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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    Biology, monitoring, and management of a tropical marine gastropod: the Queen conch (Lobatus gigas) in the Caribbean
    Boman, B.E. - \ 2019
    Wageningen University. Promotor(en): A.C. Smaal, co-promotor(en): L.A.J. Nagelkerke; M. de Graaf. - Wageningen : Wageningen University - ISBN 9789463439909 - 207

    The marine gastropod queen conch (Lobatus gigas), found throughout the Wider Caribbean Region, supports one of the most important fisheries in the region. However, several biological characteristics (e.g. density-dependent mating and survival, slow-moving, a preference for shallow depths, and aggregating behaviour during the reproductive season) make the species particularly vulnerable to overfishing. The heavy exploitation of queen conch throughout large parts of its natural range, as well as degradation of juvenile and adult habitats, also has in many areas led to a reduction in population densities to unsustainable levels to a point where mating success can be negatively affected. In addition, a new invasive seagrass species (H. stipulacea) has already caused significant alterations to the structure of native seagrass habitats which are in many parts of the Caribbean important to juvenile conch, providing both nutrition and protection from predators. However, the impacts of this invasive seagrass on life-history parameters such as growth and survival remain unknown.

    Although many Caribbean nations have implemented policies with regard to queen conch protection and exploitation, recovery of overfished populations has been slow. These measures, however, are still mostly not harmonized among nations and often based on outdated and limited biological information. Management of queen conch is also often complicated by difficulties in data acquisition, partly caused by the logistically demanding and relatively expensive surveying of conch. Conventional survey methods using scuba are also limited to ca. 25 m depth due to safety limitations, making them unsuitable for collecting data across the entire depth range of conch, which extends to 60 m.

    The main objectives of this study were to address knowledge gaps of the biology and ecology of the queen conch so that the distribution and dynamics of this species in relation to its environment are better understood. Such information will further improve our knowledge of marine gastropod biology in general, as well as our understanding of the effects of direct and indirect human-induced pressures on queen conch in the Caribbean. In addition, this study aimed to tackle some methodological shortcomings in the surveying and assessment of queen conch. Ultimately, these findings could be instrumental in the management and conservation of the species.

    Reproductive characteristics are important biological reference points for the management of species. To improve the knowledge of queen conch reproductive biology (i.e. size-at-maturity and reproductive season), evaluation and comparison of the relationship between shell lip thickness and maturity in queen conch throughout the Wider Caribbean Region, using histological analysis of queen conch gonads was carried out. Furthermore, the influence of seawater temperature on the length of the reproductive season was investigated (chapter 2). We demonstrate a clear positive relationship between the thickness of the shell lip and the onset of maturity in queen conch, and that maturity occurs following the development of the lip. Lip thickness at 50% maturity (LT50) of both females and males varied between different locations in the Caribbean, although it did not correspond with variation in water temperature. In most cases, females had a larger LT50 than males indicating sexual dimorphism. Locations with a relatively high variation in water temperature had a significantly shorter reproductive season. The implementation of adequate minimum size regulation based on lip thickness (ca. 15 mm) and a Caribbean wide seasonal closure (May–September) using the most recent biological information from this study, taking into consideration the local differences in LT50 and reproductive season, will assist in developing a long-term sustainable queen conch fishery in the Caribbean.

    To address the methodological shortcomings in the surveying of queen conch, a novel towed video method (TVM) was developed and compared with a conventional survey method (i.e. belt transect [BT] using scuba divers) in a series of calibration transects in two different habitats (i.e. high complexity (HC) and low complexity (LC)) (chapter 3). In both habitats, adult live queen conch had similar counts with both methods. Adult dead conch were not mistaken for live conch and the results validate the use of TVM as a reliable sampling tool to estimate densities of live adult conch in both HC and LC habitats throughout the species’ depth range.

