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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    Quantifying harbor porpoises foraging behavior in CPOD data
    Bergès, Benoît ; Scheidat, Meike ; Geelhoed, Steve ; Tougaard, Jakob - \ 2019
    Quantifying harbour porpoise foraging behaviour in CPOD data: identification, automatic detection and potential application
    Berges, B.P.J. ; Geelhoed, S.C.V. ; Scheidat, M. ; Tougaard, J. - \ 2019
    IJmuiden : Wageningen Marine Research (Wageningen Marine Research report C039/19) - 41
    Harbour porpoises (Phocoena phocoena) are regularly monitored to assess how they are impacted by the construction and operation of offshore wind farms. A suitable method to do this is passive acoustic monitoring (PAM), and in particular using specific stationary hydrophones called CPODs. These devices provide information on click activity, which can then be analysed to investigate habitat use over time, differences between areas and the impact of human activities. Due to their small size and high metabolism porpoises are thought to need a more or less constant supply of prey to survive. Prey occurrence is thus considered one of the main drivers in porpoise distribution. And successful feeding is vital to the fitness and survival of individual porpoises. Information on foraging behaviour, however, is difficult to obtain in the field, in particular as animals feed under water. Recently the tagging of animals has provided new insights into porpoise behaviour, but it has been done for a limited number of individuals and for short times only. CPOD data have been used in Dutch waters to monitor harbour porpoise habitat use and behaviour before, during and after the construction of wind farms. The analyses have focussed on using a number of parameters that can be derived from the data, such as porpoise positive minutes, hours or days, encounter and waiting times. From other studies, primarily in captivity, we know that during foraging porpoises produce a characteristic pattern of clicks, starting with an approach phase and ending with a so-called “terminal buzz”. Aim of our study was to investigate if we could quantify foraging behaviour from CPOD data, and we were able to use an existing data set of harbour porpoise click activity from the Gemini wind park (June 2015 to February 2016). The study consisted of three phases. First, the different existing methods were applied to a sample set of data to determine the most suitable approach to identify foraging behaviour. The results indicate that re-classification of clicks following the method developed by Pirotta (2014 a,b) to identify terminal buzzes provides the best results. Second, an algorithm was written to allow the automated analyses of CPOD data following this method. Finally, this analytical tool was applied to the Gemini wind park data to explore the potential applications of this method. The results show that foraging events could be determined in sufficient numbers to detect patterns over time, such as diel patterns, as well as to compare differences between stations. We propose that this tool is applied to a larger dataset to investigate: 1) how porpoises use existing wind parks during the operational phase, 2) if and at what scale anthropogenic activities (such as construction work) impact foraging behaviour and 3) how foraging behaviour is linked to environmental parameters, including prey occurrence. This study was funded through the WOZEP project and the data were provided by Gemini Windpark
    Impacts of underwater noise on marine vertebrates : Project introduction and first results
    Liebschner, Alexander ; Seibel, Henrike ; Teilmann, Jonas ; Wittekind, Dietrich ; Parmentier, Eric ; Dähne, Michael ; Dietz, Rune ; Driver, Jörg ; Elk, Cornelis van; Everaarts, Eligius ; Findeisen, Henning ; Kristensen, Jacob ; Lehnert, Kristina ; Lucke, Klaus ; Merck, Thomas ; Müller, Sabine ; Pawliczka, Iwona ; Ronnenberg, Katrin ; Rosenberger, Tanja ; Ruser, Andreas ; Tougaard, Jakob ; Schuster, Max ; Sundermeyer, Janne ; Sveegaard, Signe ; Siebert, Ursula - \ 2016
    In: The Effects of Noise on Aquatic Life II Springer New York LLC (Advances in Experimental Medicine and Biology ) - ISBN 9781493929801 - p. 631 - 636.
