Constantine Alexander's Journal: March 2017

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March 2017

03/29/2017

Seabird bones, fossils reveal broad food-web shift in North Pacific

Museum collections offer scientists ocean health baselines long before human records.

The Hawaiian petrel flies great distances over the north Pacific Ocean to feed, and all the while nitrogen from its diet is slowly integrated into its bone collagen. The birds come to land only to raise their young in the Hawaiian Islands. Ancient petrel bones found in archaeological and paleontological sites in Hawaii and held in the Smithsonian's National Museum of Natural History preserve stable isotopes of nitrogen in differing proportions that can help scientists understand how the birds' food web has changed over time. The birds' ancient bones are a treasury of information about historical change in a large, remote ocean. Copyright Geoffrey Jones 2016.

For thousands of years, the Hawaiian petrel has soared over the Pacific Ocean, feeding on fish and squid. Now, using evidence preserved in the birds' bones, scientists at the Smithsonian's National Museum of Natural History and Michigan State University have discovered that the now endangered seabird has experienced a significant shift in food resources most likely during the past 100 years--a disruption that may be due to industrial fishing practices.

The study, reported March 28, in the Proceedings of the Royal Society B, offers unique insight into how an ocean food web has changed since the onset of industrial fishing and other major human influences in oceanic ecology. It is difficult to survey vast expanses of open ocean to assess how human activities impact marine life far from shore, and data gathered from research vessels and fisheries in recent decades offer incomplete and inconsistent glimpses of the oceans' past and present state.

"In order to understand the rapid change that's going on globally now, we really need historical records to reconstruct how things have changed over time," said Helen James, curator-in-charge of the museum's bird collection. "But in the really remote oceans, there hasn't been systematic data collection over a long period of time, especially before the 1950s."

Petrels, however, have been collecting samples from the North Pacific for thousands of years. The birds fly thousands of miles in search of food, traveling between the equator to near the Aleutian Islands before returning to the Hawaiian Islands to breed. James says she likes to think of each bird as a drone that samples the food web across vast swaths of the North Pacific, leaving a snapshot of valuable data about its diet behind when it dies.

James, a paleontologist, makes regular trips to the Hawaiian Islands to recover that data. With collaborator Peggy Ostrom, a biogeochemist at Michigan State University, she has used the petrel bones she finds there to compare how the birds' foraging habits have changed since humans began strongly influencing the ocean.

James, Ostrom and their collaborators studied the bones of modern petrels collected from breeding sites on the islands of Hawaii and Maui, as well as fossils in the museum's collection from petrels that lived during periods dating back to before humans arrived on the islands.

To assess the structure of the birds' food webs, they analyzed the nitrogen in the bones. Two forms, or isotopes, of nitrogen exist in all organisms, from the microscopic plankton at the bottom of the food web to top predators. When one organism is consumed by another, these two forms of nitrogen are incorporated into the predator's body at different but predictable rates. As a result, scientists can analyze nitrogen isotopes to determine how many steps there are in a predator's food chain.

In a 2013 study led by Anne Wiley, a graduate student in Ostrom's lab (now a professor at the University of Akron), James and her collaborators analyzed nitrogen isotopes in the bone collagen of hundreds of petrels and detected a difference between birds from the past 100 years and those that lived in earlier periods. The team suspected a recent change in food resources had shortened the petrel's food chain--a phenomenon known as a trophic decline. But other scientists pointed out that the result might have been caused by a change in the nitrogen source at the base of the food web instead.

To differentiate between the two possibilities, James and Ostrom collaborated with Yoshito Chikaraishi, then at the Japan Agency for Marine-Earth Science & Technology, to conduct a more precise analysis. In the new approach, protein from the petrel bones was separated into individual amino acids, which allowed Chikaraishi, now at Hokkaido University, to independently analyze phenylalanine, an amino acid in which nitrogen isotopes are associated with nutrient cycling at the base of the food web, and glutamic acid, an amino acid in which nitrogen isotopes change with each step in a food chain.

The results were clear. In populations from two islands, the petrels' trophic level had declined over time. There was no evidence of a change in nitrogen processing at the base of the food web.

It is not clear whether Hawaiian petrels are feeding on smaller or different animals now and not prior to human influence, or whether the disruption occurred lower in their food chain. But it is clear that the food-web structure in the northern Pacific has changed.

"The bird is acting like a sentinel for what's happening in the ocean," Ostrom said. "Trophic structure is changing. And since this is a top predator that flies across the Pacific Ocean, that means that something at a pretty broad scale has occurred."

According to the United Nations' Food and Agriculture Organization, more than 1.9 million metric tons of food were removed from the Eastern Central Pacific (a region that includes Hawaii) in 2014. Such a depletion of limited resources could be responsible for the shift in the petrel's food web, the scientists say.

Further studies of top predators will offer a more complete picture of nutrient changes in the open oceans and help scientists predict the consequences of continued increases in global fishing productivity. "As a curator, this study highlights one good reason we preserve historical specimens in natural history museums," James said. "They represent an incredible record of ecological change that can help us understand the future."

Citation: Ostrom P, Wiley A, James H, Rossman S, Walker W, Zipkin E, & Chikaraishi Y; Broad-scale trophic shift in the pelagic North Pacific revealed by an oceanic seabird; Proceedings of the Royal Society B (March 6, 2017); DOI: 10.5061/dryad.66jd4.

