As the oceans warm, wide-ranging species will have an edge

Terra Daily via SPX: Marine species that already have large ranges are extending their territories fastest in response to climate change, according to new research from University of British Columbia biodiversity experts.

The study is one of the first comprehensive looks at how traits--other than thermal niche--impact marine animals' ability to respond to climate change. It could help improve global predictions of how different species redistribute as the oceans warm, and identify species in greatest jeopardy.

"We have a bit of a mystery as to why some animals are moving quickly into cooler waters, like the green sea urchin that is decimating kelp forests in Tasmania, while other species aren't moving at all," says UBC biodiversity researcher Jennifer Sunday, lead author of the study.

"Our findings indicate that animals which already have wide-latitudinal ranges, habitat generalists, and species with high adult mobility displayed the quickest and greatest range shifts. The flip side is that small-ranging species are in increased jeopardy as our planet's oceans continue to warm."....

Oscar (Astronotus ocellatus), a popular aquarium fish from South America, shot by Jón Helgi Jónsson (Amything), Wikimedia Commons, under the Creative Commons Attribution-Share Alike 3.0 Unported license

Warming of oceans due to climate change is unstoppable, say US scientists

Suzanne Goldenberg in the Guardian (UK): The warming of the oceans due to climate change is now unstoppable after record temperatures last year, bringing additional sea-level rise, and raising the risks of severe storms, US government climate scientists said on Thursday.

The annual State of the Climate in 2014 report, based on research from 413 scientists from 58 countries, found record warming on the surface and upper levels of the oceans, especially in the North Pacific, in line with earlier findings of 2014 as the hottest year on record.

Global sea-level also reached a record high, with the expansion of those warming waters, keeping pace with the 3.2 ± 0.4 mm per year trend in sea level growth over the past two decades, the report said. Scientists said the consequences of those warmer ocean temperatures would be felt for centuries to come – even if there were immediate efforts to cut the carbon emissions fuelling changes in the oceans.

“I think of it more like a fly wheel or a freight train. It takes a big push to get it going but it is moving now and will contiue to move long after we continue to pushing it,” Greg Johnson, an oceanographer at Noaa’s Pacific Marine Environmental Laboratory, told a conference call with reporters.

“Even if we were to freeze greenhouse gases at current levels, the sea would actually continue to warm for centuries and millennia, and as they continue to warm and expand the sea levels will continue to rise,” Johnson said....

Ocean warming leads to stronger precipitation extremes

A press release from the Helmholtz Centre for Ocean Research-Kiel: Due to climate change, not only atmospheric, but also oceanic, temperatures are rising. A study published in the international journal Nature Geoscience led by scientists at the GEOMAR Helmholtz Centre for Ocean Research Kiel shows that increases in sea surface temperature can contribute to the development of stronger precipitation events. Their findings are underpinned by flash-flooding in June in the Olympic city of Sochi, Russia.

That the temperatures on our planet are rising is clear. In particular, the increasing emissions of greenhouse gases such as carbon dioxide continue to warm the atmosphere. The effects of global warming on the hydrological cycle, however, are still not fully understood. Particularly uncertain is how the strength of extreme summertime thunderstorms have changed, and how it may change in the future. In coastal regions neighboring warm seas, the sea surface temperature can play a crucial role in the intensity of convective storms. The Black Sea and eastern Mediterranean have warmed by about 2 C since the early 1980s. Russian and German scientists investigated what impact this warming may have had on extreme precipitation in the region.

“Our showcase example was a heavy precipitation event from July 2012 that took place in Krymsk (Russia), near the Black Sea coast, resulting in a catastrophic flash food with 172 deaths”, said Edmund Meredith, lead author of the study. “We carried out a number of very-high-resolution simulations with an atmospheric model to investigate the impact of rising sea surface temperatures on the formation of intense convective storms, which are often associated with extreme rainfall”, Meredith continued. Simulations of the event with observed sea surface temperatures showed an increase in precipitation intensity of over 300%, compared to comparable simulations using sea surface temperatures representative of the early 1980s.  “We were able to identify a very distinct change, which demonstrates that convective precipitation responds with a strong, non-linear signal to the temperature forcing”, Prof. Douglas Maraun, co-author of the study added.

At the end of June 2015, the nearby Olympic city of Sochi experienced an unusually intense precipitation event. Over 175 mm of rain was recorded in 12 hours, showing the relevance of the scientists work.  “Due to ocean warming, the lower atmosphere has become more unstable over the Black Sea and eastern Mediterranean. We therefore expect that events like those in Krymsk or Sochi will become more frequent in the future”, added the Kiel-based climate scientist.

