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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The impact of networks on the innovative and financial performance of more entrepreneurial versus less entrepreneurial farmers in West Java, Indonesia
Etriya, Etriya ; Scholten, Victor E. ; Wubben, Emiel F.M. ; Omta, S.W.F. - \ 2019
NJAS Wageningen Journal of Life Sciences 89 (2019). - ISSN 1573-5214
Business ties - Entrepreneurship - Financial performance - Innovative performance - Network heterogeneity - Technology ties

Farmers may vary in their response to or anticipation of agrifood market changes, which probably depends on their entrepreneurial degree and networks. This paper aims to investigate the effects of farmers’ entrepreneurial degree and network content (i.e., business ties, technology ties, and network heterogeneity) on farm performance (i.e., innovative performance and financial performance). The data set was gathered through a survey of 262 vegetable farmers in West Java, Indonesia. Our findings reveal that more entrepreneurial farmers (106) have more business ties, technology ties, and heterogeneous networks compared to less entrepreneurial farmers (156). Further analyses using OLS regression confirm that farmers who are more entrepreneurial and have more business ties obtain both enhanced innovative and financial performance, while farmers who link to heterogeneous networks obtain only enhanced innovative performance. Overall, the findings of this study demonstrate that more entrepreneurial farmers with networks that are rich in business ties and diverse contacts have better farm performance.

Nutrition and Income Generation Intervention (NIGI) for Refugees and Host Communities in West-Nile Region, Uganda (2018- 2020) : Inception Phase Report
Pittore, Katherine - \ 2019
Wageningen : Wageningen Centre for Development Innovation (WCDI-19-072 ) - 46 p.
The relevance of connecting sustainable agricultural development with African philosophy
Boogaard, Birgit K. - \ 2019
South African Journal of Philosophy 38 (2019)3. - ISSN 0258-0136 - p. 273 - 286.
Our global food system is complex and philosophers can – or should – pose critical questions about it. One question that deserves particular attention is Western interference in agricultural development in Africa. To today, the Western scientific paradigm forms the basis for mainstream agricultural research and development – with a firm belief in technological solutions and economic progress. It is concerning that African philosophy is a largely unknown field among agricultural scientists and practitioners. The aim of this philosophical essay is therefore to explore the relevance of connecting sustainable agricultural development with African philosophy. The article explores Eurocentric thinking in agricultural research and development and why such thinking can be problematic. In a search for ways to respond to Eurocentrism, I follow Kimmerle, who engaged in intercultural dialogues between African and Western philosophies. Mutually respectful and transformative dialogues can lead to mutual understanding and a more equal relation between Africa and the West, in the sense that this relation becomes more open to African philosophies and less Eurocentric.
Roles of agroforestry in sustainable intensification of small farms and food security for societies in West Africa
Seghieri, J. ; Bastide, B. ; Ingram, V.J. ; Jourdan, C. ; Sanogo, D. - \ 2019
What’s Cooking in Berlin’s Food Policy Kitchen
Hoffmann, Dinah ; Morrow, Oona ; Pohl, Christine - \ 2019
Urban Agriculture Magazine (2019)36. - ISSN 1571-6244 - p. 37 - 39.
After years of silence on municipal food policy in Berlin, actors from civil society, academia, industry and the local senate have come together to discuss the current state and future of Berlin’s food system, and are developing the city’s first urban food strategy. The Ernährungsrat Berlin is the citizen-led urban food policy council working towards food democracy and re-localisation in the Berlin-Brandenburg region.
Recommendation domains to scale out climate change adaptation in cocoa production in Ghana
Bunn, Christian ; Läderach, Peter ; Quaye, Amos ; Muilerman, Sander ; Noponen, Martin R.A. ; Lundy, Mark - \ 2019
Climate Services (2019). - ISSN 2405-8807
Climate impacts - Cocoa - Decision support - Ghana - Recommendation domains - West Africa

