Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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    Non-aureus staphylococci species in the teat canal and milk in four commercial swiss dairy herds
    Traversari, Julia ; Borne, Bart H.P. Van Den; Dolder, Claudio ; Thomann, Andreas ; Perreten, Vincent ; Bodmer, Michèle - \ 2019
    Frontiers in Veterinary Science 6 (2019)JUN. - ISSN 2297-1769
    Intramammary infection - Mastitis - Non-aureus staphylococci - Species distribution - Teat canal

    Non-aureus staphylococci (NAS) are frequently found in milk samples as well as on the teat apex and in the teat canal and are known to be a cause of subclinical mastitis. The objective of this study was to investigate the relationship between NAS species colonizing the teat canal and those causing intramammary infection (IMI) in four commercial dairy herds. Teat canal swabs were obtained and thereafter milk samples were aseptically collected and evaluated for the presence of staphylococci using selective agar plates. Species identification was performed using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. The relationship between NAS species distribution and sample type (teat canal vs. milk samples) was quantified using hierarchical multivariable logistic regression models. The most prevalent NAS species in teat canal swabs were S. xylosus (35%), S. vitulinus (10%), and S. chromogenes (7%), whereas in milk samples S. chromogenes (5%), S. xylosus (5%), and S. haemolyticus (4%) were most prevalent. There were significantly higher odds for S. vitulinus (OR = 215), S. xylosus (OR = 20), S. sciuri (OR = 22), S. equorum (OR = 13), and S. succinus (OR = 10) to be present in teat canal swabs than in milk samples. Differences between herds in NAS species distribution were found and were most pronounced for S. succinus and a S. warneri-like species. This information aids in the understanding of NAS species as an etiology of IMI and should be taken into account when interpreting milk culture results.

    Rainfall seasonality and drought performance shape the distribution of tropical tree species in Ghana
    Amissah, Lucy ; Mohren, Godefridus M.J. ; Kyereh, Boateng ; Agyeman, Victor K. ; Poorter, Lourens - \ 2018
    Ecology and Evolution 8 (2018)16. - ISSN 2045-7758 - p. 8582 - 8597.
    Drought - Dry forest - Physiology - Species distribution - Tropical forest - Wet forest

    Tree species distribution in lowland tropical forests is strongly associated with rainfall amount and distribution. Not only plant water availability, but also irradiance, soilfertility, and pest pressure covary along rainfall gradients. To assess the role of wateravailability in shaping species distribution, we carried out a reciprocal transplantingexperiment in gaps in a dry and a wet forest site in Ghana, using 2,670 seedlings of23 tree species belonging to three contrasting rainfall distributions groups (dry species, ubiquitous species, and wet species). We evaluated seasonal patterns in climaticconditions, seedling physiology and performance (survival and growth) over a 2-yearperiod and related seedling performance to species distribution along Ghana's rainfall gradient. The dry forest site had, compared to the wet forest, higher irradiance,and soil nutrient availability and experienced stronger atmospheric drought (2.0 vs.0.6 kPa vapor pressure deficit) and reduced soil water potential (-5.0 vs.-0.6 MPasoil water potential) during the dry season. In both forests, dry species showed significantly higher stomatal conductance and lower leaf water potential, than wet species, and in the dry forest, dry species also realized higher drought survival andgrowth rate than wet species. Dry species are therefore more drought tolerant, andunlike the wet forest species, they achieve a home advantage. Species drought performance in the dry forest relative to the wet forest significantly predicted speciesposition on the rainfall gradient in Ghana, indicating that the ability to grow and survive better in dry forests and during dry seasons may allow species to occur in lowrainfall areas. Drought is therefore an important environmental filter that influencesforest composition and dynamics. Currently, many tropical forests experience increase in frequency and intensity of droughts, and our results suggest that this maylead to reduction in tree productivity and shifts in species distribution.

    Distribution of the invasive Caprella mutica Schurin, 1935 and native Caprella linearis (Linnaeus, 1767) on artificial hard substrates in the North Sea : Separation by habitat
    Coolen, Joop W.P. ; Lengkeek, Wouter ; Degraer, Steven ; Kerckhof, Francis ; Kirkwood, Roger J. ; Lindeboom, Han J. - \ 2016
    Aquatic Invasions 11 (2016)4. - ISSN 1798-6540 - p. 437 - 449.
    Artificial reefs - Habitat suitability modelling - Invasive species - Oil and gas - Shipwrecks - Species distribution - Wind farms