    In chapter 4, the spatial distribution of adult queen conch and how it varies in response to a number of known abiotic and biotic variables between sites which vary in environmental conditions was examined. By combining TVM with conventional belt-transects, a more comprehensive survey of conch abundance was performed at three sites in the Eastern Caribbean (Anguilla, St Eustatius, Saba Bank). Adult conch appeared in patchy distributions, mostly caused by spatial dependency, which was likely related to aggregating behaviour during spawning events. Environmental variables, such as algae cover, distance to the open ocean, and depth showed important non-linear effects on conch abundance, although these differed among sites. The proportion of reef and sand cover had important negative effects on conch abundance at all sites. High densities (>100 /ha) of adult conch were found only at depths >17 m at all three sites. The lack of strong generic location over-crossing relationships between abiotic and biotic factors and adult conch abundance and distribution is likely partly due to this spatial dependency, as well as different location-specific factors that affect different stages of the conch’s life-history. Furthermore, the results indicate that intermediate and deep areas (ca. 17 – 45 m) contain most of the reproductive output of conch in the survey sites and are therefore highly important for reproductive capacity. Thus, surveying areas at depths beyond the practical limitation of divers (<25 m) are of great importance to obtain more reliable population estimates.

    To provide a first insight into the possible impact of an invasive seagrass species (H. stipulacea) on queen conch, the diet and growth of juvenile conch in both native, mixed, and invasive seagrass beds was examined using stable isotope analysis and an in situ growth enclosure experiment (chapter 5). Organic material in the sediment (i.e. benthic diatoms and particulate organic matter [POM]) was found to be the most important source of carbon and nitrogen for juvenile queen conch in all three habitats investigated, and there was a significantly higher probability of positive growth in the native seagrass compared to the invasive seagrass. Due to the importance of the organic material in the sediment as a source of nutrition for juvenile conch, limited access to the sediment in the invasive seagrass can potentially cause inadequate nutritional conditions to sustain high growth rates. Thus, it is likely that there is a negative effect on juvenile queen conch growth currently inhabiting invasive seagrass beds, compared to native seagrass beds, when other potential sources of nutrition are not available. Although much uncertainty still exists regarding the effects of H. stipulacea on the population dynamics on queen conch, if lower growth rates in invasive seagrass beds is a general pattern, it would have ramifications for both births and deaths of conch and the overall carrying capacity of conch populations in the Caribbean.

    A better understanding of the spatial genetic structure (SGS) and the factors driving contemporary patterns of gene flow and genetic diversity of queen conch are fundamental for developing conservation and management plans for marine fisheries. A detailed study of SGS and genetic diversity was therefore performed using population genetic and multivariate analyses (chapter 6). Our study found that queen conch does not form a single panmictic population in the greater Caribbean. Significant levels of genetic differentiation were identified between Caribbean countries, within Caribbean countries, and among sites. Gene flow over the spatial scale of the entire Caribbean basin is constrained by oceanic distance, which may impede the natural recovery of overfished queen conch populations. Our results suggest a careful blend of local and international management will be required to ensure long-term sustainability for the species.

    This study has provided new insights into queen conch biology and population dynamics as well as methodological shortcomings so that the distribution and dynamics of this species in relation to its environment are better understood. Ultimately, the findings from this study can contribute to improving the management and conservation of the species. However, the species will in the future face new challenges, due to expected changes in abiotic and biotic factors, such as temperature, ocean currents, and seagrass species composition. As body temperature and thus their physiological functions (e.g. growth) are directly dependent on environmental condition in this ectotherm species, it is particularly vulnerable to climate change (Dillon et al. 2010). Consequently, life-history parameters (e.g. size-at-maturity, reproductive season, growth rate, spatial genetic structure) of queen conch should not be considered rigid as these can be expected to change in the short and long-term, putting an unknown time limit to the relevance of the current biological knowledge of these parameters. However, there is still much uncertainty regarding what degree queen conch and other species can adapt to environmental changes induced by climate change and invasive species. Therefore, commitment to long-term research and updates in current biological knowledge, life-history parameters and population dynamics of queen conch throughout its range will be required to adjust subsequent management and conservation strategies to ensure the long-term sustainability of the species.

