Wasous

Something peculiar is happening in the azure waters off the rocky cliffs of Ischia, Italy. There, streams of gas-filled volcanic bubbles rising up to the surface are radically changing life around them by making seawater acidic. Stanford researchers studying species living near these gassy vents have learned what it takes to survive in acidic waters, providing a glimpse of what future oceans might look like as they grow more acidic.

Volcanic carbon dioxide seeps from the ocean floor near Ischia, Italy [Credit: Pasquale Vassallo, Stazione Zoologica Anton Dohrn]

Their findings, published in Nature Communications, suggest that ocean acidification driven by human-caused carbon dioxide emissions could have a larger impact than previously thought.

"When an organism's environment becomes more acidic, it can dramatically impact not only that species, but the overall ecosystem's resilience, function and stability," said Stanford marine biologist Fiorenza Micheli, lead author on the paper. "These transformations ultimately impact people, especially our food chains."

A natural laboratory

Most ocean acidification studies to date have taken place in laboratories, making it impossible to assess how whole ecosystems comprised of multiple, interacting species would be affected. The real-life laboratory provided researchers an opportunity to examine dozens of species, from sea urchins to marine snails, that live in areas of different acidity along Ischia's volcanic carbon dioxide vents. In addition to studying how species diversity changed with acidification, they analyzed species traits, such as diet and growth, that influence how well the ecosystem performs. For example, sea snails were smaller in more acidic water, as their shells take longer to grow and are thinner and more brittle. These harmful effects on sea snails, a key food for animals higher up in the food chain, may affect fish populations.

Overall, the researchers found that the active venting zones with the most acidic waters were home to not only the least number of species, but also the lowest amounts of "functional diversity" – the range of ecosystem-support services or roles that each species can provide.

"Studying the natural carbon dioxide vents in Ischia allowed us to unravel which traits from different species, like snail shell strength, were more vulnerable to ocean acidification. These results illuminate how oceans will function under different acidification scenarios in the future," said lead author Nuria Teixidó, a marine biologist from Stazione Zoologica Anton Dohrn in Italy, who was a visiting researcher at Stanford during the research.

Acidification in the waters of Ischia displaced long-lived species, such as corals, that form habitat for other species – a process already often witnessed on reefs across the world. The researchers also found that high levels of carbon dioxide and more acidity favored species with short life spans and fast turnover as they are the only species that can resist these environmental conditions. This change could lead to further diversity loss and instability in the oceans, as biodiversity tends to increase an ecosystem's stability.

Biodiversity loss is mapped along a natural CO2 gradient [Credit: Nuria Teixidó, Stazione Zoologica Anton Dohrn]

A broader application

Localized case studies such as Ischia can shed light on how future global environmental conditions may affect ocean life. Beyond losing biodiversity, ocean acidification will threaten food security for millions of people who depend on seafood, along with tourism and other ocean-related economies.

"The effects of ocean acidification on whole ecosystems and their functioning are still poorly understood," said Micheli, a professor of biology. "In Ischia, we have gained new insights into what future oceans will look like and what key services, like food production and coastal production, will be lost when there is more carbon dioxide in the water."

Author: Nicole Kravec | Source: Stanford University [December 11, 2018]

The future of the world's coral reefs is uncertain, as the impact of global heating continues to escalate. However, according to a study published in Nature Climate Change, the response of the Great Barrier Reef to extreme temperatures in 2017 was markedly different to one year earlier, following two back-to-back bouts of coral bleaching. Remarkably, corals that bleached and survived 2016 were more resistant in 2017 to a recurrence of hot conditions.

Researchers found that the response of corals to heat stress during the second of two unprecedented back-to-back bleaching events on the Great Barrier Reef was markedly different from the first [Credit: Tane Sinclair-Taylor]

"Dead corals don't bleach for a second time. The north lost millions of heat-sensitive corals in 2016, and most of the survivors were the tougher species. As a result of bleaching, the mix of species is changing very rapidly," said lead author Prof Terry Hughes, Director of the Australian Research Council Centre of Excellence for Coral Reef Studies (Coral CoE), headquartered at James Cook University.

"We were astonished to find less bleaching in 2017, because the temperatures were even more extreme than the year before," he said.

The new research highlights the extent of damage, or "geographic footprint" of multiple coral bleaching events across the 2,300 km length of the world-heritage listed area.

The back-to-back heatwaves bring the total number of mass bleaching events on the Great Barrier Reef to four over the past two decades (in 1998, 2002, 2016 and 2017). The scientists found that only 7% of the Great Barrier Reef escaped bleaching entirely since 1998, and after the 2017 event, 61% of reefs have now been severely bleached at least once.

During an underwater survey, a researcher records the bleaching severity of a massive Porites coral colony on the Great Barrier Reef [Credit: Justin Marshall]

"We found, using the National Oceanic and Atmospheric Administration's (NOAA) satellite-based coral bleaching tools, that corals in the north of the Great Barrier Reef were exposed to the most heat stress in 2016. A year later, the central region saw the most prolonged heating," said co-author Dr Mark Eakin, from NOAA's Coral Reef Watch program, in Maryland, USA.

The southern third of the Great Barrier Reef was cooler in both years due to local weather conditions, and escaped with only minor bleaching.

"It's only a matter of time before we see another mass-bleaching event, triggered by the next marine heatwave, driven by global heating," said co-author Dr Andrew Hoey of Coral CoE at James Cook University. "One of the worst possible scenarios is we'll see these southern corals succumb to bleaching in the near future."

