Constantine Alexander's Journal

Europe shows that humans and large predators can share the same landscape

Scandinavian grey wolf (Canis lupus). Skandinavisk Dyrepark, Djursland, Denmark. Credit: Malene Thyssen (CC 2.5).

The recovery of large carnivores in Europe is a great success for nature conservation. At one third of mainland Europe, at least one species of large carnivore is present, according to an article in the scientific magazine Science that researchers from 26 countries have contributed to. It is an excellent example that humans and carnivores can share the same landscape, says main author Guillaume Chapron, from the Swedish University of Agricultural Sciences (SLU).

By the early 20th century, large carnivores had been exterminated from most of Europe, with just relict populations persisting. Now we have increasing or stable populations of brown bears, wolves, Eurasian lynx and wolverines, and they do not live in a remote wilderness but in a human-dominated landscape.

That is a great difference in comparison to the strategies being pursued in other parts of the world where carnivores are mainly protected in large national parks or wilderness areas, separated from people. If Europe had used that model we would hardly have any carnivores at all because there are not enough large areas of wilderness remaining.

"This is a success story that builds on a good legislation, political stability, strong institutions and a favourable public opinion," says Guillaume Chapron, researcher at Grimsö Wildlife Station, Department of Ecology, at SLU. In addition, Europe's forests and wild herbivore populations are in far better shape today than they were 100 years ago.

The environmental movement in the 1970's and 1980's paved the way for the Council of Europe's Bern Convention and the EU's habitat directive legislation that has given these species the opportunity to recover.

"The large carnivores are an example of species that have benefited from this pan-European legislation and that the Habitats Directive works," says Guillaume Chapron.

 

76 researchers have contributed to the article, among them five from the Swedish University of Agricultural Sciences (SLU). They have compiled data and produced a distribution map for large carnivore map across most of Europe.

• The brown bear is currently present in 22 countries. It is the most common large carnivore in Europe with 17,000 individuals that can be clustered into ten populations. All populations are relatively stable or slightly expanding, although a few remain critically small.
• Wolves are the second most common species, about 12,000 individuals, with ten populations in 28 countries. Most of the populations are increasing, but a couple of populations seem to be decreasing. One Spanish population is on the brink to extinction.
• Lynx are present in 23 countries, with 9,000 individuals. Most of the eleven populations are stable but some of them are decreasing.
• Wolverine lives only in Sweden, Norway and Finland, in two populations with 1,250 individuals. Both populations are increasing.

Guillaume Chapron says that Europe can be an example for other parts of the world.

"Europe has twice as many wolves as the USA (excluding Alaska) in spite of being half the size and more than twice as densely populated. Our experience illustrates the incredible ability that these species have to survive to the modern, human-dominated world."

 

Generally speaking people in Europe are positive to carnivores but the conflicts that caused the historical declines are still present, like predation on livestock. The most severe challenges for large carnivore conservation are in countries where large carnivores have previously been totally extirpated and where people have lost their adaptations to sharing the landscape with their wild neighbours. Furthermore, species like wolves have been coopted as powerful symbols for wider political and social tensions between rural and urban areas.

A variety of practices that reduce damage on livestock, like electric fences and livestock-guarding dogs, can facilitate co-existence. Furthermore there is a need for dialogue between stakeholders and cooperation between different sectors and different countries. It is crucial that these conflict issues are taken seriously to prevent a possible backlash against conservation in general.

Citation: G. Chapron, P. Kaczensky, J. D. C. Linnell, M. von Arx, D. Huber, H. Andren, J. V. Lopez-Bao, M. Adamec, F. Alvares, O. Anders, L. Bal iauskas, V. Balys, P. Bed , F. Bego, J. C. Blanco, U. Breitenmoser, H. Broseth, L. Bufka, R. Bunikyte, P. Ciucci, A. Dutsov, T. Engleder, C. Fuxjager, C. Groff, K. Holmala, B. Hoxha, Y. Iliopoulos, O. Ionescu, J. Jeremi , K. Jerina, G. Kluth, F. Knauer, I. Kojola, I. Kos, M. Krofel, J. Kubala, S. Kunovac, J. Kusak, M. Kutal, O. Liberg, A. Maji , P. Mannil, R. Manz, E. Marboutin, F. Marucco, D. Melovski, K. Mersini, Y. Mertzanis, R. W. Mys ajek, S. Nowak, J. Odden, J. Ozolins, G. Palomero, M. Paunovi , J. Persson, H. Poto nik, P.-Y. Quenette, G. Rauer, I. Reinhardt, R. Rigg, A. Ryser, V. Salvatori, T. Skrbin ek, A. Stojanov, J. E. Swenson, L. Szemethy, A. Trajce, E. Tsingarska-Sedefcheva, M. Va a, R. Veeroja, P. Wabakken, M. Wolfl, S. Wolfl, F. Zimmermann, D. Zlatanova and L. Boitani; Recovery of large carnivores in Europe's modern human-dominated landscapes; Science, 2014; 346 (6216): 1517 DOI: 10.1126/science.1257553.

