Are white-beaked dolphins Lagenorhynchus albirostris food specialst? Their diet in the southern North Sea

The white-beaked dolphin Lagenorhynchus albirostris is the most numerous cetacean after the harbour porpoise Phocoena phocoena in the North Sea, including Dutch coastal waters. In this study, the diet of 45 white-beaked dolphins stranded on the Dutch coast between 1968 and 2005 was determined by analysis of stomach contents. Although 25 fish species were identified, the diet was dominated by Gadidae (98.0% by weight, 40.0% in numbers), found in all stomachs. All other prey species combined contributed little to the diet by weight (2.0%W). The two most important prey species were whiting Merlangius merlangus (91.1% frequency of occurrence (FO), 30.5%N, 37.6%W) and cod Gadus morhua (73.3%FO, 7.4%N, 55.9%W). In numbers, gobies were most common (54.6%N), but contributed little to the diet by weight (0.6%W). Three stomachs contained different prey compared to the others: one animal had taken 2250 gobies, accounting for 96.4% of all gobies found; one animal had fed on 29 small sepiolids; and one animal had solely taken haddock Melanogrammus aeglefinus. Squid and haddock were not found in any other stomach. The overall diet showed a lasting predominance of whiting and cod, without clear changes over time (35 years) or differences between sexes or size-classes of dolphins. This study adds to earlier published and unpublished data for Dutch coastal waters and agrees well with studies of white-beaked dolphins from other parts of the species’ range, in the North Sea and in Canadian waters, with Gadidae dominating the diet on both sides of the Atlantic

Fishing for food : feeding ecology of harbour porpoises Phocoena phocoena and white-beaked dolphins Lagenorhynchus albirostris in Dutch waters

Harbour porpoises and white-beaked dolphins are the most common small cetaceans in the North Sea and Dutch coastal waters. The distribution and relative abundance of harbour porpoises and white-beaked dolphins from the Dutch coastal waters has changed significantly over the past decades. This thesis describes the past and present feeding ecology of these two species in Dutch coastal waters and investigates whether changes in abundance and relative distribution of porpoises reflect changes in their foodbase. For porpoises, three techniques for dietary analyses were combined, including stomach contents-, stable isotope- and fatty acid analysis, providing the most detailed description of their diet in time and space, elucidating differences between their short- and longer term diet. Stable isotope analysis (δ13C and δ15N) were carried out in bone and muscle samples collected from porpoises stranded along the Dutch coast. Muscle δ15N values revealed that neonatal enrichment occurred and that larger porpoises, in particular males, seem to feed on lower trophic level species, compared to smaller individuals. Also bone δ15N values show that larger animals had fed on lower trophic levels in distant times. Seasonal variation in bone δ15N and δ13C values revealed two distinct groups of porpoises along the Dutch coast, a winter group (mainly males) that migrated from neighbouring regions and a Dutch subpopulation in summer (Chapter 2). To assess the contribution of prey species to the porpoises’ diet, stable isotope analysis in both porpoise muscle and prey were carried out. With the use of a mixing model (Stable Isotope Analysis in R, SIAR), we revealed that 70-83% of the diet of porpoises consisted mainly of poor cod, mackerel, greater sandeel lesser sandeel, sprat and gobies. This highlights a higher importance of pelagic, schooling species in the porpoises’ diet compared to stomach contents, where 90.5% of the diet consisted of gobies, whiting, lesser sandeel, herring, cod and sprat. Porpoises thus also feed offshore on pelagic, schooling species, while they feed closer to shore on more benthic and demersal species shortly before they strand. This could be due to the distribution of prey species as well as differences in behaviour of porpoises and their prey between the coastal zone and offshore waters (Chapter 3). The use of Quantitative Fatty Acid Analysis (QFASA) showed that the diet of porpoises consisted mainly of gobies, mackerel, smelt, herring and dragonet, pointing towards profound differences between the diet as estimated by QFASA and as deduced from stomach contents. This study revealed that the longer term diet of porpoises in Dutch coastal waters consists both of coastal species (e.g. gobies, smelt and dragonet) and also pelagic, schooling species (e.g. mackerel and herring). The results also brought to dawn possible methodological problems in using QFASA for porpoise diet estimation, emphasizing the importance of applying different dietary analysis techniques when studying marine mammal diets and the need for controlled feeding experiments in order to improve the interpretation of dietary analysis results (Chapter 5). Besides new insights in the feeding ecology of porpoises, stable isotope analysis also elicited a non-food related conservation ecology issue. Distinct δ13C values in muscle of porpoises stranded in the Eastern Scheldt revealed that these porpoises foraged there for a longer period. This distinct δ13C signature of animals from the Eastern Scheldt was not observed in bone tissue, which suggests a relatively recent shift in habitat use rather than life-long residency of porpoises within the Eastern Scheldt. The high number of strandings within the Eastern Scheldt revealed a higher mortality rate compared to the Dutch coastal zone, indicating that along with other changes in the physical environment, the building of the storm surge barrier may play an important role in determining the residency of porpoises in the Eastern Scheldt, and that the area might act as an ecological trap for porpoises entering it. This is an example of the impact on marine species due to protection structures that emerge and respectively increase worldwide in response to the effects of global warming and climate change. It highlights that even semi-open structures, which are meant to ameliorate habitat loss, degradation and fragmentation, may still affect the abundance and distribution of migratory marine mammal species (Chapter 4). The analysis of stomach contents of white-beaked dolphins showed that their diet was dominated by Gadidae. All other prey species combined contributed little to the diet by weight. The two most important prey species based in weight were whiting and cod. In numbers, gobies were most common, but these contributed little to the diet by weight. The overall diet showed a lasting predominance of whiting and cod, without clear changes over time (35 years) or differences between sexes or size-classes of dolphins and revealed that white-beaked dolphins in the south-eastern North Sea are specialist feeders, with a strong preference for whiting and cod (Chapter 6). Stomach contents of juvenile white-beaked dolphins in our study revealed that at the age of about 1.5 years old, they had started feeding on solid food by taking a variety of small fish and invertebrate prey, mostly shrimp and squid. Immatures in our study, estimated to be 2-4 years old, still take small prey, including small gadoids, but also take larger gadoids. Calves apparently gradually learn to eat big fish by taking prey that is much smaller than those normally taken by their mothers. This study illustrates novel techniques for diet estimation to reconstruct sizes of shrimp and whiting from tail flaps and eye lenses, respectively (Chapter 7). Most dietary studies on porpoises and white-beaked dolphins are deduced from stomach contents. This thesis has demonstrated that using indirect methods for studying the feeding ecology of marine mammals is a valuable addition to the more direct approach using stomach contents. It supports the need for multi-method approaches because by using only one technique, key prey species in the predator-prey relation may be missed or underestimated. Future ecological and fishery impact assessment studies and management decisions for the conservation of porpoises and white-beaked dolphins should acknowledge a difference between their long- and short-term diet. Large improvement in the interpretation of the results from diet analyses can be established either by controlled feeding experiments with animals in captivity or by studies that help to understand the common principals in dietary analyses (e.g. digestion rates, turnover rates of tissues, tissue-dependent isotopic fractionation between predator and prey and lipid metabolism within the animal) and variation of these between species.</p