Contact: Ryan Lavery
Smithsonian

Posted at 01:01 AM in Biodiversity, Marine Environment, Science | Permalink | Comments (0)

03/24/2017

Corals die as global warming collides with local weather in the South China Sea

Bleached Acropora colony was photographed in July 2015. A new study finds that a 2°C rise in the sea surface temperature of the South China Sea in June 2015 was amplified to produce a 6°C rise on the Dongsha Atoll, killing approximately 40 percent of the resident coral community. Photo by Thomas DeCarlo, Woods Hole Oceanographic Institution.

In the South China Sea, a 2°C rise in the sea surface temperature in June 2015 was amplified to produce a 6°C rise on Dongsha Atoll, a shallow coral reef ecosystem, killing approximately 40 percent of the resident coral community within weeks, according to a study published in Scientific Reports this week.

Wind and waves churn the sea, flushing shallow-water coral reefs with seawater from the open ocean to help them stay cool. But according to new research from the Woods Hole Oceanographic Institution (WHOI), when the weather turns still and these natural cooling mechanisms subside, just a few degrees of ocean warming can prove lethal to the corals that live there.

Scientists at WHOI studied this phenomenon in June 2015 while conducting research on Dongsha Atoll, an almost perfectly circular coral reef in the remote South China Sea. The findings, published in the March 24, 2017 issue of the journal Scientific Reports, highlight the devastation caused when global-scale ocean warming interacts with short-lived weather anomalies, and adds urgency to the question of how reefs will fare through the end of this century.

"Dongsha Atoll is typically hit with tropical storms and strong winds in June, which keep the corals as cool as the open ocean," said Tom DeCarlo, lead author of the study and a then-graduate student in the MIT-WHOI Joint Program in Oceanography. "But in 2015, the weather in June was exceptionally calm -- at one point, there was basically no wind and no waves. This had an amplifying effect on the water temperatures, which were already feeling the heat from global warming and El Niño. The whole reef became a giant swimming pool that just sat there and baked in the sun."

According the DeCarlo, who is now a scientist with the University of Western Australia, it only took a few days of calm winds and waves before the reef lost its supply of cooler water from the open ocean. "We saw water temperatures surge to 36 °C (97 °F) - a full 6° C above normal summertime temperatures. This caused 100% of the corals to bleach, and 40% of them died," he said.

Gone and back again

DeCarlo, WHOI scientist Anne Cohen, and dive master Pat Lohmann, witnessed the start of the mass die-off on the last day of their month-long field visit to Dongsha. They had just finished up an ecological survey of coral cover on the reef, and before heading home, jumped in the water to retrieve instruments they use to monitor water temperature, pH and currents. "That's when we saw that all the corals had turned white," said DeCarlo. "We had to catch our flights the next day, but the situation looked dire so Anne sent us back out to the site within a few weeks.

According to Cohen, the lead principal investigator on the project, the timing was remarkable given they were still on site when the bleaching started. "It's quite uncommon to be out there in such a remote place as a massive bleaching event is actually happening," said Cohen. "From Tom's surveys, we knew what the healthy reef looked like just before the bleaching, so we could make a direct comparison with the post-bleaching data to assess the effects of the warming."

Upon their return, the scientists boated back out to the reef and saw a green tint shimmering through the water - a possible sign that the corals made it through the bleaching event and were returning to a normal state. But when they dove in, they realized what they had seen was actually green turf algae covering dead corals. "This was the fastest-calcifying reef we've ever studied," said DeCarlo. "So we thought it would have shown resiliency. But everything had come crashing down in the space of a few weeks."

Thomas DeCarlo diving to recover a temperature data logger that holds vital information about the local amplification of thermal stress that sparked the bleaching and mortality event. Photo by Pat Lohmann, Woods Hole Oceanographic Institution.

Cooling system shutdown

The team suspected the amplified warming was due to the weather lull, but they couldn't automatically rule out the possibility that fewer clouds and more sunlight in 2015 versus previous years had caused the event. To test this hypothesis, DeCarlo and co-author Kristen Davis, using data recorded by instruments deployed on the reef, conducted a number of "heat budget" calculations to hone in on the specific factors that drove the extreme heating.

"We saw that air-to-sea heating mechanisms like sunlight and air temperature had remained nearly constant throughout June, but the wind- and wave-driven currents pushing in cooler offshore water were essentially turned off for a few days. This was the big change that caused the water temperatures to spike on the reef, so our hypothesis was correct - the unusually calm weather pattern was the primary culprit," said DeCarlo.

Scanning history

Water temperatures stabilized in early July as the winds and waves finally kicked up. But the widespread damage had already been done. Given the magnitude of the event, the scientists wanted to know if this reef had experienced similar temperature extremes in the past, and if so, whether the corals recovered. According to Cohen, however, few historical bleaching data existed for the region.

"This is a super-remote place that takes two hours to get to by plane from mainland Taiwan," she said. There were unpublished accounts of bleaching in 1997, but the severity and extent of that event were not quantified.

Without precise historical records, the team drilled core samples from corals living on the reef and used Computed Tomography (CT) scans to look for signals of thermal stress in the past. The scans, which look like an x-rayed mop handle, reveal annual rings or "bands" of varying densities in the coral's skeleton.

"These bands are like a history book for coral reefs, allowing you to count back in time to specific years and events," said Cohen, who attributes her lab's unique "paleo perspective" to her background in paleo-oceanography. "The brighter, high-density bands, which we call 'stress bands,' are signatures of long and intense bleaching events. Based on cores we scanned, it appears there had been only three previous bleaching events between 1983 and 2015, each of which happened in El Niño years. But we detected very few stress bands in the cores, so while there had been bleaching, these events were not nearly as severe as 2015."

