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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African elephant in a cleft stick : choosing between starving or dying from thirst in arid savanna
Wato, Yussuf - \ 2016
Wageningen University. Promotor(en): Herbert Prins, co-promotor(en): Ignas Heitkonig; Frank van Langevelde. - Wageningen : Wageningen University - ISBN 9789463430005 - 126
loxodonta africana - starvation - thirst - savannas - arid zones - animal ecology - mortality - drought - loxodonta africana - uithongering - dorst - savannen - aride klimaatzones - dierecologie - mortaliteit - droogte

Elephant population studies have become important especially because of the long standing perception that high elephant densities have negative impact on vegetation and other wildlife species. Thus, in areas of high elephant density, managers attempt to re-distribute them or keep their numbers low through provision of water, translocation or culling. These approaches are thought to keep the population within the limits that can be sustained by the ecosystem, termed “the ecological carrying capacity”, a management option hinged on equilibrium theory. Equilibrium systems are considered stable, with resources and the animals that depend on them being at balance with each other. This stability is rarely the case in tropical savannas where the rule appears to be “a flux of nature” rather than “a balance of nature”.

Tropical savannas, where over half of the African elephant live, are prone to constant environmental fluctuations, especially prolonged droughts, and hence there is a growing understanding that populations of wildlife species and their communities are rarely at equilibrium. Therefore, it is critical to understand how the constant environmental flux in this system affects wildlife populations and the implication for their management. In this thesis, the central focus is to investigate the role of drought occurrences on elephant population dynamics in tropical savannas. To address this question, it is important to have a good understanding of the historical changes of elephant population in relation to drought events and the ecology of elephant in semi-arid savannas - their distribution and density, their movements and behaviour. For the historical data, I analysed the best existing long-term data in Africa of wild elephant population that has been consistently monitored for over 40 years where life histories of over 3000 wild individual elephant are known, at Amboseli National Park in Kenya. In addition, I also analysed geo-referenced elephant mortality data collected daily for 10 years from Tsavo Conservation Area. Further, I analysed 2 years data from 8 GPS collared African elephant to investigate their movement response to seasonal water and forage distribution in Tsavo Ecosystem.

First, I investigated the temporal effects of drought duration (number of consecutive dry months) and intensity (amount of rainfall) on elephant population structure in Amboseli National Park, Kenya. The result corroborates findings from past studies that calves (<2years) are more susceptible to drought caused mortality and the risk of dying decreased with age. A new finding in this study reveals that the effect of drought induced mortality for the adult elephant is sex and age dependent, with males older than 25 years being less likely to die as compared to females of the same age. This new result is because of the resolution of analysis in this study which focused on the length and severity of drought as opposed to past studies that restricted their analysis to seasonal and inter-annual differences in rainfall pattern. As they grow older and sexually mature, the foraging range of male elephant increase and they begin to take more risks and disperse to unfamiliar habitats to seek for quality forage and mates. Generally, foraging strategies between sexes in many species are more pronounced during periods of food scarcity, and the driving force in the differences appears to be driven by energy need requirements, reproductive status of an individual, body sizes and the social context, all of which differ between sexes.

In the next study, I investigated the spatial pattern of elephant mortality in relation to drought occurrences in Tsavo National Park using MaxEnt. The results shows that elephant carcasses were aggregated and elephant mortality was negatively correlated with four months cumulative precipitation prior to death, forage availability and distance to water, while local elephant density showed a positive correlation. This finding rules out dehydration as the cause of elephant mortality in Tsavo as the river where the carcasses were aggregated is perennial. Furthermore, forage availability was low close to water sources and did not show a significant difference close to or further away from the river despite high elephant density around the river. Hence, these elephant mortalities may have occurred as a result of starvation.

I went further to focus on two main limiting resources for elephants, namely forage and water, and their effect on elephant-habitat utilization in semi-arid savannas. I first investigated how water source distribution affect elephants’ seasonal movement patterns. Results indicate that male elephant moved maximally 20 km away from the nearest water source in the dry season while the female elephant foraged to a maximum of about 10 km and only moved further than this distances in the wet season. The strong directionality of elephant movement from a distance of 15km towards water sources (rho > 0.5) as they re-visited their watering source in the dry season suggest that elephant have information on location of the water sources.

Next, I investigated the factors that determine selection of a foraging site for elephant with a focus on forage nutrients or biomass. Because of their large body size, it is thought that elephant can survive on a less nutritious but high biomass of forage. The results from this study shows that elephant selected foraging site based on forage biomass in dry seasons, whereas they selected areas with higher nutrients in the wet season. Moreover, females selected sites with a higher forage biomass as compared to males. This result may be explained by the difference in social organisation and foraging strategies between the sexes. In the previous studies on human-elephant conflict, for instance, male elephant raided crops more than the mixed herd, perhaps to seek for high quality forage.

