Source: University of Texas at Austin
Posted by Jenny Griffin
In findings of relevance to conservationists and the fishing industry, new research links short-term reductions in growth and reproduction of marine animals off the California coast to increasing variability in the strength of coastal upwelling currents -- currents that supply nutrients to the region's diverse ecosystem.
Along the west coast of North America, winds lift deep, nutrient-rich water into sunlit surface layers, fueling vast phytoplankton blooms that ultimately support fish, seabirds and marine mammals.
The new study, led by Bryan Black at The University of Texas at Austin's Marine Science Institute and appearing Sept. 19 in the journal Science, shows that since 1950 the California coast has experienced winters with extremely weak upwelling more frequently than in the previous five centuries.
Winters with extremely weak upwelling are associated with slower growth in fish and lower reproductive success for seabirds, underscoring the importance of upwelling for the conservation of endangered animals and management of commercially important fisheries.
"Our study underscores the fact that California is a place of high coastal upwelling variability," said Black, assistant professor of marine science and lead author on the study. "You have to keep that in mind if you're managing a fishery -- for example, you can't plan for every year being moderate or reliable. There are a lot of ups and downs."
Black said it's not possible yet to determine whether climate change has contributed to the changes in winter upwelling variability. The strength of upwelling does seem to be related to a climate pattern called the El Niño-Southern Oscillation (ENSO). And there is evidence that ENSO has been unusually variable during the past century, which may in part explain the pattern in upwelling extremes.
"This is consistent with what we expect from climate change, but at this point, we can't attribute it to that," said Black. "This is something we need to continue watching to see how climate variability plays out in the coming years.
To reconstruct the past 600 years of upwelling along the California coast, the team used tree ring data from long-lived blue oak trees. The researchers demonstrated that growth patterns in blue oak trees near the coast are highly sensitive to the same climate factors associated with upwelling. During the past 600 years, four of the 10 most extremely poor upwelling years occurred since 1950, and seven of 10 have occurred since 1850.
To study the effects of changing strength of upwelling on marine life, the team integrated data on how quickly fish grew every year since the 1940s, the timing of seabird egg laying since the 1970s, and the fledgling success of seabirds since the 1970s.
When they compared the tree ring data with these various biological indicators, they found poor upwelling years correlated with drops in biological productivity. Because the birds and fish in this study tended to rebound from each of these events within a year or two, the increased variability of upwelling strength has not led to long-term declines.
"It's interesting to see how influential climate is on biology and what a synchronizing force it is, especially across marine and terrestrial systems," said Black.
Researchers have used tree rings to reconstruct climate patterns such as ENSO before, but this is the first study to target such a focused region with such strong and direct consequences on animal growth and reproductive success.
The tree ring data allowed researchers to understand how these ecosystems were influenced by climate variation and extremes long before systematic records were kept. Few direct observations of the climate factors associated with upwelling along the west coast of North America go back more than 70 years.
Black noted that changes in upwelling strength did not affect just fish and seabirds. In a sense, these representative species were just the tips of the iceberg.
"By studying top level predators, we get an upper level view of the entire ecosystem," said Black. "They integrate what's happening across the whole food web."
Black said his team will next try to project how upwelling might change in the future.
"We understand the atmospheric drivers behind winter upwelling, so now we plan to use climate models to see what they say about these drivers and whether they forecast change for those in the future," said Black.
B. A. Black, W. J. Sydeman, D. C. Frank, D. Griffin, D. W. Stahle, M. Garcia-Reyes, R. R. Rykaczewski, S. J. Bograd, W. T. Peterson. Six centuries of variability and extremes in a coupled marine-terrestrial ecosystem. Science, 2014; 345 (6203): 1498 DOI: 10.1126/science.1253209
Written by Joshua Brown, University of Vermont
Posted by Jenny Griffin
“Consider the subtleness of the sea; how its most dreaded creatures glide under water, unapparent for the most part,” wrote Herman Melville in Moby Dick. Today, we no longer dread whales, but their subtlety remains. “For a long time, whales have been considered too rare to make much of a difference in the oceans,” notes University of Vermont conservation biologist Joe Roman. That was a mistake.
In a new paper, Roman and a team of biologists have tallied several decades of research on whales from around the world; it shows that whales, in fact, make a huge difference — they have a powerful and positive influence on the function of oceans, global carbon storage, and the health of commercial fisheries. “The decline in great whale numbers, estimated to be at least 66% and perhaps as high as 90%, has likely altered the structure and function of the oceans,” Roman and his colleagues write in the July 3, 2014, online edition of Frontiers in Ecology and the Environment, “ but recovery is possible and in many cases is already underway.”
“The continued recovery of great whales may help to buffer marine ecosystems from destabilizing stresses,” the team of scientists writes. This recovered role may be especially important as climate change threatens ocean ecosystems with rising temperatures and acidification. “As long-lived species, they enhance the predictability and stability of marine ecosystems,” Roman said.
