Constantine Alexander's Journal

Man-made fibres and plastic found in the deepest living organisms

Animals from six of the deepest places on Earth found to contain man-made fibres and plastic in their stomachs, scientists have shown.

By Newcastle University.

A study, led by Newcastle University’s Dr Alan Jamieson, has uncovered evidence that not only have plastics now reached the deepest chasms of our oceans but they are being ingested by the animals that live there.

Revealing their findings as part of Sky Ocean Rescue - a campaign to raise awareness of how plastics and pollution are affecting our seas - the team tested samples of crustaceans found in the ultra-deep trenches that span the entire Pacific Ocean - the Mariana, Japan, Izu-Bonin, Peru-Chile, New Hebrides and Kermadec trenches.

These range from seven to over 10 kilometres deep, including the deepest point, Challenger Deep in the Mariana Trench, at a staggering 10,890 metres deep.

Using state-of-the-art facilities at Newcastle University and Shimadzu UK Ltd in Milton Keynes, the team examined 90 individual animals and found ingestion of plastic ranged from 50% in the New Hebrides Trench to 100% at the bottom of the Mariana Trench.

The fragments identified include semi-synthetic cellulosic fibres, such as Rayon, Lyocell and Ramie, which are all microfibres used in products such as textiles, to Nylon, polyethylene, polyamide, or unidentified polyvinyls closely resembling polyvinyl alcohol or polyvinylchloride - PVA and PVC.

Research lead Dr Jamieson, said: “We published a study earlier this year showing high levels of organic pollutants in the very deepest seas and lots of people asked us about the presence of plastics, so we decided to have a look. The results were both immediate and startling. This type of work requires a great deal of contamination control but there were instances where the fibres could actually be seen in the stomach contents as they were being removed. We felt we had to do this study given the unique access we have to some of the most remote places on earth, and we are using these samples to make a poignant statement about mankind’s legacy."

 

Surface to seafloor

Using deep-sea ‘landers’ developed by Dr Jamieson, the technology free-falls to the ocean floor and carries out a variety of monitoring and sampling tasks. The technology has been used at locations around the globe and the team’s deepest landers have been dropped over 200 times around the Pacific Trenches.

There is now an established appreciation of plastic pollution in our oceans and the detrimental effects this has on marine organisms. An estimated 300 million tonnes of plastic now litters the oceans, with more than 5 trillion plastic pieces weighing over 250,000 tons currently floating on the surface.

Although the majority of marine litter can be observed floating on the surface, the degradation and fragmentation of plastics will ultimately result in sinking to the underlying deep-sea habitats, where opportunities for dispersal become ever more limited.

A 'Lander' developed by Dr Jamieson. Credit: Newcastle University

“Deep-sea organisms are dependent on food raining down from the surface,” explains Dr Jamieson, “which in turn brings any adverse components, such as plastic and pollutants with it. The deep sea is not only the ultimate sink for any material that descends from the surface, but it is also inhabited by organisms well adapted to a low food environment and these will often eat just about anything. This study has shown that man-made microfibres are culminating and accumulating in an ecosystem inhabited by species we poorly understand, cannot observe experimentally and have failed to obtain baseline data for prior to contamination. These observations are the deepest possible record of microplastic occurrence and ingestion, indicating it is highly likely there are no marine ecosystems left that are not impacted by anthropogenic debris.”

Fishery yields will be dramatically reduced by 2300

By 2300, climate change may cause fishery yields to decline by as much as 20% around the globe, and by as much as 60% in the North Atlantic, a new modeling study suggests.

The study primarily attributes this decline to a lack of ocean mixing, such that nutrients sink into the deep ocean instead of staying at the ocean surface; such alterations to ocean mixing would ultimately drive a decline in fish populations near the surface, the authors say. Climate change models consistently estimate that fisheries will decline by the end of this century, yet there have been few efforts to explore what changes might occur beyond 2100. Here, J. Keith Moore and colleagues used modeling to explore the effects of climate change on fisheries under a "business-as-usual" scenario whereby carbon emissions continue apace, at the same level as they are now.

The Southern Ocean currently experiences mixing between the bottom and top oceanic layers, delivering such a substantial amount of nutrients to the surface that an abundance flows into other oceans. However, simulations by Moore et al. suggest that a combination of changing winds and warmer upper oceanic layers, plus a poleward shift of nutrient upwelling in the Antarctic, will cause an increased portion of nutrients to sink into the deeper layer of the ocean and become trapped there (for example, the amount of phosphate being upwelled will be reduced by 41%, the model estimates). This will reduce the delivery of nutrients to other oceanic areas, they note. While ocean warming and stratification will increase globally, deep mixing in the North Atlantic will be particularly reduced, the authors find. They note that the long-term effects of these changes mean that fisheries will be reduced for a thousand years or more.

Citation: J. Keith Moore Weiwei Fu, Francois Primeau, Gregory L. Britten, Keith Lindsay, Matthew Long, Scott C. Doney, Natalie Mahowald, Forrest Hoffman, James T. Randerson; Sustained climate warming drives declining marine biological productivity; Science  09 Mar 2018: Vol. 359, Issue 6380, pp. 1139-1143; DOI: 10.1126/science.aao6379 

Seabed mining could destroy ecosystems

This is a graphic examining the impacts of seabed mining. Credit: Design Studio, University of Exeter.

