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.

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De zeehond is terug, maar de groei is er uit
Brasseur, S.M.J.M. - \ 2019
7 hele nare kantjes van zeehonden
Brasseur, S.M.J.M. - \ 2019
De ecologie van het Amelander Zeegat : Een inventarisatie naar kennis over het ecologische functioneren van het Amelander Zeegat
Bogaart, Lisanne van den; Hal, Ralf van; Meijden, Mirte van der; Brasseur, Sophie ; Baptist, Martin ; Wijsman, Jeroen - \ 2019
IJmuiden : Wageningen Marine Research (Wageningen Marine Research rapport C032/19) - 60
Mogelijke ecologische gevolgen containerramp MSC Zoe voor Waddenzee en Noordzee: een quickscan
Baptist, M.J. ; Brasseur, S.M.J.M. ; Foekema, E.M. ; Franeker, J.A. van; Kuhn, S. ; Leopold, M.F. - \ 2019
Den Helder : Wageningen Marine Research (Wageningen Marine Research rapport C029/19) - 18
Top-down pressure on a coastal ecosystem by harbor seals
Aarts, Geert ; Brasseur, Sophie ; Poos, Jan Jaap ; Schop, Jessica ; Kirkwood, Roger ; Kooten, Tobias Van; Mul, Evert ; Reijnders, Peter ; Rijnsdorp, Adriaan D. ; Tulp, Ingrid - \ 2019
Ecosphere 10 (2019)1. - ISSN 2150-8925 - p. e02538 - e02538.
demersal fish - diet - harbor seal - impact - intertidaL - Phoca vitulina - predation pressure - sealing - Subtidal - top-down regulation - top predator
Historic hunting has led to severe reductions of many marine mammal species across the globe. After hunting ceased, some populations have recovered to pre-exploitation levels and may have regained their prominent position as top predator in marine ecosystems. Also, the harbor seal population in the international Wadden Sea grew at an exponential rate following a ban on seal hunting in 1960s, and the current number ~38,000 is close to the historic population size. Here we estimate the impact of the harbor seal predation on the fish community in the Wadden Sea and nearby coastal waters. Fish remains in fecal samples and published estimates on the seal’s daily energy requirement were used to estimate prey selection and the magnitude of seal consumption. Estimates on prey abundance were derived from demersal fish surveys, and fish growth was estimated using a Dynamic Energy Budget model. GPS tracking provided information on where seals most likely caught their prey. Harbor seals hauling-out in the Dutch Wadden Sea fed predominantly on demersal fish, for example, flatfish species (flounder, sole, plaice, dab), but also on sandeel, cod, and whiting. Although harbor seals acquire the majority of prey further offshore in the adjacent North Sea, and only spend 14% of their diving time in the Wadden Sea, seal predation was still estimated to cause an average annual mortality of 43% of the remaining fish in the Wadden Sea and 60% in the nearby shallow coastal waters (<20 m). There were however large sources of uncertainty in the estimated impact of seals on fish, including the migration of fish between the North Sea and Wadden Sea, and catchability estimates of the fish survey sampling gear, particularly for sandeel and other pelagic fish species. Our estimate suggested a considerable top-down pressure by harbor seals on demersal fish. However, predation by seals may also alleviate density-dependent competition between the remaining fish, allowing for increased fish growth, and partly compensating for the reduction in fish numbers. This study shows that recovering coastal marine mammal populations could become an important component in the functioning of shallow coastal ecosystems.
