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News Article | May 18, 2017
Site: www.newscientist.com

Just 35 years from now, severe coastal flooding could hit twice as often as it does now – if the seas rise by between just 5 and 10 centimetres. Such a hike would make 50-year weather events happen twice as often, according to work by Sean Vitousek, a coastal scientist at the University of Illinois at Chicago, and his colleagues. A 50-year event is an increase in sea level so large that it’s only likely to happen twice a century. Sea levels are actually projected to rise by more than this – estimates put it at between 10 and 20 centimetres over the next few decades. “It doesn’t take a ton of sea level rise to significantly change the frequency at which you have flooding,” says Vitousek. Extremely high water levels are sometimes caused by storm surges and low pressure atmospheric systems, when the easing of pressure on the sea allows water levels to rise. But normal tides and waves also play a part. Taking those factors into account in his model, Vitousek found that, by 2050, wave-exposed Indian cities like Mumbai and Kochi, and Abidjan in Ivory Coast would see increased frequency of flooding with just a 5-centimetre rise in seas. If the rise were 10 centimetres, increased flooding would also hit Shanghai, London and New York. Sea level rise is a global phenomenon that affects regions differently. The ice sheets in Antarctica and Greenland are so massive that their gravity draws ocean water towards them. As they melt, that water will go elsewhere. “If you lose Greenland, you’ll have more water in the ocean, which will elevate sea level everywhere. But the effect will be stronger farther away from Greenland,” says Anders Levermann of the Potsdam Institute for Climate Impact Research in Germany. “In Greenland or Antarctica, the water levels may even drop. The tropics always lose because they’re in the middle.” Sea levels are currently going up by about 3 to 4 millimetres across the globe somewhat uniformly, Vitousek says, but some areas are more susceptible to sea level rise than others because that makes up a larger percentage of their overall water levels. In the higher latitudes where the difference between high and low sea level in a given year could be 3 metres, a few centimetres may not be noticeable. But in the tropics, that small increase could account for 10 to 20 per cent of the variation, Vitousek says. “It’s not a trivial percentage of the water level,” he says. Aimée Slangen, a climate change scientist at the Royal Netherlands Institute for Sea Research, says regional events like El Niño could keep down some of the sea level rise in the tropics, but not forever. “I think it would only delay the inevitable: at some point, flooding frequencies are going to increase as long as sea level keeps on rising,” she says. Vitousek says possible responses are to retreat from coastlines or to invest in engineering solutions, like building up natural beaches or creating artificial ones or building sea walls that provide shoreline protection. But over the next few decades, an increase of 10 to 20 centimetres is inevitable, says Levermann. Even with large reductions in emissions, the die has already been cast for the near future. “No one has to be afraid of sea level rise, if you’re not stupid,” he says. “It’s low enough that we can respond. It’s nothing to be surprised about, unless you have an administration that says it’s not happening. Then you have to be afraid, because it’s a serious danger,” Levermann says.