Rain near a San Francisco beach, shot by the incomporable Brocken Inaglory, Wikimedia Commons, under the Creative Commons Attribution-Share Alike 3.0 Unported license

The oceans can’t take any more: researchers fear a fundamental change in the oceans – even if greenhouse emissions are successfully reduced

A press release from the Alfred Wegener Institute: Our oceans need an immediate and substantial reduction of anthropogenic greenhouse gas emissions. If that doesn’t happen, we could see far-reaching and largely irreversible impacts on marine ecosystems, which would especially be felt in developing countries. That’s the conclusion of a new review study published today in the journal Science. In the study, the research team from the Ocean 2015 initiative assesses the latest findings on the risks that climate change poses for our oceans, and demonstrates how fundamentally marine ecosystems are likely to change if human beings continue to produce just as much greenhouse gases as before.

Since the pre-industrial era, the carbon dioxide concentration in the atmosphere has risen from 278 to 400 ppm (parts per million) – a 40 percent increase that has produced massive changes in the oceans. “To date, the oceans have essentially been the planet’s refrigerator and carbon dioxide storage locker. For instance, since the 1970s they’ve absorbed roughly 93 percent of the additional heat produced by the greenhouse effect, greatly helping to slow the warming of our planet,” explains Prof Hans-Otto Pörtner, co-author of the new Ocean 2015 study and a researcher at the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research.

But the oceans have also paid a high price: as far down as 700 metres the water temperatures have risen, which has forced some species to migrate up to 400 kilometres closer to the Earth’s poles within the past decade. Given the increasing acidification in many regions, it’s becoming more and more difficult for corals and bivalves to form their calcium carbonate skeletons. In Greenland and the western Arctic, the ice is melting at an alarming rate, contributing to rising sea levels. As a result of these factors, the biological, physical and chemical processes at work in marine ecosystems are changing – which will have far-reaching consequences for marine life and humans alike.

In their new study, the research team from the Ocean 2015 initiative employs two emissions scenarios (Scenario 1: Achieving the 2-degree goal / Scenario 2: Business as usual) to compile the main findings of the IPCC’s 5th Assessment Report and the latest professional literature, and to assess those findings with regard to the risks for our oceans. “If we can successfully limit the rise in air temperature to two degrees Celsius through the year 2100, the risks, especially for warm-water corals and bivalves in low to middle latitudes, will become critical. However, the remaining risks will remain fairly moderate,” explains lead author Jean-Pierre Gattuso. But a rapid and comprehensive reduction of carbon dioxide emissions would be needed in order to achieve this ideal option, he adds....

An Australian pelican watches a beach sunrise, shot by bigwavephoto big wave photo, Wikimedia Commons, under the Creative Commons Attribution-Share Alike 4.0 International License 

Increasingly acidic oceans threaten world's mussel populations

The Guardian (UK) via Press Association: The world’s mussel population could be under threat as climate change causes the oceans to become more acidic, scientists have warned. Mussel shells become more brittle when they are formed in more acidic water, Glasgow University has reported in the Royal Society journal Interface.

Carbon dioxide in the atmosphere causes the oceans to become more acidic and reduces the concentration of the minerals mussels need to generate their shells, according to scientists. However, they also found that mussels may have an in-built biological defence mechanism which boosts shell development when water temperatures rise by 2C.

Dr Fitzer said: “What we’ve found in the lab is that increased levels of acidification in their habitats have a negative impact on mussels’ ability to create their shells. “We worked with colleagues in our School of Engineering to examine the toughness of the shells of the mussels in the more acidic water against those in control conditions.

“What we found was that the calcite outer shells of the mussels past a certain threshold of acidity was stiffer and harder, making it more brittle and prone to fracture under pressure, and the aragonite inner shell became softer.

The shellfish industry is worth more than £250m a year to the UK economy with a large part accounted for by mussels and oysters, the UK Department for Environment, Food and Rural Affairs reported in 2012....

A mussel shell from the Netherlands, shot by Emma Versteegh, Wikimedia Commons, under the Creative Commons Attribution-Share Alike 2.5 Generic license

New study explains the role of oceans in global ‘warming hiatus’

A press release from the University of Southampton: New research shows that ocean heat uptake across three oceans is the likely cause of the ‘warming hiatus’ – the current decade-long slowdown in global surface warming.  Using data from a range of state-of-the-art ocean and atmosphere models, the research shows that the increased oceanic heat drawdown in the equatorial Pacific, North Atlantic and Southern Ocean basins has played a significant role in the hiatus.

