The impact of mussel seed fishery on the dynamics of wild subtidal mussel beds in the western Wadden Sea, The Netherlands
Smaal, A.C. ; Craeymeersch, J.A. ; Stralen, M.R. van - \ 2021
Journal of Sea Research 167 (2021). - ISSN 1385-1101
Beyond baci-design - Fishery - Mussel stocks - Time series
For the cultivation of mussels, wild stocks of juveniles are harvested to collect mussel seed as starting material for the culture. These wild stocks are found in the sublittoral western Wadden Sea (NL). After summer spat fall, fisheries in Autumn on newly formed beds is carried out in areas that have the risk of washing away due to storms, or are vulnerable for starfish predation. These wild beds are considered as relatively unstable. On remaining more stable wild beds, seed fishery is carried out in next Spring. As the Wadden Sea is a nature conservation area, mussel seed fisheries is only allowed if no negative impacts on the nature management objectives can be expected. Seed fishery impacts were addressed in an extensive study including effects on sediment composition, macrobenthos and epifauna. In this paper we describe the effects of mussel seed fisheries on the development of the mussel stocks with and without fisheries in 39 pairwise studied impact and control plots. Stocks on seed beds in areas of the sublittoral Western Wadden Sea that are known as unstable, show a large decline within one year after settlement, also when there is no seed fishery. Harvesting seed on more stable beds in Spring results in a statistical significant reduction in stock size, which lasts for a period of two years after the first fishery. For the longer term, there is a gradual decline of the mussel stocks on all studied plots. On three out of the 39 plots, mussel biomass showed a large increase, both on control and impact parts. Also these mussel beds declined and eventually disappeared. A difference in life expectancy of fished and unfished beds was not demonstrated. It is concluded that sublittoral beds gradually disappear, also without fisheries. As a consequence, new recruitment is of critical importance for the long-term survival of sublittoral mussel beds. As we found no significant difference between recruitment on fished and control parts, there are no indications for negative impacts of seed fishery on new recruitment.
St-corabico : A spatiotemporal object-based bias correction method for storm prediction detected by satellite
Laverde-Barajas, Miguel ; Corzo, Gerald A. ; Poortinga, Ate ; Chishtie, Farrukh ; Meechaiya, Chinaporn ; Jayasinghe, Susantha ; Towashiraporn, Peeranan ; Markert, Amanda ; Saah, David ; Son, Lam Hung ; Khem, Sothea ; Boonya-Aroonnet, Surajate ; Chaowiwat, Winai ; Uijlenhoet, Remko ; Solomatine, Dimitri P. - \ 2020
Remote Sensing 12 (2020)21. - ISSN 2072-4292 - p. 1 - 19.
Bias correction - Object-based method - Satellite-based precipitation - Spatiotemporal analysis - Storm events
Advances in near real-time rainstorm prediction using remote sensing have offered important opportunities for effective disaster management. However, this information is subject to several sources of systematic errors that need to be corrected. Temporal and spatial characteristics of both satellite and in-situ data can be combined to enhance the quality of storm estimates. In this study, we present a spatiotemporal object-based method to bias correct two sources of systematic error in satellites: displacement and volume. The method, Spatiotemporal Contiguous Object-based Rainfall Analysis for Bias Correction (ST-CORAbico), uses the spatiotemporal rainfall analysis ST-CORA incorporated with a multivariate kernel density storm segmentation for describing the main storm event characteristics (duration, spatial extension, volume, maximum intensity, centroid). Displacement and volume are corrected by adjusting the spatiotemporal structure and the intensity distribution, respectively. ST-CORAbico was applied to correct the early version of the Integrated Multi-satellite Retrievals for the Global Precipitation Mission (GPM-IMERG) over the Lower Mekong basin in Thailand during the monsoon season from 2014 to 2017. The performance of ST-CORABico is compared against the Distribution Transformation (DT) and Gamma Quantile Mapping (GQM) probabilistic methods. A total of 120 storm events identified over the study area were classified into short and long-lived storms by using a k-means cluster analysis method. Examples for both storm event types describe the error reduction due to location and magnitude by ST-CORAbico. The results showed that the displacement and magnitude correction made by ST-CORAbico considerably reduced RMSE and bias of GPM-IMERG. In both storm event types, this method showed a lower impact on the spatial correlation of the storm event. In comparison with DT and GQM, ST-CORAbico showed a superior performance, outperforming both approaches. This spatiotemporal bias correction method offers a new approach to enhance the accuracy of satellite-derived information for near real-time estimation of storm events.
