Prop J.,University of Groningen |
Oudman T.,NIOZ |
Van Spanje T.M.,Ripperdastraat 15 zwart |
Wolters E.H.,Allersmaweg 56
Ornis Norvegica | Year: 2013
This study explored patterns of predation by polar bear Ursus maritimus on the nests of Pink-footed Geese Anser brachyrhynchus on the coastal tundra stretch Nordenskiöldkysten, west coast of Spitsbergen, Svalbard. Goose nests occurred in densities of up to 126 nests/km2 (mean=6.4), at an average distance of 1.5 km from the seashore, and were mainly associated with greenstone outcrops. Open, flat areas were avoided for nesting. Goose pairs nested in colonies of up to 23 nests, with 50% of the pairs nesting in colonies larger than 5. In 2011 and 2012, polar bears invaded the Pink-footed Goose nesting area to consume goose eggs, a behaviour that they had not exhibited in previous years. Polar bears selectively visited the taller outcrops and locations with the larger number of goose nests. Moreover there was a steep gradient in predation from the seashore towards the inland, with no predation at distances greater than 1.8 km from the coastline. We expect that the predation pressure by polar bears will aggravate in the coming years when more bears learn to exploit the inland goose colonies.
News Article | February 5, 2016
Bar-tailed godwits under assault. The plight of migrating shorebirds as a consequence of rapid shoreline habitat loss in the Yellow Sea is well illustrated by these staging Bar-tailed Godwits roosting on an active dredge-dumping site on 20 April 2012. The material was being excavated from a channel to improve access to the Donggang Fishing Port, Liaoning Province. The infilled area is planned to be part of an industrial park to be built on an area of intertidal mudflat that was excised from the Yalujiang National Nature Reserve by a boundary adjustment in 2012. Credit: David S. Melville The shrinking of mudflats along the coasts of the Chinese Yellow Sea is an increasing problem for migratory birds that travel between Siberia and Australia. Research by an international team of ecologists, led by Spinoza laureate professor Theunis Piersma, a senior scientist at NIOZ Royal Netherlands Institute for Sea Research and professor in Global Flyway Ecology at the University of Groningen, shows that three different species are in decline because of one common factor: loss of food and habitat along the coasts of the Yellow Sea, because of the increasing claim of land by the Chinese government. The research, published in the Journal of Applied Ecology, involves three migratory bird species. The red knot (Calidris canutus piersmai) breeds on islands north of eastern Siberia. The great knot (Calidris tenuirostris) breeds in the alpine areas of north-eastern Siberia, and the bar-tailed godwit (Limosa lapponica menzbieri) breeds in the lower wetlands of north-eastern Siberia. All three of these species winter in Roebuck Bay, Western Australia. On their way between Asia and Australia they roost and refuel along the coasts of the Yellow Sea. Thanks to thousands of color ringed birds, and more than thirty thousand resightings of these birds, the ecologists were able to calculate the annual, as well as the seasonal survival of the three species between 2006 and 2013. The production of eggs and fledglings was no issue in that period. Also, the survival in their Australian wintering grounds was normal. However, from 2010 onwards, the survival showed a sharp decline in a period that included the spring and fall migration, as well as the breeding period. Because the snow melted relatively early on the breeding grounds in those years, there was no reason to believe that the survival was any different during that period. That left only one culprit: the conditions during migration along the Yellow Sea, where significant loss of habitat was going on because of land claim by the Chinese government. Previous research by the group of Piersma has shown that the survival of birds like the knot and the godwit is normally evenly spread across the year. Until 2010 this was also true for the knots and the godwits that roost along the shores of the Yellow Sea. The populations were stable. With the decline in survival in 2011 and 2012, however, the populations began to shrink. 'Should the survival continue to shrink like it did in these years, we'll see a decline in these populations to half within three or four years', Piersma predicts. 'Governments are usually not that keen on putting a halt on economic development in favour of nature and biodiversity, unless there is solid proof for negative effects on the environment', Piersma says. 'With this research, that was mainly funded by Birdlife Netherlands and WWF Netherlands, we delivered the proof that land claim around the Yellow Sea puts many migratory birds at risk.' More information: Theunis Piersma et al. Simultaneous declines in summer survival of three shorebird species signals a flyway at risk, Journal of Applied Ecology (2015). DOI: 10.1111/1365-2664.12582
Capet A.,National Institute of Oceanography and Applied Geophysics - OGS |
Capet A.,University of Liège |
Meysman F.J.R.,NIOZ |
Akoumianaki I.,James Hutton Institute |
And 2 more authors.