The new analysis has been published in Geophysical Research Letters by Professor Sybren Drijfhout from the University of Southampton and collaborators from the National Oceanography Centre (NOC) Dr Adam Blaker, Professor Simon Josey, Dr George Nurser and Dr Bablu Sinha, together with Dr Magdalena Balmaseda from the European Centre for Medium Range Weather Forecasting (ECMWF).

Professor Drijfhout said: “This study attributes the increased oceanic heat drawdown in the equatorial Pacific, North Atlantic and Southern Ocean to specific, different mechanisms in each region. This is important as current climate models have been unable to simulate the hiatus. Our study gives clues to where the heat is drawn down and by which processes. This can serve as a benchmark for climate models on how to improve their projections of future global mean temperature.”

Previously, the drawdown of heat by the Equatorial Pacific Ocean over the hiatus period, due to cool sea-surface temperatures associated with a succession of cool-surface La Nina episodes, was thought to be sufficient to explain the hiatus.  However, this new analysis reveals that the northern North Atlantic, the Southern Ocean and Equatorial Pacific Ocean are all important regions of ocean heat uptake. Each basin contributes a roughly equal amount to explaining the hiatus, but the mechanisms of heat drawdown are different and specific in each basin.

...Dr Sinha concluded: “The deeper understanding gained in this study of the processes and regions responsible for variations in oceanic heat drawdown and retention will improve the accuracy of future climate projections.”

Fish at an oil platform, Gulf of Mexico, photo by US Bureau of Ocean Energy Management

Antarctica: Heat comes from the deep

A press release from the Helmholtz Centre for Ocean Research-Kiel: The water temperatures on the West Antarctic shelf are rising. The reason for this is predominantly warm water from greater depths, which as a result of global change now increasingly reaches the shallow shelf. There it has the potential to accelerate the glacier melt from below and trigger the sliding of big glaciers. These data are published today by scientists of the GEOMAR Helmholtz Centre for Ocean Research Kiel together with colleagues from the UK, the US and Japan in the international journal Science.

... "There are many large glaciers in the area. The elevated temperatures have accelerated the melting and sliding of these glaciers in recent decades and there are no indications that this trend is changing,"says the lead author of the study, Dr. Sunke Schmidtko from GEOMAR Helmholtz Centre for Ocean Research Kiel.

For their study, he and his colleagues of the University of East Anglia, the California Institute of Technology and the University of Hokkaido (Japan) evaluated all oceanographic data from the waters around Antarctica from 1960 to 2014 that were available in public databases. These data show that five decades ago, the water masses in the West Antarctic shelf seas were already warmer than in other parts of Antarctica, for example, in the Weddell Sea. However, the temperature difference is not constant. Since 1960, the temperatures in the West Antarctic Amundsen Sea and the Bellingshausen Sea have been rising. "Based on the data we were able to see that this shelf process is induced from the open ocean," says Dr. Schmidtko.

..."These are the regions in which accelerated glacial melting has been observed for some time. We show that oceanographic changes over the past 50 years have probably caused this melting. If the water continues to warm, the increased penetration of warmer water masses onto the shelf will likely further accelerate this process, with an impact on the rate of global sea level rise " explains Professor Karen Heywood from the University of East Anglia.

The scientists also draw attention to the rising up of warm water masses in the southwestern Weddell Sea. Here very cold temperatures (less than minus 1.5°C or 29°F) prevail on the shelf and a large-scale melting of shelf ice has not been observed yet. If the shoaling of warm water masses continues, it is expected that there will be major environmental changes with dramatic consequences for the Filchner or Ronne Ice Shelf, too. For the first time glaciers outside the West Antarctic could experience enhanced melting from below....

A NASA/Cryosat image of ice on the Weddell Sea

Salinity matters when it comes to sea level changes

A press release from Lawrence Livermore National Laboratory: Using ocean observations and a large suite of climate models, Lawrence Livermore National Laboratory scientists have found that long-term salinity changes have a stronger influence on regional sea level changes than previously thought.

“By using long-term observed estimates of ocean salinity and temperature changes across the globe, and contrasting these with model simulations, we have uncovered the unexpectedly large influence of salinity changes on ocean basin-scale sea level patterns,” said LLNL oceanographer Paul Durack, lead author of a paper appearing in the November issue of the journal Environmental Research Letters (link is external).