Interpreting the CT scan data, DeCarlo says many corals that had bleached in the past appear to have recovered. "The skeletal records show that less than 50 percent of the colonies had bleached during these historical events, which is a stark contrast to the 100 percent bleaching we saw in 2015. This suggests that the area had not seen thermal stress this extreme in the last forty years at least - maybe even in the last 100 years."

21st century reef

The study highlights the consequences for shallow-water coral reefs when global warming intersects with short-lived weather anomalies. But the scientists say their observations also suggest the possibility that climate model projections may underestimate what some coral reefs will experience as the ocean continues to warm over this century.

"The current global climate models and prognosis for reefs are based on a 2 °C warming scenario for the open ocean," said DeCarlo. "But these projections usually don't account for the kind of regional and local weather anomalies we saw at Dongsha. When you have weather amplification events superimposed on top of carbon dioxide-driven ocean warming, that's when things can get really bad for corals. Models based on open-ocean warming already paint a dire picture for coral reefs, but the scary reality is that they may be too optimistic for many shallow reefs."

"Projections based on open-ocean temperatures may not be 100% relevant to these shallow-water environments, where many coral communities live," Cohen added. "It's possible that coral reefs are in much more immediate danger than we have anticipated. When global and regional anomalies align, a seemingly-mild two-degree warming could be more like six degrees."

Citation: Thomas M. DeCarlo, Anne L. Cohen, George T. F. Wong, Kristen A. Davis, Pat Lohmann & Keryea Soong; Mass coral mortality under local amplification of 2 °C ocean warming; Scientific Reports 7, Article number: 44586 (23 March 2017); DOI:10.1038/srep44586.

This research was funded by the National Science Foundation, the Sustainability Science Research Program of the Academia Sinica, a WHOI Coastal Ocean Institute, and a National Science Foundation Graduate Research Fellowship.

The Woods Hole Oceanographic Institution is a private, non-profit organization on Cape Cod, Mass., dedicated to marine research, engineering, and higher education. Established in 1930 on a recommendation from the National Academy of Sciences, its primary mission is to understand the ocean and its interaction with the Earth as a whole, and to communicate a basic understanding of the ocean's role in the changing global environment.

Posted at 04:33 AM in Biodiversity, Climate Change, Environmental Disasters, Marine Environment, Science | Permalink | Comments (0)

03/23/2017

A new species of hard coral from the World Heritage-listed Lord Howe Island, Australia

A view from the study site, UNESCO World Heritage-listed Lord Howe Island, Australia. Credit: Tane Sinclair-Taylor

The discovery of a new species of hard coral, found on Lord Howe Island, suggests that the fauna of this isolated location in the Tasman Sea off south eastern Australia is even more distinct than previously recognised.

In a recent paper in ZooKeys, Prof. Andrew Baird and Dr. Mia Hoogenboom from James Cook University, Townsville Australia and Dr. Danwei Huang from the National University of Singapore, describe the new species Cyphastrea salae.

"The animal itself is quite non-descript from a distance, although it is beautifully symmetrical up close like most corals," says Dr. Hoogenboom. "But we believe this is the first of many new hard coral species to be found in this World Heritage-listed marine protected area."

Lord Howe Island is famous for its many unique plant and animal species, known from nowhere else on Earth, including at least four species of palms, nine reef fish and 47 algae. However, the coral fauna remains largely unexplored, particularly using modern genetic techniques.

A holotype of the new hard coral species Cyphastrea salae. Credit: Prof. Andrew Baird

While some of the earliest work on coral reef ecology was done on Lord Howe Island, the species lists were compiled using a morphological taxonomy that has since been revised.

"On my very first dive in the lagoon at Lord Howe I knew I was looking at something very special," says Prof. Baird. "Twenty years of diving all over the globe had not prepared me for what I saw. I could hardly put a name on any coral!"

Now, six years later, and largely due to the molecular skills of colleague Dr. Huang, the team is ready to name its first species.

"Interestingly, Cyphastrea salae looks almost exactly like other closely-related corals. However, its gene sequences are distinct and there is no doubt it is a species that is new to science," says Dr. Huang.

A view of the study site in Lord Howe Island's lagoon. Credit: Prof. Andrew Baird

The team now have hundreds of specimens to work through, but they are confident that there are more new coral species left to describe.

"The Acropora, in particular, look highly promisingly," says Prof. Baird. "There are at least five species that look unlike anything I have seen anywhere else in my travels".

Lord Howe Island lies over 900 km south of the next major area of coral diversity, the Great Barrier Reef, and therefore the populations on Lord Howe are highly isolated. Such isolation creates the potential for speciation, however, C. salae is the first new local coral species described to date. The discovery of this new species greatly increases the conservation significance of Lord Howe Island and reinforces the need for strong management measures to protect this unique fauna.

Citation: Andrew H. Baird, Mia O. Hoogenboom & Danwei Huang; Cyphastrea salae, a new species of hard coral from Lord Howe Island, Australia (Scleractinia, Merulinidae); ZooKeys, 2017; 662: 49; DOI: 10.3897/zookeys.662.11454.