Climate change is threatening cocoa production in West Africa and guidance towards site-specific adaptation is required. We developed recommendation domains with common degree of impact requiring incremental, systemic or incremental adaptation effort to provide decision support for interventions to scale out adaptive practices. We used Random Forests to divide the cocoa production belt into four zones with distinct climatic features under current and future climate conditions. To make model results actionable we used an expert validation approach. Cocoa experts evaluated and verified cocoa occurrence data for model input, prioritized climate and soil variables for modeling use and confirmed the validity of the distribution of climate zones. Climate change will reduce the available area for cocoa production in the north due to a shift of the northern transition to the Savanna zone. The current area for cocoa in central Ashanti will remain suitable but will face uncertain climatic conditions. Areas in the Western, Central and Eastern regions will likely become hotter and wetter. Each of these projected impacts will require site-specific adaptation strategies matching the degree of impacts. Failing to prepare may subject rural communities to high risks of losing their livelihoods. Our recommendation domains can support impact specific preparation so that the majority of Ghana's cocoa production area may be sustained despite adverse climatic changes. Institutional and private actors can use our work to scale out locally conceived interventions to alleviate impacts from drought, heat and erratic rainfall.

Extreme spatial heterogeneity in carbonate accretion potential on a Caribbean fringing reef linked to local human disturbance gradients
Bakker, Didier M. ; Duyl, Fleur C. ; Perry, Chris T. ; Meesters, Erik H. - \ 2019
Global Change Biology (2019). - ISSN 1354-1013 - 13 p.
Acropora cervicornis - bioerosion - Bonaire - calcification - carbonate budget - Caribbean - climate change - sea-level rise

The capacity of coral reefs to maintain their structurally complex frameworks andto retain the potential for vertical accretion is vitally important to the persistenceof their ecological functioning and the ecosystem services they sustain. However,datasets to support detailed along‐coast assessments of framework production rates and accretion potential do not presently exist. Here, we estimate, based on gross bioaccretion and bioerosion measures, the carbonate budgets and resultant estimated accretion rates (EAR) of the shallow reef zone of leeward Bonaire – between 5 and 12 m depth – at unique fine spatial resolution along this coast (115 sites). Whilst the fringing reef of Bonaire is often reported to be in a better ecological condition than most sites throughout the wider Caribbean region, our data show that the carbonate budgets of the reefs and derived EAR varied considerably across this ~58 km long fringing reef complex. Some areas, in particular the marine reserves, were indeed still dominated by structurally complex coral communities with high net carbonate production (>10 kg CaCO3 m−2 year−1), high live coral cover and complex structural topography. The majority of the studied sites, however, were defined by relatively low budget states (<2 kg CaCO3 m−2 year−1) or were in a state of net erosion. These data highlight the marked spatial heterogeneity that can occur in budget states, andthus in reef accretion potential, even between quite closely spaced areas of individual reef complexes. This heterogeneity is linked strongly to the degree of localized landbased impacts along the coast, and resultant differences in the abundance of reef framework building coral species. The major impact of this variability is that those sections of reef defined by low‐accretion rates will have limited capacity to maintain their structural integrity and to keep pace with current projections of climate change induced sea‐level rise (SLR), thus posing a threat to reef functioning and biodiversity, potentially leading to trophic cascades. Since many Caribbean reefs are more severely degraded than those found around Bonaire, it is to be expected that the findings presentedhere are rather the rule than the exception, but the study also highlights theneed for similar high spatial resolution (along‐coast) assessments of budget states and accretion rates to meaningfully explore increasing coastal risk at the country level. The findings also more generally underline the significance of reducing local anthropo‐ genic disturbance and restoring framework building coral assemblages. Appropriately focussed local preservation efforts may aid in averting future large‐scale above reef water depth increases on Caribbean coral reefs and will limit the social and economic implications associated with the loss of reef goods and services.