Harbour seal monitoring and evaluation for the Luchterduinen offshore windfarm : Final report
Brasseur, Sophie ; Schop, Jessica ; Cremer, Jenny ; Aarts, Geert - \ 2018
Texel : Wageningen Marine Research (Wageningen Marine Research rapport C074/18) - 40
Though it seems unlikely that marine mammals, including seals suffer at a large scale from direct mortality caused by the construction or operation of windfarms at sea, they are likely to be affected by disturbance and habitat alterations.In 2014, Luchterduinen windfarm was constructed in the Dutch coastal zone south west of IJmuiden and the permit (WV/2009-1229) requested monitoring with respect to both harbour and grey seals. Two main questions were formulated:1. How do seals use the coastal zone? The aim was to gain insight in harbour and grey seal movement routes along the Dutch North Sea coastal zone (between the Wadden Sea and the Delta region).2. What is the impact of Luchterduinen on seals? (with a focus on the impact of piling).This rapport discusses the results of the harbour seal studies. The initial monitoring (T0-T1; 2013-2015) based on a series of studies on the movements and habitat use of harbour seals deployed in spring (March), was timed in relation to the construction (2014) and operation of the windfarm. These studies were evaluated after T1 (in 2016). It was concluded that by limiting the study to spring deployments, the harbour seals’ habitat use during a large part of the year was missing. Since harbour seals moult in summer, the trackers attached to the fur typically fell off in June –July. In this study (T2-T3) therefore, a deliberate choice was made to study the behaviour of the seals in the post moult, from September onwards. A total of 18 seals were tracked from September onwards: in 2016 (T2) 6 from the Wadden Sea area and 6 from the Delta and again 6 from the Wadden Sea area in 2017(T3).With longer track durations of 20 to 187 days (mean 106 ± 46 days) in this last study information has been collected covering seven calendar months, six of which had not been studied before in this region. However there was large variation in behaviour, possibly but not solely as a result of the male bias in the sample (11 males, 7 females). Though the maximum and mean distance travelled by the seals was slightly less in autumn, the waters in the study area (i.e. the area off the west coast of the Netherlands enclosed by 51.95°N to 52.94°N, and from the coast offshore to 3.73°E) were used much more extensively by the seals tracked in autumn. In total the seals tracked during T2-T3 spent 27.3% of their time in the defined study area, while during spring deployments for T0-T1, this was only 1.5%. Out of the 18 seals tracked in autumn, 11 were observed in the study area. Interestingly these were animals tagged in the Wadden Sea region. During this time of the year animals are mostly feeding, which probably explains their higher presence in the study area. In contrast, during spring, mostly seals from the Delta crossed the study area en route to their breeding sites in the Wadden Sea. This probably explains the limited amount of time spent in the coastal zone. During the complete Luchterduinen study (T0-T3) comprising of 44 animals in spring and 18 in autumn, only one animal entered the Luchterduinen wind farm area. Its visits were short; which suggests it only crossed the area. Animals tracked during T2-T3 were observed more often in the vicinity of the wind farm, compared to the animals tagged during T0-T1.Based on these studies we concluded that harbour seals use the coastal zone west of North and South Holland to migrate to breeding areas in spring/summer, and use it to feed in autumn and winter. Recently, the recovery of the harbour seals in the Wadden Sea has come to a halt. However, pup production in the Wadden Sea is still increasing, and over two thousand pups are born in the Dutch Wadden Sea each year. Since the population size no longer grows, this suggest that an equal number of individuals die each year. Possibly the population has reached a ‘natural’ carrying capacity. However, human use at sea could also play a role in influencing the survival of individuals and the size of the population. Like other North Sea countries, the Dutch government has shown a clear intention to intensify the use of the marine areas in the near future, for windfarms but also sand mining, traffic and aquaculture. Quite likely this will affect the way the seals use the marine area. Further studies are needed to better understand how habitat changes play a role in the survival of individual animals.