Sea level changes are one of the most pronounced effects of climate change impacts on the Earth and are primarily driven by warming of the global ocean along with added water from melting land-based glaciers and ice sheets. In addition to these effects, changes in ocean salinity also can affect the height of the sea, by changing its density structure from the surface to the bottom of the ocean.

The team found that there was a long-term (1950-2008) pattern in halosteric (salinity-driven) sea level changes in the global ocean, with sea level increases occurring in the Pacific Ocean and sea level decreases in the Atlantic. These salinity-driven sea level changes have not been thoroughly investigated in previous long-term estimates of sea level change. When the scientists contrasted these results with models, the team found that models also simulated these basin-scale patterns, and that the magnitude of these changes was surpri
singly large, making up about 25 percent of the total sea level change.

“By contrasting two long-term estimates of sea level change to simulations provided from a large suite of climate model simulations, our results suggest that salinity has a profound effect on regional sea level change,” Durack said. “This conclusion suggests that future sea level change assessments must consider the regional impacts of salinity-driven changes; this effect is too large to continue to ignore.”...

Lined with bottles triggered at different levels of the ocean, this conductivity, temperature and depth profiler bearing a suite of sampling bottles is a mainstay of oceanography. It can be deployed to depths of 6,000 meters to study changes in ocean temperature and salinity. Photo courtesy of Ann Thresher/CSIRO

Italy ignores pleas, ends boat migrant rescue operation

Terra Daily via AFP: Italy on Friday ignored the pleas of aid agencies and confirmed the end of its search and rescue operation "Mare Nostrum", responsible for saving tens of thousands of boat migrants stranded in the Mediterranean.

"From tomorrow a new operation called 'Triton' begins," deputy prime minister and interior minister Angelino Alfano told journalists at a press conference, referring to a much more limited mission led by the EU border agency Frontex. "Mare Nostrum ends. Italy has done its duty,"

He said the government had spent some 114 million euros ($142 million) on the massive naval operation since two deadly shipwrecks in October last year left over 400 people dead.

The decision comes after growing criticism both within Italy and Europe that the rescue mission was creating an unintended "pull factor" for more migrants in makeshift boats to attempt the dangerous sea crossings.

Although the op -- which has saved over 150,000 people -- is being shelved, Italy said it will abide by the laws of the sea under which ships that spot migrants in trouble are obliged to rescue them....

A 1945 boat rescue in the Mediterranean by the UK, not Italy

Scientists suggest ocean warming in Southern Hemisphere underestimated

Anne M. Stark at Lawrence Livermore Laboratory: Using satellite observations and a large suite of climate models, Lawrence Livermore scientists have found that long-term ocean warming in the upper 700 meters of Southern Hemisphere oceans has likely been underestimated.

"This underestimation is a result of poor sampling prior to the last decade and limitations of the analysis methods that conservatively estimated temperature changes in data-€sparse regions," said LLNL oceanographer Paul Durack, lead author of a paper appearing in the October 5 issue of the journal Nature Climate Change.

Ocean heat storage is important because it accounts for more than 90 percent of the Earth's excess heat that is associated with global warming. The observed ocean and atmosphere warming is a result of continuing greenhouse gas emissions. The Southern Hemisphere oceans make up 60 percent of the world's oceans.

The team found that climate models simulate the relative increase in sea surface height -- a leading indicator of climate change -- between Northern and Southern hemispheres is consistent with highly accurate altimeter observations. However, separating the simulated upper-€ocean warming in the Northern and Southern hemispheres is inconsistent with observed estimates of ocean heat content change. These sea level and ocean heat content changes should be consistent, and suggest that until recent improvements occurred in the observational system in the early 21st century, Southern Hemisphere ocean heat content changes were likely underestimated.

Since 2004, automated profiling floats (named Argo) have been used to measure global ocean temperatures from the surface down to 2,000 meters. The 3,600 Argo floats currently observing the global ocean provide systematic coverage of the Southern Hemisphere for the first time. Argo float measurements over the last decade, as well as data from earlier measurements, show that the ocean has been gradually warming, according to Durack.

"Prior to 2004, research has been very limited by the poor measurement coverage," he said. "By using satellite data, along with a large suite of climate model simulations, our results suggest that global ocean warming has been underestimated by 24 to 58 percent. The conclusion that warming has been underestimated agrees with previous studies, however it's the first time that scientists have tried to estimate how much heat we've missed."