 

What are the mechanisms of zooxanthella expulsion from coral?

The ratio of degraded zooxanthella (Symbiodinium) cells (black bars) expelled from the two coral species are shown. Bars show the normal (white) and degraded (black) forms of zooxanthellae. Dotted lines show water temperature. Credit: Fujise et al., PLOS ONE. DOI: 10.1371/journal.pone.0114321, Fig. 4.

Coral bleaching, which often results in the mass mortality of corals and in the collapse of coral reef ecosystems, has become an important issue around the world, with the number of coral reefs decreasing annually. Associate Professor Kazuhiko Koike and Ms. Lisa Fujise of the Graduate School of Biosphere Science at Hiroshima University and their collaborators have proposed mechanisms that might cause coral bleaching and damage. This research group demonstrated that corals more actively digest and expel damaged symbiotic zooxanthellae under conditions of thermal stress, and that this is likely to be a mechanism that helps corals to cope with environmental change. On the other hand, if the stressful conditions prevail, accumulation of the damaged symbiotic zooxanthellae may not maintain the expulsion, which will gradually accumulate in coral tissues. These researchers consider that this loss of zooxanthellae and the accumulation of damaged cells results in coral bleaching. These results were published as an article in PLOS ONE.

The symbiosis between corals and zooxanthellae (dinoflagellate genus Symbiodinium) form the foundation of coral reef biology. The aforementioned research group demonstrated that the expulsion of zooxanthellae at 27°C (non-thermal stress conditions) is part of a regulatory mechanism that maintains zooxanthellal density and a stable carbon concentration with expulsion of digested or normal forms of symbionts. However, at 30°C (moderate thermal stress), Symbiodinium were damaged, and corals selectively digested the damaged cells or immediately expelled them without digestion by exocytosis, which is most likely to reflect an adaptive mechanism in response to moderate thermal stress to avoid the accumulation of damaged cells. However, under thermal stress, the accumulation of damaged cells may exceed the increased rate of expulsion of digested zooxanthella. More photosynthetically damaged zooxanthellae were observed upon prolonged exposure to thermal stress, and were released by corals without digestion, therefore preventing their accumulation. This response may be an adaptive strategy to moderate stress to ensure survival, but the accumulation of damaged Symbiodinium, which causes subsequent coral deterioration, may occur when this response cannot cope with the magnitude or duration of environmental stress, and this might be a possible mechanism underlying coral bleaching during prolonged moderate thermal stress.

Citation: Lisa Fujise, Hiroshi Yamashita, Go Suzuki, Kengo Sasaki, Lawrence M. Liao, Kazuhiko Koike. Moderate Thermal Stress Causes Active and Immediate Expulsion of Photosynthetically Damaged Zooxanthellae (Symbiodinium) from Corals. PLoS ONE, 2014; 9 (12): e114321 DOI: 10.1371/journal.pone.0114321.

Contact: Norifumi Miyokawa
Hiroshima University

 

Dolphin-power sufficient for propulsion without tricks

Common dolphins. Credit: NOAA

Gray's paradox laid to rest.

When Mr E. F. Thompson stood on a ship cruising through the Indian Ocean in the 1930s and observed a dolphin speed past the vessel in 7 seconds, he had no idea that this single observation would lead Sir James Gray to formulate the enduring paradox that bears Gray's name to this day. Based on Thompson's anecdote, Gray estimated the power required to propel the boisterous mammal through the waves at 20 knots (10.3 m/s) and concluded that the animal did not have enough muscle to pull off the feat. Puzzled by the paradox, Gray concluded that dolphins must use a trick of fluid mechanics to sustain the remarkable performance.