---Hoewel het onwaarschijnlijk is dat zeezoogdieren en dus zeehonden op grote schaal direct dodelijke gevolgen ondervinden van de bouw of ingebruikname van windparken op zee, is het hoogstwaarschijnlijk zo dat ze worden beïnvloed door de verstoring en veranderingen in hun habitat.Luchterduinen windpark werd in de Nederlandse kustzone ten zuidwesten van IJmuiden gebouwd in 2014 en de vergunning (WV/2009-1229) vereiste de monitoring van grijze en gewone zeehonden. Twee belangrijke vragen werden gesteld:1.Hoe gebruiken zeehonden de kustzone? Het doel was om inzicht te krijgen in de routes van de gewone en de grijze zeehond gedurende hun aanwezigheid in de Nederlandse kustzone (tussen de Waddenzee en het Deltagebied).2.Wat is de impact van Luchterduinen op de zeehonden? (met een focus op de hei-werkzaamheden)Dit rapport bespreekt de resultaten van de studies naar de gewone zeehond. De eerste monitoring (T0-T1; 2013-2015), gebaseerd op een reeks studies van beweging en habitat gebruik van gewone zeehonden gezenderd in het voorjaar (maart), was getimed in relatie tot de constructie (2014) en ingebruikname van het park. Deze studies werden na de T1 geëvalueerd (2016). Er werd geconcludeerd dat, door de studie te beperken tot het zenderen in het voorjaar, inzicht in het habitatgebruik van de gewone zeehonden voor een belangrijk deel van het jaar ontbrak. Aangezien de dieren in de zomer verharen, verloren ze de op de vacht geplakte zenders gewoonlijk in juni-juli. In de huidige studie (T2-T3) werd daarom een bewuste keuze gemaakt om het gedrag van de gewone zeehonden na de verharing te bestuderen, vanaf september. In totaal werden 18 zeehonden in het najaar gezenderd: in 2016 (T2) 6 in het waddengebied en 6 in het Deltagebied en het jaar erna, in 2017(T3) 6 in het waddengebied.Gemiddeld was de tijd dat de dieren gevolgd werden langer dan in de eerdere studies namelijk 20 tot 187 dagen (gem. 106 ± 46 dagen). In deze studie werd bovendien informatie verzameld over een periode van zeven maanden waarvan één maand overlap vertoonde met de eerder studiesEr was een grote variatie in gedrag tussen de dieren, mogelijk speelde o.a. de scheve geslachtsverhouding van de gezenderde zeehonden hierbij een rol; er werden 11 mannetjes en 7 vrouwtjes gezenderd. Hoewel de gemiddelde en de maximale afstand die de dieren zwommen in de herfst iets lager was, gebruikten de zeehonden in deze periode het studiegebied (ten westen van de westkust van Nederland begrensd door 51.95°N en 52.94°N, en van de kust af tot 3.73°E) veel intensiever. De zeehonden gezenderd in het najaar tijdens T2-T3 besteedden 27.3% van hun tijd in dit gebied, terwijl de dieren gezenderd in het voorjaar voor T0-T1 maar 1.5% van hun tijd hier doorbrachten. Van de 18 zeehonden gezenderd in de herfst werden er 11 in het gebied gezien. Interessant is wel, dat al deze dieren in het waddengebied waren gezenderd. In deze periode van het jaar zijn de dieren vooral aan het foerageren, wat mogelijk deze verspreiding verklaart. In tegenstelling daarmee, waren het vooral de in de Delta gezenderde dieren die in de lente het gebied doorkruisten op weg naar het waddengebied waar ze zich voortplanten. Dit verklaart mogelijk de beperkte tijd dat de dieren in het studiegebied gezien werden. Tijdens de gehele Luchterduinen-studie (T0-T3) met 44 dieren gezenderd in de lente en 18 in de herfst werd er maar één dier in het park zelf gezien. Gezien de korte verblijfsperiode in het park is het waarschijnlijk dat het dier het gebied alleen doorkruist heeft. Tijdens T2-T3 werden er meer dieren in de buurt van het windpark dan tijdens T0-T1.Gebaseerd op deze studies concluderen we dat gewone zeehonden het gebied ten westen van de Noord- en Zuid-Hollandse kust in de lente en zomer vooral gebruiken om te migreren naar de voortplantingsgebieden, en in de herfst en winter om te foerageren. De laatste jaren zijn de getelde aantallen gewone zeehonden in de Waddenzee min of meer gelijk gebleven, terwijl het aantal pups nog steeds groeit. Er worden tegenwoordig jaarlijks meer dan 2000 pups geboren. Aangezien er geen groei is suggereert dit dat er even zoveel dieren jaarlijks sterven. Mogelijk heeft de populatie de “natuurlijke” draagkracht bereikt. Echter menselijk gebruik van de zee zou ook een rol kunnen spelen en de overleving van individuen en de populatiegrootte kunnen beïnvloeden. Net als andere Noordzeelanden heeft de Nederlandse regering een duidelijke intentie getoond om in de nabije toekomst het gebruik van de zee te willen intensiveren voor windparken, en daarnaast ook voor zandwinning, vaarbewegingen en aquacultuur. Het is aannemelijk dat dit de manier waarop de zeehonden de zee gebruiken zal beïnvloeden. Verdere studies zijn nodig om te begrijpen hoe verandering van het habitat van de zeehonden een rol kan spelen op de overleving van individuele dieren.