Mining on the ocean floor could do irreversible damage to deep-sea ecosystems, says a new study of seabed mining proposals around the world. The deep sea (depths below 200m) covers about half of the Earth's surface and is home to a vast range of species.

Little is known about these environments, and researchers from the University of Exeter and Greenpeace say mining could have "long-lasting and unforeseen consequences"- not just at mining sites but also across much larger areas. The study is the first to give a global overview of all current plans to mine the seabed, in both national and international waters, and looks at the potential impacts including physical destruction of seabed habitats, creation of large underwater plumes of sediment and the effects of chemical, noise and light pollution arising from mining operations.

"Our knowledge of these ecosystems is still limited, but we know they're very sensitive," said Dr David Santillo, a marine biologist and senior Greenpeace scientist based at the University of Exeter. "Recovery from man-made disturbance could take decades, centuries or even millennia, if these ecosystems recover at all."

"As we learn more about deep sea ecosystems and the role of oceans in mitigating climate change, it seems wise to take precautions to avoid damage that could have long-lasting and unforeseen consequences."

Despite the term "mining", much seabed mining would involve extraction of minerals over very wide areas of the sea floor rather than digging down to any great depth, potentially leaving a vast 'footprint' on the deep-sea habitats in which these mineral deposits occur. Rising demand for minerals and metals, including for use in new technology, has sparked renewed interest in seabed mining. Some operations are already taking place, generally at relatively shallow depths near national coastlines. The first commercial enterprise in deeper waters, expected to target mineral-rich sulphides at depths of 1.5-2km off Papua New Guinea, is scheduled to begin early in 2019. Speaking about these plans last year, Sir David Attenborough said it was "tragic that humanity should just plough on with no regard for the consequences".

The Exeter and Greenpeace research team say there are "many questions and uncertainties" around seabed mining, including legal issues and the difficulties of predicting the scale and extent of impacts in advance, and of monitoring and regulating mining activity once it takes place in the deep sea. The paper says that alternatives to seabed mining have already been proposed, including substituting metals in short supply for more abundant minerals with similar properties, as well as more effective collection and recycling of components from disused products and wastes.

However, Dr Santillo said demand for seabed mining would also diminish if humanity could cut overproduction and overconsumption of consumer goods. "Rather than using human ingenuity to invent more and more consumer products that we don't actually need, we could deploy it instead to build good that last longer, are easier to repair and make better use of the limited natural resources we have," he said. "With the right approaches, we can avoid the need for seabed mining altogether and stop the 'race to the bottom. As governments prepare to set the rules and the first companies gear up to mine, now is the time to ask whether we just have to accept seabed mining, or should instead decide that the potential damage is just so great that we really need to find less destructive alternatives."

Citation: Kathryn A. Miller, Kirsten F. Thompson, Paul Johnston & David Santillo; An Overview of Seabed Mining Including the Current State of Development, Environmental Impacts, and Knowledge Gaps; Frontiers in Marine Science, 2018, 4; DOI: 10.3389/fmars.2017.00418.

Contact: Alex Morrison
University of Exeter

 

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Marine vegetation can mitigate ocean acidification

Conservation of shoreline plants and seaweeds could, in turn, help preserve shellfish habitats.

Study authors Nyssa Silbiger, then a UCI postdoctoral researcher, and UCI graduate student Laura Elsberry (standing) survey tide-pool communities at Corona del Mar State Beach. Credit: Cascade Sorte / UCI.

Marine plants and seaweeds in shallow coastal ecosystems can play a key role in alleviating the effects of ocean acidification, and their robust population in shoreline environments could help preserve declining shellfish life, according to a study by University of California, Irvine ecologists.

In a new study on the Pacific Coast, Nyssa Silbiger, former UCI postdoctoral researcher, and Cascade Sorte, assistant professor of ecology & evolutionary biology, determined that marine plants and seaweeds decrease the acidity of their surroundings through photosynthesis. Their findings suggest that maintaining native seawater vegetation could locally lessen the acidifying effects of rising CO2 levels on marine animals who are sensitive to ocean pH, which has declined since preindustrial times.

The study results appear online in the open-access Scientific Reports. "Our findings from sites spanning some 1,000 miles of coastline show that marine life plays a leading role in driving local pH conditions," Sorte said.

About 90 percent of fishery catch comes from coastal ecosystems. Any coastal pH decrease has a major impact on animals such as corals, oysters and mussels, whose shells and skeletons can become more brittle in low-pH environments.

This is a major concern for shellfish fisheries, which contribute over $1 billion annually to the U.S. economy while providing more than 100,000 jobs.

Due to their findings, the authors recommend efforts to conserve marine plants and seaweeds in shoreline habitats, including where commercial seafood is harvested.