"The outcome in 2017 depended on the conditions experienced by the corals one year earlier. We called that 'ecological memory,' and show that these repeating events are now acting together in ways that we didn't expect," said Prof Hughes.

"We've never seen back-to-back mass coral bleaching before on the Great Barrier Reef, in two consecutive summers. The combined footprint has killed close to half of the corals on two-thirds of the world's largest reef system," said Dr Hoey.

"We need urgent global action on greenhouse emissions to save the world's coral reefs. Australia should be -- but regrettably isn't -- at the forefront of tackling global heating," said Prof Hughes.

Source: ARC Centre of Excellence in Coral Reef Studies [December 10, 2018]

Dolphins in the northern Adriatic contain high levels of PCBs – highly toxic chemicals banned in the 1970s and 1980s – and are passing the pollutant to their young, according to new research led by a marine scientist at the University of St Andrews.

Credit: Tilen Genov/ University of St Andrews

An international team of researchers evaluated PCB and other organochlorine contaminants in bottlenose dolphins (Tursiops truncatus) living in the Gulf of Trieste (northern Adriatic Sea), the northernmost part of the Mediterranean Sea and one of the most human-impacted areas in the Mediterranean.

They found that, overall, 87.5% of dolphins had PCB concentrations above the toxicity threshold for the onset of physiological effects in marine mammals, while 65.6% had concentrations above the highest threshold published for marine mammals based on reproductive impairment in seals. Such high contaminant levels are of concern, particularly in combination with other threats to dolphins, including bycatch in fisheries, disturbance by boat traffic, and prey depletion.

The research, published in the journal Science of the Total Environment, involved Morigenos – Slovenian Marine Mammal Society (Slovenia), the Sea Mammal Research Unit at the University of St Andrews (UK), the Zoological Society of London's Institute of Zoology (UK), the Centre for Environment, Fisheries and Aquaculture Science (CEFAS, UK) and the Institute of Marine Sciences of the Italian National Research Council (Italy).

Credit: Genov et al, Morigenos – Slovenian Marine Mammal Society (Slovenia)

Tilen Genov, lead author of the study and a Ph.D. student at the University of St Andrews, said:

"We have been studying these dolphins for over 16 years, so we know most of them well. Through long-term re-sighting histories of identified individuals, we were able to link PCB levels in individual dolphins to parameters such as sex, reproductive output and social group membership.

"The research showed that males have significantly higher pollutant concentrations than females. This is because females offload a substantial amount of their toxicological burden to their young through gestation and lactation.

Credit: Tilen Genov/ University of St Andrews

"That is also why females that have not yet had calves had significantly higher concentrations than those that had previously produced at least one calf. Such results are expected based on our knowledge of mammal physiology, but it is not very common to demonstrate this phenomenon in wild whales and dolphins."

Dr. Paul Jepson, co-author of the study and specialist wildlife veterinarian at the Zoological Society of London's Institute of Zoology, said:

"This is another study showing high or very high levels of a very toxic and persistent pollutant – PCBs – in European dolphins. PCBs have the ability to cause diseases like cancer and can also suppress reproduction."

Source: University of St Andrews [December 10, 2018]

The largest extinction in Earth's history marked the end of the Permian period, some 252 million years ago. Long before dinosaurs, our planet was populated with plants and animals that were mostly obliterated after a series of massive volcanic eruptions in Siberia.

This illustration shows the percentage of marine animals that went extinct at the end of the Permian era by latitude, from the model (black line) and from the fossil record (blue dots). A greater percentage of marine animals survived in the tropics than at the poles. The color of the water shows the temperature change, with red being most severe warming and yellow less warming. At the top is the supercontinent Pangaea, with massive volcanic eruptions emitting carbon dioxide. The images below the line represent some of the 96 percent of marine species that died during the event. Includes  fossil drawings by Ernst Haeckel/Wikimedia; Blue crab photo by Wendy Kaveney/Flickr; Atlantic cod photo by Hans-Petter Fjeld/Wikimedia; Chambered nautilus photo by ©2010 John White/CalPhotos [Credit: Justin Penn and Curtis Deutsch/University of Washington]

Fossils in ancient seafloor rocks display a thriving and diverse marine ecosystem, then a swath of corpses. Some 96 percent of marine species were wiped out during the "Great Dying," followed by millions of years when life had to multiply and diversify once more.

What has been debated until now is exactly what made the oceans inhospitable to life - the high acidity of the water, metal and sulfide poisoning, a complete lack of oxygen, or simply higher temperatures.

New research from the University of Washington and Stanford University combines models of ocean conditions and animal metabolism with published lab data and paleoceanographic records to show that the Permian mass extinction in the oceans was caused by global warming that left animals unable to breathe. As temperatures rose and the metabolism of marine animals sped up, the warmer waters could not hold enough oxygen for them to survive.

"This is the first time that we have made a mechanistic prediction about what caused the extinction that can be directly tested with the fossil record, which then allows us to make predictions about the causes of extinction in the future," said first author Justin Penn, a UW doctoral student in oceanography.

This fossilized spiraling shark tooth is from the Helicoprion, an unusual shark that lived during the Permian. The tooth whorl was located inside the shark’s lower jaw. The fossil is on display at the Idaho Museum of Natural History [Credit: James St. John/Flickr]

Researchers ran a climate model with Earth's configuration during the Permian, when the land masses were combined in the supercontinent of Pangaea. Before ongoing volcanic eruptions in Siberia created a greenhouse-gas planet, oceans had temperatures and oxygen levels similar to today's. The researchers then raised greenhouse gases in the model to the level required to make tropical ocean temperatures at the surface some 10 degrees Celsius (20 degrees Fahrenheit) higher, matching conditions at that time.