Self-constraining of low-energy rivers explains low channel mobility and tortuous planforms
Candel, Jasper H.J. ; Makaske, Bart ; Kijm, Niels ; Kleinhans, Maarten G. ; Storms, Joep E.A. ; Wallinga, Jakob - \ 2020
The Depositional Record 6 (2020)3. - ISSN 2055-4877 - p. 648 - 669.
fluvial morphology - heterogeneous floodplain architecture - Holocene - river channel planform
Meandering rivers are abundant on Earth, from the largest rivers to the smallest tributaries. The classical view of meandering rivers is a sinuous planform with rounded bends, which grow and migrate until they are cut-off. However, many low-energy meandering rivers have planforms that are much more complex than this classical view due to the heterogeneity of their alluvium, and show relatively limited channel migration. Based on a detailed palaeogeographic study of the Dommel River in The Netherlands, it is inferred that low-energy meandering rivers may develop tortuous planforms with sharp bends, owing to self-formed deposits that increasingly constrain the channel mobility. This mechanism is corroborated by data from 47 meandering river reaches of varied scale from around the world, which show that erosion-resistant floodplain deposits are preserved in the river banks when the river energy is below a critical threshold. The term ‘self-constraining’ is proposed for low-energy rivers where an increase in bank stability over time results in progressive tortuous planforms and reduced mobility. A conceptual model, based on the dataset, shows that the increase in bank stability over time also increases the energy required to break out of the tendency to self-constrain. Self-constraining thereby enhances the resilience of the system to bank erosion, while an unexpected increase in bank erosion may occur if river energy exceeds the critical threshold. This study provides a novel explanation for the evolution of low-energy river planforms and dynamics, and provides new insights on their responses to climate changes.
Can plants keep up with changing climate? : Heatwaves, Droughts, Heavy Rains, Storms
Treuren, R. van; Hoekstra, R. ; Wehrens, H.R.M.J. ; Hintum, T.J.L. van - \ 2020
Prophyta - Focus on Europe (2020). - p. 32 - 34.
Uncovering dryland woody dynamics using optical, microwave, and field data-prolonged above-average rainfall paradoxically contributes to woody plant die-off in the Western Sahel
Bernardino, Paulo N. ; Brandt, Martin ; Keersmaecker, Wanda De; Horion, Stéphanie ; Fensholt, Rasmus ; Storms, Ilié ; Wigneron, Jean Pierre ; Verbesselt, Jan ; Somers, Ben - \ 2020
Remote Sensing 12 (2020)14. - ISSN 2072-4292
Drought - Drylands - NDVI - Passive microwave - Time series - Vegetation optical depth - Woody vegetation dynamics
Dryland ecosystems are frequently struck by droughts. Yet, woody vegetation is often able to recover from mortality events once precipitation returns to pre-drought conditions. Climate change, however, may impact woody vegetation resilience due to more extreme and frequent droughts. Thus, better understanding how woody vegetation responds to drought events is essential. We used a phenology-based remote sensing approach coupled with field data to estimate the severity and recovery rates of a large scale die-off event that occurred in 2014-2015 in Senegal. Novel low (L-band) and high-frequency (Ku-band) passive microwave vegetation optical depth (VOD), and optical MODIS data, were used to estimate woody vegetation dynamics. The relative importance of soil, human-pressure, and before-drought vegetation dynamics influencing the woody vegetation response to the drought were assessed. The die-off in 2014-2015 represented the highest dry season VOD drop for the studied period (1989-2017), even though the 2014 drought was not as severe as the droughts in the 1980s and 1990s. The spatially explicit Die-off Severity Index derived in this study, at 500 m resolution, highlights woody plants mortality in the study area. Soil physical characteristics highly affected die-off severity and post-disturbance recovery, but pre-drought biomass accumulation (i.e., in areas that benefited from above-normal rainfall conditions before the 2014 drought) was the most important variable in explaining die-off severity. This study provides new evidence supporting a better understanding of the "greening Sahel", suggesting that a sudden increase in woody vegetation biomass does not necessarily imply a stable ecosystem recovery from the droughts in the 1980s. Instead, prolonged above-normal rainfall conditions prior to a drought may result in the accumulation of woody biomass, creating the basis for potentially large-scale woody vegetation die-off events due to even moderate dry spells.