Land use change and the migration geography of Greater White-fronted geese in European Russia
Grishchenko, Mikhail ; Prins, Herbert H.T. ; Ydenberg, Ronald C. ; Schaepman, Michael E. ; Boer, Willem F. de; Knegt, Henrik J. de - \ 2019
Ecosphere 10 (2019)8. - ISSN 2150-8925
agriculture - geese migration - land use change - political ecology - Russia - stopover sites

Large areas of agricultural land have been abandoned in European Russia since 1991, triggering succession toward more wooded landscapes, especially in northern regions where conditions for agriculture are more challenging. We hypothesize that this process has contributed to a southward shift by migratory Atlantic Greater White-fronted geese, as stopover sites in northern Russia became progressively less suitable. To test this hypothesis, we located stopover sites from information contained in 2976 ring recoveries and sightings of neck-collared geese. These records were divided into three time periods, chosen to reflect major changes in the economy and land use of European Russia: 1960–1990, 1991–2000, and 2001–2013. We used a kernel density estimator grid to delineate areas surrounding 300 putative stopover sites, and statistically evaluated the effects of latitude, distance to nearest waterbody, settlement, and period on stopover site usage by geese. Our results show that over the three periods, usage of the stopover sites has shifted southward, indicating that Greater White-fronted geese have shifted their migration pathway, with the greatest shift in the most recent period. This shift was confirmed by a highly significant squared latitude term and significant interaction term between periods. The nearest settlements showed no significant effect on stopover site usage while the nearest waterbody term was negative, suggesting higher waterbody densities contributed to higher densities of stopover sites. We attribute the shift to the successional reforestation of the Russian landscape that has followed widespread land abandonment, especially that following the break-up of the former USSR.

Can timber provision from Amazonian production forests be sustainable?
Piponiot, Camille ; Rödig, Edna ; Putz, Francis E. ; Rutishauser, Ervan ; Sist, Plinio ; Ascarrunz, Nataly ; Blanc, Lilian ; Derroire, Géraldine ; Descroix, Laurent ; Guedes, Marcelino Carneiro ; Coronado, Euridice Honorio ; Huth, Andreas ; Kanashiro, Milton ; Licona, Juan Carlos ; Mazzei, Lucas ; Oliveira, Marcus Vinicio Neves D'; Peña-Claros, Marielos ; Rodney, Ken ; Shenkin, Alexander ; Souza, Cintia Rodrigues De; Vidal, Edson ; West, Thales A.P. ; Wortel, Verginia ; Hérault, Bruno - \ 2019
Environmental Research Letters 14 (2019)6. - ISSN 1748-9318
Amazonia - disturbance - ecosystem recovery - macroecology - Selective logging - tropical forestry

Around 30 Mm3 of sawlogs are extracted annually by selective logging of natural production forests in Amazonia, Earth's most extensive tropical forest. Decisions concerning the management of these production forests will be of major importance for Amazonian forests' fate. To date, no regional assessment of selective logging sustainability supports decision-making. Based on data from 3500 ha of forest inventory plots, our modelling results show that the average periodic harvests of 20 m3 ha-1 will not recover by the end of a standard 30 year cutting cycle. Timber recovery within a cutting cycle is enhanced by commercial acceptance of more species and with the adoption of longer cutting cycles and lower logging intensities. Recovery rates are faster in Western Amazonia than on the Guiana Shield. Our simulations suggest that regardless of cutting cycle duration and logging intensities, selectively logged forests are unlikely to meet timber demands over the long term as timber stocks are predicted to steadily decline. There is thus an urgent need to develop an integrated forest resource management policy that combines active management of production forests with the restoration of degraded and secondary forests for timber production. Without better management, reduced timber harvests and continued timber production declines are unavoidable.