Geboortegolf grijze zeehond
Brasseur, Sophie ; Schop, Jessica - \ 2018
Behavioural response of grey seals to pile-driving
Aarts, Geert ; Brasseur, Sophie ; Kirkwood, Roger - \ 2018
Den Helder : Wageningen Marine Research (Wageningen Marine Research report C006/18) - 54
TSEG grey seal surveys in the Wadden Sea and Helgoland in 2017-2018 : More than ten years of growth in the Wadden Sea area
Brasseur, S.M.J.M. ; Cremer, J.S.M. ; Czeck, Richard ; Galatius, Anders ; Jeß, Armin ; Körber, Peter ; Pund, Ralf ; Siebert, Ursula ; Teilmann, Jonas ; Klöpper, Sascha - \ 2018
Wilhelmshaven : Common Wadden Sea Secretariat - 4 p.
Brucella pinnipedialis in grey seals (Halichoerus grypus) and harbor seals (Phoca vitulina) in the Netherlands
Kroese, Michiel V. ; Beckers, Lisa ; Bisselink, Yvette J.W.M. ; Brasseur, Sophie ; Tulden, Peter W. van; Koene, Miriam G.J. ; Roest, Hendrik I.J. ; Ruuls, Robin C. ; Backer, Jantien A. ; Ijzer, Jooske ; Giessen, Joke W.B. van der; Willemsen, Peter T.J. - \ 2018
Journal of Wildlife Diseases 54 (2018)3. - ISSN 0090-3558 - p. 439 - 449.
Brucella pinnipedialis - Halichoerus grypus - MALDI-TOF MS - Marine mammals - MLST - MLVA-16 - Phoca vitulina - The Netherlands

Brucellosis is a zoonotic disease with terrestrial or marine wildlife animals as potential reservoirs for the disease in livestock and human populations. The primary aim of this study was to assess the presence of Brucella pinnipedialis in marine mammals living along the Dutch coast and to observe a possible correlation between the presence of B. pinnipedialis and accompanying pathology found in infected animals. The overall prevalence of Brucella spp. antibodies in sera from healthy wild grey seals (Halichoerus grypus; n=11) and harbor seals (Phoca vitulina; n=40), collected between 2007 and 2013 ranged from 25% to 43%. Additionally, tissue samples of harbor seals collected along the Dutch shores between 2009 and 2012, were tested for the presence of Brucella spp. In total, 77% (30/ 39) seals were found to be positive for Brucella by IS711 real-time PCR in one or more tissue samples, including pulmonary nematodes. Viable Brucella was cultured from 40% (12/30) real-time PCR-positive seals, and was isolated from liver, lung, pulmonary lymph node, pulmonary nematode, or spleen, but not from any PCR-negative seals. Tissue samples from lung and pulmonary lymph nodes were the main source of viable Brucella bacteria. All isolates were typed as B. pinnipedialis by multiple-locus variable number of tandem repeats analysis-16 clustering and matrix-assisted laser desorption ionization-time of flight mass spectrometry, and of sequence type ST25 by multilocus sequence typing analysis. No correlation was observed between Brucella infection and pathology. This report displays the isolation and identification of B. pinnipedialis in marine mammals in the Dutch part of the Atlantic Ocean.