    Auditory evoked potential - Noise logger - Stress - Tagging - Temporary threshold

    The project conducts application-oriented research on impacts of underwater noise on marine vertebrates in the North and Baltic Seas. In distinct subprojects, the hearing sensitivity of harbor porpoises and gray seals as well as the acoustic tolerance limit of harbor porpoises to impulsive noise from pile driving and stress reactions caused by anthropogenic noise is investigated. Animals are equipped with DTAGs capable of recording the actual surrounding noise field of free-swimming harbor porpoises and seals. Acoustic noise mapping including porpoise detectors in the Natura 2000 sites of the North and Baltic Seas will help to fully understand current noise impacts.

    Development of a model to assess masking potential for marine mammals by the use of air guns in Antarctic waters
    Wittekind, Dietrich ; Tougaard, Jakob ; Stilz, Peter ; Dähne, Michael ; Clark, Christopher W. ; Lucke, K. ; Benda-Beckmann, Sander von; Ainslie, Michael A. ; Siebert, Ursula - \ 2016
    In: The Effects of Noise on Aquatic Life II Springer New York LLC (Advances in Experimental Medicine and Biology ) - ISBN 9781493929801 - p. 1243 - 1249.
    Mysticetes - Pinnipeds - Propagation modeling - Seismic

    We estimated the long-range effects of air gun array noise on marine mammal communication ranges in the Southern Ocean. Air gun impulses are subject to significant distortion during propagation, potentially resulting in a quasi- continuous sound. Propagation modeling to estimate the received waveform was conducted. A leaky integrator was used as a hearing model to assess communication masking in three species due to intermittent/continuous air gun sounds. Air gun noise is most probably changing from impulse to continuous noise between 1,000 and 2,000 km from the source, leading to a reduced communication range for, e.g., blue and fin whales up to 2,000 km from the source.

    Assessment of the Effects of the Offshore wind Farm Egmond aan Zee (OWEZ) for Harbour Porpoise (comparison T0 and T1)
    Scheidat, M. ; Aarts, G.M. ; Bakker, A.G. ; Brasseur, S.M.J.M. ; Carstensen, J. ; Leeuwen, P.W. van; Leopold, M.F. ; Polanen-Petel, T. van; Reijnders, P.J.H. ; Teilmann, J. ; Tougaard, J. ; Verdaat, J.P. - \ 2012
    IJmuiden : IMARES (Report / Offshore Wind Farm Egmond aan Zee OWEZ_R_253_T1_20120202) - 64
    phocoena - windmolenpark - phocoena - wind farms
    The aim of this study was to investigate whether the Offshore Wind farm Egmond aan Zee (OWEZ) has influenced the occurrence of harbour porpoises.
    Harbour porpoises (Phocoena phocoena) and wind farms: a case study in the Dutch North Sea
    Scheidat, M. ; Tougaard, J. ; Brasseur, S.M.J.M. ; Carstensen, J. ; Polanen Petel, T. van; Teilmann, J. ; Reijnders, P.J.H. - \ 2011
    Environmental Research Letters 6 (2011)2. - ISSN 1748-9326 - 10 p.
    echolocation activity - underwater noise - t-pods - behavior - turbines - impact - waters
    The rapid increase in development of offshore wind energy in European waters has raised concern for the possible environmental impacts of wind farms. We studied whether harbour porpoise occurrence has been affected by the presence of the Dutch offshore wind farm Egmond aan Zee. This was done by studying acoustic activity of porpoises in the wind farm and in two reference areas using stationary acoustic monitoring (with T-PODs) prior to construction (baseline: June 2003 to June 2004) and during normal operation of the wind farm (operation: April 2007 to April 2009). The results show a strong seasonal pattern, with more activity recorded during winter months. There was also an overall increase in acoustic activity from baseline to operation, in line with a general increase in porpoise abundance in Dutch waters over the last decade. The acoustic activity was significantly higher inside the wind farm than in the reference areas, indicating that the occurrence of porpoises in this area increased as well. The reasons of this apparent preference for the wind farm area are not clear. Two possible causes are discussed: an increased food availability inside the wind farm (reef effect) and/or the absence of vessels in an otherwise heavily trafficked part of the North Sea (sheltering effect)
    An effective survey design for harbour seals in the Wadden Sea: tuning Trilateral Seal Agreement and EU-Habitat Directive requirement
    Meesters, H.W.G. ; Reijnders, P.J.H. ; Brasseur, S.M.J.M. ; Tougaard, S. ; Stede, M. ; Siebert, U. ; Härkönen, T. - \ 2007
    - 82 p.
