Constantine Alexander's blog

Declines in Caribbean coral reefs pre-date damage resulting from climate change

Novel excavation technique attributes prior damage to land clearing and overfishing

		Tree oyster Dendrostrea frons attached to staghorn coral Acropora cervicornis. Credit: Jill Leonard-Pingel

The decline of Caribbean coral reefs has been linked to the recent effects of human-induced climate change. However, new research led by scientists at Scripps Institution of Oceanography at UC San Diego suggests an even earlier cause. The bad news – humans are still to blame. The good news – relatively simple policy changes can hinder further coral reef decline.

Employing a novel excavation technique to reconstruct the timeline of historical change in coral reefs located on the Caribbean side of Panama, a team of scientists led by Scripps alumna Katie Cramer and current Scripps Professor of Oceanography and Smithsonian Tropical Research Institute (STRI) Emeritus Staff Scientist Jeremy Jackson has determined that damage to coral reefs from land clearing and overfishing pre-dates damage caused by anthropogenic climate change by at least decades.

"This study is the first to quantitatively show that the cumulative effects of deforestation and possibly overfishing were degrading Caribbean coral and molluscan communities long before climate change impacts began to really devastate reefs," said lead author Cramer, currently based at the Global Coral Reef Monitoring Network at the International Union for Conservation of Nature.

Coral reefs have suffered alarmingly since the 1980s due to coral bleaching and coral disease, thought to stem from the warming of the oceans due to anthropogenic, or human-induced, climate change. However, until recently, the impact of prior human activities on Caribbean coral reefs had not been studied with experimental techniques.

Historical records and qualitative surveys provide hints that declines in corals in some parts of the Caribbean occurred as far back as the early 1900s after coastal lands began to be cleared to make way for plantations. However, the current study is the first to quantify the changes that reef corals and mollusks have undergone as a result of long-term stress caused by the deposition of silt, nutrients, and pollution onto coral reefs from land clearing and the depletion of reef fish that prevent algae from overtaking reefs.

"Because researchers did not really begin to study Caribbean reefs in detail until the late 1970s, we don't have a clear understanding of why these reefs have changed so dramatically since this time," said Cramer. "So, we set out to reconstruct an older timeline of change on reefs by looking at the remains of past reefs – coral skeletons and mollusk shells."

To reconstruct this timeline, the team dug below modern reefs in incremental layers and, using radiocarbon dating of the coral skeletons they found, linked fluctuations in the types and numbers of coral and mollusks over time to historical records of land clearing. Changes in the relative numbers of these various species represent clear indicators of the overall health of the coral reef.

The team also improved upon the standard technique of taking long, narrow core samples of coral fossils that cannot track fluctuations in the numbers of larger species of coral.

"We wanted to look at the whole complement of the coral community," said Cramer.

To catalog the relative numbers of dozens of coral and molluscan species, the researchers dug two-foot-wide by three-foot-deep pits into reefs at several coastal lagoon and offshore sites near Bocas del Toro, Panama, that were heavily affected and less affected by land runoff, respectively. At each of these sites they also conducted surveys and recorded the composition of living corals.

"We dug up over a ton of coral rubble and tens of thousands of shells," said Cramer, who led the fieldwork at STRI and likened the laborious experience to doing underwater construction.

Systematically sifting through the coral and shell fossils, the scientists noted several indicators of environmental stress, including a decrease in the overall size of bivalves such as oysters, clams, and scallops, a transition from branching to non-branching species of coral, and large declines in the staghorn coral and the tree oyster, which were once the dominant coral and bivalve on these reefs.

These indicators were observed in layers of the excavated pits at coastal lagoon sites that were dated before 1960 and as far back as the 1800s, corresponding to a period of extensive deforestation in the Bocas del Toro region. Similar evidence of environmental stress at offshore sites was dated after 1960, indicating that the negative impacts of land clearing have more recently begun to affect reefs further offshore.

With the decline of the branching coral species, the reefs now have fewer nooks and crannies that are used as habitat for reef fish and other organisms. Also, the non-branching species that have taken their place grow at a much slower rate. "Consequently, there is less of a chance that the reefs will be able to keep up with sea level rise from climate change," said Cramer.

"Because the governments of the world have yet to undertake any meaningful efforts to mitigate climate change, it is of the utmost importance that locally caused stressors to reefs such as overfishing and deforestation are minimized," said Cramer. "Advocating for more intelligent use of land as well as implementing sustainable fisheries management, those are things that can be done right now."

