Constantine Alexander's Journal

Fish farm parasite drug threatens wildlife

A drug used to treat parasite infections at fish farms can contaminate the surrounding environment and threaten local wildlife, a new study shows. Following a week-long treatment at a Norwegian salmon farm, the authors found concentrations of an anti-sea-lice drug that were high enough to kill some crabs, shrimps and lobsters. However, they suggest the drug is not likely to pose a risk to humans.

Parasites kill and stunt the growth of fish and cause fish farms to lose money as a result. Salmon lice (Lepeoptheirus salmonis), for example, are a major problem in fish farms. Losses are estimated to exceed €180 million a year just in the Northern Hemisphere¹. Infestations can be treated with medicated fish feed pellets containing anti-parasitic drugs. However, these drugs can end up in the local environment — either when they are excreted by fish or when pellets are left uneaten — and can harm other organisms.

Limits have been set in the EU for drugs to be used in farmed fish — and all other food-producing animals — to ensure that unacceptable quantities are not consumed by humans (under Commission Regulation EU 37/2010²). Levels of the anti-parasitic drug teflubenzuron must be below 500 micrograms per kg in farmed salmon.

A recent laboratory-based study led by the same research team behind this current study showed that the drug, which is used to deal with lice infestations as well as in crop protection, can kill lobsters and there is concern about the amount accumulating in sediments. In the current study, the researchers followed the fate of teflubenzuron after it was used on an actual farm to treat salmon in a Norwegian fjord north of Bergen, where the drug had not been used before.

The salmon were treated for seven days starting on 2nd February 2012. Between 1st and 23rd February, the researchers examined water, sediment and aquatic life near the farm.

They detected teflubenzuron in sediment collected underneath the farm, as well as in sediment from 250m, 700m and 1100m away. However, concentrations from underneath the farm were much higher than in the surrounding area. By 23rd February, 15 days after the end of the treatment, concentrations fell across all measurement sites.

By carrying out further tests in May and October, the researchers could calculate that the half-life of teflubenzuron in sediment is 170 days. A drug's half-life is the length of time that it takes for its concentration to decrease by half.

Teflubenzuron was detected in the majority of wild species assessed, but polychaete worms, king crabs (Lithodes maja) and a fish, saith (Pollachius virens), contained the highest amounts. According to the researchers, the concentrations in king crabs, shrimp and two types of lobster were high enough to be fatal when they are moulting (shedding their exoskeleton). The drug is known to interfere with the synthesis of chitin, which is a component of the exoskeletons of moulting animals.

Eight months after the treatment ended, concentrations in all wild fish were below the limits of detection. It was still detectable in polychaete worms and crustaceans, but at a lower level.

In the EU, the safe limit for human consumption of teflubenzuron is 0.01 mg per kg of body weight per day³. The researchers calculated that if a 60kg person ate 200g of saith containing the levels of the drug detected in their study, this would equate to 45% of the person's daily limit. By comparison, teflubenzuron applied to crops may be consumed at between 14–76% of the limit, depending on a person's diet.

1. Costello, M. J. (2009) The global economic cost of sea lice to the salmonid farming industry. Journal of Fish Diseases 32: 115–118. DOI: 10.1111/j.1365-2761.2008.01011.x.
2. Commission Regulation (EU) No 37/2010 of 22 December 2009 on pharmacologically active substances and their classification regarding maximum residue limits in foodstuffs of animal origin.
3. EMEA (1997). Teflubenzurone, summary report (1), EMEA/MRL/221/97-Final, The European Agency for the Evaluation of Medicinal Products. 

Citation: Samuelsen, O. B., Lunestad, B. T., Hannisdal, R. et al. (2015) Distribution and persistence of the anti sea-lice drug teflubenzuron in wild fauna and sediments around a salmon farm, following a standard treatment. Science of the Total Environment 508: 115–121. DOI: 10.1016/j.scitotenv.2014.11.082.

Contact: O. B . Samuelsen

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Newly discovered algal species helps corals survive in the hottest reefs on the planet

A new type symbiotic alga lends its brown color to a Porites coral from Abu Dhabi reefs. Credit: Wiedenmann, Burt.

A new species of algae has been discovered in reef corals of the Persian (Arabian) Gulf where it helps corals to survive seawater temperatures of up to 36 degrees Celsius - temperatures that would kill corals elsewhere.