And there the paradox stood until Frank Fish from West Chester University, USA, got his teeth into the problem 60 years later. 'I said, "Let's see how much power a dolphin can produce," so I used some hydrodynamics models that looked at the motion of the flukes and came up with the realisation that dolphins could produce very high amounts of power', recalls Fish. But these were only theoretical calculations. To really sound the paradox's death knell he would have to measure directly the force exerted by the animal on water and, although there is a method - known as digital particle image velocimetry (DPIV) - to visualise eddies in the water in order to measure the forces exerted by fish, it wasn't clear how the same approach could be used on dolphins: 'No one is going to let you put a 55 gallon drum of glass beads in with a dolphin and no one is going to let you shine a laser beam at a dolphin', says Fish.

That was until Fish met Timothy Wei, from the University of Nebraska, USA, at a conference. Wei had encountered the same technical problems when working with Olympic swimmers, but he had got round it by asking the Olympians to swim through a curtain of microscopic bubbles. Could the same approach work for dolphins? Fish contacted his long-time friend Terrie Williams and asked if he could test the method on her dolphins, Primo and Puka.

Arriving at the University of California at Santa Cruz with a SCUBA tank of compressed air and a garden soaker hose to produce the curtain of bubbles, Fish teamed up with Wei, graduate student Paul Legac and Williams to put the dolphins through their paces. Filming the animals as they swam along the length of the bubble curtain, the team could clearly see the vortices set spinning by the dolphins' flukes demarcating the powerful jet of water propelled backwards as the animals surged forward. 'We were in this concrete underwater viewing area... it was cold and damp, but you would get really excited and forget about that as you saw the animal go past and you'd see the vortices come out so nicely', recalls Fish.

And when Legac and Wei calculated the amount of power produced by the animals as they cruised at a leisurely 3.4 m/s, the animals were producing an impressive 549 W - approximately 1.4 times the power that a fit amateur cyclist can sustain flat out for an hour - rocketing to an eye-watering 5400 W when accelerating rapidly. The team publishes their discovery that there is no paradox in the Journal of Experimental Biology.

So, the dolphins did have enough muscle to power their impressive swimming performance because they are simply stronger than humans. And, having proved that the method works for dolphins, Fish is keen to test it out on even larger animals. 'If I can do it for a dolphin, can I do it for a whale? Can I do it for a manta ray?' he grins.

Citation: Fish, F. E., Legac, P., Williams, T. M. and Wei, T. (2014). Measurement of hydrodynamic force generation by swimming dolphins using bubble DPIV. J. Exp. Biol. 217, 252-260.

Contact: Kathryn Knight
The Company of Biologists

 

Watts up - Planes go hybrid-electric

An aircraft with a parallel hybrid engine – the first ever to be able to recharge its batteries in flight – has been successfully tested in the UK, an important early step towards cleaner, low-carbon air travel. - See more at: http://www.cam.ac.uk/research/news/watts-up-aeroplanes-go-hybrid-electric#sthash.HBPUrbpa.dpuf

Credit; Boeing & University of Cambridge

Researchers from the University of Cambridge, in association with Boeing, have successfully tested the first aircraft to be powered by a parallel hybrid-electric propulsion system, where an electric motor and petrol engine work together to drive the propeller. The demonstrator aircraft uses up to 30% less fuel than a comparable plane with a petrol-only engine. The aircraft is also able to recharge its batteries in flight, the first time this has been achieved.

The demonstrator is based on a commercially-available single-seat aircraft, and its hybrid engine was designed and built by engineers at Cambridge with Boeing funding support.

The aircraft uses a combination of a 4-stroke piston engine and an electric motor / generator, coupled through the same drive pulley to spin the propeller. During take-off and climb, when maximum power is required, the engine and motor work together to power the plane, but once cruising height is reached, the electric motor can be switched into generator mode to recharge the batteries or used in motor assist mode to minimise fuel consumption. The same principle is at work in a hybrid car.

"Although hybrid cars have been available for more than a decade, what's been holding back the development of hybrid or fully-electric aircraft until now is battery technology," said Dr Paul Robertson of Cambridge's Department of Engineering, who led the project. "Until recently, they have been too heavy and didn't have enough energy capacity. But with the advent of improved lithium-polymer batteries, similar to what you'd find in a laptop computer, hybrid aircraft - albeit at a small scale - are now starting to become viable."