    The developments of the harbour seal Phoca vitulina population in the Wadden Sea are monitored via aerial surveys according to the Trilateral Seal Agreement concluded by the responsible authorities of Denmark, Schleswig Holstein, Niedersachsen and the Netherlands. A survey scheme was designed taking into account the conservation objectives formulated in the Trilateral Seal Agreement and the requirements under the EU Habitats Directive. To meet those objectives and requirements we followed the OSPAR guideline, which aims at detecting with a power of 80% and a probability of 5%, a change in abundance of minimally 10% in 10 years (amounting to a decrease of 1.05% per year). A power analysis was carried out based on the within and between variation in the annual seal counts during the moulting period in August in the period 1989 to 2001. This analysis indicates that the current monitoring programme consisting of two surveys in August, has insufficient power to detect an annual decrease of 1.05 percent at 0.05 significance. These two surveys enable only to detect 2% decrease over a 10-year period, and moreover with a significance of only 0.10. Should the variation in counts increase, e.g. because the population approaches carrying capacity, one will quickly have less than 80% power to detect changes. This implies an increase in the probability of wrongly concluding that no decrease has happened. To meet the set requirements, monitoring should be increased to at least 4 counts in August throughout the entire Wadden Sea. If a smaller area will be surveyed, e.g. by using independently only data for the sub-regions Denmark, Schleswig Holstein, Niedersachsen or the Netherlands, more surveys per year in each area would be needed to detect the same decrease with similar power. We therefore conclude that the choice is to either increase the present number of surveys or accept that the chance for detecting a decrease will be less than set by internationally proposed guidelines. In any case, there is every reason to continue the present trilaterally synchronised and standardised surveys, and co-ordinated processing of the data.
    Relatedness of Streptococcus equi subsp. zooepidemicus strains isolated from harbour seals (Phoca vitulina) and grey seals (Halichoerus grypus) of various origins of the North Sea during 1988 - 2005
    Akineden, Oe. ; Alber, J. ; Laemmler, C. ; Weiss, R. ; Siebert, U. ; Foster, G. ; Tougaard, S. ; Brasseur, S.M.J.M. ; Reijnders, P.J.H. - \ 2007
    Veterinary Microbiology 121 (2007)1-2. - ISSN 0378-1135 - p. 158 - 162.
    molecular characterization - german north - identification
    The present study was designed to identify 15 beta-hemolytic streptococci isolated during a period between 1988 and 2005 from nine harbour seals and six grey seals from various origins of the North Sea. All isolates were identified as Streptococcus equi subsp. zooepidemicus. The bacteria were additionally investigated for relatedness by restriction fragment length polymorphism analysis of PCR amplified 16S-23S rDNA intergenic spacer region and gene szp and by macrorestriction analysis of chromosomal DNA of the strains by pulsed field gel electrophoresis. The molecular analysis yielded identical or closely related patterns within the strains of the present study and with the S. equi subsp. zooepidemicus strains isolated from harbour seals of German North Sea which were investigated previously [Akineden, O., Hassan, A.A., Alber, J., El-Sayed, A., Estoepangestie, A.T.S., Lammler, C., Weiss, R., Siebert, U., 2005. Phenotypic and genotypic properties of S. equi subsp. zooepidemicus isolated from harbor seals (Phoca vitulina) from the German North Sea during the phocine distemper outbreak in 2002. Vet. Microbiol. 110, 147-152]. This indicates that this single or closely related bacterial clone existed during both phocine distemper virus epidemics in 1988 and 2002 and that a direct transmission of the strains has occurred between two seal species and between seal populations of far distant regions possibly with grey seals as a vector.