"The environmental and economic consequences resulting from ocean acidification are dire," said Silbiger, now an assistant professor of biology at California State University, Northridge. "Decreasing CO2 emissions is still the No. 1 most important way to protect our marine ecosystems, but our research indicates that marine life also has substantial control over coastal pH."

Citation: Nyssa J. Silbiger & Cascade J. B. Sorte; Biophysical feedbacks mediate carbonate chemistry in coastal ecosystems across spatiotemporal gradients; Scientific Reports 8, Article number: 796 (15 January 2018); DOI:10.1038/s41598-017-18736-6.

The study received UCI seed funding for single- and multi-investigator research projects and support from the UCI OCEANS Initiative; research travel was sponsored by GoWesty.

Contact: Tom Vasich
University of California - Irvine

 

New application for acoustics helps estimate marine life populations in world's most successful Marine Protected Area.

Scientists use hydroacoustics to find abundance of marine life in reserve is four times greater than in surrounding waters.

Fish swimming along rocky reefs at Cabo Pulmo National Park. Credit: Octavio Aburto, Scripps Institution of Oceanography at UC San Diego.

Researchers at Scripps Institution of Oceanography at the University of California San Diego were part of an international team that for the first time used hydroacoustics as a method for comparing the abundance of fishes within and outside marine protected areas (MPAs).

They found that the abundance of fishes was four times greater in Mexico's protected Cabo Pulmo National Park than in areas outside the park. Study authors said that hydroacoustics points the way toward a new, more cost-effective method of assessing fish populations.

"Managers and authorities in many countries spend a lot of financial resources assessing marine protected areas," said study co-author Octavio Aburto, a marine ecologist at Scripps. "The results of this paper demonstrate that it is possible to use acoustic technologies to generate information about marine resources inside MPAs in a faster and less expensive way, reducing the costs for governments in ocean conservation."

The study, "Hydroacoustics as a tool to examine the effects of Marine Protected Areas and habitat type on marine fish communities," appears Jan. 15 in the journal Scientific Reports. The National Science Foundation, the Baja Coastal Institute, the International Community Foundation, David and Lucile Packard Foundation, and The Helmsley Charitable Trust funded the research.

 

Cabo Pulmo has been the site of several studies by Scripps researchers since 2002. In 1995, local fishermen led the creation of a 71-square-kilometer (27-square-mile) undersea park to protect the waters they fished. The current MPA has been identified as the most successful in the world in terms of maintaining a sustainable fishery in which fleets operate just beyond the boundaries of the MPA. There, as in other parts of the world, surveys of coastal marine life are often performed through underwater visual censuses taken by scuba divers. Results of a 10-year analysis of Cabo Pulmo National Park (CPNP), published in the Public Library of Science (PLoS) ONE journal, revealed that the total amount of fish in the reserve ecosystem (the "biomass") boomed more than 460 percent from 1999 to 2009. Citizens living around Cabo Pulmo, previously depleted by fishing, established the park in 1995 and have strictly enforced its "no take" restrictions.

"We could have never dreamt of such an extraordinary recovery of marine life at Cabo Pulmo," said National Geographic Explorer-in-Residence Enric Sala, who started the study in 1999. "In 1999 there were only medium-sized fishes, but ten years later it's full of large parrotfish, groupers, snappers and even sharks."

The most striking result is that fish communities at a depleted site can recover up to a level comparable to remote, pristine sites that have never been fished by humans. Factors such as the protection of spawning areas for large predators have been key to the reserve's robustness. Most importantly, local enforcement, led by the determined action of a few families, has been a major factor in the park's success. Boat captains, dive masters and other locals work to enforce the park's regulations and share surveillance, fauna protection and ocean cleanliness efforts.

Researchers surveyed the waters of the MPA using sound waves produced by hydroacoustic equipment mounted on boats to image schools of fish and other marine life. They performed transects, scanning the water column in rows. They similarly surveyed waters outside the MPA. Fish density, total biomass, and the size of individuals were significantly greater inside the MPA. In comparison with waters outside the MPA, animal abundance in reefs was as much as 50 times higher, "highlighting the importance of both habitat complexity and protection from fishing for fish populations."

"Both hydroacoustics and marine protected areas are well-established but it is novel to use the former to assess the latter," said study lead author Jack Egerton, now a researcher at the University of Texas who performed the work while at Bangor University in Wales, UK. "Through this, we have been able to see how important the Cabo Pulmo National Park is for fish populations in the area."

Although acoustic surveys can be done much faster than underwater visual censuses, the researchers acknowledge that fish sizes can only be approximated and the method doesn't provide species-specific information. However, they concluded that the hydroacoustic method could still be useful in gauging the benefit of MPAs, as conventional survey methods are often prohibitively expensive and can be limited by issues such as diver depth limits and water clarity.

Citations:

• J. P. Egerton, A. F. Johnson, J. Turner, L. LeVay, I. Mascareñas-Osorio & O. Aburto-Oropeza; Hydroacoustics as a tool to examine the effects of Marine Protected Areas and habitat type on marine fish communities; Scientific Reports 8, Article number: 47 (15 January 2018); DOI:10.1038/s41598-017-18353-3.
• Aburto-Oropeza O, Erisman B, Galland GR, Mascareñas-Osorio I, Sala E & Ezcurra E; Large Recovery of Fish Biomass in a No-Take Marine Reserve; PLoS ONE 6(8): e23601 (2011). DOI:10.1371/journal.pone.0023601.