The model reproduces the resulting dramatic changes in the oceans. Oceans lost about 80 percent of their oxygen. About half the oceans' seafloor, mostly at deeper depths, became completely oxygen-free.

To analyze the effects on marine species, the researchers considered the varying oxygen and temperature sensitivities of 61 modern marine species -- including crustaceans, fish, shellfish, corals and sharks -- using published lab measurements. The tolerance of modern animals to high temperature and low oxygen is expected to be similar to Permian animals because they had evolved under similar environmental conditions. The researchers then combined the species' traits with the paleoclimate simulations to predict the geography of the extinction.

"Very few marine organisms stayed in the same habitats they were living in -- it was either flee or perish," said second author Curtis Deutsch, a UW associate professor of oceanography.

A fossil from Morocco of a Diademaproetus, one of the trilobites that were plentiful in the world’s oceans but went extinct at the end of the Permian [Credit: Géry Parent/Flickr]

The model shows the hardest hit were organisms most sensitive to oxygen found far from the tropics. Many species that lived in the tropics also went extinct in the model, but it predicts that high-latitude species, especially those with high oxygen demands, were nearly completely wiped out.

To test this prediction, co-authors Jonathan Payne and Erik Sperling at Stanford analyzed late-Permian fossil distributions from the Paleoceanography Database, a virtual archive of published fossil collections. The fossil record shows where species were before the extinction, and which were wiped out completely or restricted to a fraction of their former habitat.

The fossil record confirms that species far from the equator suffered most during the event.

"The signature of that kill mechanism, climate warming and oxygen loss, is this geographic pattern that's predicted by the model and then discovered in the fossils," Penn said. "The agreement between the two indicates this mechanism of climate warming and oxygen loss was a primary cause of the extinction."

A fossil of a Paramblypterus, a species of fish that went extinct during the Permian. This fossil is on display at the State Museum of Natural History in Karlsruhe, Germany [Credit: H. Zell/WikiCommons]

The study builds on previous work led by Deutsch showing that as oceans warm, marine animals' metabolism speeds up, meaning they require more oxygen, while warmer water holds less. That earlier study shows how warmer oceans push animals away from the tropics.

The new study combines the changing ocean conditions with various animals' metabolic needs at different temperatures. Results show that the most severe effects of oxygen deprivation are for species living near the poles.

"Since tropical organisms' metabolisms were already adapted to fairly warm, lower-oxygen conditions, they could move away from the tropics and find the same conditions somewhere else," Deutsch said. "But if an organism was adapted for a cold, oxygen-rich environment, then those conditions ceased to exist in the shallow oceans."

The so-called "dead zones" that are completely devoid of oxygen were mostly below depths where species were living, and played a smaller role in the survival rates. "At the end of the day, it turned out that the size of the dead zones really doesn't seem to be the key thing for the extinction," Deutsch said. "We often think about anoxia, the complete lack of oxygen, as the condition you need to get widespread uninhabitability. But when you look at the tolerance for low oxygen, most organisms can be excluded from seawater at oxygen levels that aren't anywhere close to anoxic."

This roughly 1.5-foot slab of rock from southern China shows the Permian-Triassic boundary. The bottom section is pre-extinction limestone. The upper section is microbial limestone deposited after the extinction [Credit: Jonathan Payne/Stanford University]

Warming leading to insufficient oxygen explains more than half of the marine diversity losses. The authors say that other changes, such as acidification or shifts in the productivity of photosynthetic organisms, likely acted as additional causes.

The situation in the late Permian -- increasing greenhouse gases in the atmosphere that create warmer temperatures on Earth -- is similar to today.

"Under a business-as-usual emissions scenarios, by 2100 warming in the upper ocean will have approached 20 percent of warming in the late Permian, and by the year 2300 it will reach between 35 and 50 percent," Penn said. "This study highlights the potential for a mass extinction arising from a similar mechanism under anthropogenic climate change."

The study is published in the journal Science.

Author: Hannah Hickey | Source: University of Washington [December 06, 2018]

New NASA research has found that increases in the rate at which Arctic sea ice grows in the winter may have partially slowed down the decline of the Arctic sea ice cover.

The sun setting over the Arctic sea ice pack, as observed during the Beaufort Gyre Exploration Project in October 2014 [Credit: NASA/Alek Petty]

As temperatures in the Arctic have warmed at double the pace of the rest of the planet, the expanse of frozen seawater that blankets the Arctic Ocean and neighboring seas has shrunk and thinned over the past three decades. The end-of-summer Arctic sea ice extent has almost halved since the early 1980s. A recent NASA study found that since 1958, the Arctic sea ice cover has lost on average around two-thirds of its thickness and now 70 percent of the sea ice cap is made of seasonal ice, or ice that forms and melts within a single year.

But at the same time that sea ice is vanishing quicker than it has ever been observed in the satellite record, it is also thickening at a faster rate during winter. This increase in growth rate might last for decades, a new study accepted for publication in Geophysical Research Letters found.

This does not mean that the ice cover is recovering, though. Just delaying its demise.