Researchers from the University of Southampton and the New York University Abu Dhabi identified the symbiotic algae in corals from Abu Dhabi, United Arab Emirates, the world's warmest coral reef habitat. The paper, which reports the breakthrough discovery, was published this week in the journal Scientific Reports.

"We found that commonly applied molecular methods did not give enough resolution to distinguish the dominant symbionts of Gulf corals from those in other parts of the world's oceans," explains Professor Jörg Wiedenmann, Professor of Biological Oceanography and Head of the Coral Reef Laboratory at the University of Southampton. "However, when analysed by alternative molecular biological approaches, we found pronounced differences that set this heat tolerant species clearly aside. We named it Symbiodinium thermophilum in reference to its ability to survive unusually high temperatures."

Polyps of a Porites coral are hosting the newly discovered symbiotic alga. Credit: Wiedenmann, Burt.

Reefs are made up of many coral species, most of which live in a mutually beneficial relationship with microscopically small algae hosted in their tissue. These symbiont algae produce sugars that contribute to the diet of the coral in return for shelter and nutrients that are vital for algal growth.

However, the symbiotic association is vulnerable to changes in environmental conditions, in particular to increases in seawater temperature. Heat-stress induced loss of the algal partners from the coral host can result in the often fatal process known as 'coral bleaching'.

"Understanding how corals survive under the extreme temperatures in the Gulf will give us important insights into the ability of reef corals to handle the heat stress, which is threatening their survival in the oceans that are warming up in response to climate change," explains Professor Wiedenmann.

Corals of the world's hottest seas host a special symbiotic algae. Credit: Wiedenmann, Burt, D'Angelo.

"We monitored the symbiotic partnership over several seasons to ensure that this association was stable through a range of thermal conditions," comments Professor John Burt from the New York University Abu Dhabi. "We can confirm that this new type of alga is indeed the year-round prevalent symbiont across several dominant coral species from the Abu Dhabi coast of the United Arab Emirates," he adds.

"It gives hope to find that corals have more ways to adjust to stressful environmental conditions than we had previously thought," adds Professor Wiedenmann. "However, it is not only heat that troubles coral reefs. Pollution and nutrient enrichment, overfishing and coastal development also represent severe threats to their survival. Only if we manage to reduce these different forms of stress will corals be able to benefit from their capacity to adjust to climate change."

Citations:

• Hume, B.C.C. et al. Symbiodinium thermophilum sp. nov., a thermotolerant symbiotic alga prevalent in corals of the world's hottest sea, the Persian/Arabian Gulf. Sci. Rep. 5, 8562; DOI:10.1038/srep08562 (2015).
• D'Angelo, C. and Wiedenmann, J. "Impacts of Nutrient Enrichment on Coral Reefs: New Perspectives and Implications for Coastal Management and Reef Survival." Current Opinion in Environmental Sustainability 7, no. 0 (2014): 82-93.
• Wiedenmann, J, D'Angelo, C., Smith, E.G., Hunt, A.N., Legiret, F.E., Postle, A.D. and Achterberg, E.P. "Nutrient Enrichment Can Increase the Susceptibility of Reef Corals to Bleaching." Nature Clim. Change 3, no. 2 (2013): 160-164; DOI: 10.1038/nclimate1661.

Contact: Glenn Harris
University of Southampton

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'Ecosystem services' help assess ocean energy development

Public data sources from the Northeast Ocean Data portal help determine the impact of a new tidal energy project between Martha's Vineyard and Nantucket. Green areas show show coastal bird habitat. Credit: Leslie lab/Brown University.

With many projects under development in coastal regions such as New England, tidal power -- which extracts "hydrokinetic" energy from marine environments -- seems poised to join other U.S. commercial power sources. A new study finds that little is known of the impacts that tidal power projects may have on coastal environments and the people who depend on them, but that the perspective of "ecosystem services" could provide a promising framework for evaluating impacts.

"Ecosystem services are the benefits provided by functioning ecosystems to people," wrote environmental scientist Heather Leslie, the Peggy and Henry D. Sharpe Assistant Professor of Environmental Studies and Biology, in the current edition of the Marine Technology Society Journal.

The study, written with former undergraduate student Megan Palmer, who is now with the Nature Conservancy, begins with a review of nearly 300 papers on marine and hydrokinetic (MHK) power systems. Only 36 focus on tidal power and of those only a handful specifically address ecosystem concerns, the authors found.