Deploying an Argo float. Akin to having a fleet of miniature research vessels, the global flotilla of more than 3,600 robotic profiling floats provides crucial information on upper layers of the world's ocean currents. Photo by Alicia Navidad/CSIRO

While the Arctic is melting the Gulf Stream remains

A press release from the University of Bergen (Norway): The melting Arctic is not the source for less saline Nordic Seas. It is the Gulf Stream that has provided less salt. A new study published Sunday in Nature Geoscience documents that the source of fresher Nordic Seas since 1950 is rooted in the saline Atlantic as opposed to Arctic freshwater that is the common inference.

This is an important finding as it shows that the Gulf Stream is not about to short circuit. A halting Gulf Stream has been a concern with ongoing climate change; its collapse was taken to the extreme in the Hollywood blockbuster “The Day After Tomorrow”, says Tor Elde
vik, professor in oceanography at the University of Bergen and the Bjerknes Centre.

The Nordic Seas have freshened substantially since 1950. This has happened at the same time as there has been observed increased river runoff and net ice melting in the Arctic. The concurrence of a less saline ocean and Arctic freshwater input has given the climate research community reason for concern.

 It has been a concern that a layer of Arctic freshwater could impede the Gulf Stream’s Arctic branch. Going back in time – into and through ice ages – such a freshwater lid has been understood to reduce ocean circulation and thus the Gulf Stream’s poleward heat transport, says Tor Eldevik.

Eldevik is co-author of the study where Mirjam Glessmer and colleagues at the Bjerknes Centre in Bergen, Norway, show that change in the Nordic Seas is at the receiving end of change in the more global climate system. The Nordic Seas are in this case not a precursor in a real world parallel to “The Day After Tomorrow”....

Because the story is from Norway: a fjord. Shot by Karamell, Wikimedia Commons, under the Creative Commons 3.0 license

Study finds Great Barrier Reef is an effective wave absorber

University of Southampton News Release: New research has found that the Great Barrier Reef, as a whole, is a remarkably effective wave absorber, despite large gaps between the reefs. This means that landward of the reefs, waves are mostly related to local winds rather than offshore wave conditions.

As waves break and reduce in height over reefs, this drives currents that are very important for the transport of nutrients and larvae. This reduction in wave height also has implications for shoreline stability. Transition

The Great Barrier Reef in Australia is the largest coral reef system in the world, extending 2,300 km alongshore. The reef matrix is a porous structure consisting of thousands of individual reefs, with gaps in between. The porosity varies in that is it much lower in the north where the continental shelf is narrow and there is extensive reef flats; and is greater in the south where the shelf reaches up to 300 km wide and there are extensive lagoons.

Previously, there have been several studies investigating how individual reefs in the Great Barrier Reef influence ocean waves. However, this was the first, comprehensive, large-scale study of the influence of an entire offshore reef system on ocean wave transmission. The researchers used a 16-year record of satellite altimeter measurements of wave heights.

The team was led by Dr Shari Gallop, Research Fellow in Geology and Geophysics at the University of Southampton, and included Dr Ivan Haigh, also from the University of Southampton; Professor Ian Young, Vice-Chancellor of the Australian National University (ANU); Professor Roshanka Ranasinghe, Professor of Climate Change Impacts and Coastal Risk (UNESCO-IHE, Deltares, ANU), and Dr Tom Durrant (Bureau of Meteorology, Australia).

The aim was to see how wave height reduction is influenced by the porosity of the reef matrix, sea level and wind speed. Dr Gallop says: “There was no evidence that in less porous areas wave heights are lessened. This is because individual reefs, like islands, cast a ‘wave shadow’ over a large area, so that a matrix of individual reefs is remarkably efficient at reducing waves.” ....

The Great Barrier Reef, shot by Sarah Ackerman, Wikimedia Commons via Flickr, under the Creative Commons 2.0 license

Shift in Arabian Sea plankton may threaten fisheries

A press release from the Lamont-Doherty Earth Observatory (part of the Earth Institute at Columbia University): A growing “dead zone” in the middle of the Arabian Sea has allowed plankton uniquely suited to low- oxygen water to take over the base of the food chain. Their rise to dominance over the last decade could be disastrous for the predator fish that sustain 120 million people living on the sea’s edge.

Scientists at Columbia University’s Lamont-Doherty Earth Observatory and their colleagues are the first to document the rapid rise of green Noctiluca scintillans, an unusual dinoflagellate that eats other plankton and draws energy from the sun via microscopic algae living within its cells. Noctiluca’s thick blooms color the Arabian Sea an emerald green each winter, from the shores of Oman on the west, to India and Pakistan on the east.