News Article | May 25, 2017
Site: www.newscientist.com

Plastic. There should be hundreds of thousands of tonnes of the stuff floating around in our oceans. But we are finding less than expected – perhaps because living organisms are evolving the ability to break it down. Plastic production is rising exponentially, so ever more of it should be ending up in the oceans, says Ricard Sole, who studies complex systems at the Universitat Pompeu Fabra in Barcelona. But surveys of areas where floating plastic accumulates, such as the North Atlantic gyre, are not finding nearly as much plastic as expected. In fact, there’s only a tenth to a hundredth as much plastic as expected – and the amount of floating plastic does not appear to be increasing. “The trend should be there,” Sole says. This lack of trend cannot be explained by physical processes, according to his team’s mathematical models. Instead, they propose that there has been a population boom in microbes that have evolved the ability to biodegrade plastic. Other researchers agree that surveys are finding far less plastic in the oceans than expected. However, they say there are several other possible explanations for this “missing plastic”. Surprisingly, even if ocean plastic is being degraded much faster than thought, it is not clear that this is a good thing. “It is difficult to say,” says Matthew Cole of Exeter University in the UK. For instance, biodegradation could be speeding up the breakdown of large pieces of plastic into lots of very tiny pieces, which might have a greater overall impact. Plastic also contains various additives that could get released and enter the food chain if the plastic part biodegrades, says environmental chemist Alexandra ter Halle of the Laboratoire des IMRCP in France. “To really tackle the plastic problem, we need to stop it getting into the oceans in the first place,” Cole says. In theory it is possible that some microbes have evolved the ability to break down plastics. Studies by Linda Amaral-Zettler of the Netherlands Institute for Sea Research show that the microbes colonising floating plastic are quite distinct from those in the surrounding water, and suggest some are feeding on pollutants. In effect, the plastic is creating a whole new ecosystem that Amaral-Zettler and colleagues call “the plastisphere”. But when ter Halle looked at the DNA of the organisms on floating plastic in the North Atlantic, she didn’t find any microbes known to be capable of breaking down plastic. That could be because they have not yet been discovered of course – there could be millions of unknown microbes still. Amaral-Zettler and ter Halle think it is more likely that floating plastic is simply sinking to the seafloor as colonising organisms weigh it down, or breaking into such microscopic pieces that it is not being caught in the nets of research vessels. It could also be being swallowed by living organisms, or carried by currents to unexpected parts of the ocean. The sinking explanation might also be compatible with his findings, says Sole. His study does not prove that microbes are metabolising plastic, but the lack of an upward trend can only be explained by a biological response that can increase in proportion to the amount of plastic. If a physical process was responsible, there would still be an upward trend, he says. It is possible that some plastic is being biodegraded, Amaral-Zettler says, but it could be over too long time-scale – a hundred years, say – to explain the missing plastic. And even if it is happening much faster, there’d still be a problem. Plastics are polluting every part of the ocean, from the beaches of remote islands to the deepest parts of the sea. Large pieces of plastic can accumulate in the stomach of animals such as turtles, which then starve to death. While there may be less than expected, large amounts of floating plastic are found in the subtropical gyres where surface waters circle. While terms such as the “Great Pacific Garbage Patch” conjure up visions of litter-covered seas, much of the floating plastic in the ocean consists of tiny pieces just a few millimetres wide or smaller, which are not obvious to the naked eye at all. Its impact on marine life is not clear, either. Various schemes have been proposed to remove this plastic from the oceans, but trying to clean up the oceans is impractical, says Amaral-Zettler. “We need to look at prevention and reduction at the start.”

A new study has revealed that more than 50 million years ago, some animals shrank in size in response to a series of extreme global warming events. Researchers of the study, which was published in Science Advances, found that some ancient animals which include the dog-sized Arenahippus, an early horse, became smaller as levels of carbon dioxide and temperatures rose as part of natural global warming. By analyzing fossil teeth, researchers found that the ancient compact horse became 14 percent smaller going from 17 pounds to 14. 6 pounds. "These guys were probably about the size of maybe a dog, then they dwarfed," said study researcher Abigail D'Ambrosia, from University of New Hampshire. "They may have gone down to the size of a cat." Researchers said that changes in the body could be an evolutionary response that can help animals to efficiently reduce body heat as a smaller body size would allow them to cool down faster. The availability of nutrients and quality of food may also have a role. The impact of climate change on animals, and even plants today, has also been documented by several studies. Researchers were able to conduct observations that suggest modern-day creatures also go through evolutionary processes to adapt to a warming world popularly blamed on carbon emissions. Just like the Arenahippus that evolved to adapt to a warmer planet, many animals that exist today became smaller in response to climate change. A 2014 study found that wild salamanders have been shrinking since 1957. Researchers think that the Appalachian salamanders get smaller in size due to drier and warmer conditions created by global warming. The migratory bird red knot has also experienced dramatic shrinking since 1985. Since the Arctic has been warming up earlier as a result of climate change, the snow melts two weeks earlier than decades ago. The insects in the Arctic respond to this shift by hatching earlier. When red knot chicks hatch though, the insects are already past their peak so food source becomes scarcer. As a result, the shorebirds develop smaller bodies and shorter bills. Being smaller, however, threatens the population of the birds, which could even possibly lead to their extinction. "Shorter-billed birds were forced to live on seagrass, which is a poor food source for these birds. The poor survival of shrunken first-year birds clearly contributes to the current population decline seen in red knots nowadays," explained Jan van Gils, from the Royal Netherlands Institute for Sea Research. Plants are affected as well. In a 2016 study, researchers found that extreme heat waves and droughts have led to a reduction in global cereal harvests such as wheat, rice and maize within a period of 50 years, essentially affecting agriculture and food production. In another study, researchers who looked at the DNA markers in plants found that exposure to climate change conditions led to altered genetic composition of wild plants. © 2017 Tech Times, All rights reserved. Do not reproduce without permission.