Post-fire soil erosion mitigation at the scale of swales using forest logging residues at a reduced application rate
Prats, Sergio A. ; González-Pelayo, Óscar ; Silva, Flavio C. ; Bokhorst, Koen J. ; Baartman, Jantiene E.M. ; Keizer, Jan J. - \ 2019
Earth Surface Processes and Landforms (2019). - ISSN 0197-9337
effectiveness - erosion - mulch - organic matter - wildfire

Mulching with forest residues has proved to be highly effective in reducing post-fire soil losses at the plot scale. However, its effectiveness has not been quantified at the application rates that are typically used in operational post-fire land management (2–3 Mg ha-1 using straw), as well as at scales larger than 100 m2. The present study compared post-fire erosion rates for six convergent hillslopes or swales of 500 to 800 m2, three of which were left untreated while the other three were mulched immediately after the fire with shredded eucalypt bark at a rate of 2.4 Mg ha-1. Erosion rates were monitored at irregular intervals during the first three post-fire years, whilst ground cover was assessed yearly. Selected topsoil properties (0–2 cm) such as organic matter content and aggregate stability were determined at a single occasion – two years after the wildfire, for three micro-environments separately: bare soil, and under mulch/litter and vegetation. Soil losses on the untreated swales decreased with post-fire year from 2.2 to 0.4 and 0.11 Mg ha-1 yr-1 (respectively for the first, second and third post-fire years), while the mulched swales produced 84%, 77% and 38% less soil losses than the untreated swales. Soil losses also depended on slope aspect, with the north-facing swales producing less erosion than the west-facing ones. This could be linked to their significant differences in bare soil, vegetation and stone cover, or a combination thereof. The type of micro-environment also played a significant role in topsoil properties (stone content, bulk density, resistance to penetration/shear stress, porosity and organic matter content). The present results add to the increasing evidence that forest residues should be duly considered for operational post-fire land management. Forest residues were highly effective in reducing erosion from swales at application rates as low as the typical 2 Mg ha-1 of post-fire straw mulch.

Hydrographic and Biological Survey of a Surface-Intensified Anticyclonic Eddy in the Caribbean Sea
Boog, C.G. van der; Jong, M.F. de; Scheidat, M. ; Leopold, M.F. ; Geelhoed, S.C.V. ; Schulz, K. ; Dijkstra, H.A. ; Pietrzak, J.D. ; Katsman, C.A. - \ 2019
Journal of Geophysical Research: Oceans 124 (2019)8. - ISSN 2169-9275 - p. 6235 - 6251.
anticyclone - barrier layer - Caribbean Sea - ecology - hydrographic - thermohaline staircases

In the Caribbean Sea, mesoscale anticyclonic ocean eddies impact the local ecosystem by mixing of low salinity river outflow with the nutrient-rich waters upwelling along the Venezuelan and Colombian coast. To gain insight into the physics and the ecological impact of these anticyclones, we performed a combined hydrographic and biological survey of one Caribbean anticyclone in February 2018. We found that the anticyclone had a radius of 90 km and was surface intensified with the strongest velocities (0.72 m/s) in the upper 150 m of the water column. Below, isopycnal displacements were found down to 700 dbar. The core of the anticyclone entrained waters from the Orinoco River plume and contained slightly elevated chlorophyll concentrations compared to the surroundings. At the edge of the anticyclone we observed higher densities of flying fish but not higher densities of predators like seabirds and cetaceans. Below the surface, a strong temperature inversion (0.98 °C) was present within a barrier layer. In addition, we found thermohaline staircases that originated from double diffusion processes within Tropical Atlantic Central Water.

Global prospects of the cost-efficiency of broiler welfare in middle-segment production systems
Vissers, Luuk S.M. ; Jong, Ingrid C. de; Horne, Peter L.M. van; Saatkamp, Helmut W. - \ 2019
Animals 9 (2019)7. - ISSN 2076-2615
Animal welfare - Broiler production - Cost-efficiency