Baleen and sperm whales, known collectively as the “great whales,” include the largest animals to have ever lived on Earth. With huge metabolic demands — and large populations before humans started hunting them — great whales are the ocean’s ecosystem engineers: they eat many fish and invertebrates, are themselves prey to other predators like killer whales, and distribute nutrients through the water. Even their carcasses, dropping to the seafloor, provide habitat for many species that only exist on these "whale falls." Commercial whaling dramatically reduced the biomass and abundance of great whales.
“As humpbacks, gray whales, sperm whales and other cetaceans recover from centuries of overhunting, we are beginning to see that they also play an important role in the ocean,” Roman said. “Among their many ecological roles, whales recycle nutrients and enhance primary productivity in areas where they feed." They do this by feeding at depth and releasing fecal plumes near the surface — which supports plankton growth — a remarkable process described as a “whale pump.” Whales also move nutrients thousands of miles from productive feeding areas at high latitudes to calving areas at lower latitudes.
Sometimes, commercial fishermen have seen whales as competition. But this new paper summarizes a strong body of evidence that indicates the opposite can be true: whale recovery “could lead to higher rates of productivity in locations where whales aggregate to feed and give birth,” supporting more robust fisheries.
As whales recover, there may be increased whale predation on aquaculture stocks and increased competition — real or perceived — with some commercial fisheries. But the new paper notes “ a recent investigation of four coastal ecosystems has demonstrated the potential for large increases in whale abundance without major changes to existing food-web structures or substantial impacts on fishery production.”
In death, whale carcasses store a remarkable amount of carbon in the deep sea and provide habitat and food for an amazing assortment of creatures that only live on these carcasses. “Dozens, possibly hundreds, of species depend on these whale falls in the deep sea,” Roman notes.
“Our models show that the earliest human-caused extinctions in the sea may have been whale fall invertebrates, species that evolved and adapted to whale falls,” Roman said, “These species would have disappeared before we had a chance to discover them.”
Until recently, ocean scientists have lacked the ability to study and observe directly the functional roles of whales in marine ecosystems. Now with radio tagging and other technologies they can better understand these roles. “The focus of much marine ecological research has been on smaller organisms, such as algae and planktonic animals. These small organisms are essential to life in the sea, but they are not the whole story,” Roman said.
New observations of whales will provide a more accurate understanding of historical population dynamics and “are likely to provide evidence of undervalued whale ecosystem services,” note the ten scientists who co-authored this new paper, “this area of research will improve estimates of the benefits — some of which, no doubt, remain to be discovered — of an ocean repopulated by the great whales.”
Joe Roman, James A Estes, Lyne Morissette, Craig Smith, Daniel Costa, James McCarthy, JB Nation, Stephen Nicol, Andrew Pershing, Victor Smetacek. Whales as marine ecosystem engineers. Frontiers in Ecology and the Environment, 2014; 140703070154008 DOI: 10.1890/130220
Business-as-usual management policies risks well-being of 2 billion people, say scientists
Source: United Nations University, via EurekAlert!
Posted by Jenny Griffin
Leading international environmental and marine scientists today published a joint call for societies to introduce and enforce use zoning of Earth's coastal ocean waters, mirroring approaches commonly used to manage and protect land resources.
Writing in the journal Marine Pollution Bulletin, the 24 scientists from Canada, the USA, the UK, China, Australia, New Caledonia, Sweden and Kenya underline that one fifth of humanity — mostly in developing countries — lives within 100 km of a tropical coastline. Growing populations and worsening climate change impacts ensure that pressures on tropical coastal waters will only grow, they warn.
Lacking in most locations are holistic, regional-scale management approaches to balance the growth in competing demands from fisheries, aquaculture, shipping, oil, gas and mineral extraction, energy production, residential development, tourism and conservation.
Says lead author Peter Sale of the UN University's Canadian-based Institute for Water, Environment and Health: "We zone land for development, for farms, for parks, for industry and other human needs. Required today is a comparable degree of care and planning for coastal ocean waters."
"We have tended to think of the seas as our last great wilderness," he adds, "yet we subject them, particularly along tropical shores, to levels of human activity as intense as those on land. The result is widespread overfishing, pollution and habitat degradation. Coastal marine management efforts today are just woefully inadequate to avoid irreparable degradation of the bounty and services on which so many people depend for food and well-being."
A major effort and strong political will are needed to build the holistic, regional-scale management of coastal waters now lacking in most locations. Dr. Sale and colleagues advocate substantially expanded use of Marine Spatial Planning (MSP): an objective procedure for partitioning portions of the coastal ocean among competing uses. But using MSP also forces the regional-scale, holistic approaches to coastal management that nations desperately need.
"We propose making expanded use of marine spatial planning and zoning as a framework that will apportion coastal waters for differing activities, while forcing a multi-target and multi-scale approach, and achieving agreed ecological, economic and social objectives," says Sale.
According to the paper, coastal fisheries and aquaculture, for example, are in frequent and growing conflict. Both are of major importance to the food security of tropical coastal populations. Easily remedied coastal pollution is ignored, degrading habitat and reducing the capacity of both fisheries and aquaculture efforts. Employment opportunities, health and quality of life all are reduced, along with ecological resilience when environmental health degrades.