Mogelijke effecten van opening van de Haringvlietsluizen op zeehonden
Schop, Jessica ; Cremer, Jenny ; Brasseur, Sophie - \ 2018
Den Helder : Wageningen Marine Research (Wageningen Marine Research rapport C041/18) - 20
Zeehond
Brasseur, Sophie - \ 2018
Harbour seals are regaining top-down control in a coastal ecosystem
Aarts, G.M. ; Brasseur, S.M.J.M. ; Poos, J.J. ; Schop, Jessica ; Kirkwood, R.J. ; Kooten, T. van; Mul, Evert ; Reijnders, P.J.H. ; Rijnsdorp, A.D. ; Tulp, I.Y.M. - \ 2018
BioRxiv
Historic hunting has led to severe reductions of many marine mammal species across the globe. After hunting ceased, some populations have recovered to pre-exploitation levels, and may again act as a top-down regulatory force on marine ecosystems. Also the harbour seal population in the international Wadden Sea grew at an exponential rate following a ban on seal hunting in 1960's, and the current number ~38,000 is close to the historic population size. Here we estimate the impact of the harbour seal predation on the fish community in the Wadden Sea and nearby coastal waters. Fish remains in faecal samples and published estimates on the seal's daily energy requirement were used to estimate prey selection and the magnitude of seal consumption. Estimates on prey abundance were derived from demersal fish surveys, and fish growth was estimated using a Dynamic Energy Budget model. GPS tracking provided information on where seals most likely caught their prey. Harbour seals from the Dutch Wadden Sea fed predominantly on demersal fish, e.g. flatfish species (flounder, sole, plaice, dab), but also sandeel, cod and whiting. Total fish biomass in the Wadden Sea was insufficient to sustain the estimated prey consumption of the entire seal population year-round. This probably explains why seals also acquire prey further offshore in the adjacent North Sea, only spending 13% of their diving time in the Wadden Sea. Still, seal predation was estimated to cause an average annual mortality of 43% and 60% on fish in the Wadden Sea and adjacent coastal zone, respectively. There were however large sources of uncertainty in the estimate, including the migration of fish between the North Sea and Wadden Sea, and catchability estimates of the fish survey sampling gear, particularly for sandeel and other pelagic fish species. Our estimate suggested a considerable top-down control by harbour seals on demersal fish. However predation by seals may also alleviate density-dependent competition between the remaining fish, increasing fish growth, and partly compensating for the reduction in fish numbers. This study shows that recovering coastal marine mammal populations could potentially become an important component in the functioning of shallow coastal systems.
Stranding and rehabilitation in numbers: population development and stranding data on the Dutch coasts 1990-2016 : analysis of new data from a public database
Brasseur, Sophie - \ 2018
Den Helder : Wageningen Marine Research (Wageningen Marine Research report C108/17) - 36
Seal monitoring and evaluation for the Gemini offshore windfarm: Tconstruction - 2015 report
Brasseur, Sophie ; Kirkwood, Roger ; Aarts, Geert - \ 2018
Yerseke : Wageningen Marine Research (Wageningen Marine Research report C004/18) - 64
Echoes from the past : Regional variations in recovery within a harbour seal population
Brasseur, Sophie M.J.M. ; Reijnders, Peter J.H. ; Cremer, Jenny ; Meesters, Erik ; Kirkwood, Roger ; Jensen, Lasse Fast ; Jeβ, Armin ; Galatius, Anders ; Teilmann, Jonas ; Aarts, Geert - \ 2018
PLoS ONE 13 (2018)1. - ISSN 1932-6203
Terrestrial and marine wildlife populations have been severely reduced by hunting, fishing and habitat destruction, especially in the last centuries. Although management regulations have led to the recovery of some populations, the underlying processes are not always well understood. This study uses a 40-year time series of counts of harbour seals (Phoca vitulina) in the Wadden Sea to study these processes, and demonstrates the influence of historical regional differences in management regimes on the recovery of this population. While the Wadden Sea is considered one ecologically coupled zone, with a distinct harbour seal population, the area is divided into four geo-political regions i.e. the Netherlands, Lower Saxony including Hamburg, Schleswig-Holstein and Denmark. Gradually, seal hunting was banned between 1962 and 1977 in the different regions. Counts of moulting harbour seals and pup counts, obtained during aerial surveys between 1974 and 2014, show a population growth from approximately 4500 to 39,000 individuals. Population growth models were developed to assess if population growth differed between regions, taking into account two Phocine Distemper Virus (PDV) epizootics, in 1988 and 2002 which seriously affected the population. After a slow start prior to the first epizootic, the overall population grew exponentially at rates close to assumed maximum rates of increase in a harbour seal population. Recently, growth slowed down, potentially indicative of approaching carrying capacity. Regional differences in growth rates were demonstrated, with the highest recovery in Netherlands after the first PDV epizootic (i.e. 17.9%), suggesting that growth was fuelled by migration from the other regions, where growth remained at or below the intrinsic growth rate (13%). The seals’ distribution changed, and although the proportion of seals counted in the German regions declined, they remained by far the most important pupping region, with approximately 70% of all pups being born there. It is hypothesised that differences in hunting regime, preceding the protection in the 1960’s and 1970’s, created unbalance in the distribution of breeding females throughout the Wadden Sea, which prevailed for decades. Breeding site fidelity promoted the growth in pup numbers at less affected breeding sites, while recolonisation of new breeding areas would be suppressed by the philopatry displayed by the animals born there. This study shows that for long-lived species, variable management regimes in this case hunting regulations, across a species’ range can drive population dynamics for several generations.