Together, the four studies in this thesis strongly suggest that elephant starve to death in prolonged drought contrary to the past studies that reported that adult elephant are less affected by drought. Even though prolonged droughts usually result in higher elephant mortalities, the resilience of semi-arid savannas may perhaps be as a result of these deaths that release the system from high browsing pressure and give it a window to regenerate. If that is the case, then drought induced elephant mortality may be a better way to regulate elephant numbers than culling. This finding strongly suggests that semi-arid savannas may in fact be a non-equilibrium system sustained by growth and crashes of herbivore populations. Maintaining the system as natural as possible may therefore keep elephant populations in savannas sustained for posterity. The modern day park managers have daunting challenges such as mass elephant deaths in drought, increased human-wildlife conflicts or changes in wildlife use of the landscape which may all be symptoms of wrong management interventions taken in the past or negative impacts of anthropogenic activities that have tipped the natural functioning of a non-equilibrium system. Therefore, park managers should undergo regular trainings on new conservation techniques and they should apply evidence-based science to make informed long term decision.

Dietary protein, blood pressure and mortality : the value of repeated measurements
Tielemans, S.M.A.J. - \ 2016
Wageningen University. Promotor(en): Marianne Geleijnse; Daan Kromhout, co-promotor(en): Hendriek Boshuizen. - Wageningen : Wageningen University - ISBN 9789462577916 - 169
cardiovascular diseases - blood pressure - dietary protein - mortality - cardiovascular disorders - hypertension - urea - meta-analysis - antihypertensive agents - plant protein - animal protein - hart- en vaatziekten - bloeddruk - voedingseiwit - mortaliteit - hart- en vaatstoornissen - hypertensie - ureum - meta-analyse - antihypertensiva - plantaardig eiwit - dierlijk eiwit

Cardiovascular diseases (CVD) are the main cause of death worldwide. In 2012, about 17.5 million people died from CVD, accounting for 30% of all deaths. High blood pressure (BP) is a major cardiovascular risk factor, which was responsible for 10.4 million deaths in 2013. Diet and lifestyle play an important role in the etiology of hypertension. Maintenance of a desirable body weight, physical activity, and low intake of alcohol and salt are well-known measures to avoid high BP. Whether dietary protein, or more specifically plant and animal protein, could contribute to maintaining a healthy BP is less clear. The association between BP and CVD mortality has been extensively investigated. BP in prospective studies can be analyzed using different approaches, such as single BP (measured at one moment in time), single BP adjusted for regression dilution, average BP, and trajectories of BP. It is not yet clear which of these approaches is to be preferred for CVD risk prediction.

This thesis is centered on BP as a major cardiovascular risk factor. In the first part (Chapter 2, 3 and 4), the relation of dietary protein intake with BP level and change was examined. In the second part (Chapter 5 and 6), various approaches for analyzing repeated BP measurements were compared in relation to CVD and all‑cause mortality risk. The final chapter discusses the main findings and their implications.

Chapter 2 describes the association of 24-h urinary urea excretion, as a biomarker of total protein intake, with 9-year incidence of hypertension. We analyzed data of ~4000 men and women aged 28–75 years, who participated in the Prevention of Renal and Vascular Endstage Disease (PREVEND) study, a prospective cohort study. BP was measured four times during 1997–2009 and participants were followed for hypertension incidence, defined as BP ≥140/90mmHg or use of antihypertensive medication. Urea excretion was assessed in two consecutive 24-h urine collections at baseline and approximately 4 years later, from which total protein intake was estimated. Protein intake based on 24-h urinary urea excretion was not associated with incident hypertension.

Chapter 3 presents findings for long-term total, animal and plant protein intake in relation to 5‑year BP change. Analyses were based on 702 observations of 272 men who participated in the Zutphen Elderly Study. Participants did not use antihypertensive medication and were initially free of CVD. Physical and dietary examinations were performed in 1985, 1990, 1995, and 2000. BP was measured twice at each examination and protein intake was assessed using the cross-check dietary history method. The upper tertiles of plant protein intake were associated with a mean 5‑year change in systolic BP of ‑2.9 mmHg (95% CI: ‑5.6, ‑0.2), compared with the bottom tertile. Total and animal protein intake was not associated with BP.

Chapter 4 describes a meta‑analysis of 12 observational studies and 17 randomized controlled trials (RCTs) of dietary protein, including animal and plant protein, in relation to BP. Protein intake in prospective cohort studies was not associated with incident hypertension. For RCTs that used carbohydrate as a control treatment, the pooled BP effect was ‑2.1 mmHg systolic (95% CI: ‑2.9, ‑1.4) for a weighted mean contrast in protein intake of 41 grams per day. There was no differential effect of animal and plant protein on BP.