Prevention and treatment of COVID-19 disease by controlled modulation of innate immunity
Schijns, Virgil ; Lavelle, Ed C. - \ 2020
European journal of immunology 50 (2020)7. - ISSN 0014-2980 - p. 932 - 938.
COVID-19 - cytokine - innate immunity - lung - SARS-CoV-2
The recent outbreak of coronavirus disease 2019 (COVID-19), triggered by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) poses an enormous threat to global public health and economies. Human coronaviruses normally cause no or mild respiratory disease but in the past two decades, potentially fatal coronavirus infections have emerged, causing respiratory tract illnesses such as pneumonia and bronchitis. These include severe acute respiratory syndrome coronavirus (SARS-CoV), followed by the Middle East respiratory syndrome coronavirus (MERS-CoV), and recently the SARS-CoV-2 coronavirus outbreak which emerged in Wuhan, China, in December 2019. Currently, most COVID-19 patients receive traditional supportive care including breathing assistance. To halt the ongoing spread of the pandemic SARS-CoV-2 coronavirus and rescue individual patients, established drugs and new therapies are under evaluation. Since it will be some time until a safe and effective vaccine will be available, the immediate priority is to harness innate immunity to accelerate early antiviral immune responses. Secondly since excessive inflammation is a major cause of pathology, targeted anti-inflammatory responses are being evaluated to reduce inflammation-induced damage to the respiratory tract and cytokine storms. Here, we highlight prominent immunotherapies at various stages of development which aim for augmented anti-coronavirus immunity and reduction of pathological inflammation. This article is protected by copyright. All rights reserved.
Seagrass coastal protection services reduced by invasive species expansion and megaherbivore grazing
James, Rebecca K. ; Christianen, Marjolijn J.A. ; Katwijk, Marieke M. van; Smit, Jaco C. de; Bakker, Elisabeth S. ; Herman, Peter M.J. ; Bouma, Tjeerd J. - \ 2020
Journal of Ecology 108 (2020)5. - ISSN 0022-0477 - p. 2025 - 2037.
coastal protection - conservation - ecosystem services - exotic species - marine ecology - marine vegetation - storm resilience - tropical ecology
Seagrasses provide an important ecosystem service by creating a stable erosion-resistant seabed that contributes to effective coastal protection. Variable morphologies and life-history strategies, however, are likely to impact the sediment stabilization capacity of different seagrass species. We question how opportunistic invasive species and increasing grazing by megaherbivores may alter sediment stabilization services provided by established seagrass meadows, using the Caribbean as a case study. Utilizing two portable field-flumes that simulate unidirectional and oscillatory flow regimes, we compared the sediment stabilization capacity of natural seagrass meadows in situ under current- and wave-dominated regimes. Monospecific patches of a native (Thalassia testudinum) and an invasive (Halophila stipulacea) seagrass species were compared, along with the effect of three levels of megaherbivore grazing on T. testudinum: ungrazed, lightly grazed and intensively grazed. For both hydrodynamic regimes, the long-leaved, dense meadows of the climax species, T. testudinum provided the highest stabilization. However, the loss of above-ground biomass by intensive grazing reduced the capacity of the native seagrass to stabilize the surface sediment. Caribbean seagrass meadows are presently threatened by the rapid spread of the invasive opportunistic seagrass, H. stipulacea. The dense meadows of H. stipulacea were found to accumulate fine sediment, and thereby, appear to be effective in reducing bottom shear stress during calm periods. This fine sediment within the invasive meadows, however, is easily resuspended by hydrodynamic forces, and the low below-ground biomass of H. stipulacea make it susceptible to uprooting during storm events, potentially leaving large regions vulnerable to erosion. Overall, this present study highlights that intensive megaherbivore grazing and opportunistic invasive species threaten the coastal protection services provided by mildly grazed native species. Synthesis. Seagrass meadows of dense, long-leaved species stabilize the sediment surface and maintain the seabed integrity, thereby contributing to coastal protection. These services are threatened by intensive megaherbivore grazing, which reduces the stability of the surface sediment, and opportunistic invasive species, which are susceptible to uprooting in storms and thereby can leave the seabed vulnerable to erosion.