The research team, which also includes Jill Leonard-Pingel of Scripps, Thomas Guilderson of the Lawrence Livermore National Laboratory and the Institute of Marine Sciences at the University of California at Santa Cruz, and Christopher Angioletti, will publish its findings in the April issue of Ecology Letters. An early online version has been released today.

This research was funded by the National Science Foundation, the Smithsonian Institution, the Center for Marine Biodiversity and Conservation at Scripps, the UC San Diego Academic Senate, and the PADI Foundation's Project AWARE.

Contact: Mario Aguilera
scrippsnews@ucsd.edu
858-534-3624
University of California - San Diego

Extreme weather threatens rich ecosystems

Wyland Wall

Extreme weather such as hurricanes, torrential downpours and droughts will become more frequent in pace with global warming. Consequently, this increases the risk for species extinction, especially in bio diverse ecosystems such as coral reefs and tropical rainforests.

Human impact means that flora and fauna become extinct at a rate 100 times higher than normal. Climate change has been deemed as one of the main causes of species depletion.

A research team in theoretical biology at Linköping University in Sweden has, through the use of mathematical modelling and simulation, studied how the dynamics of different types of ecosystems may be affected by significant environment fluctuations.

Linda Kaneryd, doctoral student and lead author of a study recently published in the journal, Ecology and Evolution, says the results were surprising.

"Several previous studies of food web structures have suggested that species-rich ecosystems are often more robust than species-poor ecosystems. However at the onset of increased environmental fluctuations, such as extreme weather, we see that extreme species-rich ecosystems are the most vulnerable and this entails a greater risk for a so-called cascading extinction."

In a rainforest or on coral reef there are a wide variety of species of primary producers such as green plants and algae. Since they are competitors, relatively few individuals of the same species exist, subjecting them to a greater risk of extinction should external conditions change. This could result in a depletion of food sources for a species of herbivores that, in turn, affects a predator at the top of the food chain. Biologists call this transformation a cascading extinction.

The opposite would apply to an ecosystem whereby few species exist in large numbers and animal species are adaptable generalists.

The researchers create their model food webs following on from their experiences with real ecosystems; what eats what, the composition of the species' life cycles, and how they interact with others. In this study, external conditions are represented as an increasing and unpredictable variation.

"The model we worked with is quite typical. The next step is to introduce actual, detailed climatic data," informs Bo Ebenman, Professor of Theoretical Biology who supervised Linda Kaneryds thesis.

Reference: Species-rich ecosystems are vulnerable to cascading extinctions in an increasingly variable world by L. Kaneryd, C. Borrvall, S. Berg, A. Curtsdotter, A. Eklöf, C. Hauzy, T. Jonsson, P. Münger, M. Setzer T. Säterberg and B. Ebenman. Ecology and Evolution March 30, 2012 ("Early View").

Contact: Bo Ebenman
boebe@ifm.liu.se
46-730-242-901
Linköping University

 

Some corals like it hot: Heat stress may help coral reefs survive climate change

A team of international scientists working in the central Pacific have discovered that coral which has survived heat stress in the past is more likely to survive it in the future.

The study, published today in the journal PLoS ONE, paves the way towards an important road map on the impacts of ocean warming, and will help scientists identify the habitats and locations where coral reefs are more likely to adapt to climate change.

"We're starting to identify the types of reef environments where corals are more likely to persist in the future," says study co-author Simon Donner, an assistant professor in UBC's Department of Geography and organizer of the field expedition. "The new data is critical for predicting the future for coral reefs, and for planning how society will cope in that future."

When water temperatures get too hot, the tiny algae that provides coral with its colour and major food source is expelled. This phenomenon, called coral bleaching, can lead to the death of corals.

With sea temperatures in the tropics forecast to rise by 1-3 degrees Celsius by the end of the century, the researchers say coral reefs may be better able to withstand the expected rise in temperature in locations where heat stress is naturally more common. This will benefit the millions of people worldwide who rely on coral reefs for sustenance and livelihoods, they say.

"Until recently, it was widely assumed that coral would bleach and die off worldwide as the oceans warm due to climate change," says lead author Jessica Carilli, a post-doctoral fellow in Australian Nuclear Science and Technology Organisation's (ANSTO) Institute for Environmental Research. "This would have very serious consequences, as loss of live coral – already observed in parts of the world – directly reduces fish habitats and the shoreline protection reefs provide from storms."