Chapter 5 describes repeated BP measures and their association with CVD and all‑cause mortality and life years lost in two prospective and nearly extinct cohorts of middle-aged men, the Minnesota Business and Professional Men Study (n=261) and the Zutphen Study (n=632). BP was measured annually during 1947–1957 in Minnesota and 1960–1970 in Zutphen. After 10 years of BP measurements, men were followed until death on average 20 years later. Each 25-mmHg increase in average SBP was associated with a 49% to 72% greater CVD mortality risk, 34% to 46% greater all-cause mortality risk and 3 to 4 life years lost. Four systolic BP trajectories were identified, in which mean systolic BP increased by 5 to 49 mmHg in Minnesota and 5 to 20 mmHg in Zutphen between age 50 and 60. In Zutphen, a 2-times greater CVD and all-cause mortality risk and 4 life years lost were observed when comparing trajectories. In Minnesota, associations were twice as strong. BP trajectories were the strongest predictors of CVD mortality and life years lost in Minnesota men, whereas in Zutphen men, the average BP was superior to other measures.

Chapter 6 presents findings for average BP and BP trajectories in relation to CVD and all-cause mortality, taking into account antihypertensive medication. A total of 762 participants aged ≥50 years of the Rancho Bernardo Study were examined five times from 1984 to 2002 and monitored for cause‑specific mortality from 2002 to 2013. Each 20‑mmHg increment in average systolic BP was associated with 35% greater CVD mortality and 25% greater all-cause mortality risk. We identified four trajectories for systolic BP for which BP increases ranged from 5 to 12 mmHg between age 60 and 70. In individuals who belonged to the higher trajectories, 2‑3 times greater CVD mortality and 1.5-times greater all-cause mortality risks were observed, compared to those who belonged to the lowest trajectory. Long-term systolic BP trajectories and average systolic BP were both significant predictors of CVD and all-cause mortality. The associations were not modified by antihypertensive medication.

As described in Chapter 7, various approaches were used to study the relation between protein intake and BP. Findings from individual studies and a meta-analysis suggest that dietary protein per se does not affect BP within the range of intake generally consumed in the Netherlands. Replacing carbohydrates by protein, however, has a beneficial effect on BP.

Moreover, this thesis showed that BP trajectories are not superior to average BP in predicting CVD and all-cause mortality. A few repeated BP measurements, e.g. three or four, are likely to be sufficient for obtaining a reliable average BP and had a similar predictive value for mortality compared to BP trajectories. Therefore, average BP can be considered the most practical tool for estimating mortality risk.

Omvang en overleving van schubvis bijvangst in fuikenvisserij nabij kunstwerken
Griffioen, A.B. ; Keeken, O.A. van; Chen, C. ; Blom, E. ; Schram, E. ; Graaf, M. de; Winter, Hendrik V. - \ 2016
IMARES (Rapport / IMARES C140/15) - 53
visserij - bijvangst - vissen - schade - dierenwelzijn - mortaliteit - fisheries - bycatch - fishes - damage - animal welfare - mortality
Deze rapportage geeft een schatting van de omvang van de bijvangst in de beroepsvisserij nabij kunstwerken op basis van fuikvangsten en diverse interviews. Daarnaast is er een experiment uitgevoerd waarbij er gekeken is naar de overleving van schubvis nadat zij in fuiken hebben gezeten. Hierbij zijn de baars en blankvoorn gebruikt om de overleving te testen in relatie tot de volgende variabelen: aanwezigheid aal: geen (0 stuks), weinig aal (7 stuks) en veel aal (50 stuks), staduur van de fuik: 3, 6 of 9 dagen en dichtheid van vis in een fuik: 60 stuks tegenover 240 stuks.
Genetische monitoring van de Nederlandse otterpopulatie : ontwikkeling van populatieomvang en genetische status 2014/2015
Kuiters, A.T. ; Groot, G.A. de; Lammertsma, D.R. ; Jansman, H.A.H. ; Bovenschen, J. - \ 2016
Wageningen : Wettelijke Onderzoekstaken Natuur & Milieu (WOt-technical report 62) - 30
lutra lutra - otters - populatiegenetica - inteelt - mortaliteit - monitoring - nederland - lutra lutra - otters - population genetics - inbreeding - mortality - monitoring - netherlands
Jaarlijks wordt de Nederlandse otterpopulatie genetisch gemonitord in opdracht van het Ministerie van
Economische Zaken. Daarmee wordt een vinger aan de pols gehouden wat betreft de ontwikkeling van de
genetische status van de populatie. Deze vorm van monitoring, waarbij gebruik wordt gemaakt van DNA
geïsoleerd uit uitwerpselen en doodvondsten, maakt het tevens mogelijk veranderingen in de ruimtelijke
verspreiding en de populatieomvang te volgen. De monitoringsronde van 2014/2015 laat zien dat de
populatie verder is gegroeid naar ca. 160 individuen. Op populatieniveau lijkt geen verder verlies aan
genetische variatie te zijn opgetreden. De genetische variatie binnen individuen is evenmin verder
afgenomen in tegenstelling tot voorafgaande jaren. Onderdeel van deze monitoring is ook autopsie van dode
otters, waarbij wordt gekeken naar de doodsoorzaak en de belangrijkste lichaamskenmerken. Verkeer is
verreweg de belangrijkste doodsoorzaak. Locaties waar otters worden doodgereden, worden geregistreerd
en bijgehouden in een database. Deze informatie is belangrijk voor het veiliger maken van knelpuntlocaties
om zo het aantal verkeersslachtoffers te beperken. Het aantal verkeersslachtoffers neemt nog ieder jaar toe,
waarbij de toename evenredig is aan de toename in de populatieomvang
Dietary patterns, biomarkers of atherosclerosis, cardiovascular and all-cause mortality
Sijtsma, F.P.C. - \ 2015
Wageningen University. Promotor(en): Daan Kromhout; D.R. Jacobs, co-promotor(en): Sabita Soedamah-Muthu. - Wageningen : Wageningen University - ISBN 9789462575493 - 207
dieet - hart- en vaatziekten - atherosclerose - prognostische merkers - ziektemerkers - mortaliteit - classificatiesystemen - epidemiologie - longitudinaal onderzoek - diet - cardiovascular diseases - atherosclerosis - prognostic markers - disease markers - mortality - classification systems - epidemiology - longitudinal studies