    Author Correction: Reproducible, interactive, scalable and extensible microbiome data science using QIIME 2
    Bolyen, Evan ; Rideout, Jai Ram ; Dillon, Matthew R. ; Bokulich, Nicholas A. ; Abnet, Christian C. ; Al-Ghalith, Gabriel A. ; Alexander, Harriet ; Alm, Eric J. ; Arumugam, Manimozhiyan ; Asnicar, Francesco ; Bai, Yang ; Bisanz, Jordan E. ; Bittinger, Kyle ; Brejnrod, Asker ; Brislawn, Colin J. ; Brown, C.T. ; Callahan, Benjamin J. ; Caraballo-Rodríguez, Andrés Mauricio ; Chase, John ; Cope, Emily K. ; Silva, Ricardo Da; Diener, Christian ; Dorrestein, Pieter C. ; Douglas, Gavin M. ; Durall, Daniel M. ; Duvallet, Claire ; Edwardson, Christian F. ; Ernst, Madeleine ; Estaki, Mehrbod ; Fouquier, Jennifer ; Gauglitz, Julia M. ; Gibbons, Sean M. ; Gibson, Deanna L. ; Gonzalez, Antonio ; Gorlick, Kestrel ; Guo, Jiarong ; Hillmann, Benjamin ; Holmes, Susan ; Holste, Hannes ; Huttenhower, Curtis ; Huttley, Gavin A. ; Janssen, Stefan ; Jarmusch, Alan K. ; Jiang, Lingjing ; Kaehler, Benjamin D. ; Kang, Kyo Bin ; Keefe, Christopher R. ; Keim, Paul ; Kelley, Scott T. ; Knights, Dan ; Koester, Irina ; Kosciolek, Tomasz ; Kreps, Jorden ; Langille, Morgan G.I. ; Lee, Joslynn ; Ley, Ruth ; Liu, Yong Xin ; Loftfield, Erikka ; Lozupone, Catherine ; Maher, Massoud ; Marotz, Clarisse ; Martin, Bryan D. ; McDonald, Daniel ; McIver, Lauren J. ; Melnik, Alexey V. ; Metcalf, Jessica L. ; Morgan, Sydney C. ; Morton, Jamie T. ; Naimey, Ahmad Turan ; Navas-Molina, Jose A. ; Nothias, Louis Felix ; Orchanian, Stephanie B. ; Pearson, Talima ; Peoples, Samuel L. ; Petras, Daniel ; Preuss, Mary Lai ; Pruesse, Elmar ; Rasmussen, Lasse Buur ; Rivers, Adam ; Robeson, Michael S. ; Rosenthal, Patrick ; Segata, Nicola ; Shaffer, Michael ; Shiffer, Arron ; Sinha, Rashmi ; Song, Se Jin ; Spear, John R. ; Swafford, Austin D. ; Thompson, Luke R. ; Torres, Pedro J. ; Trinh, Pauline ; Tripathi, Anupriya ; Turnbaugh, Peter J. ; Ul-Hasan, Sabah ; Hooft, Justin J.J. van der; Vargas, Fernando ; Vázquez-Baeza, Yoshiki ; Vogtmann, Emily ; Hippel, Max von; Walters, William ; Wan, Yunhu ; Wang, Mingxun ; Warren, Jonathan ; Weber, Kyle C. ; Williamson, Charles H.D. ; Willis, Amy D. ; Xu, Zhenjiang Zech ; Zaneveld, Jesse R. ; Zhang, Yilong ; Zhu, Qiyun ; Knight, Rob ; Caporaso, J.G. - \ 2019
    Nature Biotechnology (2019). - ISSN 1087-0156

    In the version of this article initially published, some reference citations were incorrect. The three references to Jupyter Notebooks should have cited Kluyver et al. instead of Gonzalez et al. The reference to Qiita should have cited Gonzalez et al. instead of Schloss et al. The reference to mothur should have cited Schloss et al. instead of McMurdie & Holmes. The reference to phyloseq should have cited McMurdie & Holmes instead of Huber et al. The reference to Bioconductor should have cited Huber et al. instead of Franzosa et al. And the reference to the biobakery suite should have cited Franzosa et al. instead of Kluyver et al. The errors have been corrected in the HTML and PDF versions of the article.