Caralli and Donner conducted the study in May 2010 in the Pacific island nation of Kiribati, near the equator. Kiribati's climate is useful for testing theories about past climate experience because its corals are pounded by El Niño-driven heat waves, while corals on the islands farther from the equator are less affected.

The researchers analyzed coral skeletal growth rates and tissue fat stores to compare how corals from different regions responded to two recent coral bleaching events in 2004 and 2009.

Donner has conducted field research in Kiribati since 2005 and will return this year to conduct follow-up research with the local government. He says the findings suggest that Marine Protected Areas – conservation areas designed to protect marine life from stressors like fishing – may be more effective in areas with naturally variable water temperatures

The research delivers mixed news for Australia's Great Barrier Reef, because the reef stretches over such massive distances; some areas have stable temperatures and some do not. The findings support previous laboratory and observational studies from other regions, suggesting they can be widely applied.

Planning is now underway for potential future studies of coral in areas of the world that have not experienced significant historical changes in water temperatures.

"Even through the warming of our oceans is already occurring, these findings give hope that coral that has previously withstood anomalously warm water events may do so again," says Carilli. "While more research is needed, this appears to be good news for the future of coral reefs in a warming climate."

Contact: Basil Waugh
basil.waugh@ubc.ca
604-822-2048
University of British Columbia

 

The Island President: trailer - video

Documentary on Mohamed Nasheed, the President who brought democracy to the Maldives, and is now fighting to keep the islands from being obliterated by flooding caused by global warming. Directed by Jon Shenk, The Island President follows President Nasheed as he takes his campaign to the 2009 Copenhagen climate summit.

 

Dolphins cultivate loose alliances

		This image shows two male dolphins in Shark Bay. Credit: The Dolphin Alliance Project

Dolphins behave uniquely. On the one hand, male dolphins form alliances with others; on the other hand, they live in an open social structure. Anthropologists from the University of Zurich detected this unusual behavior in the animal kingdom in dolphins in Shark Bay, Australia.

Male dolphins in Shark Bay, Australia, display the most complex group behavior of all mammals after us humans. Studies in the 1990s revealed that two to three male dolphins cooperate very closely with each other to isolate female dolphins from the main group for mating. Sometimes, these so-called "first-order" alliances join forces to steal females that have been monopolized by other alliances. To a degree, however, this higher-level bond among males is highly opportunistic and can change depending on the context. The formation of alliances in dolphins is only comparable with that of humans in terms of complexity.

A new study by researchers from the USA, Australia and Michael Krützen from the University of Zurich's Anthropological Institute & Museum now proves that these male alliances are based on an open social structure. Dolphins have multifaceted relationships with other individuals within a complex network without an obvious group structure, placing them almost on a par with us humans. This begs a comparison with the social structure of chimpanzees. Chimpanzee males also form alliances, but only between social groups, which enables them to defend their territory against members of the same species from other groups. However, this is not the case with dolphins: They defend the females, not territories.

		Male dolphins form alliances with others. Credit: The Dolphin Alliance Project

Another explanatory model would be that dolphin males only defend females or territories during the mating season and thus avoid each other as far as possible. However, this hypothesis does not apply to dolphins in Shark Bay, either, as the observation of over 120 adult dolphins in an area of around 600 square kilometers revealed. "Our study shows for the first time that the social structure and associated behavior of dolphins is unique in the animal kingdom," explains Krützen.

Group behavior and the social structure of other species have always fascinated biologists. Are they similar to ours and, if yes, can we learn something about ourselves from them? The comparison of humans with apes, elephants and dolphins, all of which are species with large brains and highly developed cognitive skills, enable conclusions regarding the evolution of group behavior in humans to be drawn.

Contact: Michael Krützen
michael.kruetzen@aim.uzh.ch
41-446-344-432
University of Zurich

 

Montana State study compares growth around Yellowstone, Glacier and other national parks

 

The land around Yellowstone and Glacier national parks might look like it's filling up with people and houses, but it's nothing compared to the rate of development around some other U.S. national parks, according to a new Montana State University study.

While population densities rose 246 percent around Yellowstone/Grand Teton and 210 percent around Glacier between 1940 and 2000, they surged 3,092 percent around the Mojave National Preserve in California, 2,962 percent around the Colorado River parks and almost 2,473 percent around the Everglades National Park/Big Cypress National Park in Florida.