Contact: Prof. Andrew Baird
James Cook University

Posted at 02:39 AM in Biodiversity, Marine Environment, Protected Areas, Science, Travel | Permalink | Comments (0)

Lack of staffing, funds prevent marine protected areas from realizing full potential

Marine protected areas (MPAs) are an increasingly popular strategy for protecting marine biodiversity, but a new global study demonstrates that widespread lack of personnel and funds are preventing MPAs from reaching their full potential. Only 9 percent of MPAs reported having adequate staff. Credit: David Gill.

MPAs, which include marine reserves, sanctuaries, parks, and no-take zones, are areas designated to protect marine species and habitats from both global and local threats. After four years compiling and analyzing data on site management and fish populations in 589 MPAs around the world, Dr. David Gill and his co-authors discovered that shortfalls in staffing and funding are hindering the recovery of MPA fish populations. While fish populations grew in 71 percent of MPAs studied, the level of recovery of fish was strongly linked to the management of the sites. At MPAs with sufficient staffing, increases in fish populations were nearly three times greater than those without adequate personnel. Despite the critical role of local management capacity, however, only 35 percent of MPAs reported acceptable funding levels and only 9 percent reported adequate staff to manage the MPA.

"Our study identified critical gaps in the effectiveness and equity of marine protected areas," said Gill, who conducted the research during a postdoctoral fellowship supported by the National Socio-Environmental Synthesis Center (SESYNC) and the Luc Hoffmann Institute. "We set out to understand how well marine protected areas are performing and why some perform better than others. What we found was that while most marine protected areas increased fish populations, including MPAs that allow some fishing activity, these increases were far greater in MPAs with adequate staff and budget."

Credit: David Gill

Marine protected areas are rapidly expanding in number and total area around the world. In 2011, 193 countries committed themselves to the Convention on Biological Diversity Aichi Targets, including a goal of "effectively and equitably" managing 10 percent of their coastal and marine areas within MPAs and "other effective area-based conservation measures" by 2020. In the last two years alone, over 2.6 million square kilometers have been added to the portion of the global ocean covered by MPAs, bringing the total to over 14.9 million square kilometers.

As countries continue to expand their coverage and create new MPAs to achieve national targets, many unanswered questions remain: Are MPAs meeting their social and ecological objectives? Are they being managed "effectively and equitably"? How can we ensure that MPAs deliver the ecological and social benefits they were designed to produce?

Led by Gill, a multinational and multidisciplinary research team worked to answer these key questions. The study used rigorous statistical methods to identify changes in fish populations attributable to the MPA and not due to other pre-existing factors, such as preferentially locating MPAs where threats are low.

"These results highlight the potential for an infusion of resources and staff at established MPAs - and at MPAs in the pipeline - to enhance MPA management and ensure that MPAs realize their full potential," said Dr. Helen Fox of the National Geographic Society, who led the research initiative together with Dr. Michael B. Mascia of Conservation International. "The good news is that this is a solvable problem. MPAs perform better when they have enough staff and an adequate budget."

"The risk is that MPAs proliferate without further investment in MPA management, leaving new sites without the resources they need to deliver on their promises. If resources are reallocated to new MPAs from currently protected areas, that could weaken these older sites, too," added Mascia.

Credit: David Gill

The authors propose policy solutions including increasing investments in MPA management, prioritizing social science research on MPAs, and strengthening methods for monitoring and evaluation of MPAs.

"SESYNC is a leader in bringing together scholars to address emerging problems--such as issues around marine protected areas and conservation--through new interdisciplinary research partnerships to improve understanding," said Margaret Palmer, Director of SESYNC and a Distinguished University Professor at the University of Maryland. "The scholarship that David Gill and his team have highlighted in their Nature study is a reminder that interdisciplinary synthesis research can foster actionable science."

"While the momentum around the creation of new marine protected areas is exciting, it's essential that we don't leave existing MPAs behind," said Gabby Ahmadia, WWF's lead marine scientist. "This research highlights the need to be thoughtful and critical about how we support existing MPAs to optimize benefits for both people and nature."

"There are huge expectations of MPAs in protecting marine biodiversity, but until this study we didn't have a truly comprehensive picture of whether, and under what conditions, they are likely to be effective," said Jon Hutton, Director of the Luc Hoffman Institute. "The study in some ways points out the obvious - that investing in management and capacity is key for biodiversity outcomes in MPAs. But it is alarming to see how few MPAs have sufficient financial and human capacity, pointing to a clear need for further investment."

"People around the world depend on marine resources that are managed fairly and effectively. With global collaborations, we can identify strategic future investments in marine protected areas, and track progress towards better outcomes," said Dr. Emily Darling, Associate Conservation Scientist at Wildlife Conservation Society, who leads a global coral reef monitoring program.

Citation: David A. Gill, Michael B. Mascia, Gabby N. Ahmadia, Louise Glew, Sarah E. Lester, Megan Barnes, Ian Craigie, Emily S. Darling, Christopher M. Free, Jonas Geldmann, Susie Holst, Olaf P. Jensen, Alan T. White, Xavier Basurto, Lauren Coad, Ruth D. Gates, Greg Guannel, Peter J. Mumby, Hannah Thomas, Sarah Whitmee, Stephen Woodley & Helen E. Fox; Capacity shortfalls hinder the performance of marine protected areas globally; Nature, 2017; DOI: 10.1038/nature21708.

Contact: Emily S Cassidy
National Socio-Environmental Synthesis Center

Posted at 01:45 AM in Environmental Politics, Environmental Project Financing, Marine Environment, Protected Areas, Science, Sustainable Development | Permalink | Comments (0)

03/20/2017

The carbon dioxide loop

Marine biologists quantify the carbon consumption of bacterioplankton to better understand the ocean carbon cycle.