While developers are required to perform environmental studies before installing tidal energy harvesting devices, those wouldn't necessarily encompass the full range of connections between people and marine environments.

"The ability to explicitly link ecosystem health (or functioning, as ecologists often refer to it) and benefits to people is one of the notable differences between an ecosystem services analysis and a typical environmental impact statement," Leslie said.

To illustrate how ecosystem services might be applied to a project, Leslie and Palmer looked at the Muskeget Channel Tidal Energy Project, which is planned for a site south of Cape Cod, between Martha's Vineyard and Nantucket. After some analysis, the pair identified biodiversity, tourism and recreation, and food provision as the most important ecosystem services to assess.

Drawing on public data sources available through interactive Northeast Ocean Data portal, they illustrate that while the area of the channel where the power project is planned is likely an important area for coastal birds, such as terns and gulls, it might not be especially crucial for tourism and recreation or food provision.

The case study therefore suggests that the project would benefit from studying how the tidal energy infrastructure may affect the birds and their food resources, in order to better assess how the area's ecosystems and the services they provide to people are likely to be affected by the development. For instance, if the energy infrastructure enhances local fish populations, it could in turn enhance bird populations, which could have effects on both the coastal marine food web and nature-dependent recreational activities like bird-watching.

"An ecosystem services approach enables researchers and energy developers to create an integrative description of the possible environmental and socioeconomic impacts of a particular project, which in turn can help inform project planning, implementation and monitoring," Leslie and Palmer concluded.

Contact: David Orenstein
Brown University

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Economic models provide insights into global sustainability challenges

Using models that blend global economics, geography, ecology and environmental sciences is essential to understanding how changes in trade and natural systems in one part of the world affect those in another, a review concludes.

Tom Hertel, distinguished professor of agricultural economics, collaborated with an interdisciplinary team of experts led by Jianguo Liu of Michigan State University to determine how systems integration - using holistic frameworks to model many components of both human and natural systems - could shed insights on how activities in one part of the world can have significant impacts on distant regions.

Hertel said these multivariable models could help policymakers make better-informed decisions, further scientists' understanding of the links between trade and the global environment, and aid natural resource managers in making management choices that will sustain resources such as clean water and air for future generations.

"We live in an increasingly integrated global economy and society," he said. "The planet itself is a single system - a change in one place affects another. Models that can capture these complex relationships between trade and the environment are key to creating solutions to our most pressing sustainability challenges."

The review of more than 100 studies concluded that analyses that do not take multiple dimensions - such as space and time - and disciplines into account risk overlooking important links between different system components. For example, current greenhouse gas emissions could have long-lasting effects on the climate of the future, altering agricultural productivity, sea levels and the transmission of pests and disease. These effects can in turn influence greenhouse gas emission levels - for instance, clearing more land for agriculture adds carbon dioxide to the atmosphere.

"Systems integration provides crucial global perspective on problems that previously may have only been studied at a local or regional level," Hertel said.

He offered the example of biofuels production in the U.S. as one that could have benefited from the insights systems integration can provide.

Previous "farm-to-fuel tank" analyses showed that production of corn ethanol could reduce annual carbon dioxide emissions in the U.S. Aided by this research, policymakers passed the Renewable Fuels Standard requiring that fuel sold in the U.S. contain a certain amount of renewable fuels, such as corn ethanol.

But the analyses had missed key components of global trade and land use, Hertel said: While land in the U.S. previously used to grow corn for food switched to corn for grown for ethanol, the global demand for corn for food and livestock did not decrease. This could cause other countries to clear land for crops, releasing additional carbon dioxide through the land conversion process.

Hertel and fellow researchers used systems integration modeling to show that, over a 30-year production period, emissions from land use change would largely offset the direct gains from producing the mandated amount of corn ethanol.

"It turns out that the global effects of this U.S. policy are quite large - clearly large enough to call into question the regional benefits of ethanol production," he said. "Biofuels are a great example of how the absence of a systems integrated approach led to misleading advice and misguided policy."

The review cites the Global Trade Analysis Project, a free global database founded by Purdue, as an example of a modeling tool that can be used to show the interactions between ecological and environmental systems. GTAP describes trade flows around the world and breaks down economic trade by sector. It also integrates trade with land use and the greenhouse gas emissions that can result from changing land use.