"This increase in the amount of sea ice growing in winter doesn't overcome the large increase in melting we've observed in recent decades," said Alek Petty, a sea ice scientist at NASA's Goddard Space Flight Center in Greenbelt, Maryland, and lead author of the study. "Overall, thickness is decreasing. Arctic sea ice is still very much in decline across all seasons and is projected to continue its decline over the coming decades. "

Petty and his team used climate models and observations of sea ice thickness from the European Space Agency's CryoSat-2 satellite to explore sea ice growth variability across the Arctic. The climate model results compared well both with CryoSat-2's measurements and the results of another commonly used Arctic sea ice model, giving the authors confidence in the climate model's ability to capture Arctic sea ice variability.

"The global climate model seems to do a good job of capturing the Arctic sea ice state and shows that most of the thickness change in the central Arctic is from thermodynamics, that is, ice formation and ice melt, although around the Arctic sea ice edge dynamics, which is ice transport, can play a bigger role," Petty said.

These model simulations showed that in the 1980s, when Arctic sea ice was on average 6.6 feet thick in October, about 3.3 extra feet of ice would form over the winter. That rate of growth has increased and may continue to do so for several more decades in some regions of the Arctic; in the coming decades, we could have an ice pack that would on average be only around 3.3 feet thick in October, but could experience up to 5 feet of ice growth over the winter.

It seems counterintuitive: how does a weakening ice cover manage to grow at a faster rate during the winter than it did when the Arctic was colder and the ice was thicker and stronger?

"Our findings highlight some resilience of the Arctic sea ice cover," Petty said. "If we didn't have this negative feedback, the ice would be declining even faster than it currently is. Unfortunately, the positive feedback loop of summer ice melt and increased solar absorption associated with summer ice melting still appears to be dominant and continue to drive overall sea ice declines."

Nonetheless, the increased rate of sea ice thickening in winter has other implications. As ice forms at the ocean surface, it releases a lot of the salty and dense water from which it originated, which sinks and increases the mixing of waters in the upper ocean. The more ice formation that takes place, the more mixing we expect to see in the upper ocean. Increases in this ice formation and mixing during winter may help mitigate the strong freshening of the Arctic Ocean's surface waters that has been observed in recent decades due to increased summer melt.

"This is altering the seasonal balance and the salinity distribution of the upper ocean in the Arctic; it's changing when we have fresh water, when we have salty water and how deep and seasonal that upper oceanic mixed layer is," Petty said. "And that's all going to mean that local micro-organisms and ecosystems have to adapt to these rapidly evolving conditions."

Petty's projections found that, by the middle of the century, the strong increases in atmospheric and oceanic temperatures will outweigh the mechanism that allows ice to regrow faster, and the Arctic sea ice cover will decline further. The study predicted that the switch will happen once the sea ice is less than 1.6 feet thick at the beginning of winter, or its concentration -the percentage of an area that is covered in sea ice- is less than 50 percent.

"This negative feedback mechanism increasing ice growth is unlikely to be sufficient in preventing an ice-free Arctic this century," Petty and his colleagues concluded.

Author: Maria-José Viñas | Source: NASA's Goddard Space Flight Center [December 06, 2018]

With rapid efficiency, a mysterious parasite is seeking out and killing a giant species of clam found only in the Mediterranean Sea. Unless scientists can find a way of stopping it soon, they say the mollusk could go extinct.

A diver observes a pen shell on the seabed in the Aegean Sea [Credit: Yiannis Issaris/AP]

For thousands of years, the emblematic noble pen shell has been intrinsically connected to human civilization. The largest bivalve in the Mediterranean can grow to more than a meter (three feet) long and has provided food and one of the world’s rarest materials: sea silk spun from fibers it uses to secure itself to the seabed. The mollusk also contributes to clear water by filtering out organic particulates.

The pen shell, Pinna nobilis, has been on the European Union’s protected species list for decades because of overfishing, pollution and the destruction of its natural habitat, meaning any fishing is banned. But the ban is often poorly enforced, with the animal harvested for food or for its shell, which is used for decorative purposes.

A pen shell stands on the seabed of the Aegean Sea [Credit: Yiannis Issaris/AP]

The pen shells, which have a life span of several decades and take years to reach reproductive age, were already dying faster than they could be replaced. So the spread of the microscopic parasite, which first appeared in the western Mediterranean in late 2016 and was identified just this year as a new species, has alarmed experts.

Exactly how the parasite kills isn’t completely clear, although scientists have found it attacks the pen shell’s digestive system. The infected animal is also unable to close its shell, incapacitating its defense against predators. Once infected, death is almost certain.

Yiannis Issaris, marine ecologist and research associate at the Hellenic Center for Marine Research, holds a dead noble pen shell, or Pinna nobilis, in Anavyssos, south of Athens [Credit: Thanassis Stavrakis/AP]

“In less than a year it wiped out (the pen shell population of) the Spanish coast,” said Maria del Mar Otero of the International Union for Conservation of Nature.

Soon parts of France, Malta, Tunisia and Italy were affected. In recent weeks, tests confirmed the same parasite, Haplosporidium pinnae, is responsible for pen shell die-offs in parts of Greece, and researchers have reported mass mortality as far east as Turkey and Cyprus.

Pen shells stand on the seabed in the Aegean Sea [Credit: Yiannis Issaris/AP]

Scientists are now racing to understand how the parasite spreads and its life cycle — essential information for a successful rescue program. One theory is that it could be spreading through phytoplankton, the bivalve’s food source, but nobody knows for certain.

“We cannot be sure of anything at this point,” said Pantelis Katharios, senior researcher at the Institute of Marine Biology, Biotechnology and Aquaculture of the Hellenic Center for Marine Research, or HCMR.