Harbour porpoises Phocoena phocoena in the Eastern Scheldt: A resident Stock or trapped by a storm surge barrier?

Coastal protection measures are planned and executed worldwide to combat the effects of global warming and climate change, in particular the acceleration of sea level rise, higher storm surge flooding and extensive coastal inundation. The extent to which these defensive measures may impact coastal and estuarine ecosystems is still poorly understood. Since the building of a storm surge barrier, movement of harbour porpoises Phocoena phocoena in and out of the Eastern Scheldt tidal bay (SW-Netherlands) may be limited. To measure residency, porpoises stranded along the Dutch North Sea coast between 2006 and 2008 were sampled for muscle (n = 102) and bone tissue (n = 118), of which 9 muscle (8.8%) and 12 bone samples (10.2%) were collected from animals stranded within the Eastern Scheldt. Stable carbon (d13C) was analysed to get insight into the habitat use and residency of porpoises in the Eastern Scheldt. Our data showed significantly higher d13C values in the muscle of porpoises stranded within the Eastern Scheldt (µ = -17.7‰, SD = 0.4‰) compared to animals stranded along the Dutch coast (µ = -18.3‰, SD = 0.5‰). This suggests that most porpoises stranded in the Eastern Scheldt foraged there for a longer period. The distinct d13C signature of animals from the Eastern Scheldt was not observed in bone tissue, suggesting a relatively recent shift in habitat use rather than life-long residency of porpoises within the Eastern Scheldt. The high number of strandings within the Eastern Scheldt suggests a higher mortality rate compared to the Dutch coastal zone. Our study indicates that along with other changes in the physical environment, the storm surge barrier may play an important role in determining the residency of porpoises in the Eastern Scheldt, and that the area might act as an ecological trap for porpoises entering it

Percutaneous vertebroplasty is not a risk factor for new osteoporotic compression fractures: results from VERTOS II