In the 2000s, the idea of a so-called middle-segment arose in North-West Europe to address the criticism on intensive broiler production systems. Middle-segment systems being indoor housing of slower-growing broiler strains at a stocking density ≤38 kg/m2. Previous literature showed that Dutch middle-segment systems entail a relatively large gain in animal welfare at a relatively low increase in costs, i.e., have a high cost-efficiency. The question is to what extent these findings are applicable to other countries. Therefore, the aim of this study is to gain insight in the global prospects of middle-segment systems by exploring the cost-efficiency of these systems in other parts of the world. A set of representative countries, containing the Netherlands, United States and Brazil were selected. Cost-efficiency was defined as the ratio of the change in the level of animal welfare and the change in production costs. The level of animal welfare was measured by the Welfare Quality (WQ) index score. Data was collected from literature and consulting experts. Results show that in the Netherlands, United States and Brazil a change from conventional towards a middle-segment system improves animal welfare in a cost-efficient manner (the Netherlands 9.1, United States 24.2 and Brazil 12.1). Overall, it can be concluded that in general middle-segment production systems provide a considerable increase in animal welfare at a relatively small increase in production costs and therefore offer good prospects for a cost-efficient improvement of broiler welfare.

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
Toward the improvement of total nitrogen deposition budgets in the United States
Walker, J.T. ; Beachley, G. ; Amos, H.M. ; Baron, J.S. ; Bash, J. ; Baumgardner, R. ; Bell, M.D. ; Benedict, K.B. ; Chen, X. ; Clow, D.W. ; Cole, A. ; Coughlin, J.G. ; Cruz, K. ; Daly, R.W. ; Decina, S.M. ; Elliott, E.M. ; Fenn, M.E. ; Ganzeveld, L. ; Gebhart, K. ; Isil, S.S. ; Kerschner, B.M. ; Larson, R.S. ; Lavery, T. ; Lear, G.G. ; Macy, T. ; Mast, M.A. ; Mishoe, K. ; Morris, K.H. ; Padgett, P.E. ; Pouyat, R.V. ; Puchalski, M. ; Pye, H.O.T. ; Rea, A.W. ; Rhodes, M.F. ; Rogers, C.M. ; Saylor, R. ; Scheffe, R. ; Schichtel, B.A. ; Schwede, D.B. ; Sexstone, G.A. ; Sive, B.C. ; Sosa, R. ; Templer, P.H. ; Thompson, T. ; Tong, D. ; Wetherbee, G.A. ; Whitlow, T.H. ; Wu, Z. ; Yu, Z. ; Zhang, L. - \ 2019
Science of the Total Environment 691 (2019). - ISSN 0048-9697 - p. 1328 - 1352.
Ammonia - Dry deposition - Organic nitrogen - Oxidized nitrogen - Reactive nitrogen - Wet deposition

Frameworks for limiting ecosystem exposure to excess nutrients and acidity require accurate and complete deposition budgets of reactive nitrogen (Nr). While much progress has been made in developing total Nr deposition budgets for the U.S., current budgets remain limited by key data and knowledge gaps. Analysis of National Atmospheric Deposition Program Total Deposition (NADP/TDep) data illustrates several aspects of current Nr deposition that motivate additional research. Averaged across the continental U.S., dry deposition contributes slightly more (55%) to total deposition than wet deposition and is the dominant process (>90%) over broad areas of the Southwest and other arid regions of the West. Lack of dry deposition measurements imposes a reliance on models, resulting in a much higher degree of uncertainty relative to wet deposition which is routinely measured. As nitrogen oxide (NOx) emissions continue to decline, reduced forms of inorganic nitrogen (NHx = NH3 + NH4 +) now contribute >50% of total Nr deposition over large areas of the U.S. Expanded monitoring and additional process-level research are needed to better understand NHx deposition, its contribution to total Nr deposition budgets, and the processes by which reduced N deposits to ecosystems. Urban and suburban areas are hotspots where routine monitoring of oxidized and reduced Nr deposition is needed. Finally, deposition budgets have incomplete information about the speciation of atmospheric nitrogen; monitoring networks do not capture important forms of Nr such as organic nitrogen. Building on these themes, we detail the state of the science of Nr deposition budgets in the U.S. and highlight research priorities to improve deposition budgets in terms of monitoring and flux measurements, leaf- to regional-scale modeling, source apportionment, and characterization of deposition trends and patterns.