In a study published this week in Nature Communications, the researchers show how the millions of green algae living within Noctiluca’s cells allow it to exploit an oxygen-starved dead zone the size of Texas. They hypothesize that a tide of nutrient-rich sewage flowing from booming cities on the Arabian Sea is expanding the dead zone and feeding Noctiluca’s growth.
           
“These blooms are massive, appear year after year, and could be devastating to the Arabian Sea ecosystem over the long-term,” said the study’s lead author, Helga do Rosario Gomes, a biogeochemist at Lamont-Doherty....

A NASA image of a phytoplankton bloom in the Arabian Sea

No more pause: Warming will be non-stop from now on

Michael Slezak in New Scientist: Enjoy the pause in global warming while it lasts, because it's probably the last one we will get this century. Once temperatures start rising again, it looks like they will keep going up without a break for the rest of the century, unless we cut our greenhouse gas emissions.

The slowdown in global warming since 1997 seems to be driven by unusually powerful winds over the Pacific Ocean, which are burying heat in the water. But even if that happens again, or a volcanic eruption spews cooling particles into the air, we are unlikely to see a similar hiatus, according to two independent studies.

Masahiro Watanabe of the University of Tokyo in Japan and his colleagues have found that, over the past three decades, the natural ups and downs in temperature have had less influence on the planet's overall warmth. In the 1980s, natural variability accounted for almost half of the temperature changes seen. That fell to 38 per cent in the 1990s and just 27 per cent in the 2000s.

Instead, human-induced warming is accounting for more and more of the changes from year to year, says Watanabe. With ever-faster warming, small natural variations have less impact and are unlikely to override the human-induced warming.

"The implication is that we will get fewer hiatus periods, or hiatus periods that last for a shorter period," says Wenju Cai at the CSIRO in Melbourne, Australia, who wasn't involved in the work...

Hokusai's "The Wave"

'Widespread methane leakage' from ocean floor off US coast

Matt McGrath n BBC News: Researchers say they have found more than 500 bubbling methane vents on the seafloor off the US east coast. The unexpected discovery indicates there are large volumes of the gas contained in a type of sludgy ice called methane hydrate.

There are concerns that these new seeps could be making a hitherto unnoticed contribution to global warming. The scientists say there could be about 30,000 of these hidden methane vents worldwide. Previous surveys along the Atlantic seaboard have shown only three seep areas beyond the edge of the US continental shelf.

The team behind the new findings studied what is termed the continental margin, the region of the ocean floor that stands between the coast and the deep ocean. In an area between North Carolina and Massachusetts, they have now found at least 570 seeps at varying depths between 50m and 1,700m.

Their findings came as a bit of a surprise. "It is the first time we have seen this level of seepage outside the Arctic that is not associated with features like oil or gas reservoirs or active tectonic margins," said Prof Adam Skarke from Mississippi State University, who led the study....

From 1992: mapping conducted by the USGS off North Carolina and South Carolina shows large accumulations of methane hydrates.Dr. William Dillon, U.S. Geological Survey, public domain

Viruses take down massive algal blooms - and a whole lot of carbon dioxide

Scientific Blogging: ...Using a combination of satellite imagery and laboratory experiments, researchers have evidence showing that algae is sucking up climate-warming carbon dioxide from the atmosphere and sinking it to the bottom of the ocean.  And for that, we can thank one other thing people dislike: viruses.

Viruses infecting those algae are driving the life-and-death dynamics of the algae's blooms, even when all else stays essentially the same. According to results reported in Current Biology, a single North Atlantic algal bloom, about 30 kilometers in radius, converted 24,000 tons of carbon dioxide from the atmosphere into organic carbon - a process known as carbon fixation.

Two-thirds of that carbon turned over within a week as that bloom grew at a very rapid rate and then quickly met its demise. A closer look at those algae revealed high levels of specific viruses infecting their cells. To put that in context, Assaf Vardi of the Weizmann Institute of Science in Israel says that this patch of ocean fixes about as much carbon as an equivalent patch of rainforest and then almost immediately turns much of it over.

"This is, of course, only one patch out of numerous co-occurring patches in other parts of the Atlantic Ocean," adds Ilan Koren, also of the Weizmann Institute, not to mention those algal blooms that appear in other seasons and ecosystems. "While the impact that viruses have on the entire ecosystem was previously estimated to be very large, we provide the first approach to quantify their immense impact on open ocean blooms."