"We've been working to bring in more dimensions of bioscience and ecology to GTAP," Hertel said. "It's a workhorse for this kind of modeling."

Citation: Jianguo Liu, Harold Mooney, Vanessa Hull, Steven J. Davis, Joanne Gaskell, Thomas Hertel, Jane Lubchenco, Karen C. Seto, Peter Gleick, Claire Kremen, and Shuxin Li; Systems integration for global sustainability; Science, February 2015;  DOI: 10.1126/science.1258832.

Contact: Natalie van Hoose
Purdue University

 

IPCC sea-level rise scenarios not fit for purpose for high-risk coastal areas

The sea-level rise scenarios of the Intergovernmental Panel on Climate Change (IPCC) do not necessarily provide the right information for high-risk coastal decision-making and management, according to new research involving scientists from the University of Southampton.

A commentary, published today in the journal Nature Climate Change, warns that the IPCC scenarios are often inappropriate or incomplete for the management of high-risk coastal areas as they exclude the potential for extreme sea-level rises. This missing information is also crucial for a number of policy processes, such as discussions by G7 countries to establish climate insurance policies and allocations of adaptation funding by the Green Climate Funds.

"Although the IPCC scenarios are a big step forward in understanding how the climate system works, these scenarios are not designed from the perspective of coastal risk management and, unfortunately, this is not spelled out clearly both within and beyond the IPCC reports," says lead author Dr Jochen Hinkel from the Global Climate Forum. Dr Hinkel is also Lead Author of the coastal chapter of the Working Group 2 contribution to the latest IPCC report.

The IPCC sea-level rise scenarios are developed for the purpose of understanding the physics of the earth system through process-based models, which are models based on the laws of physics. As a consequence, these scenarios cover only the central range of possible sea-level rise. For example, the scenarios of IPCC Fifth Assessment Report estimate that by 2100 global mean sea-level is likely to rise by 0.28-0.98m relative to 1986-2005. The probability of staying within this range is, however, estimated to be only at least 66 per cent.

Knowing the central range is, however, generally not sufficient for coastal risk management. This is because inhabitants of densely populated coastal zones generally prefer to avoid major damage under all circumstances, so coastal planners are particularly interested in possible high-end sea-level rise scenarios beyond the IPCC range.

"Consider, for example, the situation of London," explains Dr Hinkel, "which is protected against coastal floods through the Thames Estuary Barrier. There was concern that rapid sea-level rise would not allow sufficient time to upgrade or replace the Thames Estuary Barrier because such large engineering tasks require 25-30 years for planning and implementation."

For such a situation, the IPCC scenario range is not the right piece of information, because there is a 0-33 per cent probability of sea-level rise lying outside of this range. Such a high residual risk is not tolerable from the perspective of protecting major cities from sea-level rise. These situations require high-end scenarios in order to make sure that there are options available that can be realised even in the worst case to come.

Co-author Professor Robert Nicholls, from the University of Southampton, says: "Ongoing work on projecting the central range of sea-level rise should be complemented with the development of high-end scenarios for different time horizons that correspond to different real-world coastal management decisions."

Dr Hinkel adds: "Such scenarios should also consider all the information on future sea levels including semi-empirical models, physical constraints on ice-sheet dynamics and paleo-records of sea-level change, because coastal high-risk management requires an analysis of decisions against all available knowledge, including all uncertainties and also ambiguities amongst expert opinions and their distinct approaches."

The researchers say that the current subdivision of the IPCC is an area that needs to be addressed.

Professor Nicholls adds: "Dividing the IPCC into Working Groups by disciplines with sea-level science sitting in Working Group 1 and coastal risk management in Working Group 2 hinders a stronger focus on better understanding of the high-end tail of sea-level rise in support of risk management. Given that the mandate of the IPCC is to be policy-relevant, a more effective organisation of its assessment would be by policy questions. One of these questions should link sea-level rise information to the needs of coastal risk management."

Citation: Jochen Hinkel, Carlo Jaeger, Robert J. Nicholls, Jason Lowe, Ortwin Renn & Shi Peijun; Se-level rise scenarios and coastal risk management; Nature Climate Change (2015); DOI: 10.1038/nclimate2505.