Spatio-temporal assessment of beech growth in relation to climate extremes in Slovenia – An integrated approach using remote sensing and tree-ring data
Decuyper, Mathieu ; Chávez, Roberto O. ; Čufar, Katarina ; Estay, Sergio A. ; Clevers, Jan G.P.W. ; Prislan, Peter ; Gričar, Jožica ; Črepinšek, Zalika ; Merela, Maks ; Luis, Martin De; Notivoli, Roberto Serrano ; Castillo, Edurne Martinez Del; Rozendaal, Danaë M.A. ; Bongers, Frans ; Herold, Martin ; Sass-Klaassen, Ute - \ 2020
Agricultural and Forest Meteorology 287 (2020). - ISSN 0168-1923
Climate change is predicted to affect tree growth due to increased frequency and intensity of extreme events such as ice storms, droughts and heatwaves. Yet, there is still a lot of uncertainty on how trees respond to an increase in frequency of extreme events. Use of both ground-based wood increment (i.e. ring width) and remotely sensed data (i.e. vegetation indices) can be used to scale-up ground measurements, where there is a link between the two, but this has only been demonstrated in a few studies. We used tree-ring data together with crown features derived from the Moderate Resolution Imaging Spectroradiometer (MODIS) to assess the effect of extreme climate events on the growth of beech (Fagus sylvatica L.) in Slovenia. We found evidence that years with climate extremes during the growing season (drought, high temperatures) had a lower ring width index (RWI) but we could not find such evidence for the remotely sensed EVI (Enhanced Vegetation Index). However, when assessing specific events where leaf burning or wilting has been reported (e.g. August 2011) we did see large EVI anomalies. This implies that the impact of drought or heatwave events cannot be captured by EVI anomalies until physical damage on the canopy is caused. This also means that upscaling the effect of climate extremes on RWI by using EVI anomalies is not straightforward. An exception is the 2014 ice storm that caused a large decline in both RWI and EVI. Extreme climatic parameters explained just a small part of the variation in both RWI and EVI by, which could indicate an effect of other climate variables (e.g. late frost) or biotic stressors such as insect outbreaks. Furthermore, we found that RWI was lower in the year after a climate extreme occurred in the late summer. Most likely due to the gradual increase in temperature and more frequent drought we found negative trends in RWI and EVI. EVI maps could indicate where beech is sensitive to climate changes and could be used for planning mitigation interventions. Logical next steps should focus on a tree-based understanding of the short -and long-term effects of climate extremes on tree growth and survival, taking into account differential carbon allocation to the crown (EVI) and to wood-based variables. This research highlights the value of an integrated approach for upscaling tree-based knowledge to the forest level.
Rift Valley fever virus targets the maternal-foetal interface in ovine and human placentas
Oymans, Judith ; Wichgers Schreur, Paul J. ; Keulen, Lucien van; Kant, Jet ; Kortekaas, Jeroen - \ 2020
PLoS Neglected Tropical Diseases 14 (2020)1. - ISSN 1935-2727 - p. e0007898 - e0007898.
BACKGROUND: Rift Valley fever virus (RVFV) is an arbovirus of the order Bunyavirales that causes severe disease in ruminants and humans. Outbreaks in sheep herds are characterised by newborn fatalities and abortion storms. The association of RVFV infections with abortions of ovines and other ruminants is well recognized, whereas the pathology resulting in abortion has remained undescribed. Accumulating evidence suggests that RVFV is abortogenic in humans as well, warranting more research on the interaction of RVFV with the ruminant and human placenta. METHODOLOGY/PRINCIPAL FINDINGS: Pregnant ewes were inoculated with a highly virulent strain of RVFV and necropsied at different days post infection. Tissues were collected and analysed by PCR, virus isolation, and immunohistochemistry. The results show that RVFV replicates efficiently in maternal placental epithelial cells before the virus infects foetal trophoblasts. Moreover, the virus was shown to bypass the maternal epithelial cell layer by directly targeting foetal trophoblasts in the haemophagous zone, a region of the ovine placenta where maternal blood is in direct contact with foetal cells. Abortion was associated with widespread necrosis of placental tissues accompanied with severe haemorrhages. Experiments with human placental explants revealed that the same virus strain replicates efficiently in both cyto- and syncytiotrophoblasts. CONCLUSIONS/SIGNIFICANCE: This study demonstrates that RVFV targets the foetal-maternal interface in both ovine and human placentas. The virus was shown to cross the ovine placental barrier via two distinct routes, ultimately resulting in placental and foetal demise followed by abortion. Our finding that RVFV replicates efficiently in human trophoblasts underscores the risk of RVFV infection for human pregnancy.