News Article | May 3, 2017
Site: www.eurekalert.org

VIDEO:  Extension of Continental, Marginal and Marine environments from ~18.4 to ~10.5 Ma showing the the two marine incursions reported in this study. view more A tiny shark tooth, part of a mantis shrimp and other microscopic marine organisms reveal that as the Andes rose, the Eastern Amazon sank twice, each time for less than a million years. Water from the Caribbean flooded the region from Venezuela to northwestern Brazil. These new findings by Smithsonian scientists and colleagues, published this week in Science Advances, fuel an ongoing controversy regarding the geologic history of the region. "Pollen records from oil wells in eastern Colombia and outcrops in northwestern Brazil clearly show two short-lived events in which ocean water from the Caribbean flooded what is now the northwest part of the Amazon basin," said Carlos Jaramillo, staff scientist at the Smithsonian Tropical Research Institute and lead author of the study. "Geologists disagree about the origins of the sediments in this area, but we provide clear evidence that they are of marine origin, and that the flooding events were fairly brief," Jaramillo said. His team dated the two flooding events to between 17 to18 million years ago and between 16 to 12 million years ago. Several controversial interpretations of the history of the region include the existence of a large, shallow sea covering the Amazon for millions of years, a freshwater megalake, shifting lowland rivers occasionally flooded by seawater, frequent seawater incusions, and a long-lived "para-marine metalake," which has no modern analog. Jaramillo assembled a diverse team from the Smithsonian and the University of Illinois at Urbana-Champaign; Corporacion Geologica Ares; the University of Birmingham; the University of Ghent; the Universidad del Norte, Baranquilla, Colombia; the University of Alberta, Edmonton; the University of Zurich; Ecopetrol, S.A.; Hocol, S.A.; the Royal Netherlands Institute for Sea Research at Utrecht University; the University of Texas of the Permian Basin; and the Naturalis Biodiversity Center. Together, they examined evidence including more than 50,000 individual pollen grains representing more than 900 pollen types from oil drilling cores from the Saltarin region of Colombia and found two distinct layers of marine pollen separated by layers of non-marine pollen types. They also found several fossils of marine organisms in the lower layer: a shark tooth and a mantis shrimp. "It's important to understand changes across the vast Amazonian landscape that had a profound effect, both on the evolution and distribution of life there and on the modern and ancient climates of the continent," Jaramillo said. The Smithsonian Tropical Research Institute, headquartered in Panama City, Panama, is a part of the Smithsonian Institution. The Institute furthers the understanding of tropical nature and its importance to human welfare, trains students to conduct research in the tropics and promotes conservation by increasing public awareness of the beauty and importance of tropical ecosystems. STRI website: http://www. . C. Jaramillo, I. Romero, C. D'Apolito, J. Ortiz. "Miocene flooding events of western Amazonia." Science Advances. Manuscript Number: sciadv.1601693; Smithsonian Tropical Research Institute