Summary belonging to the thesis entitled ‘Dietary patterns, biomarkers of atherosclerosis, cardiovascular and all-cause mortality’

The long history of epidemiologic studies on diet and cardiovascular disease (CVD) has traditionally relied on analysis of specific nutrients or foods. Dietary patterns are multiple dietary components operationalized as a single exposure; they reflect the entire diet. In general, two methods are used to define dietary patterns: 1) theoretically, or a priori, defined dietary scores and 2) empirically, or a posteriori, derived dietary patterns. A priori dietary scores were developed to assess diet quality based on adherence to dietary patterns or recommendations. An example of an ‘a posteriori’ approach is factor analysis (e.g. principal components analysis (PCA)). Factor analysis reduces data into patterns based upon intercorrelations between nutrients or foods. The aim of this thesis was to create, examine and compare several dietary patterns and indices and assess these in relation to both early stage markers of CVD (markers of endothelial function and oxidative stress) and to mortality from CVD and all-causes.

In chapter 2 we described the creation of the A Priori Diet Quality Score, representing overall diet quality in the Coronary Artery Risk Development in Young Adults (CARDIA) study. The CARDIA study included 5115 black and white men and women, aged 18-30 at baseline (1985-86). Diet was assessed diet at baseline, year 7(1992-93) and 20 (2005-06) examinations. The A Priori Diet Quality Score summed 46 food groups rated by investigators as positive or negative on the basis of hypothesized health effects. In 2652 participants with 3 diet assessments, the mean (±SD) A Priori Diet Quality Score increased from 64.1± 13.0 at year 0 to 71.1 ± 12.6 at year 20, which was primarily attributable to increased age. However, the secular trend, which was estimated from differences of dietary quality scores across time at a fixed age (age matched time trend), decreased. The diet score was higher in whites than in blacks and in women than in men and increased with education, but demographic gaps in the score narrowed over 20 y. Consumption of positively rated food groups tended to increase and negatively rated food groups tended to decrease, and were similar in direction across demographic groups.

In chapter 3 we used the ‘A Priori Diet Quality Score’ and two dietary patterns derived using principal components analysis (PCA) the ‘Fruit and Vegetables’ dietary pattern and the ‘Meat’ dietary pattern in the CARDIA study. We studied prospective associations of the ‘A Priori Diet Quality Score’, the ‘Fruit and Vegetables’ dietary pattern and the ‘Meat’ dietary pattern with cellular adhesion molecules (CAMs). The ‘Fruit and Vegetables’ dietary pattern was characterized by high intakes of fruit, vegetables, and whole grains and the ‘Meat’ dietary pattern by high intakes of red meat, refined grain, and butter. The ‘A Priori Diet Quality Score’ was related to all CAMs. The ‘Fruit and Vegetables’ dietary pattern was related to E-selectin and sICAM-1 but not to P-selectin and VCAM. The ‘Meat’ dietary pattern was related to all CAMs except VCAM. Strongest associations were for the ‘Meat’ dietary pattern with E-selectin (effect size 28% of an SD (+3.9/13.7 ng/mL)) and P-selectin (effect size 37% of an SD (+4.1/11.2 ng/mL)) and the ‘A Priori Diet Quality Score’ with sICAM-1 (effect size 34% of an SD (-15.1/44.7 ng/mL)) and VCAM (effect size of 26% of an SD (-45.1/170.3 ng/mL)).