The hybrid power system in the Cambridge demonstrator is based on a Honda engine, in parallel with a custom lightweight motor. A power electronics module designed and built in the Engineering Department controls the electrical current to and from the batteries - a set of 16 large lithium-polymer cells located in special compartments built into the wings. The petrol engine is optimally sized to provide the cruise power at its most efficient operating point, resulting in an improved fuel efficiency overall.

"Our mission is to keep our sights on finding innovative solutions and technologies that solve our industry's toughest challenges and continually improve environmental performance," said Marty Bradley, Boeing's principal investigator for the programme. "Hybrid electric is one of several important elements of our research efforts, and we are learning more every day about the feasibility of these technologies and how they could be used in the future."

While the Cambridge demonstrator is an important step in the development of hybrid or fully-electric aircraft, more research is required before commercial airliners will be powered entirely with electric motors. For example, if all the engines and all the fuel in a modern jetliner were to be replaced by batteries, it would have a total flying time of roughly ten minutes.

Test flights for the project took place at the Sywell Aerodrome, near Northampton. These tests consisted of a series of 'hops' along the runway, followed by longer evaluation flights at a height of over 1,500 feet.

 

Robertson's team, which includes PhD students Christian Friedrich and Andre Thunot and MEng student Tom Corker, is conducting ongoing test flights to characterise and optimise the system for best performance and fuel economy.

The Intergovernmental Panel on Climate Change (IPCC) estimates aviation is responsible for around 2% of global man-made carbon dioxide emissions. The aerospace industry made global commitments to take action that will see carbon neutral growth from 2020 and a net reduction in CO2 emissions of 50% by 2050 compared to 2005 levels. Boeing is a member of Sustainable Aviation, which is responding to these goals in the UK.

Contact: Sarah Collins
University of Cambridge

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Weather and environmental satellite crowd sourcing: 2 new apps

National Oceanic and Atmospheric Administration (NOAA)'s academic partner, the Space Science and Engineering Center (SSEC) at the University of Wisconsin-Madison has developed two free mobile apps that bring the ability to see and capture satellite data to mobile users' fingertips. The apps received development support from NOAA and NASA.

The SatCam app for iOS devices allows mobile users to capture observations of sky and ground conditions at the same time that an Earth observing satellite is overhead. The WxSat (short for Weather Satellite) app, for iOS and android, displays and animates full-resolution, real-time weather satellite data. WxSat leverages the SSEC Data Center holdings to provide global coverage for visible, infrared, and water vapor channels.

How SatCam Works

When users capture a SatCam observation and submit it to the SatCam server, it helps to check the quality of the cloud products that are created from satellite data. In return for the observation submission, SatCam sends users the satellite image that was captured at their location. The SatCam software supports NASA's Terra and Aqua satellites as well as the NOAA/NASA Suomi-NPP satellite. SatCam images help SSEC to perfect the cloud mask products that are applied to data collected from the satellites. Cloud mask indicates whether a given view of the Earth is obstructed by clouds or aerosol and can be misinterpreted when cloud temperature is too similar to ground temperature.

"SatCam is a great example of a citizen science app that allows anyone with an iPhone to help improve the data products from instruments onboard three flagship Earth science missions," said Steve Graham, a senior outreach specialist for Global Science and Technology, Inc. at NASA's Goddard Space Flight Center, Greenbelt, Maryland. He has also been the outreach coordinator for the Aqua mission (formerly PM-1) since March 2000.

How WxSat Works

Geostationary and polar orbiting weather satellites, like Suomi-NPP, continuously capture observations of the earth. Data from these satellites are acquired by the SSEC Data Center which has one of the most extensive collections of real-time and archived weather satellite data in the world. WxSat blends those images into single hourly global composites for three different products (Visible, Infrared, and Water Vapor) and is updated every hour at 36 minutes past the hour.

The names of the different images in the WxSat app refer to the parts of the electromagnetic spectrum from which the satellite sensors are sampling. The three most widely used atmospheric channels are the visible, infrared, and water vapor. NOAA forecasters combine information from the three types of images to predict weather, monitor forest fires, ice flows, ocean currents, and long term climate patterns from a global perspective that only satellites can provide.

These SSEC apps are freely available to all interested users. To download and learn more about the SatCam and WxSat apps, click here.