Contact: Glenn Harris
University of Southampton

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Isolated wetlands have significant impact on water quality

Credit: NOAA

Geographically isolated wetlands play an outsized role in providing clean water and other environmental benefits even though they may lack the regulatory protections of other wetlands, according to an article by Indiana University researchers and colleagues.

Given those benefits, the authors argue, decision-makers should assume that isolated wetlands are critical for protecting aquatic systems, and the burden of proof should be on those who argue on a case-by-case basis that individual wetlands need not be protected.

"Geographically isolated wetlands provide important benefits such as sediment and carbon retention, nutrient transformation and water-quality improvement, all of which are critical for maintaining water quality," said lead author John M. Marton, assistant scientist at the IU Bloomington School of Public and Environmental Affairs. "We demonstrate that continued loss of these wetlands would likely cause serious harm to North American waters."

The article, "Geographically Isolated Wetlands Are Important Biogeochemical Reactors on the Landscape," will appear in BioScience, the journal of the American Institute of Biological Sciences, and is available online. Co-authors include Christopher B. Craft, the Janet Duey Professor in Rural Land Development with SPEA at IU Bloomington, along with researchers from the U.S. Environmental Protection Agency, the University of Western Ontario, the University of Waterloo, the University of Florida and the University of South Florida.

Geographically isolated wetlands are formed by natural forces that create depressions in the landscape, resulting in conditions suitable for wetland plants and soils. They include the prairie potholes of the upper Midwest, the playas of the Southwest, vernal pools in New England and California, and the Carolina Bays.

Citing research literature, the authors say geographically isolated wetlands are highly effective "biogeochemical reactors" that improve water quality. They often retain water longer than protected waters, such as streams and wetlands that are directly connected to navigable water. And they have a higher ratio of perimeter to area, allowing more opportunities for reactions to take place.

While scientists are only starting to map the extent of isolated wetlands, it is estimated that the U.S. has lost approximately half of those that were present before European settlement. And losses have been especially heavy in some regions.

The authors estimate that the loss of wetlands in the prairie pothole region of the U.S. and Canada has resulted in an increase of 5 million to 150 million tons per year of sediment entering surface waters. The loss decreased the carbon sequestered by the wetlands by about 1 million to 14 million tons per year, they estimate.

Their calculations, they write, "reveal that even rudimentary estimates of lost potential for water-quality protection are huge."

Citation: John M. Marton, Irena F. Creed, David B. Lewis, Charles R. Lane, Nandita B. Basu, Matthew J. Cohen and Christopher B. Craft; Geographically Isolated Wetlands Are Important Biogeochemical Reactors on the Landscape; BioScience (2015); DOI: 10.1093/biosci/biv009.

Contact: Steve Hinnefeld
Indiana University

 

Climate-warmed leaves change lake ecosystems

Rising soil temperatures significantly affect autumn leaves and consequently the food web, appearance and biochemical makeup of the lakes and ponds those leaves fall into, a Dartmouth College-led study finds.

The study is one of the first to rigorously explore climate warming's impact on "ecological subsidies," or the exchange of nutrients and organisms between ecosystems. "Our findings could have profound consequences for conceptualizing how climate warming impacts linkages between terrestrial and aquatic ecosystems," says the study's lead author Samuel Fey, a visiting scholar at Dartmouth and a postdoctoral fellow at Yale University.

The researchers collected maple leaves during autumn from experimental forest plots where the soil had been warmed or left untouched. They added the leaves to experimental freshwater enclosures containing plankton food webs consisting of zooplankton, algae and bacteria, thus creating "no leaf," "ambient leaf" and "heated leaf" conditions. They then monitored the physical, chemical and biological responses in these artificial ponds until the enclosures froze six weeks later.

The results showed that soil warming caused a two-fold decrease in the leaves' phosphorus concentrations, and that the addition of these "warmed" leaves to the ponds decreased the water's phosphorus, dissolved organic carbon and density of bacteria, but improved the water's clarity and caused a three-fold increase in the density of cladoceran zooplankton, commonly called water fleas. Zooplankton provide a crucial source of food to many larger aquatic organisms such as fish.

"Virtually nothing is known about how climate change may alter ecological subsidies," Fey says. "Our results suggest that changes in soil temperature can have unexpected consequences for lake ecology and that predicting the consequences of climate change will require research across ecosystem boundaries."