Multi-level socioecological drivers of agrarian change: Longitudinal evidence from mixed rice-livestock-aquaculture farming systems of Bangladesh
Aravindakshan, Sreejith ; Krupnik, Timothy J. ; Groot, Jeroen C.J. ; Speelman, Erika N. ; Amjath- Babu, T.S. ; Tittonell, Pablo - \ 2020
Agricultural Systems 177 (2020). - ISSN 0308-521X
Coastal systems are facing natural and human-driven change coupled with a rising population. With increasing shifts in socioecological conditions during the past several decades, it is important to understand how socioecological drivers at different hierarchical levels: -micro, -meso, and -macro affect coastal farming systems, which play a crucial role in the livelihoods of coastal dwellers. Mixed rice-livestock-aquaculture farming in Southern Bangladesh exemplifies the rapid change occurring in many of the world's coastal farming systems in response to these drivers. We used panel data observations from the above study area and modeled trajectories of farm typologies, and the impact of multi-level socioecological drivers by a novel approach. Our approach integrates: (1) a well-articulated conceptual frame of change observed using (2) a temporal view of the potential drivers, change process and farm type outcomes, with the twenty years panel data of 502 households that is analyzed by means of (3) multivariate statistics in conjunction with panel data models that operationalize the conceptual frame. Our approach allows (a) estimating dynamic effects over time that typically cannot be estimated in a cross-sectional data set, (b) distinguishing between time-invariant fixed and time dependent random effects of multi-level socioecological drivers, and (c) controlling for omitted variables to a certain extent. Considering farming systems both within and outside of polder embankment systems intended to protect against oceanic water intrusion, we found a gradual shift from heterogeneous, rice-livestock farm types to more homogenous farms with less livestock and more off-farm activities. Micro-level factors including farm plot fragmentation, farmers' experience in cropping, machinery, salinity and soil fertility were influencing changes in farming systems. Meso-level factors including markets, road infrastructure, labor availability, access to extension and land tenure also affect the trajectory of farming systems change. Among macro-level drivers, increasing population density positively and significantly influenced cropping intensity among farms outside polder systems. Within polders, a positive but non-significant trend was observed for the influence of population density on cropping intensity. Our data also indicate negative and significant influence of cyclonic storms on cropping intensity over time in both areas. Our results underscore the importance of accounting for multiple levels of socioecological drivers of change when developing appropriate policy options for sustainable development in South Asia's coastal farming systems.
Ecological engineering with oysters for coastal resilience : Habitat suitability, bioenergetics, and ecosystem services
Chowdhury, Mohammed Shah Nawaz - \ 2019
Wageningen University. Promotor(en): A.C. Smaal; T. Ysebaert, co-promotor(en): S. Hossain. - Wageningen : Wageningen University - ISBN 9789463433938 - 193
Ecosystem based coastal management has gained in interest over the last decades. Development was achieved by incorporating different ecosystems services into coastal protection that can deal with threats related to climate change, such as accelerating sea level rise and increased storminess. The ecosystem-based approach not only tries to minimize anthropogenic impacts of coastal protection infrastructures on ecosystems but also aims at offering possibilities to enhance ecosystem functioning and resilience. Natural coastal ecosystems, such as biogenic reefs, dunes, beaches and tidal wetlands have potential value in protecting the coast from erosion and waves, with the benefit that these systems have some ability to self-repair and adapt in changing climate. The use of sustainable ecosystems that integrate human society with its natural environment for the beneﬁt of both is called ecological engineering. It attempts to combine engineering principles with ecological processes to reduce environmental impacts from built infrastructure. Certain key species inhabiting those coastal habitats are known as ecosystem engineers. A number of ecosystem engineers such as coral reefs, reef forming bivalves, vegetation of kelps and seagrasses, marshes and mangroves are known to play engineering roles in shallow estuarine and coastal areas.