Contact: Rob Monroe
University of California - San Diego

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No-fishing zones help endangered penguins

African penguins. Credit: Richard Sherley.

Small no-fishing zones around colonies of African penguins can help this struggling species, new research shows.

Working with the South African government, researchers from the universities of Exeter and Cape Town tested bans on catching "forage fish" such as sardines and anchovies - key prey for the endangered penguins - from 20km around their breeding islands. The body condition and survival of chicks improved when the no-fishing zones were in place. More research is needed, but the scientists say the fishing closures should continue in South Africa and should be considered elsewhere.

"The amount of forage fish caught worldwide is increasing and - although the effects are disputed - the impact on marine ecosystems could be severe," said Dr Richard Sherley, of the Environment and Sustainability Institute on the University of Exeter's Penryn Campus in Cornwall.

"Forage fish are a key link in the food chain as they eat plankton and are preyed on by numerous species including tuna, dolphins, whales and penguins.

"We need to do more to understand the circumstances in which small no-fishing zones will improve the food available to predators, but our research shows this is a promising way to help African penguins."

The test areas were on a small scale compared to some no-fishing zones worldwide, which can cover hundreds of thousands of square kilometres. Researchers examined colonies at Dassen Island, Robben Island, St Croix Island and Bird Island, and compared fishing bans of about three years with similar periods when fishing was allowed. The study says evidence for overall effects was "subtle and inconsistent", with clear benefits for penguin populations at only two of the four islands. Dr Sherley said it was difficult to discover the full effects of the no-fishing zones because many other factors also affect the birds.

"Decades of research may be needed to be absolutely certain of the impact on the penguins' population size," he said.

However, the researchers used a statistical method called Bayesian inference to demonstrate beyond doubt that the zones improved the health and survival rates of penguin chicks.

"There's never going to be a quick answer to problems in complex ecosystems," Dr Sherley said.

"However, without conservation action, there's a good chance African penguins will go extinct in at least some of their current colonies.

"We are calling for a precautionary and adaptive approach - no-fishing zones to protect this species, with an open mind to change as more evidence emerges."

Dr Stephen Votier, senior author of the study, added: "This is an excellent example of how a collaboration between government, fisheries and scientists can lead to positive outcomes for conservation. Statistics have played an important role here - only by using the approach we adopted was it possible to understand fully that these fisheries closures do indeed work."

Citation: Richard Sherley, Barham B, Barham P, Campbell K, Crawford R, Grigg J, Horswill C, McInnes A, Morris T, Pichegru L, Steinfurth A, Weller F, Winker H & Votier S; Bayesian inference reveals positive but subtle effects of experimental fishery closures on marine predator demographics; Proceedings of the Royal Society B (December 12, 2017); DOI: 10.5061/dryad.d4977.

Contact: Alex Morrison
University of Exeter

 

Bright lights reveal the 'dark' fleet

A new partnership between Global Fishing Watch and NOAA matches night-time imagery with monitoring data from fishing vessels.

Arufura Sea, January, 2018. Vessel Monitoring System (VMS) data from Indonesia is shown in the Global Fishing Watch map as yellowish dots. This image is overlayed with data from NOAA's satellite-based Visible Infrared Imaging Radiometer Suite (VIIRS) which detects many vessels not broadcasting VMS. VIIRS-detected vessels are shown here as blue sailboats. Credit: Global Fishing Watch 2018.

Global Fishing Watch has entered into a new data-sharing partnership with the U.S. National Oceanic and Atmospheric Administration (NOAA) to improve understanding of the activity of fishing vessels in Indonesian waters. Through the partnership, Global Fishing Watch and NOAA are matching Vessel Monitoring System (VMS) data from the Indonesian government with NOAA's satellite based Visible Infrared Imaging Radiometer Suite (VIIRS), which reveals the locations of brightly lit vessels at night. The idea is to identify fishing vessels that are not picked up by other monitoring systems and to test and refine the use of VIIRS for identifying and distinguishing different types of fishing vessels.

By cross matching VMS from Indonesia with VIIRS, the team found that roughly 80 percent of VIIRS detections could not be correlated to a vessel broadcasting VMS. The vast majority of these vessels are likely to be fishing vessels using bright lights to attract fish. While a small number may be other types of vessels, most ships do not use lights bright enough for detection. This work indicates that the addition of VIIRS data can greatly enhance transparency in commercial fishing in Indonesia.

The team believes most of the VIIRS detections are from fishing vessels not required to carry VMS because they are under the 30 gross ton (GT) threshold established by the government of Indonesia. It is also possible that some vessels detected only by VIIRS meet the size requirement but have switched off their VMS or have a faulty device. Another possibility is that VIIRS is detecting foreign boats that are not carrying VMS because they are poaching from Indonesian waters.