MSP can be expected to help address such use conflicts while also protecting and conserving ecologically critical areas to allow healthy ecosystem function. Its real value, however, will lie in the way its use brings multiple stakeholders together around a holistic vision of environmental management, addressed at ecologically appropriate spatial and temporal scales.
"At the moment, we are trying to map uses onto marine spaces with insufficient attention to competing needs," says co-author Tim Daw of the UK's University of East Anglia. "More systematic planning is clearly required along tropical coasts, where so much of the population depends directly on the adjacent sea for livelihood and well-being. Here, we face a challenge, and an opportunity, to put in place truly effective management of coastal waters, and improve the lives of millions of people."
According to the authors, management attempts frequently fail today because they:
* are mounted at too small a geographic scale and/or over too short a period of time
* focus on single issues (conservation, fisheries enhancement, land-based pollution) without regard to other problems that act together to degrade coastal environments
* are imposed from "outside," often in a one-size-fits-all or cookie-cutter approach, without the consultation and consensus-building needed to gain real traction with the local community, management agencies or governments.
"While there are a few exceptional places," the paper says, "all too often, current management of development, habitat destruction, pollution, and overfishing is seriously inadequate, and if this management is not improved we are confident in stating the following:
* Most coastal fisheries will be chronically overfished or collapsed
* Loss of reef habitat will further reduce fisheries production and strain food security.
* Land-based pollution will increase to the extent that hypoxia and harmful algal blooms are routinely present
* Pressures of coastal development will combine with sea level rise and more intense storms to further intrude on and erode natural coastlines, severely reducing mangrove, salt marsh and sea grass habitats
* The cost of dealing with these impacts will further strain coastal economies, and the future for people on tropical coasts in 2050 will be substantially more bleak than at present."
Worldwide, the 100 km wide coastal strip comprises 21% of all land, occupied by over 2.6 billion people at densities ranging from less than 20 to more than 15,000 per sq. km (average: 97). That's over twice the density of inland regions (41 per sq. km).
Over half these people (1.36 billion) live on tropical coasts (just 7% of all land) at even higher densities (averaging 145 per sq. km). Tropical coasts hold 9 of 19 coastal megacities (over 10 million), and are most densely populated (mean: 198 per sq. km) in South and Southeast Asia ￼In the world's tropics, the coastal population is expected to grow 45% to 1.95 billion people by 2050, while the number of people occupying the inland tropics will grow by 71% to 2.26 billion.
However, the total area of inland tropical land is four times that of coastal regions, so tropical population density in 2050 is projected to be 57 per sq. km inland; 199 on coasts.
Coastal communities will generate increased local environmental stresses, although improved management may keep some or all of this increase unrealized.
Peter F. Sale, Tundi Agardy, Cameron H. Ainsworth, Blake E. Feist, Johann D. Bell, Patrick Christie, Ove Hoegh-Guldberg, Peter J. Mumby, David A. Feary, Megan I. Saunders, Tim M. Daw, Simon J. Foale, Phillip S. Levin, Kenyon C. Lindeman, Kai Lorenzen, Robert S. Pomeroy, Edward H. Allison, R.H. Bradbury, Jennifer Corrin, Alasdair J. Edwards, David O. Obura, Yvonne J. Sadovy de Mitcheson, Melita A. Samoilys, Charles R.C. Sheppard. Transforming management of tropical coastal seas to cope with challenges of the 21st century. Marine Pollution Bulletin, 2014; DOI: 10.1016/j.marpolbul.2014.06.005
The full paper can be viewed at: http://www.sciencedirect.com/science/article/pii/S0025326X1400366X
Source: UGA Today, University of Georgia News Service
Posted by Jenny Griffin
The 2010 Deepwater Horizon blowout discharged roughly five million barrels of oil and up to 500,000 metric tonnes of natural gas into Gulf of Mexico offshore waters over a period of 84 days. In the face of a seemingly insurmountable cleanup effort, many were relieved by reports following the disaster that naturally-occurring microbes had consumed much of the gas and oil.
Now, a team of researchers led by University of Georgia marine scientists have published a paper in the journal Nature Geoscience that questions this conclusion and provides evidence that microbes may not be capable of removing contaminants as quickly and easily as once thought.
"Most of the gas injected into the Gulf was methane, a potent greenhouse gas that contributes to global climate change, so we were naturally concerned that this potent greenhouse gas could escape into the atmosphere," said Samantha Joye, senior author of the paper, director of the study and professor of marine science in UGA's Franklin College of Arts and Sciences. "Many assumed that methane-oxidizing microbes would simply consume the methane efficiently, but our data suggests that this isn't what happened."
Joye and colleagues from other universities and government organizations measured methane concentrations and the activity of methane-consuming bacteria for ten months, starting before the blowout with collection of an invaluable set of pre-discharge samples taken in March 2010.
The abundance of methane in the water allowed the bacteria that feed on the gas to flourish in the first two months immediately following the blowout, but their activity levels dropped abruptly despite the fact that methane was still being released from the wellhead.