While housing densities grew 13.2 percent around Yellowstone and 11.4 percent around Glacier, they increased 75.6 percent around the Santa Monica Mountains National Recreation Area in California.

"We are quite impressed locally with the increase in density of rural homes around both parks and with the density of people that live around the ecosystem, but when compared to 57 parks, we are quite on the lower end of that development," MSU ecologist Andrew Hansen said of Yellowstone and Glacier.

After conducting the country's first study into population density and land use changes in the ecosystems around U.S. national parks, Hansen and lead author Cory Davis published their findings in "Ecological Applications," a journal published by the Ecological Society of America. Davis, a former biologist at Glacier National Park, is an MSU graduate student in ecology and works as a research associate in the College of Forestry and Conservation at the University of Montana. Hansen is a professor in MSU's Department of Ecology.

The MSU study -- which complemented a UM study on climate change – focused on 57 national parks in the lower 48 states and found that population densities around the parks rose an average of 224 percent between 1940 and 2000, while housing densities grew 329 percent. Those surprising increases are considerably higher than the national increases in population and housing densities in the United States during the same time.

At the same time, the researchers noted that the increases were averages. Changes differed widely among the 57 parks in their study.

"Parks largely in the East like Great Smoky Mountain changed dramatically from being surrounded mostly by forests and farms to cities, suburbs and ranchettes," Hansen said. "This was also true at a moderate level for some western parks such as Olympic and Rocky Mountain. Others, such as Yellowstone and Bighorn Canyon, that we locally think are changing rapidly, had very slow rates of growth relative to the national rates."

In the course of their work, the researchers divided the 57 national parks into five categories according to types and rates of land use change around the parks. Twenty-five parks were classified as wildland-protected. Sixteen were "wildland developable." Five were agricultural. Eight were exurban. Three were urban.

Yellowstone, Glacier, the Grand Canyon and Yosemite National Park were among the wildland-protected parks. As such, they share some common issues, Hansen said. The parks may experience increasing conflicts between humans and wildlife as private land is developed outside their boundaries, for example. Administrators may have to work to maintain or, potentially, restore top predators to their ecosystems. They may be concerned about resource extraction disrupting migration corridors, wintering grounds or key ecological processes if federal or state mandates allow mining, logging and livestock grazing near the parks. Many of the private lands around wildland parks are protected by conservation easements and support wildlife, such as bison on Ted Turner's Flying D Ranch near Yellowstone.

Approximately 35 percent of the land around Yellowstone and 45 percent of the land around Glacier is private, Hansen said. Of that private land, 75 percent remains undeveloped. Tribal land is included in private land.

Each category in the study faces unique challenges, so the researchers hope that park administrators in the same category will band together to find solutions, Hansen said.

For their study, Hansen and Davis selected large national parks that were located in the lower 48 states and had significant natural resources. They excluded parks that were primarily surrounded by water and parks that were managed for their cultural resources. Their final selections represent a wide distribution of climate and land uses. Those parks are managed primarily for natural values, biodiversity or recreation.

Davis and Hansen then looked at development on the land outside the parks. The size of those "protected-area centered ecosystems," or PACES, was determined by what was needed to sustain the species and ecological processes present within the parks.

Davis and Hansen conducted their study with statistics from the U.S. Census between1940 through 2000, the latest year that Census figures were available while the study was being conducted. They updated their findings with 2007 estimates of population and housing densities.

The researchers also visited several national parks and worked with park administrators and staff for their study. Among them was John Gross, climate change ecologist in the National Park Service's Inventory and Monitoring Program.

"I was impressed with the thoughtfulness of their analyses and with the clarity of the presentation of results," Gross wrote by email.

"This study greatly expanded the estimation of the PACEs, and parks have found these useful to help identify scientifically credible and defensible areas for monitoring, identifying conservation issues, and for other planning purposes," Gross continued. "We are using the PACEs as the basis for defining study areas as we further examine threats to park resources and try to anticipate actions that might prevent degradation or loss of park resources due to activities outside parks."

Contact: Evelyn Boswell
evelynb@montana.edu
406-994-5135
Montana State University

 

CO2 was hidden in the ocean during the Ice Age

Why did the atmosphere contain so little carbon dioxide (CO2) during the last Ice Age 20,000 years ago? Why did it rise when the Earth's climate became warmer? Processes in the ocean are responsible for this, says a new study based on newly developed isotope measurements. This study has now been published in the scientific journal "Science" by scientists from the Universities of Bern and Grenoble and the Alfred Wegener Institute for Polar and Marine Research in the Helmholtz Association.