Important questions remain about the ultimate fate of all that carbon taken in by algal blooms, the researchers say. Much of it is probably recycled back to the atmosphere by bacteria. But it's also possible that the virus-infected algae release sticky sugars and lipids, leading their cells and the carbon within them to sink faster to the ocean floor. "If the latter scenario is true, it will have a profound impact [on] the efficiency of carbon dioxide 'pumping' from the atmosphere to the deep ocean," Vardi says. "This carbon will then have a better chance [of being] buried in the ocean sediment."...

An algal bloom off the Volga delta in the Caspian Sea, shot by NASA

Study shows three times more mercury in upper ocean since Industrial Revolution

A press release from the Woods Hole Oceanographic Institute: Although the days of odd behavior among hat makers are a thing of the past, the dangers mercury poses to humans and the environment persist today.

Mercury is a naturally occurring element as well as a by-product of such distinctly human enterprises as burning coal and making cement. Estimates of "bioavailable" mercury—forms of the element that can be taken up by animals and humans—play an important role in everything from drafting an international treaty designed to protect humans and the environment from mercu
ry emissions, to establishing public policies behind warnings about seafood consumption.

Yet surprisingly little is known about how much mercury in the environment is the result of human activity, or even how much bioavailable mercury exists in the global ocean. Until now.

A new paper by a group that includes researchers from the Woods Hole Oceanographic Institution (WHOI), Wright State University, Observatoire Midi-Pyréneés in France, and the Royal Netherlands Institute for Sea Research appears in this week's edition of the journal Nature and provides the first direct calculation of mercury in the global ocean from pollution based on data obtained from 12 sampling cruises over the past 8 years. The work, which was funded by the U.S. National Science Foundation and the European Research Council and led by WHOI marine chemist Carl Lamborg, also provides a look at the global distribution of mercury in the marine environment.

"It would seem that, if we want to regulate the mercury emissions into the environment and in the food we eat, then we should first know how much is there and how much human activity is adding every year," said Lamborg, who has been studying mercury for 24 years. "At the moment, however, there is no way to look at a water sample and tell the difference between mercury that came from pollution and mercury that came from natural sources. Now we have a way to at least separate the bulk contributions of natural and human sources over time."...

Bohr model of mercury, author unknown, Wikimedia Commons, under the Creative Commons 2.0 license

A new way to track bigeye tuna

Janet Lathrop at UMassAmherst News & Media Relations: A first-of-its-kind study of bigeye tuna movements in the northwestern Atlantic Ocean led by Molly Lutcavage, director of the Large Pelagics Research Center at the University of Massachusetts Amherst, found among other things that these fish cover a wide geographical range with pronounced north-south movements from Georges Bank to the Brazilian shelf, and they favor a high-use area off Cape Hatteras southwest of Bermuda for foraging.

This NOAA-funded research, which used a new approach to study one of the most important commercial tuna species in the Atlantic, provides the longest available fishery-independent record of bigeye tuna movements to date. Data should help researchers to further characterize habitat use and assess the need for more monitoring in high-catch areas.

...Fisheries oceanographer Lutcavage says, “Although Atlantic bigeye tuna are delivering high prices to the U.S. commercial fleet and are highly sought by recreational fishermen and fishing tournaments, there’s been a surprising lack of scientific research on this species. And in contrast to the Pacific, where tuna fisheries programs have deployed over 400,000 tags over 25 years, the Atlantic lacks the fisheries infrastructure that would increase the odds of reco
vering tags. We have to rely on popup satellite tags that are fishery independent to make sure we get information back from the tuna.”

...Working with pelagic longline vessel captains Scott Drabinowicz and John Caldwell of the FV Eagle Eye II out of Fairhaven, Mass., Lutcavage, with LPRC colleagues Tim Lam and doctoral candidate Ben Galuardi, deployed 21 pop-up satellite archival tags (PSAT) on adult bigeye tuna between 2008 and 2010 in the northwest Atlantic. The sea captains fit tags on fish in good condition and return them to the sea. The PSATs were programmed to record relative light level, temperature and pressure (depth) every two minutes for eight or 12 months.

...Lam explains, “Bigeye tuna dive deeply, like clockwork, at dusk and dawn, making it hard to use light-based geolocation methods to estimate their daily locations. Here, we showcase a new positioning technique to get around the problem of low light levels at depth by using temperature and the bigeyes’ spatial ecology and movements in the western Atlantic. But there’s much more to learn.”

The authors hope their results will inform the International Commission for the Conservation of Atlantic Tuna’s upcoming tagging effort and assist ICCAT scientists as they plan new research to better understand the population....