    Reproducible, interactive, scalable and extensible microbiome data science using QIIME 2
    Bolyen, Evan ; Rideout, Jai Ram ; Dillon, Matthew R. ; Bokulich, Nicholas A. ; Abnet, Christian C. ; Al-Ghalith, Gabriel A. ; Alexander, Harriet ; Alm, Eric J. ; Arumugam, Manimozhiyan ; Asnicar, Francesco ; Bai, Yang ; Bisanz, Jordan E. ; Bittinger, Kyle ; Brejnrod, Asker ; Brislawn, Colin J. ; Brown, Titus C. ; Callahan, Benjamin J. ; Caraballo-Rodríguez, Andrés Mauricio ; Chase, John ; Cope, Emily K. ; Silva, Ricardo da; Diener, Christian ; Dorrestein, Pieter C. ; Douglas, Gavin M. ; Durall, Daniel M. ; Duvallet, Claire ; Edwardson, Christian F. ; Ernst, Madeleine ; Estaki, Mehrbod ; Fouquier, Jennifer ; Gauglitz, Julia M. ; Gibbons, Sean M. ; Gibson, Deanna L. ; Gonzalez, Antonio ; Gorlick, Kestrel ; Guo, Jiarong ; Hillmann, Benjamin ; Holmes, Susan ; Holste, Hannes ; Huttenhower, Curtis ; Huttley, Gavin A. ; Janssen, Stefan ; Jarmusch, Alan K. ; Jiang, Lingjing ; Kaehler, Benjamin D. ; Kang, Kyo Bin ; Keefe, Christopher R. ; Keim, Paul ; Kelley, Scott T. ; Knights, Dan ; Koester, Irina ; Kosciolek, Tomasz ; Kreps, Jorden ; Langille, Morgan G.I. ; Lee, Joslynn ; Ley, Ruth ; Liu, Yong Xin ; Loftfield, Erikka ; Lozupone, Catherine ; Maher, Massoud ; Marotz, Clarisse ; Martin, Bryan D. ; McDonald, Daniel ; McIver, Lauren J. ; Melnik, Alexey V. ; Metcalf, Jessica L. ; Morgan, Sydney C. ; Morton, Jamie T. ; Naimey, Ahmad Turan ; Navas-Molina, Jose A. ; Nothias, Louis Felix ; Orchanian, Stephanie B. ; Pearson, Talima ; Peoples, Samuel L. ; Petras, Daniel ; Preuss, Mary Lai ; Pruesse, Elmar ; Rasmussen, Lasse Buur ; Rivers, Adam ; Robeson, Michael S. ; Rosenthal, Patrick ; Segata, Nicola ; Shaffer, Michael ; Shiffer, Arron ; Sinha, Rashmi ; Song, Se Jin ; Spear, John R. ; Swafford, Austin D. ; Thompson, Luke R. ; Torres, Pedro J. ; Trinh, Pauline ; Tripathi, Anupriya ; Turnbaugh, Peter J. ; Ul-Hasan, Sabah ; Hooft, Justin J.J. van der; Vargas, Fernando ; Vázquez-Baeza, Yoshiki ; Vogtmann, Emily ; Hippel, Max von; Walters, William ; Wan, Yunhu ; Wang, Mingxun ; Warren, Jonathan ; Weber, Kyle C. ; Williamson, Charles H.D. ; Willis, Amy D. ; Xu, Zhenjiang Zech ; Zaneveld, Jesse R. ; Zhang, Yilong ; Zhu, Qiyun ; Knight, Rob ; Caporaso, J.G. - \ 2019
    Nature Biotechnology 37 (2019)8. - ISSN 1087-0156 - p. 852 - 857.
    Special Section: Moving from Citizen to Civic Science to Address Wicked Conservation Problems
    Dillon, Justin ; Stevenson, Robert B. ; Wals, Arjen E.J. - \ 2016
    Conservation Biology 30 (2016)3. - ISSN 0888-8892 - 6 p.
    Genetic variants of FADS gene cluster, plasma LC-PUFA levels and the association with cognitive function of under-two-year-old Sasaknese Indonesian children
    Fahmida, Umi ; Htet, Min Kyaw ; Adhiyanto, Chris ; Kolopaking, Risatianti ; Yudisti, Miza Agria ; Maududi, Allay ; Suryandari, Dwi Anita ; Dillon, Drupadi ; Afman, Lydia ; Müller, Michael - \ 2015
    Asia Pacific Journal of Clinical Nutrition 24 (2015)2. - ISSN 0964-7058 - p. 323 - 328.
    Cognitive function - FADS - Indonesia - LC-PUFA - Under-two-year-old children