Bacterioplankton (dots) surrounded by a nanoflagellate (white), which preys on the bacteria. Credit: Rachel Parsons.

The oceans are great at absorbing carbon dioxide (CO₂) from the air, but when their deep waters are brought to the surface, the oceans themselves can be a source of this prevalent greenhouse gas.

Wind patterns together with the Earth's rotation drive deep ocean water -- and the CO₂ it sequesters -- upward, replacing surface water moving offshore. A process known as upwelling, it occurs on the west coasts of continents. And it's part of a never-ending loop in which CO₂ levels in the surface ocean rise and fall in a natural rhythm.

But when CO₂ levels rise, ocean pH falls, causing ocean acidification. Seeking to explore how short-term periods of elevated CO₂ from upwelling impact the bacteria in the water, UC Santa Barbara researchers found that the additional CO₂ -- and corresponding drop in pH -- increased the respiration of these organisms. This means more resources are recycled rather than retained in the food web. The results appear in the journal PLOS ONE.

"Despite their microscopic size, these bacteria drive the major cycling of carbon in the ocean's surface," said lead author Anna K. James, a graduate student in UCSB's Interdepartmental Graduate Program in Marine Science. "I wanted to see how much dissolved organic carbon the bacteria were eating and what proportion they dedicated to biomass."

In addition to measuring the organisms' biomass, James calculated bacterial respiration. When these microbes respire, the organic carbon they consume is converted back to CO₂, which -- as a gas -- has the potential to go back into the atmosphere or to once again dissolve in the surface ocean.

"The elevated bacterial respiration could limit the oceans' ability to store organic carbon by converting it back to CO₂," James explained.

To measure the flow of carbon through bacteria, James conducted remineralization experiments -- seawater culture incubations that use filtered surface seawater. She collected natural bacterial communities from the surface ocean, added them to the filtered seawater and measured how much carbon the bacteria consumed. From that, James was able too calculate their biomass, abundance and respiration.

"It important to know what bacterial respiration is because it has a number of implications for the ocean carbon cycle," James said. "The first is the movement of organic carbon from the surface into the deep ocean either via physical mixing or sinking. The other is, if the organic carbon is contained in bacterial biomass, it can be consumed by other organisms that eat bacteria."

The upshot: Factors that affect the recycling rate of microbes alter the fate of organic matter in the ocean's water column. "It is really surprising to realize that tiny bacteria respond to the concentration of CO₂ available and in turn influence the amount of carbon the ocean takes up," said co-author Uta Passow, a research oceanographer at UCSB's Marine Science Institute.

"Anna's work demonstrates an unexpected but important finding that shows marine bacteria can directly respond to rapid decreases in ocean pH," said co-author Craig Carlson, a professor in UCSB's Department of Ecology, Evolution and Marine Biology. "By increasing their recycling rate, bacteria convert some of the organic matter back to CO₂, which has implications in food web and ocean biogeochemical processes."

Citation: James AK, Passow U, Brzezinski MA, Parsons RJ, Trapani JN, Carlson CA (2017); Elevated pCO₂ enhances bacterioplankton removal of organic carbon. PLoS ONE 12(3): e0173145; DOI:10.1371/journal.pone.0173145.

Contact: Julie Cohen
University of California - Santa Barbara

Posted at 04:58 AM in Biodiversity, Climate Change, Environment, Marine Environment, Science | Permalink | Comments (0)

03/18/2017

Highly contagious infection threatens endangered San Joaquin kit fox population

San Joaquin kit foxes face numerous threats, including habitat encroachment and sarcoptic mange. The highly contagious infection can lead to death. Credit: Rick Derevan

Endangered San Joaquin kit foxes face many threats to their survival, including loss of habitat and competition with non-native species such as the red fox. Now, scientists are rushing to save remaining fragile populations from a new danger - sarcoptic mange, a skin disease caused by mites.

A recent publication by Morris Animal Foundation-funded researchers sheds light on the dynamics of this highly contagious disease, and gives desperately needed information to those working to save the San Joaquin kit fox, a subspecies of the smallest canid in North America. The paper was published in the January 2017 Journal of Wildlife Diseases.

The San Joaquin kit fox (Vulpes macrotis mutica) is endemic to central California's San Joaquin Valley, but development of the area over the last century has led to a sharp decline in its population. Currently, there are fewer than 7,000 San Joaquin kit foxes, according to the California Department of Fish and Wildlife. A critical population located in the city of Bakersfield is threatened by sarcoptic mange, first identified in spring of 2013.

Sarcoptic mange is a highly contagious, zoonotic disease caused by Sarcoptes scabiei, a mite that burrows into the skin. Hair loss and skin lesions, compounded by intense itching and self-trauma, can be fatal in severe cases. Urgent management strategies are needed to stop transmission of the disease to other members of this unique population, as well as to to other kit fox groups and other canids, both wild and domestic.

"The research results presented in this paper established a critical foundation for understanding the epidemiology of sarcoptic mange and its impacts on an extremely important population of endangered San Joaquin kit foxes," said Dr. Brian Cyphers, Associate Director and Research Ecologist of the Endangered Species Recovery Program at California State University, Stanislaus, and one of the paper's authors.

During the study, the research team confirmed the diagnosis of sarcoptic mange in 15 kit foxes either captured or found deceased. The team successfully treated three animals of nine found alive. They found no evidence that untreated kit foxes can recover from the infection, meaning prevention and treatment are critical to containing the spread of the disease.