This new data suggests the sudden drop in bacterial activity was not due to an absence of methane, but a host of environmental, physiological, and physical constraints that made it difficult or impossible for bacteria to consume methane effectively.
"For these bacteria to work efficiently, they need unlimited access to nutrients like inorganic nitrogen and trace metals, but they also need elevated methane levels to persist long enough to support high rates of consumption," Joye said. "The bacteria in the Gulf were probably able to consume about half of the methane released, but we hypothesize that an absence of essential nutrients and the dispersal of gas throughout the water column prevented complete consumption of the discharged methane."
Joye insists that while her group's conclusions differ from those presented in previous studies, there is no serious conflict between their analyses.
"The issue here was short-term sampling versus long-term time series sampling," she said. "I hope our paper clearly relays the message that long-term sampling is the only way to capture the evolution of a natural system as it responds to large perturbations like oil well blowouts or any other abrupt methane release."
Ultimately, scientists need to better understand the behavior of these microbes so that they may better gauge the environmental impacts of future accidents and methane releases due to climate change, she said.
"It's only a matter of time before we face another serious incident like Deepwater Horizon," Joye said. "The key is understanding the things that regulate how fast bacteria can consume methane, and that will give us insight into the ultimate fate of this potent greenhouse gas in our oceans."
M. Crespo-Medina, C. D. Meile, K. S. Hunter, A-R. Diercks, V. L. Asper, V. J. Orphan, P. L. Tavormina, L. M. Nigro, J. J. Battles, J. P. Chanton, A. M. Shiller, D-J. Joung, R. M. W. Amon, A. Bracco, J. P. Montoya, T. A. Villareal, A. M. Wood, S. B. Joye. The rise and fall of methanotrophy following a deepwater oil-well blowout. Nature Geoscience, 2014; DOI: 10.1038/ngeo2156
The full article is available online at:
A new study quantifies for the first time future losses in deep-sea marine life, using advanced climate models. Results show that even the most remote deep-sea ecosystems are not safe from the impacts of climate change.
An international team of scientists predict seafloor dwelling marine life will decline by up to 38 per cent in the North Atlantic and over five per cent globally over the next century. These changes will be driven by a reduction in the plants and animals that live at the surface of the oceans that feed deep-sea communities. As a result, ecosystem services such as fishing will be threatened.
In the study, led by the National Oceanography Centre, the team used the latest suite of climate models to predict changes in food supply throughout the world oceans. They then applied a relationship between food supply and biomass calculated from a huge global database of marine life.
The results of the study are published this week in the scientific journal Global Change Biology.
These changes in seafloor communities are expected despite living on average four kilometres under the surface of the ocean. This is because their food source, the remains of surface ocean marine life that sink to the seafloor, will dwindle because of a decline in nutrient availability. Nutrient supplies will suffer because of climate impacts such as a slowing of the global ocean circulation, as well as increased separation between water masses – known as 'stratification' – as a result of warmer and rainier weather.
Lead author Dr Daniel Jones says: "There has been some speculation about climate change impacts on the seafloor, but we wanted to try and make numerical projections for these changes and estimate specifically where they would occur.
"We were expecting some negative changes around the world, but the extent of changes, particularly in the North Atlantic, were staggering. Globally we are talking about losses of marine life weighing more than every person on the planet put together."
The projected changes in marine life are not consistent across the world, but most areas will experience negative change. Over 80 per cent of all identified key habitats – such as cold-water coral reefs, seamounts and canyons – will suffer losses in total biomass. The analysis also predicts that animals will get smaller. Smaller animals tend to use energy less efficiently, thereby impacting seabed fisheries and exacerbating the effects of the overall declines in available food.
JOURNAL REFERENCE: Jones, D.O.B., Yool, A., Wei, C-L., Henson, S.A., Ruhl, H.A., Watson, R.A., Gehlen, M. (2013) Global reductions in seafloor biomass in response to climate change, Global Change Biology, doi: 10.1111/gcb.12480
Carbon dioxide pumped into the air since the Industrial Revolution appears to have changed the way the coastal ocean functions, according to a new analysis published recently in Nature.
A comprehensive review of research on carbon cycling in rivers, estuaries and continental shelves suggests that collectively this coastal zone now takes in more carbon dioxide than it releases. The shift could impact global models of carbon's flow through the environment and future predictions related to climate change.
"We need to better understand the role of the coastal ocean in carbon dioxide exchange between the atmosphere and the ocean," said study co-author Wei-Jun Cai, professor of oceanography in the University of Delaware's School of Marine Science and Policy within the College of Earth, Ocean, and Environment. "That will give us a much better capacity to predict future global carbon budgets and fluxes due to climate change and other anthropogenic factors."
Cai and other environmental scientists have been examining the complex dynamics that move different forms of carbon through coastal waters. Numerous variables, from rainfall to temperature to plant photosynthesis, can influence how much carbon is present in water at any given time.
"Carbon is not stationary," Cai said. "It flows and changes among its different forms."