On the left, blue boats represent vessels detected by NOAA's satellite-based Visible Infrared Imaging Radiometer Suite (VIIRS) over the Arufura Sea on January, 2018. On the right, yellow dots represent active fishing vessels using Indonesia's Vessel Monitoring System plotted on the Global Fishing Watch map. About 80 percent of VIIRS-detected vessels do not broadcast VMS, and so combining the two data sources provides a more complete picture of fishing activity in Indonesia. Credit: Global Fishing Watch 2018.

"I'm excited for this opportunity to see the dark fleet," said David Kroodsma, Global Fishing Watch Research Program Director. The dark fleet being a common term used to describe vessels that don't show up in vessel monitoring systems and therefore are said to operate in the dark. "NOAA's VIIRS data shows us vessels we can't see by any other means and helps us to gain a more complete picture of fishing activity."

Global Fishing Watch detects nearly all large fishing vessels in Indonesian waters by combining Indonesia's VMS data and publicly broadcast AIS data which is required on vessels exceeding 300 GT. Global Fishing Watch can even tell when vessels turn off their monitoring devices. But the system is unable to see vessels when they are not broadcasting either AIS or VMS. Incorporating VIIRS, which represents a completely new source of data, into the Global Fishing Watch database and, eventually, the public mapping platform, will reveal the activity of even more of the world's commercial fishing fleet.

To cross match VMS and VIIRS, NOAA's Earth Observation Group developed an orbital model that predicts the probable location of each VMS-broadcasting vessel at the time of the VIIRS data collection. The model checks the predicted location against the actual VIIRS detections to define matches. Prior to the partnership with Global Fishing Watch, NOAA had access to two months of Indonesia VMS data, which they used to develop their cross-matching algorithm.

The partnership with Global Fishing Watch has provided three years-worth of Indonesian VMS data, which NOAA has now matched to its VIIRS vessel detections. In addition, the partnership has provided NOAA with valuable information on vessel gear types and identification numbers in the VMS records.

Arufura Sea, January, 2018. Comparing Vessel Monitoring System (VMS) data from Indonesia with satellite-based Visible Infrared Imaging Radiometer Suite (VIIRS) data reveals a more complete picture of fishing activity in Indonesia. Credit: Global Fishing Watch 2018.

This new data is enabling NOAA to calculate the frequency of VIIRS boat detections for the different fishing gear types and to work towards a calibration for estimating wattage from the VIIRS detected radiance. "When I saw what Global Fishing Watch could provide in the data, I said, Wow, that could really help us a lot, because we don't have access to this information in any other way," said Chris Elvidge, NOAA's Earth Observation Group Lead. His team is creating an atlas of fishing grounds for Indonesia using the three years of VMS provided by Global Fishing Watch and multiple years of VIIRS data.

Global Fishing Watch is able to provide the VMS data because of its partnership with Indonesia, which began publicly sharing their VMS through the Global Fishing Watch platform in June 2017. They are the first nation to take such bold steps toward transparency, and Peru has recently signed an MOU to do the same.

Now that Global Fishing Watch has access to the VIIRS boat detection data they can vastly expand the number of fishing boat records reported in the public database. In addition, it would be possible to cross match VMS or AIS data with VIIRS boat detections to identify "dark vessels" which may be fishing illegally. The combined data sources could also be analyzed to detect clusters of fishing boats straddling international boundaries, or fishing in Marine Protected Areas.

Contact: Samantha Emmert
Global Fishing Watch

 

New study reveals strong El Niño events cause large changes in Antarctic ice shelves

Oscillations of water temperature in the tropical Pacific Ocean can induce rapid melting of Antarctic ice shelves.

Front of the Getz Ice Shelf. Credit: Jeremy Harbeck/NASA.

A new study published Jan. 8 in the journal Nature Geoscience reveals that strong El Nino events can cause significant ice loss in some Antarctic ice shelves while the opposite may occur during strong La Nina events.

El Niño and La Niña are two distinct phases of the El Niño/Southern Oscillation (ENSO), a naturally occurring phenomenon characterized by how water temperatures in the tropical Pacific periodically oscillate between warmer than average during El Niños and cooler during La Niñas.

The research, funded by NASA and the NASA Earth and Space Science Fellowship, provides new insights into how Antarctic ice shelves respond to variability in global ocean and atmospheric conditions.

The study was led by Fernando Paolo while a PhD graduate student and postdoc at Scripps Institution of Oceanography at the University of California San Diego. Paolo is now a postdoctoral scholar at NASA's Jet Propulsion Laboratory. Paolo and his colleagues, including Scripps glaciologist Helen Fricker, discovered that a strong El Niño event causes ice shelves in the Amundsen Sea sector of West Antarctica to gain mass at the surface and melt from below at the same time, losing up to five times more ice from basal melting than they gain from increased snowfall. The study used satellite observations of the height of the ice shelves from 1994 to 2017.