Cadee G.C.,Netherlands Institute for Sea Research
Palaios | Year: 2011

In the Wadden Sea, shell repair frequency in the small gastropod Hydrobia ulvae varied from 2.8% to 11.2%. On tidal flats of the Mok, a small bay on the island of Texel, The Netherlands, in the Wadden Sea, higher repair frequencies varying from 11.8% to 41.8% were measured. The shelduck, Tadorna tadorna, a predator of Hydrobia, occurs here in densities far above average densities for the Wadden Sea. Shelducks ingest their prey whole and crush the shells of H. ulvae internally. Live specimens of H. ulvae were collected from shelduck feces. Those with intact operculum and only a damaged outer aperture rim of the shell were kept in aquaria and repaired their shell rapidly. This indicates that predators that ingest shelled prey can also leave repair scars on shells. Such scars, however, are indistinguishable from those resulting from failed predation by predators using such pre-ingestive shell breakage as decapod crustaceans. Copyright © 2011, SEPM (Society for Sedimentary Geology).

Van Haren H.,Netherlands Institute for Sea Research
Journal of Geophysical Research: Oceans | Year: 2011

An accurate bottom pressure sensor has been moored at different sites varying from a shallow sea strait via open ocean guyots to a 1900 m deep Gulf of Mexico. All sites show more or less sloping bottom topography. Focusing on frequencies (σ) higher than tidal, the pressure records are remarkably similar, to within the 95% statistical significance bounds, in the internal gravity wave continuum (IWC) band up to buoyancy frequency N. The IWC has a relatively uniform spectral slope: log(P(σ)) = -αlog(σ), α= 2 ± 1/3. The spectral collapse is confirmed from independent internal hydrostatic pressure estimate, which suggests a saturated IWC. For σ > N, all pressure-spectra transit to a bulge that differs in magnitude. This bulge is commonly attributed to long surface waves. For the present data it is suggested to be due to stratified turbulence-internal wave coupling, which is typically large over sloping topography. The bulge drops off at a more or less common frequency of 2-3 × 10-2 Hz, which is probably related with typical turbulent overturning scales. Copyright 2011 by the American Geophysical Union.

van Gils J.A.,Netherlands Institute for Sea Research
Proceedings. Biological sciences / The Royal Society | Year: 2013

Recent insights suggest that predators should include (mildly) toxic prey when non-toxic food is scarce. However, the assumption that toxic prey is energetically as profitable as non-toxic prey misses the possibility that non-toxic prey have other ways to avoid being eaten, such as the formation of an indigestible armature. In that case, predators face a trade-off between avoiding toxins and minimizing indigestible ballast intake. Here, we report on the trophic interactions between a shorebird (red knot, Calidris canutus canutus) and its two main bivalve prey, one being mildly toxic but easily digestible, and the other being non-toxic but harder to digest. A novel toxin-based optimal diet model is developed and tested against an existing one that ignores toxin constraints on the basis of data on prey abundance, diet choice, local survival and numbers of red knots at Banc d'Arguin (Mauritania) over 8 years. Observed diet and annual survival rates closely fit the predictions of the toxin-based model, with survival and population size being highest in years when the non-toxic prey is abundant. In the 6 of 8 years when the non-toxic prey is not abundant enough to satisfy the energy requirements, red knots must rely on the toxic alternative.

Villanueva L.,Netherlands Institute for Sea Research | Damste J.S.S.,Netherlands Institute for Sea Research | Schouten S.,Netherlands Institute for Sea Research
Nature Reviews Microbiology | Year: 2014

Archaea produce unique membrane lipids in which isoprenoid alkyl chains are bound to glycerol moieties via ether linkages. As cultured representatives of the Archaea have become increasingly available throughout the past decade, archaeal genomic and membrane lipid-composition data have also become available. In this Analysis article, we compare the amino acid sequences of the key enzymes of the archaeal ether-lipid biosynthesis pathway and critically evaluate past studies on the biochemical functions of these enzymes. We propose an alternative archaeal lipid biosynthetic pathway that is based on a 'multiple-key, multiple-lock' mechanism. © 2014 Macmillan Publishers Limited. All rights reserved.