Ocean Modelling | Year: 2016
Three-dimensional (3D) ecosystem models of shelf environments should properly account for the biogeochemical cycling within the sea floor. However, a full and explicit representation of sediment biogeochemistry into 3D ocean models is computationally demanding. Here, we describe a simplified approach to include benthic processes in 3D ocean models, which includes a parameterization of the different pathways for organic matter mineralization and allows for organic matter remobilization by bottom currents and waves. This efficient approach enables decadal simulations that resolve the inertial contribution of the sea floor to the biogeochemical cycling in shelf environments. The model was implemented to analyze the benthic-pelagic coupling in the northwestern shelf of the Black Sea. Three distinct biogeochemical provinces were identified on the basis of fluxes and rates associated with benthic-pelagic coupling. Our model simulations suitably capture the seasonal variability of in situ flux data as well as their regional variation, which stresses the importance of incorporating temporally varying sediment biogeochemistry and resuspension/redeposition cycles in shelf ecosystem models. © 2016 Elsevier Ltd.
Smaal A.C.,Imares |
Schellekens T.,Imares |
van Stralen M.R.,MarinX |
Aquaculture | Year: 2013
In the Oosterschelde estuary, primary production has decreased by 50% in the last 15. years. Nutrient concentrations are low but primary production is nutrient limited only for short periods during the growing season. Dominant bivalve filter feeder stocks consist of mussels (Mytilus edulis), cockles (Cerastoderma edule) and the introduced Pacific oysters (Crassostrea gigas). The mussel stock, which is under control of the mussel farmers, has decreased due to shortage of mussel seed, cockle stocks have maintained and oysters have expanded. Total filtration capacity has increased, also due to the invasion of Ensis americanus.Bivalve growth and condition are food limited, as shown by a negative correlation between average mussel meat content and bivalve filter feeder stock size in a certain year. The annual growth of cockles has decreased, and the fraction picoplankton is now up to 30% of total phytoplankton. Food limitation, high filtration capacity, picoplankton abundance, and only short-term bottom-up control of primary production by nutrient limitation, point to overgrazing as a cause of primary production decline. Further expansion of shellfish stocks may induce the risk of overexploitation. © 2013 Elsevier B.V.
Clavier J.,Institut Universitaire de France |
Chauvaud L.,Institut Universitaire de France |
Carlier A.,Institut Universitaire de France |
Amice E.,Institut Universitaire de France |
And 4 more authors.
Aquatic Botany | Year: 2011
Community respiration and primary production were measured in a dense intertidal Zostera noltii bed on the Banc d'Arguin, Mauritania (West Africa) under aerial and submerged conditions. Metabolism was studied in situ in dark and transparent benthic chambers. CO2 fluxes in the air were measured over a series of short-term incubations (3min) using an infrared gas analyzer. Dissolved inorganic carbon fluxes were calculated from concentration changes during one-hour underwater incubations. Air and underwater irradiance levels were measured every minute throughout the experiments. Carbon respiration was lower in the air (2.2mmolm-2h-1) than underwater (5.0mmolm-2h-1); similarly, a production-irradiance model fitted to the data indicated that gross maximal photosynthetic rate was markedly lower during emergence (6.0mmolCm-2h-1) than under water (42.7mmolCm-2h-1). The δ13C values observed in shoots indicated a decrease in atmospheric CO2 contribution, compared to dissolved inorganic carbon, in Z. noltii metabolism along a depth gradient within a single location. As the seagrass bed remains under a thin layer of water at low tide at the studied site, the large difference in primary production can be mainly attributed to photosynthesis inhibition by high pH and oxygen concentration, as well as to the negative feedback of self-shading by seagrass leaves during emersion. The observed differences in respiration can be explained by the oxygen deficit at night during low tide near the sediment surface, a deficit that is consistent with the abundance of anoxia-tolerant species. © 2011 Elsevier B.V.