"With this foundational study, we have been able to leverage additional funding to continue our research, including identifying potential strategies to eliminate the disease from portions of this kit fox population and possibly from the entire population," said Dr. Cyphers.

Citation: Brian L. Cypher, Jaime L. Rudd, Tory L. Westall, Leslie W. Woods, Nicole Stephenson, Janet E. Foley, Donald Richardson, and Deana L. Cliffor; Sarcoptic mange in endangered kit foxes (Vulpes macrotis mutica): Case histories, diagnoses, and implications for conservation; Journal of Wildlife Diseases 53(1):46-53. 2017; DOI: 10.7589/2016-05-098.

Contact: Carol Borchert
Morris Animal Foundation

Posted at 12:39 AM in Bears, Wolves & Big Cats, Biodiversity, Science | Permalink | Comments (0)

03/16/2017

How plankton cope with turbulence

Algal population split into two equally sized groups when exposed to turbulence. Downward swimming cells become egg-shaped, while those swimming upwards are pear-shaped. This change of shape involves a difference of just one micrometre. Credit: © ETH Zürich.

Shape-shifting plankton.

Microscopic marine plankton are not helplessly adrift in the ocean. They can perceive cues that indicate turbulence, rapidly respond to regulate their behaviour and actively adapt. ETH researchers have demonstrated for the first time how they do this .

Plankton in the ocean are constantly on the move. By day, these tiny organisms, one-tenth the diameter of a human hair, actively migrate towards the sunlit ocean surface to carry out photosynthesis. At night, they make their way to depths of tens of metres, where the supply of nutrients is greater.

During their regular trips between well-lit and nutrient-rich zones, plankton cells frequently encounter turbulent layers, which disrupt this essential migratory pattern. It is still a mystery how these minute organisms can navigate through the dangers of turbulent waters. Plankton cells are whirled around by turbulence -- particularly by the smallest, millimetre-sized flow vortices -- as if they were in a miniature washing machine, which can induce permanent damage to their propulsion appendages and cell envelope. In the worst case, they can perish in turbulence.

Migratory behaviour observed in micro-chambers

Certain microalgae have, however, developed a sophisticated response to such turbulent cues. Post-doctoral researchers Anupam Sengupta and Francesco Carrara, together with their advisor Roman Stocker, Professor at the ETH Zurich Institute of Environmental Engineering, have shown this in a study recently published in the journal Nature.

Using laboratory experiments, the three scientists "brought the ocean into the lab" and examined the migratory behaviour of Heterosigma akashiwo, an alga known for forming toxic algal blooms. To examine swimming behaviour, the researchers used a microfabricated chamber, just a few cubic millimetres in volume, in which they introduced the Heterosigma cells. The chamber could be rotated along its axis using a computer-controlled motor, exposing cells to periodic flips in orientation replicating how tiny turbulent vortices flip the cells upside down in the ocean.

Diving with foresight

The scientists were able to observe that an algal population moving upwards split into two equally sized groups over a period of 30 minutes after the chamber was repeatedly flipped by 180 degrees. One group of cells continued to strive upwards, whereas the other group switched behaviour and began to swim in the opposite direction. This population split did not occur with algae in stationary chambers, in which all swam continuously upwards and accumulated near the top surface.

By zooming into single cells, the researchers discovered the reason for the change in swimming behaviour. When exposed to the turbulence-like cues, the cells were able to actively and rapidly change their shape: from asymmetric pear-shaped cells swimming upwards, the cells morphed into egg-shaped structures swimming downwards. Strikingly, this shift involved changes of less than a micrometre. "It is spectacular that a cell barely 10 micrometres in size can adapt its shape to change its swimming direction," says the study's co-author Francesco Carrara.

Perfect adaptation

Roman Stocker does not view this mechanism as just a coincidence. "The algae have adapted perfectly to their ocean habitat: they can actively swim, they perceive a range of different environmental signals, including turbulence, and they rapidly adapt and regulate their behaviour accordingly." Anupam Sengupta adds: "We now better understand how these microorganisms confront potentially detrimental situations, however, at the moment we can only speculate as to why the cells do this."

The researchers argue that splitting into two groups creates an evolutionary advantage for the population: in this manner, the entire population is not lost when it encounters a layer of strong turbulence, but in the worst case, only half. In avoiding the turbulence by diving, the downward-swimming cells suffer the short-term cost of receiving too little light to carry out photosynthesis, meaning that they cannot grow. The researchers also found evidence that the flipping by turbulence has a physiological impact on the algae. Cells that were flipped in their experiment exhibited higher levels of stress than those in the stationary chambers.

Climate change influences turbulence

The researchers now plan to observe the algae in a larger tank, where they will expose the cells not only to flipping but also to real turbulence. Understanding how these minute cells respond to turbulence holds great importance for our understanding of the ocean. "As we now know that global climate change will modify the turbulence landscape in the ocean, it is particularly important to understand how the organisms that are the foundation of the marine food web respond to it. This work contributes a piece of the puzzle, by demonstrating that phytoplankton are not just at the mercy of turbulence, but can actively cope with it," says the ETH professor.

Citation: Anupam Sengupta, Francesco Carrara and Roman Stocker; Phytoplankton can actively diversify their migration strategy in response to turbulent cues; Nature, 2017; DOI: 10.1038/nature21415.