Citation: Fey, S. B., Mertens, A. N., Beversdorf, L. J., McMahon, K. D. and Cottingham, K. L. (2015); Recognizing cross-ecosystem responses to changing temperatures: soil warming impacts pelagic food webs; Oikos. DOI: 10.1111/oik.01939.

Contact: John Cramer
Dartmouth College

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World's protected natural areas receive 8 billion visits a year

Bialowieza National Park in Poland. Credit: Jacek Karczmarz (CC 3.0)

The world's national parks and nature reserves receive around eight billion visits every year, according to the first study into the global scale of nature-based tourism in protected areas. The paper, by researchers in Cambridge, UK, Princeton, New Jersey, and Washington, DC, published in the open access journal PLOS Biology, is the first global-scale attempt to answer the question of how many visits protected areas receive, and what they might be worth in terms of tourist dollars.

The authors of the study say that this number of visits could generate as much as US$600 billion of tourism expenditure annually - a huge economic benefit which vastly exceeds the less than US$10 billion spent safeguarding these sites each year.

Scientists and conservation experts describe current global expenditure on protected areas as "grossly insufficient", and have called for greatly increased investment in the maintenance and expansion of protected areas - a move which this study shows would yield substantial economic return - as well as saving incalculably precious natural landscapes and species from destruction.

"It's fantastic that people visit protected areas so often, and are getting so much from experiencing wild nature - it's clearly important to people and we should celebrate that," said lead author Professor Andrew Balmford, from Cambridge University's Department of Zoology.

"These pieces of the world provide us with untold benefits: from stabilising the global climate and regulating water flows to protecting untold numbers of species. Now we've shown that through tourism nature reserves contribute in a big way to the global economy- yet many are being degraded through encroachment and illegal harvesting, and some are being lost altogether. It's time that governments invested properly in protected areas."

Dr Andrea Manica, a corresponding author also at Cambridge, says these are ballpark estimates based on limited data, so the researchers have been careful not to overstate the case: "These are conservative calculations. Visit rates are likely to be higher than eight billion a year, and there's no doubt we are talking about hundreds of billions of tourism dollars a year," he said.

The attempt to calculate these figures was in part borne from frustration, says Balmford. "We study what people get out of nature, so-called 'ecosystem services'. While some ecosystem services are difficult to measure - such as cultural or religious benefits - we thought that nature-based recreation would be quite tractable: there's a market and tangible visits you can count.

"However, when we started to investigate we found no-one had yet pieced the data together. So we got to work trawling for figures ourselves. After a few months we had constructed a database from which we could build our models. It's limited, but it's the best there is at the moment," Balmford said.

The database consists of visiting figures for 550 sites worldwide, which were then used to build equations that could predict visit rates for a further 140,000 protected areas based on their size, remoteness, national income, and so on.

The results surprised even seasoned conservation researchers. Nature tourism expert and team member Dr Matt Walpole of UNEP's World Conservation Monitoring Centre calls their cautious estimate of eight billion annual visits an "astonishing figure that illustrates the value people place on experiencing nature".

Visit rates were highest in North America, where protected areas receive a combined total of over three billion visits a year, and lowest in Africa, where many countries have less than 100,000 protected area visits annually.

The Golden Gate National Recreation Area near San Francisco had the highest recorded visit rate in the database with an annual average of 13.7m visits, closely followed by the UK's Lake District and Peak District National Parks, with 10.5m and 10.1m. By contrast, Tanzania's Serengeti National Park got an annual average during the study period of 148,000 visits.

Team member Dr Jonathan Green, based in Cambridge, points out that it is far from just exotic places and large national parks that contribute to the visitation value of protected areas. "For many people, it's the nature reserve on their doorstep where they walk the dog every Sunday". Fowlmere nature reserve, a few miles south of Cambridge University, receives an average of almost 23,000 visits a year.

By combining regional visit rates with region-specific averages for visitor spending - on everything from entry fees to transport and accommodation - the researchers were able to derive the most complete picture yet of the global economic significance of protected area visitation.

"Our US$600 billion figure for the annual value of protected area tourism is likely to be an underestimate - yet it dwarfs the less than US$10 billion spent annually on safeguarding and managing these areas," said Dr Robin Naidoo of World Wildlife Fund, another author of the study. "Through previous research, we know that the existing reserve network probably needs three to four times what is current being spent on it".