Contact: Rob Gutro
NASAGoddard
301-286-4044

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Distribution of fish on the northeast US shelf influenced by both fishing and climate

Scup (Stenotomus chrysops). Credit: Donald Flescher, NEFSC/NOAA

Scientists studying the distribution of four commercial and recreational fish stocks in Northeast U.S. waters have found that climate change can have major impacts on the distribution of fish, but the effects of fishing can be just as important and occur on a more immediate time scale.

The four species studied - black sea bass, scup, summer flounder, and southern New England/Mid-Atlantic Bight winter flounder - have varied in abundance and have experienced heavy fishing pressure at times over the past 40 years. Scientists examined the distribution of the four species using Northeast Fisheries Science Center (NEFSC) research trawl survey data collected between 1972 and 2008. Generalized additive models were used to determine if the distributions of the four species had changed over time, and if these changes reflect changes in temperature or fishing pressure.

The researchers found that black sea bass, scup, and summer flounder exhibited significant poleward shifts in distribution in at least one season. The shifts in black sea bass and scup were related to temperature, while the shift in summer flounder was related to a decrease in fishing pressure and an expansion of the population age structure. The southern New England/Mid-Atlantic Bight stock of winter flounder showed no change in distribution.

"The study combined a range of resources at the Center, long-term oceanographic data and trawl survey data," said Richard Bell, a National Research Council research associate working at the NEFSC's Narragansett Laboratory in Rhode Island and lead author of the study. "Using these data, we demonstrated how a combination of fishing and climate can influence the distribution of marine fish. It is not one or the other."

Winter flounder (Pseudopleuronectes americanus) in Narragansett Bay. Credit: Jerry Prezioso, NEFSC/NOAA

Increasing ocean temperatures have significantly affected marine life, inducing shifts in distribution and changes in abundance. Climate change alters the distribution of suitable habitats, forcing organisms to move to a more favorable area of their range or attempt to survive under less than ideal conditions. Fishing reduces the abundance of marine populations and truncates their size and age structure, which can lead to range contractions or shifts.

Fishing typically removes the larger fish from a population. Larger, older summer flounder are typically found further north, and as exploitation reduced the numbers of summer flounder in the 1980s and 1990s, larger fish were preferentially harvested by the fishery. The remaining summer flounder population, dominated by smaller fish, subsequently became centered further south. The northward shift of the stock in recent decades was linked to an increase in the number of larger, older fish as the population has rebuilt.

"The fish were not shifting northward with warmer conditions, but simply re-colonizing their former habitat areas," said Bell.

Northerly shifts in scup and black sea bass are linked to increases in temperature and are more tied to climate than fishing.

The study suggests multiple factors specific to individual species need to be considered when developing management regulations for living marine resources. The management of each of the four species analyzed in this study is based on spatial allocations, and shifts in stock distributions can cause a mismatch between the distribution of fish and the catch allocations for different regions and states.

Citation: R. J. Bell, J. A. Hare, J. P. Manderson, D. E. Richardson. Externally driven changes in the abundance of summer and winter flounder. ICES Journal of Marine Science, 2014; 71 (9): 2416 DOI: 10.1093/icesjms/fsu069.

Related links:

• ICES Journal of Marine Science article
• Potential Impacts of Climate Change on the Biota of the U.S. Northeast Shelf Large Marine Ecosystem (NES LME)
• Assessing the Vulnerability of Fish Stocks in a Changing Climate
• Ecosystem Considerations

Contact: Shelley Dawicki
NOAA

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Trade winds ventilate the tropical oceans

Kiel marine scientists find explanation for increasing oxygen deficiency.

Scheme of the tropical Pacific: Strong growth of plankton (1) leads to a high oxygen consumption and extended oxygen minimum zones (2). Ocean currents (3) at a few hundred meters depth provide an influx of oxygenated water from the subtropics (4). Fluctuations of the trade winds (5) influence the strength of these currents. Graphics: Claus Böning, Markus Scheinert, GEOMAR

The changes can be measured, but their reasons were unknown. For several decades, scientists have carefully observed that the oxygen minimum zones (OMZ) in the tropical oceans are expanding. These zones are a paradise for some specially adapted microorganisms, but for all larger marine organisms such as fish and marine mammals they are uninhabitable. Thus, their expansion has already narrowed down the habitat of some fish species.