Contact: Prof. Roman Stocker
ETH Zurich

Scientists at MIT and Oxford University have shown that the motility of phytoplankton, which are tiny ocean plants, helps them determine their fate in ocean turbulence. Rather than acting to distribute them evenly, as physics would demand of small particles mixed into a fluid, the individual vortices that make up ocean turbulence are like social mixers for phytoplankton, bringing similar cells into close proximity, potentially enhancing sexual reproduction and other ecologically desirable activities. In a paper, William Durham of Oxford, Roman Stocker of MIT and co-authors described how at the scale of millimeters, phytoplankton caught in a watery vortex form highly concentrated patches at the center of the swirl. In the turbulent ocean where short-lived vortices form continually, this process repeats itself, carrying the microorganisms from social mixer to social mixer.

Citation: William M. Durham, Eric Climent, Michael Barry, Filippo De Lillo, Guido Boffetta, Massimo Cencini & Roman Stocker; Turbulence drives microscale patches of motile phytoplankton; Nature Communications 4, Article number: 2148 (15 July 2013); DOI:10.1038/ncomms3148.

Posted at 04:28 AM in Biodiversity, Marine Environment, Science | Permalink | Comments (0)

When the sea ice melts, juvenile polar cod may go hungry

Biologists confirm how heavily the fish depend on ice algae.

Arctic oceanic food web dependence on Arctic cod (Boreogadus saida). Credit: Oceans North, The Pew Charitable Trusts

Polar cod fulfil a key role in the Arctic food web, as they are a major source of food for seals, whales and seabirds alike. But the polar cod themselves might soon be the hungry ones. Under the ice of the central Arctic, the juvenile fish are indirectly but heavily dependent on ice algae. As a result, retreating sea ice could have far-reaching impacts on the food web. Though researchers have long since suspected this relation existed, an international team of researchers led by the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI), have now successfully confirmed it.

Arctic sea ice offers a veritable nursery ground for polar cod: young fish between one and two years old live in cracks and crevices under the ice. They drift along with the ice, which is most likely how they make their way from their spawning grounds in the waters of northern Siberia to the central Arctic. During their journey, the young polar cod feed on amphipod crustaceans, which in turn feed on ice algae. As such, there is a direct relation between the polar cod and the ice algae, which could ultimately threaten the young polar cod's survival. This was the key outcome of a study recently published in the journal "Progress in Oceanography". Amongst others, the research institute Wageningen Marine Research in the Netherlands joined in the study.

"Generally speaking, our findings indicate that polar cod are heavily dependent on ice algae," says first author and AWI biologist Doreen Kohlbach. "That means the rapid retreat of Arctic sea ice poses an especially serious threat for polar cod. When the ice retreats, it takes with it the basis of their diet. Given the polar cod's pivotal role, this could also produce changes throughout the entire food web."

In the study, Kohlbach and her colleagues analysed the stomach contents of the fish -- which they had caught directly under the sea ice in the course of a several-week-long expedition to the Arctic Ocean on board the research vessel Polarstern. Between Greenland, Spitsbergen and Russia, the researchers dragged a specially designed under-ice net alongside the ship.

The fish's stomach contents showed the researchers what they had recently eaten. What they found: the amphipod crustacean Apherusa glacialis is at the top of the young polar cod's menu. In turn, the crustacean primarily feeds on diatoms that grow directly on or under the sea ice.

In a second step, the researchers confirmed the presence of carbon from the ice algae in the fish. To do so, they analysed the fatty-acid patterns and the composition of stable isotopes in the polar cod's muscle and other tissues. In the food web, certain fatty acids are passed on unchanged from the algae to the animals that feed on them. "When we find the fatty acids from the ice algae in the meat or tissues of a fish, it tells us the fish or its prey must have fed on the algae," says Kohlbach. A subsequent isotope analysis makes it possible to determine the precise percentage of ice-algae carbon in the fish's diet.

"The analysis shows that diatoms make up the most important source of carbon for polar cod," explains Kohlbach. In fact, the outcomes indicate that between 50 and 90 per cent of the young polar cod's carbon stems from ice algae. "Even though we had assumed there was a connection between the ice algae and polar cod from the outset of the study, these high values surprised us."

Last year the researchers successfully confirmed the importance of ice algae as a food source for animal species primarily found in deeper waters. Their latest study proves that this dependency also applies to the next link in the food chain. In addition, both studies have yielded valuable data that can be integrated into ecosystem models -- which are in turn essential to forecasts of how the retreat of sea ice will affect the Arctic ecosystem.

Citation: Doreen Kohlbach, Fokje L. Schaafsma, Martin Graeve, Benoit Lebreton, Benjamin Allen Lange, Carmen David, Martina Vortkamp and Hauke Flores; Strong linkage of polar cod ( Boreogadus saida ) to sea ice algae-produced carbon: evidence from stomach content, fatty acid and stable isotope analyses; Progress in Oceanography, 2017; DOI: 10.1016/j.pocean.2017.02.003.

Contact: Nadine Michel
Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research

Posted at 03:49 AM in Biodiversity, Climate Change, Marine Environment, Science | Permalink | Comments (0)

03/15/2017

Discovery of surf breaks creates economic growth

Study analyzes 5,000 surf breaks globally; finds growth reversed where breaks were destroyed; shows Western Australia is a hotspot for growth near breaks.

University of Sydney research reveals high quality surf breaks boost economic growth in nearby areas - and by how much.