The multiple sources and processes at play make coastal carbon challenging to study, however, and Cai said it has traditionally been overlooked in global carbon budget calculations. The annual estimate of how much anthropogenically-released carbon dioxide is trapped by land, for example, has been determined by subtracting the amount taken up by the ocean from the amount put into the air.
"If there is another reservoir — the coastal ocean — that also takes up carbon dioxide, then that changes the balance," Cai said.
The coastal zone may be relatively small compared to the open ocean, but the researchers point out that it represents a disproportionately large amount of the carbon dioxide exchanged between air and water.
That suggests that the coastal ocean may have its own mechanism for holding carbon dioxide — something Cai first suspected in 2005 on a cruise off the coast of Georgia. There he was surprised to see that sea surface carbon dioxide levels were about the same as 10 years prior, even though there were significantly greater amounts of the greenhouse gas in the atmosphere.
Conventional wisdom would hold that sea surface carbon dioxide should rise in tandem with levels in the atmosphere, as is the case in most of the ocean basin.
"However, if the coastal ocean has its own way to hold sea surface carbon dioxide and atmospheric carbon dioxide keeps increasing, that makes the coastal ocean more important as a carbon dioxide sink in the future — as the rate of carbon dioxide uptake by the ocean is determined by the concentration difference between the atmosphere and the ocean, which is increasing," Cai said. "The global carbon cycling model should take this additional carbon dioxide sink into account."
In the Nature paper, Cai and his co-authors posit that an increased physical uptake of atmospheric carbon dioxide explains the continental shelf switching from a carbon dioxide source to a sink — or repository — over the industrial age. They also provided a mechanism to explain the slower carbon dioxide increase in the coastal ocean. Others have suggested that agricultural fertilizers feeding extra nutrients into water caused the shift.
New instrumentation allows scientists to generate new best estimates of carbon cycling in coastal areas. Using the latest measures available, Cai and his colleagues created a model estimating that coastal areas released, on average, about 150 million metric tons of carbon per year a century ago. Now, these same waters are estimated to absorb approximately 250 million metric tons of carbon each year.
The researchers call for ongoing observations and field studies to better understand the complicated dynamics in coastal systems, including additional human-caused changes such as land-use modification, waterway construction and wetland degradation. The work has implications for predictions on ocean acidification, global warming and climate change.
"Compared to the open ocean, we know less about the coastal ocean's carbon cycle even though it's right in front of us," said James Bauer, professor of evolution, ecology and organismal biology in Ohio State University's College of Arts and Sciences and lead author of the paper. "We just have to commit to increasing the number and types of coastal regions being studied."
REFERENCE: The article, titled "The Changing Carbon Cycle of the Coastal Ocean," appears in the Dec. 5 issue of Nature. Cai and Bauer's co-authors are Peter A. Raymond of Yale University, Thomas S. Bianchi of the University of Florida, Charles S. Hopkinson of the University of Georgia and Pierre A.G. Regnier of Université Libre de Bruxelles.
Climate change has increased concern over possible large and rapid changes in the physical climate system, which includes the Earth's atmosphere, land surfaces, and oceans. Some of these changes could occur within a few decades or even years, leaving little time for society and ecosystems to adapt. A new report from the National Research Council extends this idea of abrupt climate change, stating that even steady, gradual change in the physical climate system can have abrupt impacts elsewhere -- in human infrastructure and ecosystems for example -- if critical thresholds are crossed. The report calls for the development of an early warning system that could help society better anticipate sudden changes and emerging impacts.
"Research has helped us begin to distinguish more imminent threats from those that are less likely to happen this century," said James W.C. White, professor of geological sciences at the University of Colorado, Boulder, and chair of the committee that wrote the report. "Evaluating climate changes and impacts in terms of their potential magnitude and the likelihood they will occur will help policymakers and communities make informed decisions about how to prepare for or adapt to them."
Abrupt climate changes and impacts already under way are of immediate concern, the report says. These include the disappearance of late-summer Arctic sea ice and increases in extinction rates of marine and terrestrial species.
Other scenarios, such as the destabilization of the west Antarctic ice sheet, have potentially major consequences, but the probability of these changes occurring within the next century is not well-understood, highlighting the need for more research.
In some cases, scientific understanding has progressed enough to determine whether certain high-impact climate changes are likely to happen within the next century. The report notes that a shutdown in the Atlantic Ocean circulation patterns or a rapid release of methane from high-latitude permafrost or undersea ice are now known to be unlikely this century, although these potential abrupt changes are still worrisome over longer time horizons.
But even changes in the physical climate system that happen gradually over many decades or centuries can cause abrupt ecological or socio-economic change once a "tipping point" is reached, the report adds. For example, relatively slow global sea-level rise could directly affect local infrastructure such as roads, airports, pipelines, or subway systems if a sea wall or levee is breached. And slight increases in ocean acidity or surface temperatures could cross thresholds beyond which many species cannot survive, leading to rapid and irreversible changes in ecosystems that contribute to further extinction events.
Further scientific research and enhanced monitoring of the climate, ecosystems, and social systems may be able to provide information that a tipping point is imminent, allowing time for adaptation or possibly mitigation, or that a tipping point has recently occurred, the report says.