Marine scientists from the GEOMAR Helmholtz Centre for Ocean Research Kiel and the Kiel Collaborative Research Centre (Sonderforschungsbereich, SFB) 754 "Climate - Biogeochemical Interactions in the Tropical Ocean" now have found a possible reason for these changes by using a model simulation of climate and biological processes. As their study shows, the trade winds north and south of the Equator play a crucial role in the supply of oxygen to tropical sea water. "So fluctuations in the trade winds could also be responsible for the observed enlargement of the oxygen minimum zones in recent years," explains Dr. Olaf Duteil, lead author of the study, which has now been published in the international journal Geophysical Research Letters.

OMZs exist in different intensities at the eastern edges of all tropical oceans. Because nutrient-rich water from the depths reaches the surface in these areas plankton thrives particularly well. Therefore large amounts of plankton organisms die there, too. After their death they sink down to the ocean floor. On the way down bacteria start to decompose the biomass. In doing so they consume the oxygen. The largest of these OMZs stretches from the coasts of Chile and Peru far into the Pacific ocean.

At the same time currents at a few hundred meters depth transport oxygen-rich water from the subtropics towards the tropics, where the oxygen minimum zones lie. "One can think of the tropical Pacific Ocean as a bathtub. When I open the tap, I fill the bathtub with water or 'oxygen', respectively. When the siphon is open, too, we lose oxygen at the same time. We then have an instable equilibrium between input and output," explains Dr. Duteil, "If I turn off the tap a little, the tub empties slowly."

As the researchers were able to determine in a computer simulation of the oxygen balance now, the strength of the currents and thus the oxygen flow to the tropics is directly related to the strength of the trade winds. "It is well known that they vary on a decadal time scale," says co-author Prof. Dr. Claus Böning from GEOMAR, "but these variations haven never been investigated in relation to the oxygen budget of tropical oceans. "

Since the trade winds have been in a weak phase since the mid-1970s, this could be the explanation for the observed enlargement of the oxygen minimum zones. "The oxygen bathtub of the tropical oceans is emptying," says Dr. Duteil. Once the trade winds come back into a stronger phase, the process will be reversed.

This does not mean that external processes such as the general global warming have no influence on the oxygen concentrations in the tropical oceans. "There is evidence that global change affects the major wind systems of the Earth. That would have a direct impact on the oxygen transport in the subtropical and tropical ocean," explains Prof. Andreas Oschlies, co-author and speaker of the SFB 754. "But it is important that according to this study the trade winds in any case as must be considered as a factor for long-term development of tropical oxygen minimum zones," Oschlies adds.

Citation: Duteil, O., C. W. Böning, A. Oschlies (2014): Variability in subtropical-tropical cells drives oxygen levels in the tropical Pacific Ocean. Geophysical Research Letters,  DOI: 10.1002/2014GL061774.

Contact: Dr. Olaf Duteil, GEOMAR, RD1 – Theory and Modeling.

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New challenges for ocean acidification research

Experts look back at a successful decade and carve out future priorities.

To continue its striking development, ocean acidification research needs to bridge between its diverging branches towards an integrated assessment. This is the conclusion drawn by Prof. Ulf Riebesell from GEOMAR Helmholtz Centre for Ocean Research Kiel and Dr. Jean-Pierre Gattuso from the French Centre National de la Recherche Scientifique (CNRS) and Université Pierre et Marie Curie. In a commentary in the journal “Nature Climate Change”, the two internationally renowned experts reflect on the lessons learned from ocean acidification research and highlight future challenges.

Over the past decade, ocean acidification has received growing recognition not only in the scientific area. Decision-makers, stakeholders, and the general public are becoming increasingly aware of "the other carbon dioxide problem". It is time to reflect on the successes and deficiencies of ocean acidification research and to take a look forward at the challenges the fastest growing field of marine science is facing. In the January issue of the journal Nature Climate Change Ulf Riebesell, professor for Biological Oceanography at GEOMAR Helmholtz Centre for Ocean Research Kiel, and Jean-Pierre Gattuso from the French Centre National de la Recherche Scientifique (CNRS) urge the international scientific community to undertake a concerted interdisciplinary effort. According to the two experts, future ocean acidification research will have to deal with three major challenges: It needs to expand from single to multiple drivers, from single species to communities and ecosystems, and from evaluating acclimation to understanding adaptation. "The growing knowledge in each of the diverging research branches needs to be assimilated into an integrated assessment", Prof. Riebesell points out.