Around 20,000 years ago, the atmospheric CO2 concentration during the last Ice Age was distinctly lower than in the following warm period. Measurements from Antarctic ice cores showed this already two decades ago. An international team of glaciologists thereafter looked even further back in time. The climate researchers found that this close connection between carbon dioxide and temperature has existed over the past 800,000 years: with low CO2 concentrations during the Ice Ages and higher CO2 values during warm periods. Now they tried to answer also the question as to where the carbon dioxide was hidden during the Ice Ages and how it got back into the atmosphere at their ends.

"We have now been able to identify processes in the ocean which are connected to the observed rise in CO2", says Dr. Jochen Schmitt, lead author of the recently published study and researcher at the Oeschger Centre for Climate Change Research at the University of Bern. According to Schmitt, during the Ice Age more and more carbon dioxide accumulated in the deep ocean, causing the concentration of atmospheric CO2 to drop. Only at the end of the Ice Age was this stored CO2 transported back to the sea surface through changing ocean circulation and thus emitted back into the atmosphere, write the scientists in the scientific journal "Science".

A new method for isotope measurements has now made it possible for the first time "to reliably decode the fingerprint of the CO2 preserved in the ice", explains Schmitt. He and his colleague Prof. Hubertus Fischer initially developed these new isotope measurement methods for ice cores at the Alfred Wegener Institute for Polar and Marine Research and further refined them in many years of research work after moving to Bern. Using the new method the glaciologists extract the air trapped in the ice core completely and the CO2 contained in the air is thoroughly cleaned. The different isotopes of the CO2 are analysed in a mass spectrometer and from this data the origin of the carbon dioxide can be derived.

Researchers suggested back in the eighties that this puzzle could be solved using an isotopic "CO2 fingerprint". However, it had so far not been possible to make a precise analysis of the carbon dioxide trapped in the Antarctic ice due to the technical hurdles. The glaciologists and the climate researchers at the Universities of Bern and Grenoble and of the Alfred Wegener Institute for Polar and Marine Research have now managed a breakthrough with their study.

Development of Future Scenarios

"The new data have already enabled us to revise and improve a few theories about the possible reasons for CO2 fluctuations. Measurement data from the past enable us to gain a clearer idea about how the climate must have looked at the end of the Ice Age", says Jochen Schmitt. And now the data must be compared with the results from climate models to verify and further develop the models. "In addition to the scientific curiosity about how our Earth functioned in the past, the main question to be asked is how the Earth will develop under the influence of man", explains Jochen Schmitt. These are important scenarios for the future because the CO2 content in the atmosphere has never been anywhere near as high over the past 800,000 years as today, says the climate researcher.

Reference: Jochen Schmitt, Robert Schneider, Joachim Elsig, Daiana Leuenberger, Anna Lourantou, Jérôme Chappellaz, Peter Köhler, Fortunat Joos, Thomas F. Stocker, Markus Leuenberger & Hubertus Fischer. Carbon Isotope Constraints on the Deglacial CO2 Rise from Ice Cores. Science Express, 2012

Contact: Dr Folke Mehrtens
medien@awi.de
49-047-148-312-007
Helmholtz Association of German Research Centres

Ocean acidification pushes coral reefs into decline

Coral reef formation is already decreasing worldwide. A new study predicts that formation will drop to 60% of its natural rate if anthropogenic CO₂ emissions continue to rise over the next century and keep acidifying the oceans.

Many marine organisms, including coral polyps, use calcium carbonate in seawater to build external skeletons and shells, a process known as calcification. However, nearly a third of the CO₂ that has been released into the atmosphere since the start of the industrial revolution has been absorbed by the oceans, increasing the acidity of the water and reducing the concentration of carbonate. When seawater is no longer saturated with carbonate, the rate of calcification decreases because calcium carbonate structures begin to dissolve.

This is already happening in many parts of the world’s oceans, but measuring it accurately over large areas can be challenging. The new study used a state-of-the-art computer model to simulate current ocean acidification and calcification rates in coral reefs, using historical data on CO₂ emissions (1750 to 2005), solar and volcanic activity, land use changes, aerosol concentrations and changes in the Earth’s orbit. The model also forecast the reduction in calcification over the next century (2005 to 2100) under the International Panel on Climate Change’s (IPCC) A1B scenario, which predicts rapid economic growth and an equal balance between fossil fuels and clean energy sources.