Researchers analysed satellite images of night-time lights as a 'proxy' for economic growth. They found that a surfing community's discovery of a high-quality break can raise growth by 2.2 percentage points a year. The study of more than 5000 surf break locations in 146 countries spans data between 1992 and 2013, with a concentration toward breaks in Australia and the United States.

"We conducted four sets of experiments, and they all confirm that good waves significantly increase growth, particularly after recent discoveries and during El Niño years," said Dr Sam Wills, of the University of Sydney's School of Economics.

While it's well understood that natural features like rivers and fertile soil matter for economic growth, this provides some of the first evidence that natural amenities are also important. Researchers investigated data in two locations where surf breaks were removed and found that nearby economies shrink when this occurs. A break at Jardim do Mar, Portugal, was removed though the construction of a coastal road, while another at Mundaka, Spain, disappeared after a river mouth was dredged.

The paper suggests policymakers can use surf breaks as a way to create jobs and reduce poverty, especially in developing countries. To do this they can promote public and private investment needed to enjoy surf breaks, while protecting their environmental quality.

"Discovering a high-quality break - or battery-heated wetsuits that made cold-water breaks more accessible - increased growth in the surrounding areas," said Dr Wills. "But destroying a break reduced growth, even if it was replaced by a new road or a dredged river."

Dr Wills - who enjoys surfing in his spare time - will present the findings at the International Surfing Symposium conference at the Gold Coast this week, in the lead-up to the Quicksilver Pro - the first stop on the 2017 surfing World Championship Tour.

"I had the idea for the paper straight after I submitted my PhD thesis," he said.

"It was November and I needed to get out of Oxford, so I looked for somewhere warm and sunny with good waves. I settled on Taghazout in Morocco, thinking it would be quiet. Flying in at sunset over the desert I noticed that everything was dark, except for one little spot that was lit up like Pitt Street: Taghazout.

"Once I arrived I realised that this previously sleepy little fishing village had been overrun by surfers, and so I wanted to figure out whether it was systematically happening around the world."

Top 10 Fastest Growing Surf Breaks from 1992-2013:

Australia*

10. Express Point, VIC
9. Smiths Beach, WA
8. Smiths Reef, WA
7. Mouse Traps, WA
6. Supertubes, WA
5. Yallingup, WA
4. Palestines, WA
3. Rabbits, WA
2. Isolators, WA
1. Yallingup (shorebreak), WA

The World*

10. Rabbits, Australia (WA)
9. Isolators, Australia (WA)
8. Yallingup, Australia (WA)
7. Playa Guiones, Costa Rica
6. Playa Lagosta
5. Omaha, New Zealand
4. Dark Reef, Vietnam
3. Shabandar, Malaysia
2. Yacila, Peru
1. Nosara, Costa Rica

Contact: Luke O'Neill
University of Sydney

Posted at 12:08 AM in Environment, Environmental Politics, Environmental Project Financing, Marine Environment, Sustainable Development, Travel | Permalink | Comments (0)

03/14/2017

Democrats and Republicans draw different conclusions when seasons are too hot or too cold

Attitudes about global warming are more pronounced when people reside in states experiencing unseasonably warm (or cold) temperatures.

When the weather is unseasonably hot or cold, Americans across the political spectrum have even stronger views about whether climate change caused by human activity is a reality or not. Republicans are then less likely to conform to the scientific consensus on global warming, while Democrats are much more likely to do so. This is according to the findings of Jeremiah Bohr of the University of Wisconsin Oshkosh in the US, published in Springer's journal Climatic Change.

It is well known that people with conservative leanings are more prone to deny the existence or severity of human-induced global warming than others. This divide exists among political elites as well as the American public. In the current analysis, Bohr wanted to find out if people's particular political orientations and beliefs about global warming changed at all during periods of so-called temperature anomalies, when temperatures above or beyond the normal are experienced.

Bohr used data from two sources in his study. Data concerning people's beliefs about global warming and the social setting they find themselves in came from four nationally representative CBS/New York Times surveys of American adults, collected in February 2013, March 2013, February 2014 and May 2014. These months represent moments when different regions in the US experienced temperatures both five degrees Fahrenheit above or below the average temperature for the previous three decades. Bohr then merged the survey data with state-specific monthly temperature averages collected by the National Oceanic and Atmospheric Administration's National Center for Environmental Information.

His models indicate that temperature anomalies exacerbate existing political polarization and thoughts over what causes global warming. This is especially so when unseasonal temperatures at least five degrees Fahrenheit above or below the established five-year baseline are experienced.

Democrats are more likely in such cases to attribute global warming to human activity. Republicans, on the other hand, are less likely to conform to the scientific consensus on global warming during very cold or very warm periods. When breaking down Republican identity between those who do and do not support the Tea Party movement, Bohr further found that both kinds of Republicans converge in their global warming beliefs during extreme temperature anomalies, but diverge during more seasonable temperature conditions.

"This would be consistent with the elite cues hypothesis, in that we would expect political leaders who deny anthropogenic global warming to claim victory during unseasonably cold periods or amplify their denial during unseasonably warm periods that invite challenge to their worldview," says Bohr.

He is not surprised that political polarization over global warming beliefs increases during unseasonable temperature anomalies. "These are precisely the locations and moments when partisan differences over the role of human activity in global warming may resonate most," adds Bohr.

Citation: Bohr Jeremiah; Is it hot in here or is it just me? Temperature anomalies and political polarization over global warming in the American public; Climatic Change (13 March 2017); DOI 10.1007/s10584-017-1934-z.

Contact: Melanie Lehnert
Climatic Change