Patterns of distribution and drivers of change in shallow seagrass and algal assemblages of a non-estuarine Southern Caribbean mangrove lagoon
Debrot, A.O. ; Hylkema, A. ; Vogelaar, W. ; Prud'homme van Reine, W.F. ; Engel, M.S. ; Hateren, J.A. van; Meesters, E.H. - \ 2019
Aquatic Botany 159 (2019). - ISSN 0304-3770
Drivers of assemblage structure - Mangrove land reclamation - Non-estuarine mangrove system model - Tropical seagrass

Shallow marine macrophyte communities serve key roles in the tropical coastal ecosystem but are undergoing large and rapid deterioration worldwide, as is also the case in the non-estuarine mangrove lagoon of Lac Bay, Bonaire, in the Southern Caribbean. To help better understand both the drivers of assemblage structure and potential consequences of the changes taking place in the bay, we here quantify and describe the distribution of algal and seagrass assemblages along the environmental gradient from the turbid, inner mangrove pools to the clear, open bay conditions, based on 98 randomly-chosen, 4 m2 survey plots. Seven assemblages were described along this land-to-sea gradient, five of which were dominated by marine macrophytes, one by sponges and one by a polychaete. With exception of the hypersaline backwaters which were devoid of benthic macrophyte vegetation, isolated mangrove pools showed the lowest total benthic cover, species richness and biodiversity of all habitats. Salinity and substrate particle-size composition accounted for most variation between the different assemblages and appear to be the key known determinants of assemblage composition. We developed a conceptual model to help disentangle the relationship between and the relative roles of the two principal drivers, as part of a cascade of effects which ultimately result from terrestrial run-off into the bay as mediated by mangrove encroachment into the bay. The model links spatial patterns to ongoing processes and implies that the assemblage patterns described are not only a reflection of, but also allow prediction of how the assemblages develop through time.

The vulnerabilities of agricultural land and food production to future water scarcity
Fitton, N. ; Alexander, P. ; Arnell, N. ; Bajzelj, B. ; Calvin, K. ; Doelman, J. ; Gerber, J.S. ; Havlik, P. ; Hasegawa, T. ; Herrero, M. ; Krisztin, T. ; Meijl, H. van; Powell, T. ; Sands, R. ; Stehfest, E. ; West, P.C. ; Smith, P. - \ 2019
Global environmental change : human and policy dimensions 58 (2019). - ISSN 0959-3780
Food security - Land use - Shared socio-economic pathways - Water availability

Rapidly increasing populations coupled with increased food demand requires either an expansion of agricultural land or sufficient production gains from current resources. However, in a changing world, reduced water availability might undermine improvements in crop and grass productivity and may disproportionately affect different parts of the world. Using multi-model studies, the potential trends, risks and uncertainties to land use and land availability that may arise from reductions in water availability are examined here. In addition, the impacts of different policy interventions on pressures from emerging risks are examined. Results indicate that globally, approximately 11% and 10% of current crop- and grass-lands could be vulnerable to reduction in water availability and may lose some productive capacity, with Africa and the Middle East, China, Europe and Asia particularly at risk. While uncertainties remain, reduction in agricultural land area associated with dietary changes (reduction of food waste and decreased meat consumption) offers the greatest buffer against land loss and food insecurity.