For the scientific community, it is obvious that ocean acidification does not occur in isolation. Rising temperatures, loss of oxygen, eutrophication, pollution and other drivers happen simultaneously and interact to influence the development of marine organisms and communities. "The effects can be additive, synergistic or antagonistic and it is generally not possible to extrapolate from single- to multiple-driver responses", Prof. Riebesell explains. "But with an increasing number of parameters, experiments become increasingly challenging in terms of time, space and costs. Also, it becomes ever more difficult to compare and verify results of similar studies."

There is now an impressive body of scientific literature on how individual species react to ocean acidification as a single driver. Many calcifying organisms such as corals, mussels or snails will find it more and more difficult to build their shells and skeletons. The extra energy needed for calcification will be lacking for other biological processes, such as growth or reproduction. „But an open question is to what extent results from short-term, single-driver laboratory experiments can be extrapolated to the real world", Dr. Gattuso states.

As shown in laboratory experiments, evolutionary adaptation to ocean acidification is possible. The larger the population size of a species and the shorter its generation time is, the higher the chances are that it can adapt to new environmental conditions through selection or mutation. "But can adaptation keep up with the fast changes we are experiencing today? Are the organisms able to maintain their functions within the changing ecosystem," Dr. Gattuso wonders.

To make further significant progress in the future, ocean acidification research has to integrate the knowledge gained in its three diverging branches - addressing multiple stress factors, competitive and trophic interactions, and adaptation through evolution. "This requires an interdisciplinary effort, for example through long-term experiments that examine the effects of multiple drivers over many generations at the community level. "Experiments have to be tightly integrated with field studies and model simulations", Prof. Riebesell recommends. "A key factor in this process will be that funding opportunities are opened up for large-scale integrative projects, long-term monitoring and international collaborations." Now that a basic understanding of ocean acidification impacts is developing, it is critical to pay special attention to aspects relevant for society. "This will then pave the way to develop management options and provide science-based policy advice."

Links:

• BIOACID (Biological Impacts of Ocean Acidification)
• Intergovernmental Panel on Climate Change (IPCC) box on ocean acidification
• Ocean Acidification Summary for Policymakers
• Ocean Acidification International Coordination Centre (OA-ICC)
• GEOMAR Helmholtz Centre for Ocean Research Kiel
• Villefranche Oceanographic Laboratory

Citation: Riebesell, U., Gattuso, J.-P. (2015) Lessons learned from ocean acidification research. Reflection on the rapidly growing field of ocean acidification research highlights priorities for future research on the changing ocean. Nature Climate Change 5, 12-14 (2015), DOI: 10.1038/nclimate2456.

Contact: Prof. Dr. Ulf Riebesell
GEOMAR

 

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Is it safe to eat the fish you caught yourself?

Viltava River in Prague, Czech Republic. (Wikimedia Commons)

By Science for Environment Policy

Persistent organic pollutants (POPs) and toxic metals can remain in the environment for a long time, allowing levels to build up, with damaging effects on wildlife. For instance, POPs collect in the fatty tissues of animals and can interfere with hormonal systems; mercury, cadmium and lead act as nerve toxins. Despite this, clear information on this type of contamination in in wild fish in Europe is lacking. As a result, keen anglers and their families may be consuming higher levels of these chemicals than the rest of population without knowing it.

Angling is popular in the Czech Republic, and although most Czechs eat no more than 6 kg of fish each year, those who fish for sport, and their families, may eat twice that much - on average, about six 170 g portions of fish a month.

The researchers tested fish from 27 of the most popular fishing areas in the Czech Republic, looking for mercury, lead, cadmium and a variety of POPs, including the banned insecticide DDT. They tested common bream (Abramis brama) at all sites, as well as fish typical of each locality, and then compared the contamination found with the maximum allowable levels in food, as outlined in EU-wide and Czech national regulations. They also evaluated health risks posed to humans by eating contaminated fish.

Mercury was found in all tested fish species at all 27 sites and the maximum level was exceeded at 17 sites. In bream, concentrations of mercury slightly exceeded the maximum levels at four sites.

According to the researchers' calculations, to avoid consuming unsafe levels, anglers would have to limit the number of portions of bream they ate to between 6-115 portions a month—this wide range is because levels varied considerably between sites. Higher concentrations were detected in predatory fish, such as the asp (Aspius aspius), whereas carp (Cyprinus carpio) tended to be much less contaminated. This is because they were artificially stocked and came from uncontaminated pond breeding facilities. Approximately 80% of fish caught by anglers in the Czech Republic are carp, but some do specialise in predatory fish.