Hydro International | Year: 2013
KM3NeT is a future deep-sea research facility that will be built at depths between 2.5 and 5km in the Mediterranean Sea. The facility will host several hundreds of detection units, which are vertical mechanical structures that suspend very sensitive optical sensor modules. For this design, novel deployment methods were recently tested in the Ionian Sea (Eastern Mediterranean Sea). Eventually, some 10,000 optical modules distributed over about 600 detection units of 700m length and moored 100m apart will constitute a neutrino telescope (NeT) that occupies several cubic kilometres (km3). The array will also be used for unique oceanographic observations.
Hodell D.,University of Cambridge |
Lourens L.,University Utrecht |
Crowhurst S.,University of Cambridge |
Konijnendijk T.,University Utrecht |
And 4 more authors.
Global and Planetary Change | Year: 2015
We produced a composite depth scale and chronology for Site U1385 on the SW Iberian Margin. Using log(Ca/Ti) measured by core scanning XRF at 1-cm resolution in all holes, a composite section was constructed to 166.5meter composite depth (mcd) that corrects for stretching and squeezing in each core. Oxygen isotopes of benthic foraminifera were correlated to a stacked δ18O reference signal (LR04) to produce an oxygen isotope stratigraphy and age model.Variations in sediment color contain very strong precession signals at Site U1385, and the amplitude modulation of these cycles provides a powerful tool for developing an orbitally-tuned age model. We tuned the U1385 record by correlating peaks in L* to the local summer insolation maxima at 37°N. The benthic δ18O record of Site U1385, when placed on the tuned age model, generally agrees with other time scales within their respective chronologic uncertainties.The age model is transferred to down-core data to produce a continuous time series of log(Ca/Ti) that reflect relative changes of biogenic carbonate and detrital sediment. Biogenic carbonate increases during interglacial and interstadial climate states and decreases during glacial and stadial periods. Much of the variance in the log(Ca/Ti) is explained by a linear combination of orbital frequencies (precession, tilt and eccentricity), whereas the residual signal reflects suborbital climate variability. The strong correlation between suborbital log(Ca/Ti) variability and Greenland temperature over the last glacial cycle at Site U1385 suggests that this signal can be used as a proxy for millennial-scale climate variability over the past 1.5. Ma.Millennial climate variability, as expressed by log(Ca/Ti) at Site U1385, was a persistent feature of glacial climates over the past 1.5Ma, including glacial periods of the early Pleistocene ('41-kyr world') when boundary conditions differed significantly from those of the late Pleistocene ('100-kyr world'). Suborbital variability was suppressed during interglacial stages and enhanced during glacial periods, especially when benthic δ18O surpassed ~3.3-3.5‰. Each glacial inception was marked by appearance of strong millennial variability and each deglaciation was preceded by a terminal stadial event. Suborbital variability may be a symptomatic feature of glacial climate or, alternatively, may play a more active role in the inception and/or termination of glacial cycles. © 2015 The Authors.
Wang Z.B.,Technical University of Delft |
Hoekstra P.,University Utrecht |
Burchard H.,Leibniz Institute for Baltic Sea Research |
Ridderinkhof H.,NIOZ |
And 2 more authors.
Ocean and Coastal Management | Year: 2012
The Wadden Sea and its associated barrier island system exhibit highly dynamic behaviour. Of major concern is the movement of water and air and the transport, erosion and deposition of sand and mud. These processes result in an ever-changing morphology (topography/bathymetry) of the islands, tidal channels, inter-tidal shoals and tidal flats. This dynamic development of the shape and nature of the Wadden area forms together with the biotic systems, the present Wadden system. The morphodynamic development of the Wadden Sea is influenced by changing environmental conditions e.g. sea-level rise as well as by human interferences. For the management and protection of the Wadden system knowledge on the morphodynamic development is essential. However, our present knowledge is not sufficient to predict the effects of human interferences under different climate change scenarios in sufficient detail and accuracy. This paper identifies the existing knowledge gaps, based on a review of the state of the art on morphodynamics of the Wadden Sea that is confronted with major requirements from a coastal zone management point of view. The identified knowledge gaps have to inspire and stimulate research in the fields of the large-scale sediment budgets, morphodynamic changes at smaller scales, processes and mechanisms of sediment transport, erosion and deposition and modelling tools. © 2012 Elsevier Ltd.