Diversity of tryptophan halogenases in sponges of the genus Aplysina
Gutleben, Johanna ; Koehorst, Jasper J. ; McPherson, Kyle ; Pomponi, Shirley ; Wijffels, René H. ; Smidt, Hauke ; Sipkema, Detmer - \ 2019
FEMS microbiology ecology 95 (2019)8. - ISSN 0168-6496
bioactive compounds - environmental enzymes - Halogenase - host-associated microbiome - marine sponges - phylogenetic diversity

Marine sponges are a prolific source of novel enzymes with promising biotechnological potential. Especially halogenases, which are key enzymes in the biosynthesis of brominated and chlorinated secondary metabolites, possess interesting properties towards the production of pharmaceuticals that are often halogenated. In this study we used a polymerase chain reaction (PCR)-based screening to simultaneously examine and compare the richness and diversity of putative tryptophan halogenase protein sequences and bacterial community structures of six Aplysina species from the Mediterranean and Caribbean seas. At the phylum level, bacterial community composition was similar amongst all investigated species and predominated by Actinobacteria, Chloroflexi, Cyanobacteria, Gemmatimonadetes, and Proteobacteria. We detected four phylogenetically diverse clades of putative tryptophan halogenase protein sequences, which were only distantly related to previously reported halogenases. The Mediterranean species Aplysina aerophoba harbored unique halogenase sequences, of which the most predominant was related to a sponge-associated Psychrobacter-derived sequence. In contrast, the Caribbean species shared numerous novel halogenase sequence variants and exhibited a highly similar bacterial community composition at the operational taxonomic unit (OTU) level. Correlations of relative abundances of halogenases with those of bacterial taxa suggest that prominent sponge symbiotic bacteria, including Chloroflexi and Actinobacteria, are putative producers of the detected enzymes and may thus contribute to the chemical defense of their host.

Diet and growth of juvenile queen conch Lobatus gigas (Gastropoda: Strombidae) in native, mixed and invasive seagrass habitats
Boman, Erik Maitz ; Bervoets, Tadzio ; Graaf, Martin De; Dewenter, Jana ; Maitz, Anna ; Meijer Zu Schlochtern, Melanie P. ; Stapel, Johan ; Smaal, Aad C. ; Nagelkerke, Leopold A.J. - \ 2019
Marine Ecology Progress Series 621 (2019). - ISSN 0171-8630 - p. 143 - 154.
Caribbean - Halophila stipulacea - Invasive species - Mollusca - Stable isotope

Juvenile queen conch are primarily associated with native seagrass such as Thalassia testudinum in large parts of their range in the Caribbean and the southern Gulf of Mexico. Here, a number of non-native seagrass species have been introduced including Halophila stipulacea, which is natural to the Red Sea and the Indo-Pacific. In the Caribbean, H. stipulacea often creates dense continuous mats with little or no sediment exposed, compared to native seagrass, which grows much less dense. We examined the diet and growth of juvenile conch in both native, mixed, and invasive seagrass beds using stable isotope analysis and an in situ growth enclosure experiment. Organic material in the sediment (i.e. benthic diatoms and particulate organic matter) was found to be the most important source of carbon and nitrogen for juvenile queen conch in all 3 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.

Low-level stratiform clouds and dynamical features observed within the southern West African monsoon
Dione, Cheikh ; Lohou, Fabienne ; Lothon, Marie ; Adler, Bianca ; Babić, Karmen ; Kalthoff, Norbert ; Pedruzo-Bagazgoitia, Xabier ; Bezombes, Yannick ; Gabella, Omar - \ 2019
Atmospheric Chemistry and Physics 19 (2019)13. - ISSN 1680-7316 - p. 8979 - 8997.