The model results revealed that in the western tropical Pacific and the Caribbean Oceans, calcification rates are presently, on average, 15% lower than they were in pre-industrial times. The model predicts a drop to 60% of pre-industrial levels by the end of the century.

Corals have evolved to tolerate large fluctuations in acidity and calcium carbonate concentration, caused by natural events. This natural tolerance range can be represented by the maximum and minimum concentrations found in the pre-industrial data, before human-induced impacts took effect. The researchers found that in vast areas of the world’s oceans, the reduction in calcium carbonate caused by ocean acidification has already exceeded the natural (pre-industrial) range of variability by a factor of two. In Micronesia, Polynesia and Melanesia, it has exceeded it by a factor of 30. The El Nino Southern Oscillation (ENSO) means that coral in the equatorial pacific experience bigger natural fluctuations calcium carbonate and anthropogenic ocean acidification is still within their tolerance range.

At the end of the last glacial period, between 17,000 to 11,000 years ago, there was an increase in atmospheric CO₂ levels similar in size to increase observed today. The scientists simulated changes in the abundance of calcium carbonate for that period and found that the reduction over the 20 years prior to 2009 has happened at least 30 times faster than at the end of the last glacial period. In the Caribbean Ocean, the reduction in calcium carbonate has occurred up to 80 times faster.

As well as affecting the formation of coral reefs, reduced calcification rates result in lower body mass and shell weight of coccolithophores and foraminifera. These plankton species play an important role in Earth’s carbon cycle and the ocean’s natural ability to absorb CO₂ from the atmosphere, mitigating anthropogenic climate change. Further research is needed to understand how reduced calcification rates, together with additional stress factors, such as coral bleaching and coastal pollution, affect different species and the overall functioning of the ecosystem.

Friedrich, T., Timmerman, A., Abe-Ouchi, A. et al. (2012). Detecting regional anthropogenic trends in ocean acidification against natural variability. Nature Climate Change. DOI: 10.1038/NCLIMATE1372.

Contact: tobiasf@hawaii.edu

Antibiotic contamination of soils mapped across Europe

A new study provides an approach for estimating the risk of antibiotic contamination associated with different soils and different antimicrobial products. The researchers estimated and mapped soil contamination risk across Europe and suggest that their methods could be used to inform antibiotic resistance monitoring or policies designed to reduce contamination.

Previous studies have found that releasing antibiotics into the environment contributes to the development of antibiotic resistance. A major source of antibiotics entering the environment is through agricultural use, in the prevention and treatment of livestock diseases. The drugs are transferred to soils when manure from the animals is spread on farmland. Under Directive EC 92/18/EC, all drugs used in veterinary medicine are subject to ecotoxicological assessment of their environmental risks, but after a product is marketed, there is no requirement to monitor build up in the environment, or resistance.

The characteristics of different antibiotics and soils affect how the drugs accumulate in the environment. In environmental risk assessment, the contamination risk associated with an antibiotic depends on its behaviour in the environment, including how quickly it breaks down and how well it sticks to particles in the soil. Soil factors, such as organic matter content, as well as the chemical nature of the drug itself, can influence this behaviour.

This study estimated the effects of different soil types and farming practices on soil contamination by antibiotics. The results were mapped to reveal how the risk of contamination varies across Europe. Contamination risk was estimated using a measure the researchers called ‘soil vulnerability’, focusing on 12 common antibiotics used in pig and cattle feed. They calculated soil vulnerability based on livestock densities (determining the amount of antibiotic released), soil and antibiotic type, and land use.

According to their assessment, Belgium, Ireland, the Netherlands, Switzerland, Denmark, Germany and the UK face the highest risk of contamination, while Bulgaria, Greece and Sweden face a much lower risk. The antibiotic enrofloxacin, which previous studies have found in soil fertilized with poultry and cattle manure, was associated with the highest risk of soil contamination in this study of soils fertilized with cattle and pig manure. Tetracycline antibiotics, tylosin and sulfodiazine were also high risk, while chlorpyridazine, florfenicol and sulfamethazine were low risk. Tetracyclines are the most heavily used antibiotics in agriculture, and have been found previously in soils fertilized with manure from pigs, cattle and poultry. But the high risks associated with tetracyclines and enrofloxacin are also related to values describing their ability to stick to and remain in the soil – compared to some of the lower risk antibiotics they stick tightly and take a long time to break down.