    Background/Aims: Long-chain polyunsaturated fatty acids (LC-PUFA) are regarded as essential for child cognition. Genetic variation in fatty acid (FA) desaturase enzyme (FADS) has been recognized as an important effect modifier in the relation between LC-PUFA and child cognitive function. This study aimed to identify the distribution of genetic variant (genotype) SNP rs174468 and to assess plasma FA and developmental outcome by the genotype among under-2 year old Sasaknese Indonesian children. Methods: Data was collected at baseline of a randomized trial (NUPICO, clinicaltrials.gov NCT01504633) in East Lombok district, Indonesia. Breastfed, 12- 17 month old children were recruited and 240 subjects were included in the study. Child cognition was assessed as Bayley Mental Developmental Index (MDI). Results: From 206 subjects whose blood samples can be collected, only two genotypes were found (90.3% GG homozygotes, 9.7% AG heterozygotes), and minor allele AG was significantly associated with higher level of arachidonic acid (20:4 n-6), n-6 LC-PUFA and FADS1 index. MDI score was associated with a FADS2 index (DHA:EPA ratio) but not genotype (Adjusted R-square= 0.043). Conclusions: FADS2 index was associated with cognitive function. No difference was found between children with GG and AG genotypes who were all breastfed and not low birth weight.

    Propojení přírodovědného a environmentálního vzdělávání
    Wals, A.E.J. ; Brody, M. ; Dillon, J. ; Stevenson, R.B. - \ 2015
    Envigogika 10 (2015)2. - ISSN 1802-3061 - 5 p.
    Environmental education - science education - civic science
    What is written about in Science journal? A paraphrase of the article: Wals, Arjen E. J., Michael Brody, Justin Dillon, Robert B. Stevenson (2014). Convergence Between Science and Environmental Education. Science, 344(6184), 583–584. DOI:10.1126/science.1250515
    Foreword
    Wals, A.E.J. ; Dillon, J. - \ 2015
    In: Educating Science Teachers for Sustainability / Stratton, Susan K., Hagevik, Rita, Feldman, Allan, Bloom, Mark, Cham : Springer International Publishing Switzerland (ASTE Series in Science Education ) - ISBN 9783319164106 - p. 1 - 3.
    Multi-species swards and multi scale strategies for multifunctional grassland-base ruminant production systems: An overview of the FP7-MultiSward project
    Peyraud, J.L. ; Pol - Van Dasselaar, A. Van Den; Collins, R.P. ; Huguenin-Elie, O. ; Dillon, P. ; Peeters, B.P.H. - \ 2014
    In: 25th EGF General Meeting on “EGF at 50: The Future of European Grasslands. - Zurich, Switzerland : European Grassland Federation EGF - p. 695 - 715.
    Life cycle assessment of energy use on Irish dairy farms
    Upton, J. ; Humphreys, J. ; Groot Koerkamp, P.W.G. ; French, P. ; Dillon, P. ; Boer, I.J.M. de - \ 2014
    In: Proceedings of the Agricultural Research Forum 2014. - - p. 48 - 48.
    Convergence between science and environmental education
    Wals, A.E.J. ; Brody, M. ; Dillon, J. ; Stevenson, R.B. - \ 2014
    Science 344 (2014)6184. - ISSN 0036-8075 - p. 583 - 584.
    citizen science - public engagement - green
    Urgent issues such as climate change, food scarcity, malnutrition, and loss of biodiversity are highly complex and contested in both science and society (1). To address them, environmental educators and science educators seek to engage people in what are commonly referred to as sustainability challenges. Regrettably, science education (SE), which focuses primarily on teaching knowledge and skills, and environmental education (EE), which also stresses the incorporation of values and changing behaviors, have become increasingly distant. The relationship between SE and EE has been characterized as “distant, competitive, predatorprey and host-parasite” (2). We examine the potential for a convergence of EE and SE that might engage people in addressing fundamental socioecological challenges.
    Learning and Knowing in Pursuit of Sustainability: Concepts and Tools for Trans-Disciplinary Environmental Research
    Peters, S. ; Wals, A.E.J. - \ 2013
    In: Trading Zones in Environmental Education: Creating Trans-disciplinary Dialogue / Krasny, M., Dillon, J., New York : Peter Lang - ISBN 9781433111792 - p. 79 - 104.
    Energy demand on dairy farms in Ireland
    Upton, J.R. ; Humphreys, J. ; Groot Koerkamp, P.W.G. ; French, P. ; Dillon, P. ; Boer, I.J.M. de - \ 2013