Pelagic longline vessel Captain Scott Drabinowicz and crew preparing to deploy a tag from the deck of the FV Eagle Eye II. From the UMass Amherst website

Has Antarctic sea ice expansion been overestimated?

A press release from the European Geosciences Union: New research suggests that Antarctic sea ice may not be expanding as fast as previously thought. A team of scientists say much of the increase measured for Southern Hemisphere sea ice could be due to a processing error in the satellite data. The findings are published today in The Cryosphere, a journal of the European Geosciences Union (EGU).

Arctic sea ice is retreating at a dramatic rate. In contrast, satellite observations suggest that sea ice cover in the Antarctic is expanding – albeit at a moderate rate – and that sea ice extent has reached record highs in recent years. What’s causing Southern Hemisphere sea ice cover to increase in a warming world has puzzled scientists since the trend was first spotted. Now, a team of researchers has suggested that much of the measured expansion may be due to an error, not previously documented, in the way satellite data was processed.

“This implies that the Antarctic sea ice trends reported in the IPCC’s AR4 and AR5 [the 2007 and 2013 assessment reports from the Intergovernmental Panel on Climate Change] can’t both be correct: our findings show that the data used in one of the reports contains a significant error. But we have not yet been able to identify which one contains the error,” says lead-author Ian Eisenman of the Scripps Institution of Oceanography at University of California San Diego in the US.

...In the study published in The Cryosphere, Eisenman and collaborators compare two datasets for sea ice measurements. The most recent one, the source of AR5 conclusions, was generated using a version of Bootstrap updated in 2007, while the other, used in AR4 research, is the result of an older version of the algorithm.

The researchers found a difference between the two datasets related to a transition in satellite sensors in December 1991, and the way the data collected by the two instruments was calibrated. “It appears that one of the records did this calibration incorrectly, introducing a step-like change in December 1991 that was big enough to have a large influence on the long-term trend,” explains Eisenman.

“You’d think it would be easy to see which record has this spurious jump in December 1991, but there’s so much natural variability in the record – so much ‘noise’ from one month to the next – that it’s not readily apparent which record contains the jump. When we subtract one record from the other, though, we remove most of this noise, and the step-like change in December 1991 becomes very clear.”

With the exception of the longer time period covered by the most recent dataset, the two records were thought to be nearly identical. But, by comparing the datasets and calculating Antarctic sea ice extent for each of them, the team found that there was a stark difference between the two records, with the current one giving larger rates of sea ice expansion than the old one in any given period. If the error is in the current dataset, the results could contribute to an unexpected resolution for the Antarctic sea ice cover enigma.

An iceberg off the Antarctic coast, shot by Christopher Michel - 091203_iceberg_6964, Wikimedia Commons via Flickr, under the Creative Commons 2.0 license 

Microplastics worse for crabs and other marine life than previously thought

A press release from the University of Exeter: The tiny plastic particles polluting our seas are not only orally ingested by marine creatures, but also enter their systems through their gills, according to a new study led by the University of Exeter. Scientists also discovered that when microplastics are drawn in through this method they take over six times longer to leave the body compared with standard digestion.

Lead author Dr Andrew Watts of Biosciences at the University of Exeter said: “Many studies on microplastics only consider ingestion as a route of uptake into animals. The results we have just published stress other routes such as ventilation. We have shown this for crabs, but the same could apply for other crustaceans, molluscs and fish – simply any animal which draws water into a gill-like structure to carry out gas exchange. “This is highly important from an ecological point of view, as if these plastics are retained longer within the animal there is more chance of them being passed up the food chain.”

The researchers used fluorescently labelled polystyrene microspheres to show how ingested microplastics were retained within the body tissues of the common shore crab, Carcinus maenas. Multiphoton imaging suggested that most microspheres were retained in the foregut after sticking to hair-like ‘setae’ structures within the crabs.

...It has been suggested that 10 per cent of plastic which is thrown away ends up in the marine environment. At 2013 production levels this equates to 11 million tonnes of packaging ending up in the marine environment every year. This plastic is then degraded by wave action, heat or UV damage and is created into microplastic (particles smaller than 5mm).

Dr Watts added: “This is a human issue. We have put this plastic there, mostly accidently, but it is our problem to solve. The best way to do this is to reduce our dependency on plastic. It comes back to the old phrase: reduce, reuse and recycle.”...

A commons shore crab, shot by D. Hazerli, Wikimedia Commons, under the Creative Commons CC0 1.0 Universal Public Domain Dedication.\