    Studying offshore natural and artificial hard substrates in the southern North Sea (51ºN–57ºN/1ºW–9ºE), the invasive introduced Japanese skeleton shrimp Caprella mutica Schurin, 1935 was found to co-exist with the native Caprella linearis (Linnaeus, 1767) only on near-shore locations that had an intertidal zone (e.g., wind farm foundations). In contrast, on far offshore and strictly subtidal locations, such as shipwrecks and rocky reefs, only C. linearis was found. Based on these exploratory observations, we hypothesised that artificial structures that are only subtidal are inhabited exclusively by C. linearis, and never by C. mutica. To test this hypothesis and understand factors driving each species’ habitat preferences, habitat suitability models were constructed using generalised additive models, based on samples collected in 2013–2015 from offshore gas platforms, buoys, shipwrecks, and rocky reefs and combined with data from other published and unpublished surveys (2001–2014). The models showed that the presence of C. mutica is explained by the availability of intertidal and floating hard substrates, suspended particulate matter density (SPM), mean annual sea surface temperature, salinity, and current velocity. The C. linearis model included subtidal hard substrates, SPM, salinity, temperature, and current velocity. The modelled distributions showed a significant difference, demonstrating that C. linearis’ habitat preference does not fully overlap with that of C. mutica. Thus, the native and alien Caprella species are likely to be able to co-exist in the North Sea.

    Harbour porpoise movement strategy affects cumulative number of animals acoustically exposed to underwater explosions
    Aarts, Geert ; Benda-Beckmann, Alexander M. Von; Lucke, K. ; Özkan Sertlek, H. ; Bemmelen, Rob Van; Geelhoed, Steve C.V. ; Brasseur, Sophie ; Scheidat, Meike ; Lam, Frans Peter A. ; Slabbekoorn, Hans ; Kirkwood, Roger - \ 2016
    Marine Ecology Progress Series 557 (2016). - ISSN 0171-8630 - p. 261 - 275.
    Acoustics - Anthropogenic sound - Cumulative effects - Impact assessment - Individual-based model - Marine mammals - Population consequences of disturbance - Species distribution

    Anthropogenic sound in the marine environment can have negative consequences for marine fauna. Since most sound sources are intermittent or continuous, estimating how many individuals are exposed over time remains challenging, as this depends on the animals' mobility. Here we explored how animal movement influences how many, and how often, animals are impacted by sound. In a dedicated study, we estimated how different movement strategies affect the number of individual harbour porpoises Phocoena phocoena receiving temporary or permanent hearing loss due to underwater detonations of recovered explosives (mostly WWII aerial bombs). Geo-statistical distribution models were fitted to data from 4 marine mammal aerial surveys and used to simulate the distribution and movement of porpoises. Based on derived dose-response thresholds for temporary (TTS) or permanent threshold shifts (PTS), we estimated the number of animals affected in a single year. When individuals were free-roaming, an estimated 1200 and 24 000 unique individuals would suffer PTS and TTS, respectively. This equates to respectively 0.50 and 10% of the estimated North Sea population. In contrast, when porpoises remained in a local area, fewer animals would receive PTS and TTS (1100 [0.47%] and 15 000 [6.5%], respectively), but more individuals would be subjected to repeated exposures. Because most anthropogenic sound-producing activities operate continuously or intermittently, snapshot distribution estimates alone tend to underestimate the number of individuals exposed, particularly for mobile species. Hence, an understanding of animal movement is needed to estimate the impact of underwater sound or other human disturbance.

    Impact on bird fauna of a non-native oyster expanding into blue mussel beds in the Dutch Wadden Sea
    Waser, Andreas M. ; Deuzeman, Symen ; Kangeri, Arno K.W. ; Winden, Erik van; Postma, Jelle ; Boer, Peter de; Meer, Jaap van der; Ens, Bruno J. - \ 2016
    Biological Conservation 202 (2016). - ISSN 0006-3207 - p. 39 - 49.
    Crassotrea gigas - Habitat complexity - Mytilus edulis - Oyster reef - Shorebirds - Species distribution

    Intertidal mussel beds are important for intertidal ecosystems, because they feature a high taxonomic diversity and abundance of benthic organisms and are important foraging grounds for many avian species. After the introduction of the Pacific oyster (Crassostrea gigas) into the European Wadden Sea, many mussel beds developed into oyster dominated bivalve beds. Despite the fact that oysters have been colonizing many European intertidal areas for about two decades, their impact on the ecosystem is still poorly understood. Here, we investigated the impact of oysters on the condition of mussels and on the spatial distribution of birds on 18 bivalve beds with different grades of oyster occurrence throughout the Dutch Wadden Sea. Moreover, in comparing bird densities on bivalve beds with densities expected on the total intertidal area, we could detect which species exhibit a preference for the structured habitat. Overall, 50 different bird species were observed on the beds, of which about half regularly frequent intertidal flats. Most of these species showed a preference for bivalve beds. The condition of mussels decreased with the oyster dominance, whereas the majority of bird species was not affected by the oyster occurrence. However, three of the four species that were negatively affected depend on intertidal mussels as food source. Even though the Pacific oyster is a nonnative species, attempts to fight it may do more harm to avian biodiversity than good.

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