Chapter 4 described prospective associations of the A Priori Diet Quality Score, ‘Fruit and Vegetables’ dietary pattern and ‘Meat’ dietary pattern and a plasma biomarker of lipid peroxidation, F2-isoprostanes also in the CARDIA study. We estimated associations between each dietary pattern and plasma F2-isoprostanes cross-sectionally (at year 20, n=2736) and prospectively (year 0/7 average diet and year 15/20 average F2-isoprostanes, n=2718). In the cross-sectional analysis, the A Priori Diet Quality Score and the ‘Fruit and Vegetables’ dietary pattern were inversely, and the ‘Meat’ dietary pattern was positively, associated with F2-isoprostanes (all p values <0.001). These associations were also statistically significant in prospective analysis.

In chapter 5 we described a food classification system derived from the Food-based Dietary Guidelines in the Netherlands that can be used to systematically and objectively classify foods in relation to their effects on health. Classification criteria for each food group were developed based on presumed positive, neutral or negative effects on chronic diseases of five nutrients: four that likely increase (saturated fatty acids, mono-trans unsaturated fatty acids, sodium, and added sugar) and one that likely decreases (dietary fiber) the risk of chronic diseases. This classification system also provided a framework to create food-based dietary scores for epidemiologic research on diet and chronic disease relationships.

Chapter 6 describes the creation of two dietary scores the ‘Dutch Healthy Nutrient and Food Score’ and the ‘Dutch Undesirable Nutrient and Food Score’ based on the food classification system described in chapter 5 in the Alpha Omega Trial. The Alpha Omega Trial is a randomized controlled trial; however the current analyses were done from an observational prospective cohort perspective (with adjustment for intervention groups). We included 4307 cardiac patients aged 60-80 years and monitored mortality for 10 years. Patients in the highest quintile of the ‘Dutch Healthy Nutrient and Food Score’ had 30% (HR 0.70; 95% CI 0.55-0.91) lower CVD and 32% (HR 0.68; 95%CI 0.47-0.99) lower all-cause mortality risk compared to patients in the first quintile. The ‘Dutch Undesirable Nutrient and Food Score’ was unrelated to both CVD and all-cause mortality.

In Chapter 7 we also created a ‘Dutch Healthy Nutrient and Food Score’ and a ‘Dutch Undesirable Nutrient and Food Score’ in the Zutphen Elderly Study. We assessed the association of these scores with 25 year CVD and all-cause mortality and life-years gained. We divided the men (age 65-84 years) into those with (n=210) and without (n=616) cardiovascular-metabolic diseases at baseline in 1985. During a median follow-up of 10.6 years (IQR 5.8-15.9) 806 participants died, of whom 359 from CVD. Diet scores did not predict death in all men. Among men with cardiovascular-metabolic diseases, ‘Dutch Healthy Nutrient and Food Score’ was associated with lower CVD (HR: 0.57; 95%CI: 0.35-0.93) and all-cause mortality risk (HR: 0.64; 95% CI: 0.44-0.94) comparing highest vs. lowest tertiles of the score. Men with cardiovascular-metabolic diseases in the highest vs. lowest tertile of the ‘Dutch Healthy Nutrient and Food Score’ lived 2.5 year longer. The ‘Dutch Healthy Nutrient and Food Score’ was not associated with CVD and all-cause mortality in men without cardiovascular-metabolic diseases. The ‘Dutch Undesirable Nutrient and Food Score’ was not associated with any of the outcomes.

In Chapter 8 we summarized the main findings of this thesis and reflected on some methodological considerations. First, we discussed the different approaches to derive dietary scores and patterns and the advantages and disadvantages of these methods. Second, we reflected on important aspects for creating a priori dietary scores and on further research. Finally, the general conclusions and implications were presented.

From the results presented in this thesis we conclude that adherence to a healthy diet is inversely associated with early stage markers of CVD (markers of endothelial function and oxidative stress), CVD and all-cause mortality. In summary, a healthy diet consists of plenty of vegetables and fruit, legumes, whole grains, nuts and seeds, moderate intake of fish/poultry/lean meats and low fat dairy, and limited intake of processed meats, refined grains, sugar sweetened beverages, ready meals and snacks. However, this thesis also showed that a high quality dietary pattern can be achieved in several different ways, and may differ among populations.