"While that may seem a lot of money, it's a fraction of the economic benefit we get from protected areas - nature-based tourism is just one part," said Balmford.

By way of context, he points to the recent announcement by computing giant Apple of record profits of US$18 billion in a single quarter. "Stopping the unfolding extinction crisis is not unaffordable. Three months of Apple profits could go a long way to securing the future of nature. Humanity doesn't need electronic communication to survive. But we do need the rest of the planet."

Citation: Andrew Balmford, Jonathan M. H. Green, Michael Anderson, James Beresford, Charles Huang, Robin Naidoo, Matt Walpole and Andrea Manica; Walk on the Wild Side: Estimating the Global Magnitude of Visits to Protected Areas; PLOS Biology, 2015; 13 (2): e1002074 DOI: 10.1371/journal.pbio.1002074.

Contact: Fred Lewsey
University of Cambrisdge

 

New Florida Tech study links coral disease to a warming Atlantic

White-band disease, culprit in disappearing reefs, driven by rising temperatures.

White-band disease is readily apparent on this coral found in Jardines, Puerto Morelos, Mexico. Photo by Carly Randall, Florida Institute of Technology

Over the last four decades, the iconic elkhorn and staghorn corals that dominated Caribbean reefs for millions of years have all but disappeared. According to a new study from Florida Institute of Technology, ocean warming has played a significant role in this dramatic decline.

The results of the study also suggest that limiting the rate of ocean warming, which would require curbing greenhouse gas emissions, could support the recovery of these critical reef-building corals.

White-band disease is a widespread coral disease that affects elkhorn and staghorn corals, and this disease has been plaguing these corals for decades. Florida Tech Ph.D. student Carly Randall and her faculty advisor, Robert van Woesik, studied the relationship between ocean temperatures and white-band disease and reported their findings in the February issue of Nature Climate Change.

Randall and van Woesik wanted to know if changes in ocean temperatures associated with climate change have contributed to the spread of the disease throughout the Caribbean. The answer, according to their research, was that the rising temperatures did affect the disease's spread.

"Our data show that climate change has helped drive down staghorn and elkhorn corals by boosting white-band disease," Randall said. "We still don't know if the disease is caused by a marine microbe, but now we do know that changes in the environment contributed to the problem."

The study also found that the disease is more common in places where the waters have been warming most rapidly and where the waters stay unusually warm in the winter season. The scientists think that without a cooling-off period, the effects of the hot summers linger, and the disease is more likely to worsen.

Corals build the foundation of coral reefs, and these ecosystems provide critical services including shoreline protection and erosion prevention. Coral reefs also provide habitat for commercial and recreational fisheries.

Because of their decline, both the elkhorn and staghorn coral species are now listed as threatened under the U.S. Endangered species act.

White-band disease, which is named for the stark white bands that advance along the coral's branches, has been around for decades. Yet scientists have struggled to identify the causes of the disease. The results of this study are a critical step forward in our understanding of white-band disease.

"The discipline has been stumped for more than 20 years because the environment played a larger role than we first anticipated," van Woesik said. "We are a step closer to predicting where diseases are occurring because now we know why they are occurring."

Citation: C. J. Randall and R. van Woesik; Contemporary white-band disease in Caribbean corals driven by climate change; Nature Climate Change, 2015; DOI: 10.1038/nclimate2530.

Contact: Adam Lowenstein
Florida Institute of Technology

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Sea level spiked for 2 years along northeastern North America

The tide gauge station in Montauk, New York, is located on the Rough Rider Condominum Pier, pictured here. The water level sensor and other monitoring equipment are located on the far side of the pier. Photo credit: NOAA.

Sea levels from New York to Newfoundland jumped up about four inches in 2009 and 2010 because ocean circulation changed, a University of Arizona-led team reports in an upcoming issue of Nature Communications.

The team was the first to document that the extreme increase in sea level lasted two years, not just a few months.

"The thing that stands out is the time extent of this event as well as the spatial extent of the event," said first author Paul Goddard, a UA doctoral candidate in geosciences.

Independent of any hurricanes or winter storms, the event caused flooding along the northeast coast of North America. Some of the sea level rise and the resulting flooding extended as far south as Cape Hatteras.

The paper is also the first to show that the unusual spike in sea level was a result of changes in ocean circulation.