Aerial surveys of Harbour Seals in the Wadden Sea in 2017 : Population counts still in stagnation, but more pups than ever
Galatius, Anders ; Brasseur, S.M.J.M. ; Czeck, Richard ; Jeß, Armin ; Körber, Peter ; Pund, Ralf ; Siebert, Ursula ; Teilmann, Jonas ; Klöpper, Sascha - \ 2017
Wilhelmshaven : Common Wadden Sea Secretariat - 5 p.
Wadden Sea Quality Status Report : Marine mammals
Jensen, Lasse Fast ; Teilmann, Jonas ; Galatius, Anders ; Pund, Ralf ; Czeck, Richard ; Jess, Armin ; Siebert, Ursula ; Körber, Peter ; Brasseur, S.M.J.M. - \ 2017
Wilhelmshaven : Common Wadden Sea Secretariat - 29 p.
In-situ observations using tagged animals
Roquet, F. ; Boehme, L. ; Bester, M.N. ; Bornemann, H. ; Brasseur, S.M.J.M. ; Charrassin, J.B. ; Costa, D. ; Fedak, M.A. ; Guinet, C. ; Hall, A. ; Harcourt, R. ; Hindell, M.A. ; Kovacs, K.M. ; Lea, M.A. ; Lovell, P. ; Lowther, A. ; Lyderson, C. ; Mcmahon, C. ; Picard, B. ; Reverdin, G. ; Vincent, C. - \ 2017
- 5 p.
Marine mammals help gather information on some of the harshest environments on the planet, through the use of miniaturized ocean sensors glued on their fur. Since 2004, hundreds of diving marine animals, mainly Antarctic and Arctic seals, have been fitted with a new generation of Argos tags developed by the Sea Mammal Research Unit of the University of St Andrews in Scotland, UK. These tags investigate the at-sea ecology of these animals while simultaneously collecting valuable oceanographic data. Some of the study species travel thousands of kilometres continuously diving to great depths (up to 2100 m). The resulting data are now freely available to the global scientific community at http://www.meop.net. Despite great progress in their reliability and data accuracy, the current generation of loggers while approaching standard ARGO quality specifications have yet to match them. Yet, improvements are underway; they involve updating the technology, implementing a more systematic phase of calibration and taking benefit of the recently acquired knowledge on the dynamical response of sensors. Together these efforts are rapidly transforming animal tagging into one of the most important sources of oceanographic data in polar regions and in many coastal areas
TSEG grey seal surveys in the Wadden Sea and Helgoland in 2016-2017 : General growth but local drop in numbers
Brasseur, S.M.J.M. ; Czeck, Richard ; Galatius, Anders ; Jensen, Lasse Fast ; Jeß, Peter ; Körber, Peter ; Pund, Ralf ; Siebert, Ursula ; Teilmann, Jonas ; Klöpper, Sascha - \ 2017
Wilhemshaven : Common Wadden Sea Secretariat - 4 p.
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