A dead pen shell stands open in a seagrass meadow in the Aegean Sea's Saronic Gulf [Credit: Elena Becatoros]

“What we know now is that the Pinnas are dying, that the cause is this parasite, and we know that it’s spreading very, very rapidly,” he said. “And that is going to be a huge problem (for) the ecology and the balance of the ecosystem in the Mediterranean.”

Yiannis Issaris, marine ecologist at the HCMR’s Institute of Oceanography, initially noticed widespread pen shell death off the coast of Anavyssos, southeast of Athens, in mid-summer. He suspected the culprit could be the same one causing mortality in Spain — and testing proved him right.

A pen shell stands anchored in the seabed of the Aegean Sea [Credit: Yiannis Issaris/AP]

Now the question is how to tackle the outbreak.

“This is very fresh for the scientific community,” Issaris said. “We’re still at the stage of recording where it has spread to.”

Yiannis Issaris, marine ecologist and research associate at the Hellenic Center for Marine Research, takes measurements of a dead noble pen shell, or Pinna nobilis, in Anavyssos, south of Athens [Credit: Thanassis Stavrakis/AP]

Some parts of Greece still have healthy populations of the mollusks, he noted, whereas in other areas they have been wiped out.

Protecting the pen shell in its natural habitat — sandy seabeds or seagrass meadows — appears “difficult to impossible,” Issaris said, particularly without knowing how the parasite spreads. In Spain, some healthy individuals were moved to aquariums.

Yiannis Issaris, marine ecologist and research associate at the Hellenic Center for Marine Research, takes measurements of a dead noble pen shell, or Pinna nobilis, in Anavyssos, south of Athens [Credit: Thanassis Stavrakis/AP]

Although tests are pending in some Mediterranean countries witnessing mass die-offs, experts have little doubt what the results will show.

“It’s very, very, very likely” to be the same parasite, Otero said. “There’s almost no question.”

Christina Pavloudi, foreground, post-doctoral researcher at the Hellenic Center for Marine Research laboratory on the Greek island of Crete, and Georgia Sarafidou, a student at the same facility, carry out tests on samples of noble pen shells stricken by a new parasite [Credit: Thanassis Stavrakis/AP]

One thing’s clear: the parasite is very particular in its choice of victim. A smaller, related species, the Pinna rudis, which also exists outside the Mediterranean, is unaffected.

“We don’t know how it has appeared in the Mediterranean... We only know that it causes mortality only in the Pinna nobilis,” Issaris said.

Yiannis Issaris, marine ecologist and research associate at the Hellenic Center for Marine Research, holds a dead noble pen shell, or Pinna nobilis, in Anavyssos, south of Athens [Credit: Thanassis Stavrakis/AP]

In the clear, shallow waters south of the Greek capital, dozens of dead pen shells lie scattered in a seagrass meadow, testament to the devastation.

Peering through a microscope at the tissue of an infected individual in his office in Crete, Katharios points out the culprit: small, oval-shaped parasites spread throughout the sample.

Scientists are puzzling over why an organism would be so lethal to the very species it depends on for its own survival.

Pantelis Katharios, senior researcher at the Institute of Marine Biology, Biotechnology and Aquaculture of the Hellenic Center for Marine Research on the Greek island of Crete, checks microscope imaging of a new parasite killing  the noble pen shell, or Pinna nobilis [Credit: Elena Becatoros]

“Normally parasites in nature do not have any benefit from harming the host, because they depend on the host,” Katharios explained. “But once in a while we may come across incidents like this, where we have massive mortalities.”

This could just be a natural phenomenon in which the parasite will eventually be wiped out along with its host, he said. Another possibility is that it originated in a different species and for some reason jumped to the pen shell. A third is that the pen shell’s immune system has been compromised by factors such as pollution, climate change or water temperature fluctuations.

“It’s extremely, extremely difficult to find the truth at this stage,” Katharios said.

Author: Elena Becatoros | Source: Associated Press [December 04, 2018]

Tests on more than 100 sea turtles—spanning three oceans and all seven species—have revealed microplastics in the guts of every single turtle.

Credit: Belle Co, Pexels.com

Researchers from the University of Exeter and Plymouth Marine Laboratory, working with the Greenpeace Research Laboratories, looked for synthetic particles (less than 5mm in length) including microplastics in 102 sea turtles in the Atlantic, Pacific and Mediterranean.

Synthetic particles were found in all of the turtles, the most common being fibres, which can potentially come from sources including clothing, tyres, cigarette filters and maritime equipment such as ropes and fishing nets.

"The effect of these particles on turtles is unknown," said lead author Dr. Emily Duncan, of the Centre for Ecology and Conservation on the University of Exeter's Penryn Campus in Cornwall.

"Their small size means they can pass through the gut without causing a blockage, as is frequently reported with larger plastic fragments. However, future work should focus on whether microplastics may be affecting aquatic organisms more subtly. For example, they may possibly carry contaminants, bacteria or viruses, or they may affect the turtle at a cellular or subcellular level. This requires further investigation."

In total, more than 800 synthetic particles were found in the 102 turtles studied. But researchers only tested part of each animal's gut—so the total number of particles is estimated to be about 20 times higher.

Researchers do not currently understand how synthetic particles are ingested by turtles, but the likely sources are polluted seawater and sediments, and eating via prey or plants.