Co-author Jianjun Yin, UA assistant professor of geosciences, said, "We are the first to establish the extreme sea level rise event and its connection with ocean circulation."

Goddard detected the two-year-long spike in sea level by reviewing monthly tide-gauge records, some of which went back to the early 1900s, for the entire Eastern Seaboard. No other two-year period from those records showed such a marked increase.

The team linked the spike to a change in the ocean's Atlantic Meridional Overturning Circulation and also a change in part of the climate system known as the North Atlantic Oscillation.

The researchers then used computer climate models to project the probability of future spikes in sea level.

The team found that, at the current rate that atmospheric carbon dioxide is increasing, such extreme events are likely to occur more frequently, Goddard said.

Goddard's and Yin's research paper, "An Extreme Event of Sea Level Rise along the Northeast Coast of North America in 2009-2010," was published online in Nature Communications on Feb. 24. Stephen Griffies and Shaoqing Zhang of the National Oceanographic and Atmospheric Administration's Geophysical Fluid Dynamics Laboratory in Princeton, New Jersey, are also co-authors. NOAA funded the research.

By using historical data from the 40 tide gauges shown on this map, University of Arizona geoscientist Paul Goddard and his colleagues figured out that sea level rose four inches (100 mm) from New York to Newfoundland (red dots) in 2009 and 2010. Gauges from New York south to Cape Hatteras (pink dots) showed a smaller spike in sea level for the same time period. No sea level spike was recorded on the gauges (white dots) south of Cape Hatteras. Credit: Paul Goddard/ University of Arizona department of geosciences.

Yin's previous work on climate models suggests that weakening of the Atlantic Meridional Overturning Circulation could cause sea levels to rise faster along the northeast coast of North America.

Yin wondered whether such sea level rise had actually been observed, so he asked Goddard to compile the tide-gauge records for the east coast of North America. The 40 gauges, spanning the coast from Key West, Florida, north to Newfoundland, have been recording sea levels as far back as the 1920s.

Goddard's work revealed a surprise - that during 2009 and 2010, sea level between New York and Newfoundland rose an average of four inches (100 mm). Sea level from Cape Hatteras to New York also had a notable spike, though not as dramatic.

"The sea level rise of 2009-2010 sticks out like a sore thumb for the Northeast," Goddard said.

His research also confirmed that, as others have reported, sea level has been gradually rising since the 1920s and that there is some year-to-year variation.

About the time Goddard finished analyzing the tide-gauge records, another group of researchers reported that the Atlantic Meridional Overturning Circulation, or AMOC, had a 30 percent decline in strength in 2009-2010. Those researchers reported the decline started just two months before the tide gauges started recording the spike in sea level.

"To me, it was like putting together a puzzle," Goddard said.

The more he and his colleagues examined the timing of the AMOC downturn and the subsequent increase in sea level, the more it fit together, he said.

The AMOC brings warm water from the tropics and the southern Atlantic Ocean to the North Atlantic and the polar regions. The water then cools and sinks, eventually flowing south in the deep ocean. Yin's climate model predicted that when the AMOC weakened, sea level in northeastern North America would rise.

In addition to the weakening AMOC, during 2009-2010 the region's atmosphere was in a very negative phase of the climate mode called the North Atlantic Oscillation. The NAO flip-flops between negative and positive phases.

"The negative North Atlantic Oscillation changes the wind patterns along the northeast coast, so during the negative NAO the winds push water onto the northeast coast," Goddard said.

Although the NAO has resumed flipping between positive and negative states, observations show that the AMOC, while somewhat stronger, has still not recovered its previous strength.

Even now, sea level is still higher than before 2009, Yin said. He's not surprised, because most of the climate models predict a weakening of the AMOC over the 21st century.

Yin said that at the current rate of increase in greenhouse gases, most climate models predict a weakening of the AMOC over the 21st century. Therefore, such extreme sea level rise events and coastal flooding are quite likely to occur along the densely populated northeast coast of North America more often.

Citation: Paul B. Goddard, Jianjun Yin, Stephen M. Griffies and Shaoqing Zhang; An extreme event of sea-level rise along the Northeast coast of North America in 2009–2010; Nature Communications, 2015; 6: 6346 DOI: 10.1038/ncomms7346.

Contact: Mari N. Jensen
University of Arizona

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