Reef forming bivalves that occur in coastal waters can attenuate erosive wave energies, stabilize sediments and reduce marsh retreat. Oysters are commonly said to be ecosystem engineers as they form structures that influence the environment around them in ways that are beneficial to other species. There is a positive feedback of oyster reefs on the settlement of new recruits which makes the reefs self-sustaining. They provide a variety of ecologically and economically valuable goods and services. Oyster reefs serve as natural coastal buffers, absorbing wave energy directed at shorelines and reducing erosion from boat wakes, sea level rise, and storms. Given adequate recruitment and survival, oyster reefs could be self-sustaining elements of coastal protection that enhance other habitats. More than fifty studies were conducted throughout the world since 1995 to evaluate the different ecosystem services provided by oyster reefs including coastal defence. Several studies showed that created oyster reefs can reduce the coastal erosion rate in comparison to control sites with no reefs. This PhD study utilized this concept of oysters as ecosystem engineers and studied the rock oyster, Saccostrea cucullata, in a subtropical, monsoon dominated environment in Bangladesh. This particular environment imposes dynamic conditions for oysters to grow and act as ecosystem engineers. This study investigated the critical factors that determine oyster (S. cucullata) growth and development in a dynamic, monsoon dominated coastal ecosystem of Bangladesh. This study performed experiments by using oyster breakwater reefs to evaluate their eco-engineering effect on: (1) erosion control; and (2) biodiversity of benthic macroinvertebrates and fishes. It was aimed that the application of oyster breakwater reefs can be beneficial to mitigate erosion of tidal flats, promote sediment accretion and facilitate habitats for increasing saltmarsh growth and faunal abundance.
At first, the question was where oysters can settle and grow out, so the focus is on boundary conditions in terms of habitat quality (Chapter 2). To answer this, a habitat suitability index (HSI) model was developed to identify potential suitable sites around the south-eastern Bangladesh coast, where oysters can establish. Seven habitat factors were used as input variables for the HSI model: water temperature, salinity, dissolved oxygen, particulate inorganic matter (PIM), pH, Chlorophyll-a, and water flow velocity. Comprehensive field surveys were conducted at 80 locations to collect geo-spatial environmental data, which were used to determine HSI scores using habitat suitability functions. The model results clearly showed that sites from the mouth of Sangu River to the tip of Teknaf, including the offshore islands (Kutubdia and Maheshkhali), are found suitable (HSI >0.50) habitats for oysters, except a few areas near small river mouths which become dynamic with freshwater flashes during monsoon months. These areas showed relative high salinity, Chlorophyll-a, dissolved oxygen and pH. In contrast, freshwater dominated estuaries and nearby coastal areas (i.e. northern part of the study area coving Sandwip, Feni, Mirsarai, Chittagong) with high suspended sediment concentrations from river discharges were found less suitable (HSI <0.50) for oysters. Salinity, Chlorophyll-a, dissolved oxygen and pH were identified as driving factors that determine the habitat quality for oyster in Bangladesh coast. The HSI model results match the current distribution of oysters throughout the investigated area. The good correspondence with the field data enhances the reliability of the presented HSI model as an interactive and quantitative tool for planning and managing oyster resources along the south-eastern coast of Bangladesh.
Secondly, seasonal dynamics in oyster performances are analysed by measurements of the physiological performance of the oysters as a function of environmental conditions (Chapter 3 and 4). Chapter 3 provides physiological information of S. cucullata related to different ecological parameters, which were synthesized from large number of eco-physiological experiments and the outcomes were further used to estimate the DEB model parameters. It is concluded that the hydrometeorological aspects, i.e. a monsoon regime and high turbidity levels, are quite different from temperate regions and drives the physiological traits of shellfish organisms in Bangladesh coastal waters. The estimated DEB parameters for Saccostrea cucullata and their related univariate data provided opportunities (see chapter 4) to simulate the oyster growth in a monsoon dominated hydrodynamic environment. Chapter 4 utilizes the dynamic energy budget (DEB) theory, which allows to establish links between the physiology of an organism and its environment by capturing the metabolic dynamics of an individual organism through its entire life cycle. Developed DEB model was validated by simulating S. cucullata growth under varying hydro-biological conditions. The model results are compared with independent field observations on the growth (length and weight) of S. cucullata at three different sites (Sonadia, Kutubdia and Inani) located in the south-eastern coast of Bangladesh, covering a distinct environmental gradient. The sites vary spatially and temporally in environmental conditions such as salinity, total particulate matter (TPM) and Chlorophyll-a concentrations due to the monsoonal river discharges. At the three sites, field observations of oyster growth, temperature and food availability (Chlorophyll-a and Particulate Organic Matter-POM) have been carried out in the period between September 2014 - August 2017. The DEB model reproduced temporal as well as spatial variation in oyster growth as a function of the prevailing environmental conditions. Growth rates of oysters were highest (shell length: 3cm yr-1) in Sonadia Island due to better food conditions. Whereas, the growth rates were relatively low (1.94 cm yr-1) in Kutubdia and none of oysters survived in Inani during the monsoon event due to high suspended load (889 ± 101 mg l-1) and low Chlorophyll-a (1.86 ± 0.16 µg l-1) conditions. Temporal variation is largely monsoon driven: the period between November to May was the main growing season for oysters along the Bangladesh coast, while growth slowed down in the monsoon months (June-September). DEB model simulations for S. cucullata showed good fit (>8.54 score out of 10) with measured growth data under the different in situ conditions throughout the seasons. It means that the DEB model for S. cucullata demonstrated accuracy for simulating growth in its natural environment along the Bay of Bengal. Therefore, the model can be used to evaluate potential sites for oyster culture development or restoration to enhance coastal resilience.