"Right now we don't know what many of these thresholds are," White said. "But with better information, we will be able to anticipate some major changes before they occur and help reduce the potential consequences." The report identifies several research needs, such as identifying keystone species whose population decline due to an abrupt change would have cascading effects on ecosystems and ultimately on human provisions such as food supply.
If society hopes to anticipate tipping points in natural and human systems, an early warning system for abrupt changes needs to be developed, the report says. An effective system would need to include careful and vigilant monitoring, taking advantage of existing land and satellite systems and modifying them if necessary, or designing and implementing new systems when feasible. It would also need to be flexible and adaptive, regularly conducting and alternating between data collection, model testing and improvement, and model predictions that suggest future data needs.
REFERENCE: National Research Council. Abrupt Impacts of Climate Change: Anticipating Surprises. Washington, DC: The National Academies Press, 2013.
The report can be downloaded or viewed online for free (or a print copy can be purchased) at the following link:
A new study predicts a sixfold increase in the number of potential invaders by 2100.
Just think of the warty comb jelly or sea walnut, as it is also known. It has caused tremendous damage to fisheries in the Black Sea after arriving in ballast water from its original habitat along the East coast of North America. This example should serve as a warning to everyone to take care and not to introduce new species into our waters.
In the Arctic, the cold water has so far prevented harmful low latitude species from establishing themselves but this will change as the climate becomes warmer. In addition, the expected warmer climate will lead to an increasing number of ships in the Arctic as the routes through the Northeast Passage and the Northwest Passage are becoming ever more navigable. All in all the researchers expect a much greater pressure on the marine ecosystems of the Arctic, where fishing is very important for the population in e.g. Norway and Greenland.
An international team of researchers led by PhD candidate Chris Ware from the University of Tromsø in Norway has for the first time been able to calculate the risk of new species establishing themselves in Arctic waters. Specifically, the researchers have investigated the maritime traffic to Svalbard. Chris Ware explains:
"For the first time we have shown that in the future the port of departure will be more similar to the port of destination in the Arctic than it is today with regard to climate and the environment. This development will increase the chance of survival for those organisms that could arrive with ballast water or through biofouling.
One example could be the Red King Crab, a species that would thrive in the Arctic. This is an example of an animal that could change the balance between the current species, as it would become very dominant in the fragile environment," explains Chris Ware.
Other potential invaders are the shore crab, certain tunicates like Didemnum vexillum and the so-called "Japanese skeleton shrimp" (Caprella mutica).
The survey shows that up to one third of the 155 ships that entered the ports of Svalbard during 2011 came from ports that will in the future have an environmental match with Svalbard, thereby increasing the risk that harmful species, which may be brought in as stowaways on ships, will be able to establish themselves.
THE POTENTIAL DONOR POOL WILL MULTIPLY
The stowaways can arrive either as biofouling on the outside of the ships or via water in the ballast tanks.
In 2011 ships that called at Svalbard emptied their ballast tanks 31 times, producing a total volume of 653,000 cubic meters, equivalent to more than 261 Olympic-size swimming pools. Considering each cubic metre of ballast water may contain hundreds of thousands of organisms, billions of organisms can be introduced by ships every year. Slightly more than half of the vessels had replaced the water at sea as required, for example in the North Sea.
The vessels had connections to four ecoregions with similar environmental conditions. Here the researchers know of a total of 16 introduced species, one of which comes from Svalbard.
14 of the remaining 15 species will be able to act as biofouling on the ships' hulls. Therefore, if the aim is to keep introduced species out, then only taking ballast water into consideration will not be enough.
Already in 2050 the climate around Svalbard will be more similar to the climate found in the ports to the south where ships to Svalbard typically depart from. This increases the risk that introduced species will survive and compete with the original species around Svalbard.
In 2100, the number of matching ecoregions will increase to nine, increasing the number of known harmful species with connections to Svalbard more than sixfold.
EARLY WARNING TO GREENLAND
Senior Researcher Mary Wisz from Aarhus University has contributed to the study. She is worried about these figures: "We consider our results as an 'early warning' for what could happen, not just in Svalbard but also in Greenland and other parts of the Arctic."
WHAT CAN WE DO?
"The next step is to find out which stowaways will have the greatest chance to survive the journey in ballast tanks or on the ship hulls, and which are most likely to establish breeding populations after arriving in the Arctic. These questions are the focus of our current research.
Each species has its own physiological characteristics and relationship to the environment, so if we can foresee that some particularly problematic species are at risk of becoming established as the climate warms, we are in a better position to concentrate specific effort and resources to keep them out."
HOW TO CURB HARMFUL SPECIES?
The UN's International Maritime Organization (IMO) is on the verge of entering the Ballast Water Management Convention into force, but this will not happen until 12 months after countries with a combined total of at least 35 % of the World's commercial fleet (measured in gross tonnage) have ratified the Convention. Denmark and Norway have both done so, although the Convention does not presently apply to Greenland. It is up to Greenland's government to decide whether or when they want to join.