    Aerial surveys of harbour and grey seals in the Wadden Sea in 2006
    Reijnders, P.J.H. ; Brasseur, S.M.J.M. ; Abt, K.F. ; Siebert, U. ; Stede, M. ; Tougaard, S. - \ 2006
    Wadden Sea Newsletter 32 (2006)1. - ISSN 0922-7989 - p. 9 - 11.
    Baseline data on the harbour porpoise, Phocoena phocoena, in relation to the intended wind farm site NSW, in the Netherlands
    Brasseur, S.M.J.M. ; Reijnders, P.J.H. ; Damsgaard Henriksen, O. ; Carstensen, J. ; Tougaard, J. ; Teilmann, J. ; Leopold, M.F. ; Camphuysen, K. ; Gordon, J. - \ 2004
    Wageningen : Alterra (Alterra-rapport 1043) - 80
    phocoena - windenergie - windmolens - milieueffect - inventarisaties - karteringen - kustgebieden - nederland - phocoena - wind power - windmills - environmental impact - inventories - surveys - coastal areas - netherlands
    To evaluate the possible impact of the planned Near Shore Wind farm on harbour porpoises, a baseline study has been carried out to provide a thorough description of the ecological reference situation. Three methods were used to collect baseline data on harbour porpoise in the intended wind farm area as well as reference areas. Firstly, during a whole year echolocation sounds of the animals were collected via fixed hydrophones, so-called T-PODs. This will provide information on relative density of porpoises. Secondly, bi-monthly ship-surveys were conducted to obtain an estimate for density. Finally, hydrophones were towed behind the survey ship to corroborate the visual data. These studies proved that porpoises frequently occurred in the target area and also in the control sites. Intensity of the porpoise activity was clearly higher in winter months. Observations surpass the expectations with respect to the amount of animals and recording
    The harbour seal population in the Wadden Sea as revealed by the aerial surveys in 2003
    Reijnders, P.J.H. ; Brasseur, S.M.J.M. ; Abt, K.F. ; Siebert, U. ; Stede, M. ; Tougaard, S. - \ 2003
    Wadden Sea Newsletter 29 (2003)2. - ISSN 0922-7989 - p. 11 - 12.
    Sense and sensibility in evaluating aerial counts of harbour seals in the Wadden Sea
    Reijnders, P.J.H. ; Abt, K. ; Brasseur, S.M.J.M. ; Tougaard, S. ; Siebert, U. ; Vareschi, E. - \ 2003
    Wadden Sea Newsletter (2003)1. - ISSN 0922-7989 - p. 9 - 12.
    It is the intention of this paper to discuss possible differences in estimating abundance trends for the entire Wadden Sea seal population when using different methods to incorporate regional counts
    Population development of harbour seals Phoca vitulina in the Wadden Sea after the 1988 virus epizootic
    Reijnders, P.J.H. ; Ries, E.H. ; Tougaard, S. ; Norgaard, N. ; Heidemann, G. ; Schwarz, J. ; Vareschi, E. ; Traut, I.M. - \ 1997
    Journal of Sea Research 38 (1997). - ISSN 1385-1101 - p. 161 - 168.
    Red List of Mammals of the Wadden Sea
    Tougaard, S. ; Kinze, C. ; Benke, H. ; Heidemann, G. ; Reijnders, P.J.H. ; Leopold, M.F. - \ 1996
    Helgoländer Meeresuntersuchungen 50 (1996)SUPPL.. - ISSN 0174-3597 - p. 129 - 135.
    In the Wadden Sea, 4 species of marine mammals are threatened (2 seals and 2 small cetacean species) and are therefore placed on the trilateral Red List. The status of 3 species of marine mammals is critical and the status of 1 species is vulnerable.
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