Professor Brendan Godley, senior author of the study, added: "It really is a great shame that many or even all of the world's sea turtles have now ingested microplastics. At the moment, this is not the main threat to this species group but it is a clear sign that we need to act to better govern global waste."

Necropsies were carried out on the turtles after they died either by stranding or bycatch (accidental catching in fishing). The study sites were North Carolina, USA (Atlantic), Northern Cyprus (Mediterranean) and Queensland, Australia (Pacific).

The turtles with the most synthetic particles were in the Mediterranean—thought to have higher rates of contamination than the Atlantic or Pacific—but this study's sample sizes and methodology did not allow for detailed geographical comparisons.

Dr. Penelope Lindeque, of Plymouth Marine Laboratory, said: "While this study has been successful, it does not feel like a success to have found microplastic in the gut of every single turtle we have investigated.

"From our work over the years we have found microplastic in nearly all the species of marine animals we have looked at; from tiny zooplankton at the base of the marine food web to fish larvae, dolphins and now turtles. This study provides more evidence that we all need to help reduce the amount of plastic waste released to our seas and maintain clean, healthy and productive oceans for future generations."

Louise Edge, plastics campaigner at Greenpeace, said: "This important research demonstrates the breadth of our plastics pollution problem. Our society's addiction to throwaway plastic is fuelling a global environmental crisis that must be tackled at source."

The paper is published in the journal Global Change Biology.

Source: University of Exeter [December 04, 2018]

Sharks that use a whip-like tail to stun their prey, rays with saws on their faces, and river rays half the length of a bus are among the most unique species at risk of extinction according to the latest ranking from international conservation charity ZSL's (Zoological Society of London) pioneering EDGE of Existence programme.

The largetooth sawfish (Pristis pristis) is not only #1 on the EDGE sharks and rays list, but is also the highest ranking  EDGE species across all the different animal groups ranked, including corals, reptiles, amphibians, mammals and birds [Credit: (c) Simon Fraser University]

The new list revealed today (4 December) ranks the world's 50 most Evolutionarily Distinct and Globally Endangered (EDGE) sharks, rays and chimeras - known collectively as Chondrichthyes.

These mythical-sounding (but very real) creatures have no bones in their bodies, only cartilage and appeared more than 400 million years ago, roaming the seas when dinosaurs lived. Each species on this list has few or no remaining close relatives, effectively representing distinct branches of the tree of life and making each of them truly irreplaceable. If they go extinct, we will have nothing like them left on the planet.

Topping the new list, at number one is the largetooth sawfish (Pristis pristis), which also holds the distinction of being the highest-ranking EDGE species in the world. Using an elongated snout (rostrum) lined with teeth on each side to slash at its prey, the large-tooth sawfish is facing threats from unsustainable fishing activities as it's often caught as by-catch in nets.

Despite the fearsome reputation of the great white shark and the well-recognised appearance of the hammerhead, sharks are one of the least-studied groups of animals - some so elusive they've never been captured on camera. Many of these species are threatened by targeted fishing, driven by a desire for shark fins or other body parts, as well as being unintentionally caught (bycatch).

Habitat degradation, due to coastal development, mangrove deforestation, water pollution and trawling, is also to blame for the steep decline in many of these populations. However, the new EDGE List gives conservationists another tool to identify and prioritise species where there is a most pressing need for action.

EDGE Sharks co-ordinator and marine biologist, Fran Cabada said: "Sharks, rays and chimeras - making up the cartilaginous fish, have been around since the age of the dinosaurs, but due to human activities, their modern relatives are facing threats all over the world. They're found in almost every aquatic environment and as many are apex predators, i.e., at the top of the food chain - they're crucial to maintaining healthy ecosystems.

Representative phylogeny tree (taxon-complete) of Chondrichthyes. Red dotes highlight nodes defining orders [Credit: Stein et al. (2018)/EDGE]

"Unfortunately, sharks have a bad image. This means people often can't see beyond the negative, and usually exaggerated stories, and don't understand just how threatened and important they are.

"The new EDGE Sharks and Rays list gives us the opportunity to highlight the most unique sharks and rays on our planet which are also the most endangered, so that we can target conservation efforts where it's needed most. Many are overlooked and poorly known, so conservation actions targeted at these survivors of ancient lineages should be prioritised."

ZSL's Marine and Freshwater Conservation Programme Manager, Dr. Matthew Gollock added: "The EDGE Sharks and Rays list comprises some of the most interesting and unique fish we have on this planet. The modern extinction of a single species from this list would cause the loss of millions of years of evolutionary history.

"Since 2013, we have been working in collaboration with partner organisations in the Canary Islands for the conservation of the angel shark (Squatina squatina), #5 in the EDGE list, increasing our knowledge of this species and working with divers, fishers and policymakers to improve management and policy.

"Our successes from this project have allowed us to expand our work to Wales, UK, where we have taken a similar stakeholder-lead approach to collect sightings and community memories of the angel shark in order to better understand and conserve this Critically Endangered species across its range."

First established in 2007, the EDGE of Existence programme has previously published lists for amphibians, birds, corals, mammals and reptiles. The EDGE lists provide conservationists worldwide with a scientifically rigorous method of focusing their conservation efforts on animals and plants that represent a significant amount of threatened evolutionary history.

ZSL's EDGE of Existence programme works with partners including the National Geographic Photo Ark and Fondation Segré to fund early-career conservationists striving to secure the future of EDGE species all around the world, through the EDGE Fellowship initiative. The first ever EDGE Fellowships on Sharks and Rays will begin in early 2019, implementing conservation actions for the largetooth sawfish and the pelagic thresher shark (Alopias pelagicus) in Asia.