In Denmark the Danish Nature Agency states that Denmark is working on ensuring that the Convention enters into force as soon as possible, and that the Convention can be expected to come into effect in 2015. Among other things, they have established a partnership on ballast water with the Danish Maritime Administration and the Danish Shipowners Association and, as one of its activities, the partnership organised an international conference in Copenhagen on 1 November.
In addition to ballast water, biofouling on the hulls is also a source of introduced species. All shipowners are interested in alleviating fouling because a coating of algae etc. on the hull increases the consumption of fuel. However, there is no legislation that requires the shipping industry to take special measures to stop stowaways on the outside of the hulls. The UN's maritime organization has, however, adopted a set of guidelines for this area.
Climate change, non-indigenous species and shipping: assessing the risk of species introduction to a high-Arctic archipelago. Ware, C. et al. Diversity and Distributions, (2013), pp. 1
A UC Riverside-led study points to an ancient
oxygen-free and hydrogen sulfide-rich ocean that may foreshadow our future.
Oxygen in the atmosphere and ocean rose dramatically about 600 million years ago, coinciding with the first proliferation of animal life. Since then, numerous short lived biotic events — typically marked by significant climatic perturbations — took place when oxygen concentrations in the ocean dipped episodically.
The most studied and extensive of these events occurred 93.9 million years ago. By looking at the chemistry of rocks deposited during that time period, specifically coupled carbon and sulfur isotope data, a research team led by University of California, Riverside biogeochemists reports that oxygen-free and hydrogen sulfide-rich waters extended across roughly five percent of the global ocean during this major climatic perturbation — far more than the modern ocean's 0.1 percent but much less than previous estimates for this event.
The research suggests that previous estimates of oxygen-free and hydrogen sulfide-rich conditions, or 'euxinia', were too high. Nevertheless, the limited and localized euxinia were still sufficiently widespread to have dramatic effect on the entire ocean's chemistry and thus biological activity.
"These conditions must have impacted nutrient availability in the ocean and ultimately the spatial and temporal distribution of marine life," said team member Jeremy D. Owens, a former UC Riverside graduate student, who is now a postdoctoral scientist at the Woods Hole Oceanographic Institution. "Under low-oxygen environments, many biologically important metals and other nutrients are removed from seawater and deposited in the sediments on the seafloor, making them less available for life to flourish."
"What makes this discovery particularly noteworthy is that we mapped out a landscape of bioessential elements in the ocean that was far more perturbed than we expected, and the impacts on life were big," said Timothy W. Lyons, a professor of biogeochemistry at UCR, Owens's former advisor and the principal investigator on the research project.
Across the event 93.9 million years ago, a major biological extinction in the marine realm has already been documented. Also associated with this event are high levels of carbon dioxide in the atmosphere, which are linked to elevated ocean and atmospheric temperatures. Associated consequences include likely enhanced global rainfall and weathering of the continents, which further shifted the chemistry of the ocean.
"Our work shows that even though only a small portion of the ocean contained toxic and metal-scavenging hydrogen sulfide, it was sufficiently large so that changes to the ocean's chemistry and biology were likely profound," Owens said. "What this says is that only portions of the ocean need to contain sulfide to greatly impact biota."
For their analysis, the researchers collected seafloor mud samples, now rock, from multiple localities in England and Italy. They then performed chemical extraction on the samples to analyze the sulfur isotope compositions in order to estimate the chemistry of the global ocean.
According to the researchers, the importance of their study is elevated by the large amount of previous work on the same interval and thus the extensive availability of supporting data and samples. Yet despite all this past research, the team was able to make a fundamental discovery about the global conditions in the ancient ocean and their impacts on life.
"Today, we are facing rising carbon dioxide contents in the atmosphere through human activities, and the amount of oxygen in the ocean may drop correspondingly in the face of rising seawater temperatures," Lyons said. "Oxygen is less soluble in warmer water, and there are already suggestions of such decreases. In the face of these concerns, our findings from the warm, oxygen-poor ancient ocean may be a warning shot about yet another possible perturbation to marine ecology in the future."
JOURNAL REFERENCE: Jeremy D. Owens,Benjamin C. Gill, Hugh C. Jenkyns, Steven M. Bates, Silke Severmann, Marcel M. M. Kuypers, Richard G. Woodfine, and Timothy W. Lyons. Sulfur isotopes track the global extent and dynamics of euxinia during Cretaceous Oceanic Anoxic Event 2. PNAS 2013 110 (46) 18407-18412; published ahead of print October 29, 2013, doi:10.1073/pnas.1305304110
A new approach to analyzing paleo-climate reconstructions of the El Niño Southern Oscillation (ENSO) phenomenon resolves disagreements and reveals that ENSO activity during the 20th century has been unusually high compared to the past 600 years. The results are published in Climate of the Past by a team of scientists from the University of New South Wales, the University of Hawaii International Pacific Research Center and the NOAA Geophysical Fluid Dynamics Laboratory.