"We've described for the first time the effect of El Niño/Southern Oscillation on the West Antarctic ice shelves," Paolo said. "There have been some idealized studies using models, and even some indirect observations off the ice shelves, suggesting that El Niño might significantly affect some of these shelves, but we had no actual ice-shelf observations. Now we have presented a record of 23 years of satellite data on the West Antarctic ice shelves, confirming not only that ENSO affects them at a yearly basis, but also showing how."

The opposing effects of El Niño on ice shelves - adding mass from snowfall but taking it away through basal melt - were at first difficult to untangle from the satellite data. "The satellites measure the height of the ice shelves, not the mass, and what we saw at first is that during strong El Niños the height of the ice shelves actually increased," Paolo said. "I was expecting to see an overall reduction in height as a consequence of mass loss, but it turns out that height increases."

After further analysis of the data, the scientists found that although a strong El Niño changes wind patterns in West Antarctica in a way that promotes flow of warm ocean waters towards the ice shelves to increase melting from below, it also increases snowfall particularly along the Amundsen Sea sector. The team then needed to determine the contribution of the two effects. Is the atmosphere adding more mass than the ocean is taking away or is it the other way around?

"We found out that the ocean ends up winning in terms of mass. Changes in mass, rather than height, control how the ice shelves and associated glaciers flow into the ocean," Paolo said. While mass loss by basal melting exceeds mass gain from snowfall during strong El Niño events, the opposite appears to be true during La Niña events.

 

Over the entire 23-year observation period, the ice shelves in the Amundsen Sea sector of Antarctica had their height reduced by 20 centimeters (8 inches) a year, for a total of 5 meters (16 feet), mostly due to ocean melting. The intense 1997-98 El Nino increased the height of these ice shelves by more than 25 centimeters (10 inches). However, the much lighter snow contains far less water than solid ice does. When the researchers took density of snow into account, they found that ice shelves lost about five times more ice by submarine melting than they gained from new surface snowpack.

"Many people look at this ice-shelf data and will fit a straight line to the data, but we're looking at all the wiggles that go into that linear fit, and trying to understand the processes causing them," said Fricker, who was Paolo's PhD adviser at the time the study was conceived. "These longer satellite records are allowing us to study processes that are driving changes in the ice shelves, improving our understanding on how the grounded ice will change," Fricker said.

"The ice shelf response to ENSO climate variability can be used as a guide to how longer-term changes in global climate might affect ice shelves around Antarctica," said co-author Laurie Padman, an oceanographer with Earth & Space Research, a nonprofit research company based in Seattle. "The new data set will allow us to check if our ocean models can correctly represent changes in the flow of warm water under ice shelves," he added.

Melting of the ice shelves doesn't directly affect sea level rise, because they're already floating. What matters for sea-level rise is the addition of ice from land into the ocean, however it's the ice shelves that hold off the flow of grounded ice toward the ocean.

Understanding what's causing the changes in the ice shelves "puts us a little bit closer to knowing what's going to happen to the grounded ice, which is what will ultimately affect sea-level rise," Fricker said. "The holy grail of all of this work is improving sea-level rise projections," she added.

Citation: F. S. Paolo, L. Padman, H. A. Fricker, S. Adusumilli, S. Howard & M. R. Siegfried; Response of Pacific-sector Antarctic ice shelves to the El Nino/Southern Oscillation; Nature Goscience (08 January 2018); DOI: 10.1038/s41561-017-0033-0.

Contact: Lauren Fimbres Wood
University of California - San Diego

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The ocean is losing its breath

In broadest view yet of world's low oxygen, scientists reveal dangers and solutions.

Low oxygen caused the death of these corals and others in Bocas del Toro, Panama. The dead crabs pictured also succumbed to the loss of dissolved oxygen. Credit: Arcadio Castillo/Smithsonian.

In the past 50 years, the amount of water in the open ocean with zero oxygen has gone up more than fourfold. In coastal water bodies, including estuaries and seas, low-oxygen sites have increased more than 10-fold since 1950. Scientists expect oxygen to continue dropping even outside these zones as Earth warms.

To halt the decline, the world needs to rein in both climate change and nutrient pollution, an international team of scientists including Lisa Levin, a biological oceanographer at Scripps Institution of Oceanography at the University of California San Diego, asserted in a new paper published Jan. 4 in Science.

"Oxygen is fundamental to life in the oceans," said Denise Breitburg, lead author and marine ecologist with the Smithsonian Environmental Research Center. "The decline in ocean oxygen ranks among the most serious effects of human activities on the Earth's environment."

"It's a tremendous loss to all the support services that rely on recreation and tourism, hotels and restaurants and taxi drivers and everything else," said Levin. "The reverberations of unhealthy ecosystems in the ocean can be extensive."

The study came from a team of scientists from GO2NE (Global Ocean Oxygen Network), a new working group created in 2016 by the United Nation's Intergovernmental Oceanographic Commission. The review paper is the first to take such a sweeping look at the causes, consequences and solutions to low oxygen worldwide, in both the open ocean and coastal waters. The article highlights the biggest dangers to the ocean and society, and what it will take to keep Earth's waters healthy and productive.