During the boreal summer, the monsoon season that takes place in West Africa is accompanied by low stratus clouds over land that stretch from the Guinean coast several hundred kilometers inland. Numerical climate and weather models need finer description and knowledge of cloud macrophysical characteristics and of the dynamical and thermodynamical structures occupying the lowest troposphere, in order to be properly evaluated in this region. The Dynamics-Aerosol-Chemistry-Cloud Interactions in West Africa (DACCIWA) field experiment, which took place in summer 2016, addresses this knowledge gap. Low-level atmospheric dynamics and stratiform low-level cloud macrophysical properties are analyzed using in situ and remote sensing measurements continuously collected from 20 June to 30 July at Savè, Benin, roughly 180&thinsp;km from the coast. The macrophysical characteristics of the stratus clouds are deduced from a ceilometer, an infrared cloud camera, and cloud radar. Onset times, evolution, dissipation times, base heights, and thickness are evaluated. The data from an ultra-high-frequency (UHF) wind profiler, a microwave radiometer, and an energy balance station are used to quantify the occurrence and characteristics of the monsoon flow, the nocturnal low-level jet, and the cold air mass inflow propagating northward from the coast of the Gulf of Guinea. The results show that these dynamical structures are very regularly observed during the entire 41&thinsp;d documented period. Monsoon flow is observed every day during our study period. The so-called "maritime inflow" and the nocturnal low-level jet are also systematic features in this area. According to synoptic atmospheric conditions, the maritime inflow reaches Savè around 18:00-19:00&thinsp;UTC on average. This timing is correlated with the strength of the monsoon flow. This time of arrival is close to the time range of the nocturnal low-level jet settlement. As a result, these phenomena are difficult to distinguish at the Savè site. The low-level jet occurs every night, except during rain events, and is associated 65&thinsp;% of the time with low stratus clouds. Stratus clouds form between 22:00 and 06:00&thinsp;UTC at an elevation close to the nocturnal low-level jet core height. The cloud base height, <span classCombining double low line"inline-formula">310±30</span>&thinsp;m above ground level (a.g.l.), is rather stationary during the night and remains below the jet core height. The cloud top height, at <span classCombining double low line"inline-formula">640±100</span>&thinsp;m&thinsp;a.g.l., is typically found above the jet core. The nocturnal low-level jet, low-level stratiform clouds, monsoon flow, and maritime inflow reveal significant day-to-day and intra-seasonal variability during the summer given the importance of the different monsoon phases and synoptic atmospheric conditions. Distributions of strength, depth, onset time, breakup time, etc. are quantified here. These results contribute to satisfy the main goals of DACCIWA and allow a conceptual model of the dynamical structures in the lowest troposphere over the southern part of West Africa.

Vulnerability and adaptation options to climate change for rural livelihoods – A country-wide analysis for Uganda
Wichern, Jannike ; Descheemaeker, Katrien ; Giller, Ken E. ; Ebanyat, Peter ; Taulya, Godfrey ; Wijk, Mark T. van - \ 2019
Agricultural Systems 176 (2019). - ISSN 0308-521X
Crop suitability - East Africa - Household food security - Impact assessment - Multi-level

Rural households in sub-Saharan Africa earn a substantial part of their living from rain-fed smallholder agriculture, which is highly sensitive to climate change. There is a growing number of multi-level assessments on impacts and adaptation options for African smallholder systems under climate change, yet few studies translate impacts at the individual crop level to vulnerability at the household level, at which other livelihood activities need to be considered. Further, these assessments often use representative household types rather than considering the diversity of households for the identification of larger-scale patterns at sub-national and national levels. We developed a framework that combines crop suitability maps with a household food availability analysis to quantify household vulnerability to climate-related impacts on crop production and effects of adaptation options. The framework was tested for Uganda, identifying four hotspots of household vulnerability across the country. Hotspots were visually identified as areas with a relatively high concentration of vulnerable households, experiencing a decline in household crop suitability. About 30% of the households in the hotspots in (central) southwest were vulnerable to a combination of 3 °C temperature increase and 10% rainfall decline through declining suitability for several key crops (including highland banana, cassava, maize and sorghum). In contrast only 10% of the households in West Nile and central northern Uganda were negatively affected, and these were mainly affected by declining suitability of common beans. Households that depended on common beans and lived at lower elevations in West Nile and central north were vulnerable to a 2 to 3 °C temperature increase, while households located at higher elevations (above 1100–2000 m.a.s.l. depending on the crop) benefited from such an increase. Options for adaptation to increasing temperatures were most beneficial in northern Uganda, while drought-related adaptation options were more beneficial in the southwest. This framework provides a basis for decision makers who need information on where the vulnerable households are, what crops drive the vulnerability at household level and which intervention efforts are most beneficial in which regions.

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