El Niño events can wreak havoc across the globe, spawning floods or giving rise to droughts in many regions of the world. How ENSO behaves as a result of a warming planet, however, is still uncertain. One window to determine its sensitivity to climate change is a look into the past. Because the instrumental record is too short for getting a reliable picture of natural variations in ENSO magnitude and frequency, climate scientists rely on geological and biological clues, such as from lake sediment cores, corals, or tree rings as proxies for past ENSO behavior. The problem has been, though, that reconstructions of ENSO from such paleo-proxies have not been telling the same story.
Some of these discrepancies in ENSO reconstructions arise because the methods typically applied to combine individual paleo-proxy records do not handle small dating uncertainties amongst the proxies well. The usual approach has been to combine the individual ENSO proxies and then to calculate the activity of this combined ENSO signal. McGregor and his team found that by turning this analysis around -- first calculating the activity of ENSO in each of the individual paleo-climate reconstructions and then combining the activity time series -- yields a much more consistent and robust view of ENSO's past activity. The scientists confirmed this new approach with virtual ENSO data obtained from two multi-century-long climate model simulations.
Applying their improved method of reconstructing ENSO activity by synthesizing many different existing proxies and comparing these time series with instrumental data, the scientists found that ENSO was more active during 1979-2009 than during any 30-year period between 1590 and 1880.
"Our results represent a significant step towards understanding where current ENSO activity sits in the context of the past." says Axel Timmermann, professor at the University of Hawaii and co-author of the study.
"Climate models provide no clear indication of how ENSO activity will change in the future in response to greenhouse warming, so all we have to go on is past records," explains McGregor. "We can improve the projections of climate models, however, by selecting those that produce past changes in ENSO activity consistent with the past instrumental records.
"Our new estimates of ENSO activity of the past 600 years appear to roughly track global mean temperature," says McGregor, "but we still don't know why."
S. McGregor, A. Timmermann, M. H. England, O. Elison Timm, and A. T. Wittenberg: Inferred changes in El Niño–Southern Oscillation variance over the past six centuries. Clim. Past, 9, 2269, 2013. doi:10.5194/cp-9-2269-2013
Tiny sea creatures are heading for extinction, and could take local fisheries with them.
A species of one of the world's tiniest creatures, ocean plankton, is heading for extinction as it struggles to adapt to changes in sea temperature. And it may take local fisheries with it.
Research led by Deakin University (Warrnambool, Australia) and Swansea University (UK) has found that a species of cold water plankton in the North Atlantic, that is a vital food source for fish such as cod and hake, is in decline as the oceans warm. This will put pressure on the fisheries that rely on abundant supplies of these fish.
"There is overwhelming evidence that the oceans are warming and it will be the response of animals and plants to this warming that will shape how the oceans look in future years and the nature of global fisheries," explained Deakin's professor of marine science, Graeme Hays.
"We know that warm water species are expanding their ranges as warming occurs, and vice versa. What is not known is whether species are able to adapt to new temperatures. Will, for example, cold water species gradually adapt so they can withstand warming seas and not continually contract their ranges. From the results of our study, it is looking like the answer is no."
Answering the question of adaptation is not easy as it requires long-term observations spanning multiple generations. For this study, the research team examined a 50-year time series from the North Atlantic on the distribution and abundance of two very common but contrasting species of ocean plankton, Calanus helgolandicus that lives in warmer water and Calanus finmarchicus that lives in cold water. These crustaceans are vital food for fish and underpin many commercial fisheries in the North Atlantic region.
The researchers were surprised to find that the cold water C. finmarchicus has continued to contract its range over 50 years of warming.
"In other words, even over 50 generations (each plankton lives for one year or less) there is no evidence of adaptation to the warmer water," Professor Hays said.
The consequences of this study are profound. It suggests that cold water plankton will continue to become scarcer as their ranges contract to the poles, and ultimately disappear. So certainly for these animals, thermal adaptation appears unlikely to limit the impact of climate change.
"C. finmarchicus is a key food source for fish such as cod and hake. So continued declines in abundance will have a negative impact on the long-term viability of cold water fisheries in the North Sea and other areas in the southern part of their range. At the same time the continued increase in abundance of the warm water plankton, C. helgolandicus, will likely play a role in the emergence of new fisheries for warm water species."
Professor Hays said that the impact of ocean warming was not confined to the North Atlantic region.
"Ocean warming is occurring globally and so these findings are likely to apply to other areas around the world including southern hemisphere locations such as Australia, South Africa and South America that support important fisheries dependant on plankton," Professor Hays said.
"Plankton recorders deployed in the southern hemisphere, for example as part of the Australian Continuous Plankton Recorder Project (a joint project of CSIRO Marine and Atmospheric Research and the Australian Antarctic Division), will continue to document these changes."
Stephanie L. Hinder, Mike B. Gravenor, Martin Edwards, Clare Ostle, Owen G. Bodger, Patricia L. M. Lee, Antony W. Walne, Graeme C. Hays. Multi-decadal range changes vs. thermal adaptation for north east Atlantic oceanic copepods in the face of climate change. Global Change Biology, 2013; DOI: 10.1111/gcb.12387