    Journal of Dairy Science 96 (2013)10. - ISSN 0022-0302 - p. 6489 - 6498.
    life-cycle assessment - milk-production - impact
    Reducing electricity consumption in Irish milk production is a topical issue for 2 reasons. First, the introduction of a dynamic electricity pricing system, with peak and off-peak prices, will be a reality for 80% of electricity consumers by 2020. The proposed pricing schedule intends to discourage energy consumption during peak periods (i.e., when electricity demand on the national grid is high) and to incentivize energy consumption during off-peak periods. If farmers, for example, carry out their evening milking during the peak period, energy costs may increase, which would affect farm profitability. Second, electricity consumption is identified in contributing to about 25% of energy use along the life cycle of pasture-based milk. The objectives of this study, therefore, were to document electricity use per kilogram of milk sold and to identify strategies that reduce its overall use while maximizing its use in off-peak periods (currently from 0000 to 0900 h). We assessed, therefore, average daily and seasonal trends in electricity consumption on 22 Irish dairy farms, through detailed auditing of electricity-consuming processes. To determine the potential of identified strategies to save energy, we also assessed total energy use of Irish milk, which is the sum of the direct (i.e., energy use on farm) and indirect energy use (i.e., energy needed to produce farm inputs). On average, a total of 31.73 MJ was required to produce 1 kg of milk solids, of which 20% was direct and 80% was indirect energy use. Electricity accounted for 60% of the direct energy use, and mainly resulted from milk cooling (31%), water heating (23%), and milking (20%). Analysis of trends in electricity consumption revealed that 62% of daily electricity was used at peak periods. Electricity use on Irish dairy farms, therefore, is substantial and centered around milk harvesting. To improve the competitiveness of milk production in a dynamic electricity pricing environment, therefore, management changes and technologies are required that decouple energy use during milking processes from peak periods
    Economic values for yield, survival, calving interval and beef daily gain for three breeds in Slovenia
    Haas, Y. de; Veerkamp, R.F. ; Shalloo, L. ; Dillon, P. ; Kuipers, A. ; Klopcic, M. - \ 2013
    Livestock Science 157 (2013)2-3. - ISSN 1871-1413 - p. 397 - 407.
    production circumstances - output limitations - production traits - selection - milk - fertility - objectives - efficiency - situations - weights
    Breeding indices need to be looked at periodically to evaluate the objective of the breeding program. In recent times the economic perspective of the breeding program has received a higher priority in deciding breeding objectives than in the past. However, prices of input and output products are becoming more difficult to predict with increased fluctuations in most prices, which adds a level of complexity to their inclusion in the selection index. With these challenges in mind, the breeding program in a new EU country (Slovenia) was evaluated. All three national Breeding Associations joined the deliberations. The aim of this study was to develop an economic selection index for three breeds (Simmental, Brown Swiss and Holstein-Friesian) in Slovenia. Because farming circumstances differ within Slovenia, differences in the production systems were also taken into account; e.g., flat land vs. hilly/mountainous areas, and for conventional vs. organic farming. Economic values (€) were calculated for milk, fat and protein yields (€/cow/year/kg), survival (€/cow/year/%survival), calving interval (€/cow/year/day), and beef daily gain (€/cow/year/kg). Economic values were calculated by changing one of these traits whilst keeping the other traits at the default level. Economic indices were calculated using a farm economic model (Moorepark Dairy Systems Model). Herd parameters (e.g., number of milking cows, replacements, young stock and calving pattern), milk production, feed requirements and ration, land use and labour requirements were re-parameterised in order to be relevant to the Slovenian circumstances. Absolute economic values were slightly negative