For more information please see the original paper presenting ED values for these species.

Click here to explore the Top 50 EDGE Sharks and Rays List.

Click here for the latest EDGE Sharks and Rays List.

Source: Zoological Society of London [December 04, 2018]

The pattern of uneven sea level rise over the last quarter century has been driven in part by human-caused climate change, not just natural variability, according to a new study.

Altimeter era sea level trends [Credit: John T. Fasullo]

The findings suggest that regions of the world where seas have risen at higher than average rates -- including the Eastern Seaboard of the United States and the Gulf of Mexico -- can expect the trend to continue as the climate warms.

The study, published today in the Proceedings of the National Academy of Sciences, was authored by scientists John Fasullo at the National Center for Atmospheric Research (NCAR) and Steve Nerem at the University of Colorado Boulder.

"By knowing that climate change is playing a role in creating these regional patterns, we can be more confident that these same patterns may linger or even intensify in the future if climate change continues unabated," Fasullo said. "With sea levels projected to rise a couple of feet or more this century on average, information about expected regional differences could be critical for coastal communities as they prepare."

The research was funded by the National Science Foundation, which is NCAR's sponsor, the NASA Sea Level Change Team, and the U.S. Department of Energy.

Finding the signal of climate change

For the study, Fasullo and Nerem, both members of the NASA Sea Level Change Team, analyzed the satellite altimetry sea level record, which includes measurements of sea surface heights stretching back to 1993. They mapped global average sea level rise as well as how particular regions deviated from the average.

For example, the oceans surrounding Antarctica and the U.S. West Coast have had lower-than-average sea level rise, while the U.S. East Coast and Southeast Asia, including the Philippines and Indonesia, have experienced the opposite. In some parts of the world, the rate of local sea level rise has been as much as twice the average.

Regional differences in sea level rise are influenced by where heat is stored in the ocean (since warm water expands to fill more space than cold water) and how that heat is transported around the globe by currents and wind. Uneven sea level rise is also influenced by ice sheets, which lose mass as they melt and shift the gravitational forces affecting regional sea surface height.

Natural shifts in ocean cycles -- including the Pacific Decadal Oscillation, a pattern of sea surface temperatures similar to El Niño but longer lasting -- are therefore known to affect sea levels. So scientists were not surprised to find that as the ocean rises, it rises unevenly. But it's been difficult to say whether these natural cycles were the dominant influence on regional differences.

To investigate the role of climate change, the scientists turned to two sets of climate model runs, known as "large ensembles": one created using the NCAR-based Community Earth System Model and one created using the Earth System Model at the National Oceanic and Atmospheric Administration. These large ensembles -- many model simulations by the same model, describing the same time period -- allow researchers to disentangle natural variability from the impacts of climate change. With enough runs, these impacts can be isolated even when they are relatively small compared to the impacts from natural variability.

The climate models suggest that in regions that have seen more or less sea level rise than average, as much as half of that variation may be attributed to climate change. The scientists also found that the impacts from climate change on regional sea level rise sometimes mimic the impacts from natural cycles.

"It turns out the sea level rise response to climate change in the Pacific resembles what happens during a particular phase of the Pacific Decadal Oscillation," Fasullo said. "This explains why it's been so difficult to determine how much of the pattern was natural or not, until now."

Improving forecasts

The research findings have implications for local officials, who are interested in improved forecasts of sea level rise for the areas they oversee. In the past, forecasters have had to rely on the global rate of change -- about 3 millimeters a year and accelerating -- and knowledge of the uneven regional impacts associated with continued melting of the ice sheets covering Greenland and Antarctica.

The findings add the possibility that the regional patterns of sea level rise tied to climate change can also be included, because the models predict that the regional patterns observed in the satellite measurements will continue into the future.

"We now have a new tool -- long-term satellite altimeter measurements -- that we can use to help stakeholders who need information for specific locations," said Nerem, a fellow of the Cooperative Institute for Research in Environmental Sciences at the University of Colorado Boulder and a professor of aerospace engineering.

Author: Laura Snider | Source: National Center for Atmospheric Research [December 03, 2018]

The research, led by the University of Plymouth, examined the uptake of nanoparticles by a commercially important mollusc, the great scallop (Pecten maximus). After six hours exposure in the laboratory, billions of particles measuring 250nm (around 0.00025mm) had accumulated within the scallop's intestines. However, considerably more even smaller particles measuring 20nm (0.00002mm) had become dispersed throughout the body including the kidney, gill, muscle and other organs.

These are some of the scallops used as part of the current research [Credit: University of Plymouth]

The study is the first to quantify the uptake of nanoparticles at predicted environmentally relevant conditions, with previous research having been conducted at far higher concentrations than scientists believe are found in our oceans.

Dr Maya Al Sid Cheikh, Postdoctoral Research Fellow at the University of Plymouth, led the study. She said: "For this experiment, we needed to develop an entirely novel scientific approach. We made nanoparticles of plastic in our laboratories and incorporated a label so that we could trace the particles in the body of the scallop at environmentally relevant concentrations. The results of the study show for the first time that nanoparticles can be rapidly taken up by a marine organism, and that in just a few hours they become distributed across most of the major organs."