Background and purpose: Pv is increasingly used as treatment for osteoporotic vcfs. However, controversy exists as to whether pv increases the risk for new vcfs during follow-up. The purpose of our research was to assess the incidence of new vcfs in patients with acute vcfs randomized to pv and conservative therapy. Materials and methods: Vertos ii is a prospective multicenter randomized controlled trial comparing pv with conservative therapy in 202 patients. Incidence, distribution, and timing of new vcfs during follow-up were assessed from spine radiographs. In addition, further height loss during follow-up of treated vcfs was measured. Results: After a mean follow-up of 11.4 Months (Median, 12.0; Range, 1-24 months), 18 New vcfs occurred in 15 of 91 patients after pv and 30 new vcfs in 21 of 85 patients after conservative therapy. This difference was not significant (P = .44). There was no higher fracture risk for adjacent-versus-distant vertebrae. Mean time to new vcf was 16.2 Months after pv and 17.8 Months after conservative treatment (Logrank, p = .45). The baseline number of vcfs was the only risk factor for occurrence (Or, 1.43; 95% Ci, 1.05-1.95) And number (P = .01) Of new vcfs. After conservative therapy, further height loss of treated vertebrae occurred more frequently (35 Of 85 versus 11 of 91 patients, p < .001) And was more severe (P < .001) Than after pv. Conclusions: Incidence of new vcfs was not different after pv compared with conservative therapy after a mean of 11.4 Months' follow-up. The only risk factor for new vcfs was the number of vcfs at baseline. Pv contributed to preservation of stature by decreasing both the incidence and severity of further height loss in treated vertebrae

Magnetoresistance and electronic structure of asymmetric GaAs/AlGaAs double quantum wells in the in-plane/tilted magnetic field

Bilayer two-dimensional electron systems formed by a thin barrier in the GaAs buffer of a standard heterostructure were investigated by magnetotransport measurements. In magnetic fields oriented parallel to the electron layers, the magnetoresistance exhibits an oscillation associated with the depopulation of the higher occupied subband and the field-induced transition into a decoupled bilayer. Shubnikov-de Haas oscillations in slightly tilted magnetic fields allow to reconstruct the evolution of the electron concentration in the individual subbands as a function of the in-plane magnetic field. The characteristics of the system derived experimentally are in quantitative agreement with numerical self-consistent-field calculations of the electronic structure.Comment: 6 pages, 5 figure

Generating Sustainable Value from Open Data in a Sharing Society

Part 1: Creating ValueInternational audienceOur societies are in the midst of a paradigm shift that transforms hierarchal markets into an open and networked economy based on digital technology and information. In that context, open data is widely presumed to have a positive effect on social, environmental and economic value; however the evidence to that effect has remained scarce. Subsequently, we address the question how the use of open data can stimulate the generation of sustainable value. We argue that open data sharing and reuse can empower new ways of generating value in the sharing society. Moreover, we propose a model that describes how different mechanisms that take part within an open system generate sustainable value. These mechanisms are enabled by a number of contextual factors that provide individuals with the motivation, opportunity and ability to generate sustainable value

Correlation of gene expression with magnetic resonance imaging features of retinoblastoma: a multi-center radiogenomics validation study.

To validate associations between MRI features and gene expression profiles in retinoblastoma, thereby evaluating the repeatability of radiogenomics in retinoblastoma. In this retrospective multicenter cohort study, retinoblastoma patients with gene expression data and MRI were included. MRI features (scored blinded for clinical data) and matched genome-wide gene expression data were used to perform radiogenomic analysis. Expression data from each center were first separately processed and analyzed. The end product normalized expression values from different sites were subsequently merged by their Z-score to permit cross-sites validation analysis. The MRI features were non-parametrically correlated with expression of photoreceptorness (radiogenomic analysis), a gene expression signature informing on disease progression. Outcomes were compared to outcomes in a previous described cohort. Thirty-six retinoblastoma patients were included, 15 were female (42%), and mean age was 24 (SD 18) months. Similar to the prior evaluation, this validation study showed that low photoreceptorness gene expression was associated with advanced stage imaging features. Validated imaging features associated with low photoreceptorness were multifocality, a tumor encompassing the entire retina or entire globe, and a diffuse growth pattern (all p &lt; 0.05). There were a number of radiogenomic associations that were also not validated. A part of the radiogenomic associations could not be validated, underlining the importance of validation studies. Nevertheless, cross-center validation of imaging features associated with photoreceptorness gene expression highlighted the capability radiogenomics to non-invasively inform on molecular subtypes in retinoblastoma. Radiogenomics may serve as a surrogate for molecular subtyping based on histopathology material in an era of eye-sparing retinoblastoma treatment strategies. • Since retinoblastoma is increasingly treated using eye-sparing methods, MRI features informing on molecular subtypes that do not rely on histopathology material are important. • A part of the associations between retinoblastoma MRI features and gene expression profiles (radiogenomics) were validated. • Radiogenomics could be a non-invasive technique providing information on the molecular make-up of retinoblastoma

Search for direct production of charginos and neutralinos in events with three leptons and missing transverse momentum in √s = 7 TeV pp collisions with the ATLAS detector

A search for the direct production of charginos and neutralinos in final states with three electrons or muons and missing transverse momentum is presented. The analysis is based on 4.7 fb−1 of proton–proton collision data delivered by the Large Hadron Collider and recorded with the ATLAS detector. Observations are consistent with Standard Model expectations in three signal regions that are either depleted or enriched in Z-boson decays. Upper limits at 95% confidence level are set in R-parity conserving phenomenological minimal supersymmetric models and in simplified models, significantly extending previous results