The Stakes

"Approximately half of the oxygen on Earth comes from the ocean," said Vladimir Ryabinin, executive secretary of the International Oceanographic Commission that formed the GO2NE group. "However, combined effects of nutrient loading and climate change are greatly increasing the number and size of 'dead zones' in the open ocean and coastal waters, where oxygen is too low to support most marine life."

In areas traditionally called "dead zones," like those in Chesapeake Bay and the Gulf of Mexico, oxygen plummets to levels so low many animals suffocate and die. As fish avoid these zones, their habitats shrink and they become more vulnerable to predators or fishing. But the problem goes far beyond "dead zones," the authors point out. Even smaller oxygen declines can stunt growth in animals, hinder reproduction and lead to disease or even death. It also can trigger the release of dangerous chemicals such as nitrous oxide, a greenhouse gas up to 300 times more powerful than carbon dioxide, and toxic hydrogen sulfide. While some animals can thrive in dead zones, overall biodiversity falls.

Climate change is the key culprit in the open ocean. Warming surface waters make it harder for oxygen to reach the ocean interior. Furthermore, as the ocean as a whole gets warmer, it holds less oxygen. In coastal waters, excess nutrient pollution from land creates algal blooms, which drain oxygen as they die and decompose. In an unfortunate twist, animals also need more oxygen in warmer waters, even as it is disappearing.

People's livelihoods are also on the line, the scientists reported, especially in developing nations. Smaller, artisanal fisheries may be unable to relocate when low oxygen destroys their harvests or forces fish to move elsewhere. In the Philippines, fish kills in a single town's aquaculture pens cost more than $10 million. Coral reefs, a key tourism attraction in many countries, also can waste away without enough oxygen.

Some popular fisheries could benefit, at least in the short term. Nutrient pollution can stimulate production of food for fish. In addition, when fish are forced to crowd to escape low oxygen, they can become easier to catch. But in the long run, this could result in overfishing and damage to the economy.

Low-oxygen zones are spreading around the globe. Red dots mark places on the coast where oxygen has plummeted to 2 milligrams per liter or less, and blue areas mark zones with the same low-oxygen levels in the open ocean. Credit: GO2NE working group. Data from World Ocean Atlas 2013 and provided by R. J. Diaz.

Winning the War: A Three-Pronged Approach

To keep low oxygen in check, the scientists said the world needs to take on the issue from three angles:

Address the causes: nutrient pollution and climate change. While neither issue is simple or easy, the steps needed to win can benefit people as well as the environment. Better septic systems and sanitation can protect human health and keep pollution out of the water. Cutting fossil fuel emissions not only cuts greenhouse gases and fights climate change, but also slashes dangerous air pollutants like mercury.

Protect vulnerable marine life. With some low oxygen unavoidable, it is crucial to protect at-risk fisheries from further stress. According to the GO2NE team, this could mean creating marine protected areas or no-catch zones in areas animals use to escape low oxygen, or switching to fish that are not as threatened by falling oxygen levels. Improve low-oxygen tracking worldwide. Scientists have a decent grasp of how much oxygen the ocean could lose in the future, but they do not know exactly where those low-oxygen zones will be. Enhanced monitoring, especially in developing countries, and numerical models will help pinpoint which places are most at risk and determine the most effective solutions.

"This is a problem we can solve," Breitburg said. "Halting climate change requires a global effort, but even local actions can help with nutrient-driven oxygen decline." As proof Breitburg points to the ongoing recovery of Chesapeake Bay, where nitrogen pollution has dropped 24 percent since its peak thanks to better sewage treatment, better farming practices and successful laws like the Clean Air Act. While some low-oxygen zones persist, the area of the Chesapeake with zero oxygen has almost disappeared. "Tackling climate change may seem more daunting," she added, "but doing it is critical for stemming the decline of oxygen in our oceans, and for nearly every aspect of life on our planet."

Citation: Denise Breitburg, Lisa A. Levin, Andreas Oschlies, Marilaure Gregoire, Francisco P. Chavez, Daniel J. Conley, Veronique Garcon, Denis Gilbert, Dimitri Gutierrez, Kirsten Isensee, Gil S. Jacinto, Karin E. Limburg, Ivonne Montes, S.W.A. Naqvi, Grant C. Pitcher, Nancy N. Rabalais, Michael R. Roman, Kenneth A. Rose, Brad A. Seibel, Maciej Telszewski, Moriaki Yasuhara & Jing Zhang; Declining oxygen in the global ocean and coastal waters; Science, Vol. 359, Issue 6371, eaam7240 (5 January 2018); DOI: 10.1126/science.aam7240.

Contact: Rob Monroe
University of California - San Diego

 

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Scientists find surprising evidence of rapid changes in the Arctic

Diminishing sea ice near the Arctic coast leaves more open water near the coast for winds to create waves. The increased wave action reaches down and stirs up sediments on shallow continental shelves, releasing radium and other chemicals that are carried up to the surface and swept away into the open ocean by currents such as the Transpolar Drift. A new study found surprising evidence that climate change is rapidly causing coastal changes in the Arctic that could have significant impacts on Arctic food webs and animal populations. (Natalie Renier, Woods Hole Oceanographic Institution).