Vallen en opstaan: update overlevingsprojecten ILVO en IMARES (interview met Karin van der Reijden)
Reijden, K.J. van der - \ 2015
Visserijnieuws 35 (2015)17. - ISSN 1380-5061 - p. 5 - 5.
visserijbeleid - visserijbeheer - discards - zeevisserij - wetgeving - eu regelingen - visserij - mortaliteit - visstand - demersale visserij - dierenwelzijn - diergezondheid - fishery policy - fishery management - marine fisheries - legislation - eu regulations - fisheries - mortality - fish stocks - demersal fisheries - animal welfare - animal health
De Europese aanlandplicht is een feit. De visserijsector vreest een negatieve invloed op de bestanden door een hogere vissterfte. In de wetgeving is een uitzonderingsmaatregel voor de discardban opgenomen als vis een hoge overlevingskans heeft. Zowel in Nederland als België wordt daarom in de kottervisserij wetenschappelijk onderzocht hoe groot de overlevingskansen van gevangen vis zijn. Karin van der Reijden (WUR - IMARES) en Ruben Theunynck (ILVO) geven inzicht in de stand van zaken.
Genetische monitoring van de Nederlandse otterpopulatie 2013/2014 : ontwikkeling van populatieomvang en populatiegenetische status
Kuiters, A.T. ; Groot, G.A. de; Lammertsma, D.R. ; Jansman, H.A.H. ; Bovenschen, J. - \ 2015
Wageningen : Alterra, Wageningen-UR (Alterra-rapport 2624) - 39
lutra lutra - otters - fauna - populatiedichtheid - populatiegenetica - inteelt - mortaliteit - dna - monitoring - friesland - noordwest-overijssel - drenthe - population density - population genetics - inbreeding - mortality
Jaarlijks wordt in opdracht van het ministerie van Economische Zaken de Nederlandse otterpopulatie genetisch gemonitord. Daarmee wordt een vinger aan de pols gehouden wat betreft de ontwikkeling van de genetische status van de populatie. Deze vorm van monitoring, gebaseerd op DNA-profielen op basis van DNA geïsoleerd uit verse spraints (uitwerpselen), maakt het tevens mogelijk veranderingen in de ruimtelijke verspreiding en de populatieomvang van jaar tot jaar te volgen. De monitoringsronde van 2013/2014 laat zien dat de populatie verder is gegroeid naar een aantal van ca. 140 individuen. Echter, de genetische variatie binnen individuen is sterker afgenomen vergeleken met voorafgaande jaren. Onderdeel van deze monitoring is ook autopsie van dode otters, waarbij wordt gekeken naar de doodsoorzaak en de belangrijkste lichaamskenmerken. Knelpuntlocaties waar otters worden doodgereden worden in beeld gebracht. Er is een sterke toename van het jaarlijkse aantal verkeersslachtoffers. Deze lijkt gelijke tred te houden met de toename van de populatieomvang.
Effecten microklimaat op teken : Manipulatie habitat kan risico op ziekte van Lyme verminderen
Brink, N.W. van den; Baan, M. van der; Paree, J. ; Lange, H.J. de - \ 2014
Landschap : tijdschrift voor landschapsecologie en milieukunde 31 (2014)3. - ISSN 0169-6300 - p. 155 - 157.
natuurbeheer - natuurgebieden - metastigmata - ziekten overgebracht door teken - lyme-ziekte - habitats - habitatbeheer - mortaliteit - correlatie - temperatuur - vochtigheid - biologische bestrijding - nature management - natural areas - tickborne diseases - lyme disease - habitat management - mortality - correlation - temperature - humidity - biological control
Teken zijn een belangrijke vector in de overdracht van de ziekte van Lyme op mensen. De overleving en
het gedrag van teken zou beïnvloed kunnen worden door de manipulatie van hun microhabitat. In een
experiment zijn we dat nagegaan. De mortaliteit van de teek blijkt negatief gecorreleerd te zijn aan de
relatieve luchtvochtigheid en temperatuur en het gedrag positief aan de temperatuur. In het beheer van
natuurgebieden kan hier op worden ingespeeld.
Contaminanten in aangespoelde bruinvissen langs de Nederlandse kust; spekkwaliteit, neonaten en chemische profielen
Heuvel-Greve, M.J. van den; Kwadijk, C.J.A.F. ; Kotterman, M.J.J. - \ 2014
Yerseke : IMARES (Rapport / IMARES Wageningen UR C113/14) - 24
zeezoogdieren - phocoena - ecotoxicologie - mortaliteit - noordzee - marine mammals - ecotoxicology - mortality - north sea
In de afgelopen decennia is het aantal bruinvissen dat aanspoelt op de Nederlandse stranden toegenomen. Om te bepalen of gehalten aan contaminanten in aangespoelde bruinvissen wijzen op mogelijke effecten op de gezondheid van deze bruinvissen, zijn een aantal specifieke aspecten in dit rapport benoemd. Zo is spekdikte een maat voor de gezondheid van de bruinvis. Het onderzoek is verricht aan de hand van aangespoelde pasgeboren en jonge bruinvissen uit Nederland en Denemarken