for milk yield for all breeds (-0.02 to -0.04€ per kg milk), but positive for milk components (0.55 to 1.45€ per kg fat, and 2.89 to 3.38€ per kg protein). High absolute economic values were calculated for survival (7.37 to 9.55€ per %). Absolute economic values for calving interval were approximately -1€ per day for all breeds, while the economic value for beef daily gain was 0.14€ per kg for Brown Swiss and 0.32€ per kg for Simmental. The constructed economic indices ranked bulls in a significantly different manner than how the Slovenian Total Merit Indices ranked the bulls. The economic indices were robust towards changes in prices and farming system. Ranking was most sensitive towards variation in milk price. Assumptions concerning feed intake in relation to growth influenced the economic value for beef daily gain. Assumptions regarding the farming system (i.e., organic farming systems) only slightly affected the ranking of the bulls.
    The Evolving Characteristics of Environmental Education Research
    Stevenson, B. ; Dillon, J. ; Wals, A.E.J. ; Brody, M. - \ 2013
    In: International Handbook of Research on Environmental Education / Stevenson, R.B., Brody, M., Dillon, J., Wals, A.E.J., London : Routledge - ISBN 9780415892384 - p. 512 - 517.
    Situating the Handbook in the Evolving Characteristics of Environmental Education Research
    Stevenson, R.B. ; Dillon, J. ; Wals, A.E.J. ; Brody, M. - \ 2013
    In: International Handbook of Environmental Education Research / Stevenson, B., Brody, M., Dillon, J., Wals, A.E.J., London, UK : Routledge - ISBN 9780415892391 - p. 508 - 513.
    Probing Normative Research in Environmental Education: Ideas about Education and Ethics
    Jickling, B. ; Wals, A.E.J. - \ 2013
    In: International Handbook of Environmental Education Research / Stevenson, R.B., Brody, M., Dillon, J., Wals, A.E.J., London : Routledge - ISBN 9780415892384 - p. 74 - 86.
    Introduction: An Orientation to Environmental Education and the Handbook
    Stevenson, R.B. ; Brody, M. ; Dillon, J. ; Wals, A.E.J. - \ 2013
    In: International Handbook of Environmental Education Research / Stevenson, R.B., Brody, M., Dillon, J., Wals, A.E.J., London : Routledge - ISBN 9780415892384 - p. 1 - 6.
    Tentative Directions for Environmental Education Research in Uncertain Times
    Wals, A.E.J. ; Stevenson, R.B. ; Brody, M. ; Dillon, J. - \ 2013
    In: International Handbook of Research on Environmental Education / Stevenson, R.B., Brody, M., Dillon, J., Wals, A.E.J., New York : Routledge - ISBN 9780415892384 - p. 542 - 548.
    Conventional and Emerging Learning Theories: Implications and Choices for Educational Researchers with a Planetary Consciousness
    Wals, A.E.J. ; Dillon, J. - \ 2013
    In: International Handbook of Environmental Education Research / Stevenson, R.B., Brody, M., Dillon, J., Wals, A.E.J., New York : Routledge - ISBN 9780415892384 - p. 253 - 261.
    International Handbook of Research on Environmental Education
    Stevenson, R.B. ; Brody, M. ; Dillon, J. ; Wals, A.E.J. - \ 2012
    London : Routledge - ISBN 9780415892384 - 592
    milieueducatie - milieuwetenschappen - onderzoek - onderwijzen - leren - milieu - duurzaamheid (sustainability) - wereld - handboeken - environmental education - environmental sciences - research - teaching - learning - environment - sustainability - world - handbooks
    The environment and contested notions of sustainability are increasingly topics of public interest, political debate, and legislation across the world. Environmental education journals now publish research from a wide variety of methodological traditions that show linkages between the environment, health, development, and education. The growth in scholarship makes this an opportune time to review and synthesize the knowledge base of the environmental education (EE) field. The purpose of this 51-chapter handbook is not only to illuminate the most important concepts, findings and theories that have been developed by EE research, but also to critically examine the historical progression of the field, its current debates and controversies, what is still missing from the EE research agenda, and where that agenda might be headed. Published for the American Educational Research Association (AERA).
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