News Article | February 1, 2017
The carbon dioxide in the air acidifies the oceans, and this acidification is believed to negatively affect shellfish and corals. However, new research suggests that unicellular shellfish can create better shells thanks to the more acidic environment. Prior to this study, researchers believed that shellfish and corals find it harder to survive, because the process of chalk formation is more difficult in acidic seawater. The research, published Jan. 27, in the journal Nature Communications, was conducted by scientists at the Royal Dutch Institute for Sea Research (NIOZ) and the Japanese Agency of Marine-Earth Science and Technology (JAMSTEC). The team concluded, after having conducted a series of experiments, that the ocean acidification could make the shellfish shells even more vigorous. The tiny shellfish are formed from one single cell and exist in large numbers in the seawater. However, since the acidity levels of the ocean have inflated by 30 percent since 1750, scientists were concerned about the well-being of these ocean creatures. "Ongoing ocean acidification is widely reported to reduce the ability of calcifying marine organisms to produce their shells and skeletons. Whereas increased dissolution due to acidification is a largely inorganic process, strong organismal control over biomineralization influences calcification and hence complicates predicting the response of marine calcifyers," noted the research. The theory supporting the scientific concern regarding shellfish and their capacity to form their shells under acidic water is based on the chemical interaction of the elements involved in this process. Limestone, which is made of calcium carbonate, will dissolve more easily in acidic water, which implies that less carbonate will be available for shellfish. As part of the experiments carried out in the study, the foraminifera regulated the acidity at a micro level; the acidity was significantly lower in those parts where shell formation took place compared to the rest of the seawater. Foraminifera produce large quantities of hydrogen ions through their cell walls, which leads to a higher acidity level in the near micro-environment. "Our physical model for calcification shows the dependence of foraminiferal biomineralization on the various inorganic carbon species present in seawater. We validate the importance of pH regulation on the foraminiferal calcification by application of a V-type H+ ATPase inhibitor, which plays a key role in aragonite production in scleractinian corals," also noted the research. This chemical reaction leads to an increase in the level of carbon dioxide at the expense of the carbonate. When this happens, the organisms immediately absorb the higher concentration of carbon dioxide through their cell walls, creating a lower acidity level on the inner side of the wall. Once this process is complete, the carbon dioxide is turned into carbonate once again, reacting with the existing calcium to form the lime. "Such an active biochemical regulation mechanism has never been found before," noted Lennart de Nooijer, NIOZ researcher and shared first author of the research. According to the scientists, future research could be carried out as an attempt to validate the connection between the formation of carbon dioxide and its consequences on global warming. If most of the organisms can go through the same process as the foraminifera in the research, the concentration of dissolved carbon dioxide in the oceans would grow, which would conflict with the water's ability to absorb the existing carbon dioxide in the air. Should this hypothesis be confirmed, this adaptive mechanism would speed up global warming. © 2017 Tech Times, All rights reserved. Do not reproduce without permission.
News Article | January 14, 2016
"They are two males," said Jan Boon from the Royal Netherlands Institute for Sea Research (NIOZ), which is based on the northern Dutch island of Texel where the whales washed up. One was found near the Texel port in front of NIOZ's buildings in the village of 't Hoorntje, while the other became stranded further to the north. "The one I've seen here in the south has unfortunately been dead already for some time," Boon told AFP. "There's blood, it's mouth is open," he said. The two whales and the five others that died on Wednesday after floundering ashore late Tuesday are "probably from the same pod of six whales" that came ashore in Germany earlier this week. Sperm whale beachings in the Netherlands are relatively rare with one incident annually between 2011 and 2014, while four whales beached in 2004 and five in 1997. "A group like this is even rarer," said Boon, adding the North Sea is too shallow for the large, deep-diving animals. The sperm whale is the largest of the toothed whales, and the largest toothed predator. It can measure up to 20 metres (67 feet) long and weigh over 50 tonnes.