Imidacloprid niet de oorzaak van wintersterfte bij bijen
Steen, J.J.M. van der - \ 2014
Boerderij 99 (2014)27. - ISSN 0006-5617 - p. 62 - 62.
apidae - honingbijen - bijenziekten - imidacloprid - chemische bestrijding - insecticiden - gewasbescherming - mortaliteit - doodsoorzaken - honey bees - bee diseases - chemical control - insecticides - plant protection - mortality - causes of death
Volgens Wageningen UR heeft Imidacloprid geen invloed op de overwintering van bijen.
Demonstratieproef varroabestrijding en wintersterfte (mei 2012 – juli 2013)
Steen, J.J.M. van der; Hok-A-Hin, C.H. ; Cornelissen, B. - \ 2013
Wageningen : Plant Research International, Wageningen UR - 23
honingbijkolonies - professionele bijenhouderij - mortaliteit - doodsoorzaken - winter - varroa - mijtenbestrijding - diergezondheid - projecten - wetenschappelijk onderzoek - kennisoverdracht - imkers - honey bee colonies - commercial beekeeping - mortality - causes of death - mite control - animal health - projects - scientific research - knowledge transfer - beekeepers
Deze demonstratieproef is opgezet als een Citizen Scientist (CS) project waarbij het praktische veldwerk en de waarnemingen, op aanwijzing van en gecoördineerd door PRI bijen@wur, uitgevoerd werden door bijenhouders. De analyses, interpretatie van de data en de rapportage zijn uitgevoerd door PRI bijen@wur. Voor de demonstratieproef 2012-2013 is aan 25 bijengezondheidsscoördinatoren (BGC’rs) gevraagd de varroabestrijding uit te voeren volgens de PRI bijen@wur brochure “Effectieve bestrijding van varroa”.
Waarnemingen van Bruinvissen in maart 2013 vanaf een zandzuiger in het slijkgat bij Ouddorp
Leopold, M.F. ; Baptist, M.J. ; IJsseldijk, L. ; Engels, B. - \ 2013
Den Burg : IMARES (Rapport / IMARES Wageningen UR C096/13) - 34
zeezoogdieren - mariene gebieden - beschadigingen - mortaliteit - inventarisaties - noordzee - marine mammals - marine areas - injuries - mortality - inventories - north sea
Jaarlijks spoelen in Nederland honderden bruinvissen dood aan op de kust. Onderzoek heeft laten zien dat “scherp trauma" (snij- en rijtwonden, amputaties) veelvuldig voorkomt. Vanaf 2005 hadden gemiddeld 14.4% van de gestrande bruinvissen scherp trauma, met uitschieters tot 20.5% in 2012 en 21.4% in 2010. Veel gevallen van scherp trauma worden gemeld van de kop van Goeree, in de eerste maanden van het jaar. Dieren worden hier vaak ernstig verminkt, maar in verse toestand gevonden. Dit doet vermoeden dat deze dieren vlak onder de kust gewond zijn geraakt. De eerste verminkte bruinvissen werden rond Ouddorp opgemerkt in 2006 (Leopold & Camphuysen 2006) en zijn sindsdien jaarlijks gevonden, al waren er in 2011 opvallend weinig in vergelijking met andere jaren. De aantallen lagen in 2012 en 2013 fors hoger dan in eerdere jaren.
Voer van invloed op biggensterfte
Makkink, C.A. ; Wientjes, J.G.M. - \ 2013
De Molenaar 116 (2013)7. - ISSN 0165-4284 - p. 18 - 19.
varkenshouderij - dierenwelzijn - mortaliteit - biggen - varkensvoeding - biggenvoeding - voeropname - insuline - colostrum - varkens - dierlijke productie - diergezondheid - diervoeding - pig farming - animal welfare - mortality - piglets - pig feeding - piglet feeding - feed intake - insulin - pigs - animal production - animal health - animal nutrition
Marginale verschillen in voeding en metabolisme vóór inseminatie kunnen leiden tot grote verschillen in prenatale en postnatale biggensterfte. Dit was een van de conclusies tijdens het seminar van de leerstoelgroep Adaptatiefysiologie in Wageningen University.
Evaluatie stroboscooplampen en FishTrack bij gemaal Offerhaus : stroomafwaartse migratie
Kroes, M.J. ; Boer, M. de; Winter, H.V. - \ 2013
Utrecht : Tauw, BU Meten, Inspectie & Advies - 63
vismigratie - european eels - lampen - diergedrag - geleiding - mortaliteit - pompstations - polders - friesland - fish migration - lamps - animal behaviour - guidance - mortality - pumping stations
Het onderzoeksproject heeft de volgende vraagstellingen: - Hoe is de toepassingsefficiëntie van de beide systemen (FishTrack en stroboscoop lampen) ten behoeve van visweren en visgeleiding bij gemalen voor schieraal? - Wat zijn de daarbij behorende waterhuishoudkundige en visecologische uitgangspunten en randvoorwaarden? - Hoe is de technische toepasbaarheid bij bestaande (Nederlandse) grote én kleine gemalen en wat is de kostenefficiëntie per systeem in zowel een grootschalige als kleinschalige toepassing? Doel daarbij is het verbeteren van de passeerbaarheid van gemalen, zodat schade en sterfte onder passerende (trek)vissen, en dan voornamelijk van de met uitsterven bedreigde Aal, aanzienlijk verminderd wordt.