Professor Richard Thompson OBE, Head of the University's International Marine Litter Research Unit, added: "This is a ground breaking study, in terms of both the scientific approach and the findings. We only exposed the scallops to nanoparticles for a few hours and, despite them being transferred to clean conditions, traces were still present several weeks later. Understanding the dynamics of nanoparticle uptake and release, as well as their distribution in body tissues, is essential if we are to understand any potential effects on organisms. A key next step will be to use this approach to guide research investigating any potential effects of nanoparticles and in particular to consider the consequences of longer term exposures."

A scan showing particles accumulated within the scallop's gills (GI), kidney (K), gonad (GO), intestine (I), hepatopancreas (HP) and muscle (M) [Credit: University of Plymouth]

Accepted for publication in the Environmental Science and Technology journal, the study also involved scientists from the Charles River Laboratories in Elphinstone, Scotland; the Institute Maurice la Montagne in Canada; and Heriot-Watt University.

It was conducted as part of RealRiskNano, a £1.1million project funded by the Natural Environment Research Council (NERC). Led by Heriot-Watt and Plymouth, it is exploring the effects which microscopic plastic particles can have on the marine environment.

In this study, the scallops were exposed to quantities of carbon-radiolabeled nanopolystyrene and after six hours, autoradiography was used to show the number of particles present in organs and tissue.

It was also used to demonstrate that the 20nm particles were no longer detectable after 14 days, whereas 250nm particles took 48 days to disappear.

Ted Henry, Professor of Environmental Toxicology at Heriot-Watt University, said: "Understanding whether plastic particles are absorbed across biological membranes and accumulate within internal organs is critical for assessing the risk these particles pose to both organism and human health. The novel use of radiolabelled plastic particles pioneered in Plymouth provides the most compelling evidence to date on the level of absorption of plastic particles in a marine organism."

Source: University of Plymouth [December 03, 2018]

The scientists made this discovery when they compared neodymium isotope signatures of deep sea sediment samples from both regions of the Atlantic. Their paper - 'Major intensification of Atlantic overturning circulation at the onset of Paleogene greenhouse warmth' - published in Nature Communications, reveals that the more vigorous circulation together with an increase in atmospheric CO2 led to a climatic tipping point. With a resulting more even distribution of heat over the earth, a long-term cooling phase ended and the world headed into a new greenhouse period.

Collecting deep sea sediments which are valuable archives of ocean circulation and past climates [Credit: Department of Earth Sciences]

Neodymium (Nd) isotopes are used as a tracer of water masses and their mixing. Surface waters acquire a Nd-isotope signature from surrounding land masses through rivers and wind-blown dust. When surface waters sink to form a deep-water mass, they carry their specific Nd-isotope signature with them. As a deep-water mass flows through the ocean and mixes with other water masses, its Nd-isotope signature is incorporated into sediments. Deep sea sediments are valuable archives of ocean circulation and past climates.

The story revealed in this paper begins at the end of the Cretaceous period (ending 66 million years ago), when the world was between two greenhouse states. Climate had been cooling for tens of millions of years since the peak hothouse conditions of the mid-Cretaceous, around 90 million years ago. Despite long-term cooling, temperatures and sea level at the end of the Cretaceous period were higher than at present day.

Dr Sietske Batenburg says: 'Our study is the first to establish how and when a deep-water connection formed. At 59 million years ago, the Atlantic Ocean truly became part of the global thermohaline circulation, the flow that connects four of the five main oceans.'

Deep sea sediments are valuable archives of ocean circulation and past climates [Credit: Department of Earth Sciences]

The Atlantic Ocean was still young, and the North and South Atlantic basins were shallower and narrower than today. The equatorial gateway between South America and Africa only allowed a shallow, surface-water connection for much of the late Cretaceous period. Active volcanism formed underwater mountains and plateaus that blocked deep-water circulation. In the South Atlantic, the Walvis Ridge barrier formed above an active volcanic hotspot. This ridge was partially above sea level and formed a barrier for the flow of deep-water masses.

As the Atlantic Ocean continued to open, the oceanic crust cooled and subsided. Basins became deeper and wider, and submarine plateaus and ridges sank, along with the crust. At some point, deep water from the Southern Ocean was able to flow north across the Walvis Ridge and fill the deeper parts of the Atlantic basins.

From 59 million years ago onwards, Nd-isotope signatures from the North and South Atlantic were remarkably similar. This may indicate that one deep-water mass, likely originating from the south, made its way through the Atlantic Ocean and filled the basin from deep to intermediate depths. The enhanced deep water exchange, together with increasing atmospheric CO2, may have enabled a more efficient distribution of heat over the planet.

This is a neodymium isotope ratio [Credit: Department of Earth Sciences]

This study shows that to understand the role of ocean circulation in past greenhouse climates, it is important to understand the different roles of geography and climate.

The current rate of climate change by CO2 emissions from human activity by far surpasses the rate of warming during past greenhouse climates. Studying ocean circulation during the most recent greenhouse interval in the geologic past may provide clues as to how ocean circulation might develop in the future, and how heat will be distributed over the planet by ocean currents.

This research is the result of an international collaboration with the Goethe-University Frankfurt; the Ruprecht-Karls-University of Heidelberg; the GEOMAR Helmholtz Centre for Ocean Research Kiel; the Federal Institute for Geosciences and Natural Resources in Hannover; the Royal Holloway University of London and the University of Oxford.

The sediments for this study were all taken from long ocean drill cores. The International Ocean Discovery Program (IODP) coordinates scientific expeditions to drill the ocean floor to recover these sediments, and stores the sediment cores so that they are available to the whole scientific community.

Source: University of Oxford [November 26, 2018]