Agency: GTR | Branch: NERC | Program: | Phase: Research Grant | Award Amount: 42.91K | Year: 2012

For the last approximately 200 years since the Industrial Revolution, human activity, primarily by burning of fossil fuels, has added carbon dioxide to planet Earths atmosphere. Carbon dioxide is an important greenhouse gas and increasing concentrations of this chemical compound in the atmosphere causes climate warming. Understanding the temporal and spatial response of Earths climate system to changing atmospheric carbon dioxide concentrations is a pressing issue for all of human society across the planet. One way to make such an assessment is to look back into the past and to reconstruct past temperature changes and to relate such variability to records of past atmospheric composition. Despite the significance of global warming, long instrumental records of changing seawater temperature in the past are not available for all of the geographical regions which interest climate scientists, or such instrumental records do not extend far enough back in time. Therefore, in order to place the most recent instrumental records of seawater temperature change in a longer temporal context, as well as to enable reconstruction of past seawater temperature where instrumental records do not exist, it is important to delve deeper into history by application of what is called a proxy-based temperature reconstruction approach. Elements and isotope ratios of some elements, when incorporated into calcium carbonate biominerals (including corals, mollusc shells and some plankton), have demonstrated potential to be used as the proxy means of reconstructing the magnitude and rates of change of seawater temperatures, for those time periods before the existence of instrumental records and for geographical regions where such instrumental records do not exist. Such an approach has long been applied to low latitude warm-water corals, since they form easily dated annual growth increments, but these organisms are restricted in distribution to the warm low latitudes. Arctica islandica is a marine bivalve mollusc that inhabits those middle to high latitude shelf seas that border the North Atlantic Ocean and individuals of this species have been shown to live for up to ~400 years. Furthermore, this organism (like a warm-water coral) deposits easily identified and dated annual shell growth increments, the composition of which has the potential to enable reconstruction of proxy-based records of past seawater temperature, on a calendar timescale (by counting annual growth increments from a known date of death), for the last few centuries and even for the last millennium (when shells of individuals are cross-correlated using the same approach as is applied to tree rings). However, to be able to generate these proxy-based records of past seawater temperature it is critically important that robust calibrations are derived, which document the strength of the relationship between the proxy measurement and seawater temperature, as well as identifying any limitations with any proxy. This detailed and systematic study will be the first use of specimens of A. islandica, which have already been cultured at constant seawater temperatures in laboratory aquaria, under controlled conditions, to derive calibrations for three novel temperature proxies. Such laboratory experiments are fundamental to the development of proxies for reconstructing past seawater temperatures, because such experiments allow for shell growth under controlled conditions. Once these calibrations have been determined the next step, in a follow-up project, will be to generate long time-series records of past seawater temperature change in different parts of the North Atlantic Ocean. Such records then will further climate scientists understanding of the past and future evolution of climate in a geographical region which is of direct relevance to the UK and western Europe.

de Jager M.,Netherlands Institute for Sea Research
Proceedings. Biological sciences / The Royal Society | Year: 2014

Ecological theory uses Brownian motion as a default template for describing ecological movement, despite limited mechanistic underpinning. The generality of Brownian motion has recently been challenged by empirical studies that highlight alternative movement patterns of animals, especially when foraging in resource-poor environments. Yet, empirical studies reveal animals moving in a Brownian fashion when resources are abundant. We demonstrate that Einstein's original theory of collision-induced Brownian motion in physics provides a parsimonious, mechanistic explanation for these observations. Here, Brownian motion results from frequent encounters between organisms in dense environments. In density-controlled experiments, movement patterns of mussels shifted from Lévy towards Brownian motion with increasing density. When the analysis was restricted to moves not truncated by encounters, this shift did not occur. Using a theoretical argument, we explain that any movement pattern approximates Brownian motion at high-resource densities, provided that movement is interrupted upon encounters. Hence, the observed shift to Brownian motion does not indicate a density-dependent change in movement strategy but rather results from frequent collisions. Our results emphasize the need for a more mechanistic use of Brownian motion in ecology, highlighting that especially in rich environments, Brownian motion emerges from ecological interactions, rather than being a default movement pattern.

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