scientists from UH Mānoa, NIOZ, Scripps Institution of Oceanography and University of California, Santa Barbara, conducted experiments on bleached and unbleached corals gathered during a bleaching event in Moorea, French Polynesia in 2019.

“Although coral bleaching is a well-documented and increasingly widespread phenomenon in reefs across the globe, there has been relatively little research on the implications for reef water column microbiology and biogeochemistry,” said Craig Nelson, senior author on the study and professor in SOEST.