Scientists have found surprising evidence of rapid climate change in the Arctic: In the middle of the Arctic Ocean near the North Pole, they discovered that the levels of radium-228 have almost doubled over the last decade.

The finding indicates that large-scale changes are happening along the coast--because the source of the radium is the land and shallow continental shelves surrounding the ocean. These coastal changes, in turn, could also be delivering more nutrients, carbon, and other chemicals into the Arctic Ocean and lead to dramatic impacts on Arctic food webs and animal populations.

The research team, led by Woods Hole Oceanographic Institution (WHOI), suspects that melting sea ice has left more open water near the coast for winds to create waves. The wave action reaches down to the shallow shelves and stirs up sediments, releasing radium that is carried to the surface and away into the open ocean. The same mechanism would likely also mobilize and deliver more nutrients, carbon, and other chemicals into the Arctic Ocean, fueling the growth of plankton at the bottom of the food chain. That, in turn, could have significant impacts on fish and marine mammals and change the Arctic ecosystem.

The study was published Jan. 3, 2018, in the journal Science Advances. The research team included Lauren Kipp, Matthew Charette, and Paul Henderson (WHOI), Willard Moore (University of South Carolina), and Ignatius Rigor (University of Washington).

Scientists have long used radium-228 to track the flow of material from land and sediments into the ocean. It is a naturally occurring isotope produced by the radioactive decay of thorium in sediments. But unlike thorium, it dissolves into water, where scientists can track the sources, amounts, rates, and direction of its flow, said Kipp, who is lead author of the study and a graduate student in the MIT-WHOI Joint Program in Oceanography.

Kipp led efforts to measure radium at 69 locations from the western edge of the Arctic Ocean to the Pole on a two-month voyage aboard the icebreaker Healy in the summer of 2015. The cruise was part of the international GEOTRACES program, which aims to measure chemical tracers in the world's ocean to understand ocean circulation and provide a baseline to assess future chemical changes in the oceans. The U.S. GEOTRACES program and this study are both funded by the National Science Foundation.

Scientists aboard the icebreaker Healy measured seawater chemistry across the Arctic Ocean and found that levels of radium-228 have almost doubled over the last decade in the middle of the ocean. The radium was transported from land and shallow continental shelves by currents such as the Transpolar Drift. The surprising finding is evidence that rapid climate change is causing large-scale changes along the Arctic coast, such as diminishing sea ice. These coastal changes, in turn, could also deliver more nutrients, carbon, and other chemicals into the Arctic Ocean and have significant impacts on the Arctic food web. (Natalie Renier, Woods Hole Oceanographic Institiution).

To their surprise, the research team found that radium-228 concentrations in the central Arctic Ocean had increased substantially since measurements had last been made in 2007. What was its source and why had it increased?

The team investigated the trajectories of sea ice drifting in the ocean and saw a pattern of ice--and hence water--flowing northward from the vast northern coast of Russia toward the middle of the Arctic Ocean, where the radium concentrations had increased. The pattern aligned with the Transpolar Drift, a powerful current flowing in same direction that could transport radium from coastal sources.

They concluded that the excess radium had to have come from sediments in the East Siberian Arctic Shelf off Russia, the largest continental shelf on Earth. It is relatively shallow, with an average depth of 170 feet, but it extends 930 miles off shore and contains a vast reservoir of radium and other chemical compounds.

Something had to have changed along the coast to explain the dramatic surge in radium in the middle of the Arctic Ocean. The scientists theorize that a warming Arctic environment has reduced sea ice cover, allowing for more wave action that stirs up sediments and mobilizes more radium.

But there are other possible contributing factors that are causing changes over the shelf, the scientists say. More wave action can also cause more coastline erosion, adding more terrestrial sediment into the ocean. Warming temperatures can thaw permafrost, liberating more material into the ocean, and increasing river and groundwater runoff can carry more radium, nutrients, carbon, and other material into the Arctic.

"Continued monitoring of shelf inputs to Arctic surface waters is therefore vital to understand how the changing climate will affect the chemistry, biology, and economic resources of the Arctic Ocean," the study's authors wrote.

Data coverage over the East Siberian Shelf is currently very limited, so it is important to conduct more studies in this region in order to pinpoint the direct causes of the increased shelf inputs and allow future monitoring. "Evidence from Kipp and co-workers for substantial ongoing change in the chemical environment of the Arctic Ocean emphasizes the need for sustained study of these changes and of the processes involved," said Bob Anderson, an Ewing-Lamont Research Professor at the Lamont-Doherty Earth Observatory of Columbia University and the director of the U.S. GEOTRACES Program Office. "It would be great if related efforts by marine geochemists in Russia could be integrated with future studies by other nations, for example under the auspices of the international GEOTRACES program."

Citation: Lauren Kipp, Matthew Charette, Paul Henderson, Willard Moore, and Ignatius Rigor; Science Advances , Vol. 4 no. 1 eaao 1302 (o3 January 2018); DOI: 10.1126/sciadv.aao1302.

Woods Hole Oceanographic Institution