The researchers say their study, based purely on data analysis and mapping of vulnerability, provides a framework for evaluating antibiotic contamination risk over large areas. Using grids with 10km-wide squares, they were also able to illustrate risk at smaller scales, for instance, they could pinpoint contamination hotspots in the southwest of England and the north-western tip of France.

Approaches that rank different regions and antimicrobial products according to contamination risk may be useful in decision-making about antibiotic use and in prioritising monitoring of antibiotic resistance. However, in the current study, estimates were produced without detailed national data, requiring assumptions and oversimplifications that may leave the results open to some inaccuracy. It would be preferable to use data accurate to the level of individual farms or even individual animals. Environmental risk data for antibiotics were also limited because companies are not required to release such information publicly. The researchers say open access to this data would help improve future contamination risk assessments.

Source: De La Torre, A. Iglesias, I., Carballo, M., Ramírez, P., Muñoz, M.J. (2012). An approach for mapping the vulnerability of European Union Soils to Antibiotic Contamination. Science of the Total Environment. 414: 672-679.

Contact: torre@inia.es iglesias@inia.es carballo@inia.es reoyo@inia.es

Concentrating Solar Power’s potential for Europe

A recent study has highlighted the potential of one form of solar power, Concentrating Solar Power (CSP), to make a significant contribution to meeting future electricity demands from renewable sources in Europe.

The EU is committed to reducing greenhouse gas (GHG) emissions by 20% by 2020, and by 80-95% by 2050, compared with 1990 levels. In addition, the share of renewable energy in the energy mix should reach 20% by 2020. The electricity sector is required to achieve zero GHG emissions by 2050.

This study examined the role that CSP could play in helping the EU meet its GHG reduction targets and increase the share of renewable energy in the European electricity grid by 2050. CSP is a reliable, renewable technology, which captures the sun’s energy to produce electricity. Using curved mirrors or lenses, sunlight arriving at the Earth's surface is concentrated to 25-3000 times the intensity of natural sunlight. There are different configurations of CSP, but typically the captured energy heats water, which drives a steam-turbine generator to produce electricity.

Importantly, the technology allows heat to be stored and then released to produce electricity at times when the sun is not shining. This overcomes the intermittent nature of electricity generation common to many renewable technologies, such as wind power.

Southern Mediterranean countries and countries in the Middle East and North Africa (the MENA region) with high levels of sunshine have tremendous potential to produce clean energy from the sun. Being close to Europe, the MENA region is well placed to export electricity to the European grid and to benefit locally from renewable supplies of energy, the development of skills and the creation of jobs. However, the degree to which CSP is developed in southern Europe and the MENA region will be influenced by a number of factors. These include:

1. Costs. The costs of CSP generation need to be reduced to allow the technology to compete with fossil fuels and other renewables technologies. Current costs of electricity from CSP plants are 2-3 times higher than the cost of electricity from fossil-fuelled sources without carbon capture and storage. It is anticipated that CSP could be cost-competitive with fossil-fuelled power between 2020 and 2030. Although CSP plants worldwide produced 1.3 GW (gigawatts) of power in 2011, and worldwide plants with a capacity of 2.3 GW are under construction, incentives and subsidies are essential to enable further research and development, construction of more demonstration plants and continued commercialisation of the technology.
2. Location. Physical constraints, such as high water demand, will need to be overcome, particularly as plants are typically located in dry regions. Alternative dry cooling systems¹ should be further developed. In addition, issues around land ownership, planning permissions and the availability of skilled labour could slow development in some areas.
3. Grid infrastructure. New grid connections between Europe and the MENA region will need to be built and transmission and distribution systems in Europe upgraded, to enable incorporation of a larger share of renewable energy sources.
4. Security of energy supply. CSP located in southern Europe would increase Europe’s energy security by cutting reliance on imported fossil fuels. However, there could be risks associated with importing electricity from the MENA region if energy supplies are disrupted for any reason.

1. Current CSP technologies rely on water cooling towers. Dry cooling systems refers to technologies that use alternatives to water, such as air cooling. See for example the FP7 funded MACCSOL project.

Source: European Academies Science Advisory Council (EASAC) (2011) Concentrating solar power: its potential contribution to a sustainable energy future. Halle: European Academies Science Advisory Council. Available to download here.

Contact: secretariat@easac.eu