Cadmium and lead levels in bream were below the maximum levels at all sites. Furthermore, these metals did not accumulate further up the food chain in the muscle of predatory fish, as mercury did.

The most common POPs contaminating fish were DDT and 'non-dioxin-like polychlorinated biphenyls' (NDL-PCBs). Despite being banned in 1974 in the Czech Republic, DDT was present at all sites, although it was always below maximum levels set for pesticides. Anglers would have to eat thousands of portions of fish a month to consume anywhere near unsafe levels. Levels of NDL-PCBs were generally below maximum levels, except at four sites. Higher levels of both POPs were found in fish with bigger fat stores, such as eels. The highest concentrations of NDL-PCBS were found in European eels (Anguilla anguilla) from a reservoir in Zermanice in the east.

Citation: Cerveny, D., Zlabek, V., Velisek, J. et al. (2014). Contamination of fish in important fishing grounds of the Czech Republic. Ecotoxicology and Environmental Safety, 109: 101–9. DOI:10.1016/j.ecoenv.2014.07.034.

Contact: D. Cerveny

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New 'bird-washing machine' dramatically improves survival of birds caught in oil spills

Albatrosses covered in oil. Credit: Leary Pete, U.S. Fish and Wildlife Service

By Science for Environment Policy

Oil spills can decimate seabird populations. Some birds can be saved, if the oil is washed from their feathers in time; however, this long process is stressful for the birds and requires numerous volunteers. Researchers have now developed a 'bird-washing machine' which reduces the washing time from two hours to four minutes. When trialled on oiled birds rescued from the Caspian Sea this resulted in a substantial increase in survival: 88.5% survival after seven days compared to 50% survival with current washing techniques.

Since 1970 more than 5.17 million metric tonnes of oil have been released in to the world's oceans from more than 1800 reported oil spills. Such disasters can have serious impacts on marine wildlife. In the case of seabirds, the oil sticks to their feathers, preventing them from flying, reducing their buoyancy, and making movement difficult. Birds trying to remove the oil can ingest it, leading to poisoning.

Removing oil from birds is therefore an important part of limiting the ecological effects of oils spills. However, care needs to be taken in how this is done. For example, cleansing solutions must be chosen which can disperse the oil, but are non-toxic to birds. Cleaning of birds is also a laborious process, requiring around three people and about two hours to wash each bird by hand. This process is highly stressful for birds and is associated with a high rate of mortality.

Researchers have now developed an automatic 'washing machine' for cleaning oil from birds while minimising stress. The machine consisted of a stainless steel basket, in which the bird is placed, and a larger surrounding structure. The surrounding structure rotates and moves up and down around the static bird cage, using a set of 19 nozzles to spray water and cleansing solutions on the bird. The machine operates a four minute wash cycle for each bird, dramatically reducing the time the bird needs to be held in a stressful situation.

Furthermore, the researchers also created a new cleansing solution, of two parts hydrogen carboxylic acid and five parts acetic acid that was effective at dispersing oil but non-toxic to birds. The whole structure, including all parts such as reservoirs, pumps and mixers, is mounted on a wheeled trolley, allowing mobility.

The bird-washer was tested at the Anzali Lagoon, in the Caspian Sea in the northern Iranian province of Gilan. The Anzali Lagoon hosts many native and migratory birds, but has high levels of pollution, including oil discharges. Oil-covered birds were rescued over 40 days between January and February 2013. The birds were visually inspected to assess if they had a poor, medium or good chance of recovery. Birds with a medium chance of survival were selected. In total 26 birds were washed, and kept for observation for seven days before release.

Of the 26, three died within the first four hours, and the remaining 23 survived through to the end of the observation period. This rate (11.5%) compares favourably with current forms of washing which have a survival rate of just 50%, the authors report.

Other automatic bird-washing machines have been described and used. However, this machine has a number of advantages over the alternatives, say the researchers, including increased portability, reduced washing time and lower energy consumption.

Citation: Rajabi, H., Monsef, H., Moghadami, et al. (2014). Design, development and demonstration of an improved bird washing machine. Ecotoxicology, 23(5): 960–5. DOI:10.1007/s10646-014-1238-2. 

Contact: H. Rajabi