Field test for mortality of eel after passage through the newly developed turbine of Pentair Fairbanks Nijhuis and FishFlow Innovations
Winter, H.V. ; Bierman, S.M. ; Griffioen, A.B. - \ 2012
IJmuiden : IMARES (Report / IMARES Wageningen UR C111/12) - 14
pompstations - veldproeven - vismigratie - palingen - mortaliteit - dierenwelzijn - pumping stations - field tests - fish migration - eels - mortality - animal welfare
Sterfte van vis tijdens het passeren van turbines in waterkrachtcentrales is een wereldwijd probleem, met name voor migrerende vissoorten. In deze studie testen we een nieuw type turbine die is ontwikkeld om visvriendelijk te zijn door Pentair Fairbanks Nijhuis/FishFlow Innovations. In een gecontroleerd experiment zijn groepen Europese paling Anguilla anguilla gedwongen blootgesteld aan passage via deze nieuwe turbine en zijn de directe en vertraagde sterfte van deze groepen vergeleken met controle groepen paling die afgezien van turbine passage een gelijke behandeling hebben gehad.
Neonicotinoïden en Fipronil en sterfte van bijen en bijenvolken : overzicht van open beschikbare peer reviewed laboratorium-, veld- en monitoringsstudies
Blacquiere, T. ; Smagghe, G. ; Gestel, K. van; Mommaerts, V. - \ 2012
Wageningen : Plant Research International (Rapport / Plant Research International 439) - 74
honingbijen - apidae - wilde bijenvolken - diergezondheid - mortaliteit - fipronil - pesticiden - monitoring - literatuuroverzichten - risicofactoren - toxiciteit - honey bees - wild honey bee colonies - animal health - mortality - pesticides - literature reviews - risk factors - toxicity
De hoofdvraag die dit rapport beantwoordt is 'Geeft de open beschikbare peer reviewed wetenschappelijke literatuur aanwijzingen dat met de huidige toelatingsbeoordeling ontoelaatbare risico's voor bijen (zijn) ontstaan?'
Neonicotinoïden en sterfte van bijenvolken: causaal verband?
Blacquiere, T. - \ 2011
wilde bijenvolken - dierenwelzijn - apidae - honingbijen - diergezondheid - mortaliteit - insecticiden - wild honey bee colonies - animal welfare - honey bees - animal health - mortality - insecticides
De onderzoeksopdracht aan Wageningen UR voor het literatuuronderzoek 'Neonicotinoïden en fipronil en sterfte van bijen en bijenvolken'.
Bijensterfte: bijen verliezen terrein
Blacquiere, T. ; Steen, J.J.M. van der - \ 2011
Wageningen : Plant Research International
bijenhouderij - bijenstanden - apidae - doodsoorzaken - bijenziekten - mortaliteit - bijensterfte - beekeeping - apiaries - causes of death - bee diseases - mortality - bee mortality
In dit dossier vindt u relevante informatie rondom bijensterfte.
Lamvitaliteit bij melkschapen
Verkaik, J.C. - \ 2011
BioKennis bericht Geiten 2011 (2011)11. - 4
lammeren - schapenhouderij - dierverzorging - biologische landbouw - opfoktechnieken - agrarische bedrijfsvoering - colostrum - diergezondheid - mortaliteit - lambs - sheep farming - care of animals - organic farming - rearing techniques - farm management - animal health - mortality
In de biologische melkschapenhouderij is de lammerensterfte relatief hoog. De sector wil de sterfte graag verminderen. In dit BioKennisbericht enkele tips en aanbevelingen naar aanleiding van onderzoek door Wageningen UR Livestock Research. De lamvitaliteit blijkt verbeterd te kunnen worden door een betere biestopname, een lagere besmettingsdruk, beter (gebruik van) managementinformatie en het inkruisen van andere rassen.
Biggensterfte in biologische kraamhokken: effect van overleggen en toomgrootte
Vermeer, H.M. ; Houwers, H.W.J. ; Binnendijk, G.P. - \ 2011
Lelystad : Wageningen UR Livestock Research (Rapport / Wageningen UR Livestock Research 467) - 16
varkenshouderij - biggen - mortaliteit - worpgrootte - biologische landbouw - worpen - varkens - pig farming - piglets - mortality - litter size - organic farming - litters - pigs
To reduce mortality in newborn organic piglets the effect of crossfostering was studied. Crossfostered piglets had a higher survival, but grew less and litter size had no effect on survival after day 3, but the piglets grew slower than in small litters.
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