Thirdly, in Chapters 5 and 6, it was tested if the application of oyster breakwater reefs contribute to reducing coastal erosion in the context of monsoon-dominated subtropical coast and at the same time be beneficial in facilitating other habitats (i.e. mudflat, saltmarsh) and species (macro-invertebrates, fishes). Therefore a suitable site was chosen based on model outputs and observations, namely an eroding mudflat on Kutubdia Island. Here, concrete rings with oysters overgrown for 2 years were placed as oyster breakwater reefs in the lower intertidal zone of the mudflat. The oyster breakwater reefs were tested to see whether it reduced sediment erosion, promoted mudflat stability and enhanced seaward salt marsh expansion and growth, in comparison with areas without such reefs. The results demonstrated that oyster breakwater reefs are particularly useful to reduce erosion at lower intertidal areas as the reefs successfully trapped sediments by dissipating waves. Oyster breakwater reefs modified the mudflat morphology up to 35 m distance at the lee side with accretion of 29 cm clayey sediments and erosion rate was two times lower during the monsoon period compared to control sites. By doing so, it enhanced the growth of new salt marsh vegetation and expanded their seaward edge effectively, thereby further stabilizing the unconsolidated sediments. Therefore, along the coast of Bangladesh, where oyster larval supply is abundant, the eco-engineered breakwater structures have the potential to contribute to a more sustainable shoreline protection against erosion.
Chapter 6 aims to analyze the effects of these breakwater reefs on abundance and composition of macrobenthic soft-bottom assemblages together with transient and resident mobile fauna (fish, shrimp, crabs and other macro-invertebrates) in comparison with adjacent control sites without reefs. Seasonal influences were also considered to understand whether the effects of reefs depend on seasons. This study clearly indicates that oyster breakwater reefs had a positive effect on mudflat fauna communities. It shows higher abundances and biomass of fish and macroinvertebrates relative to the adjacent control sites. Seasonal variation was obvious, but didn’t overrule the reef impact. Multivariate analyses also demonstrated that the reef sites held distinct faunal communities, which differed from the control sites. Changes in macrobenthic community composition were associated with the variations in sediment load and characteristics, which were influenced by the breakwater reefs. Oyster breakwater reefs help to stabilize find sediments locally in lee side (landward) of the reefs, which is found as key reason to observe higher rates of macrobenthic colonization. Higher abundance of transient fish and mobile macro-invertebrates in reef sites indicated that breakwater oyster reefs attract mobile species as the reefs offer food and shelter. In fact, the study suggested that three-dimensional oyster breakwater reefs not only provide the shelter functions for mobile resident fauna, but also extend the ecosystem services related to nursing, breeding and foraging for numerous transient species by augmenting different prey resources for them. Though the ecological impact of oyster breakwater reefs was limited to a local area surrounding the reefs, this study provided hands-on evidence of ecological benefits using these reef configurations in estuarine and coastal habitats.
This PhD study demonstrates that the use of the oyster breakwater reefs has multiple benefits. It can locally protect tidal flats against erosion and promote saltmarsh growth at the lee side of the reefs. These reefs act as breakwater and dissipate wave energy that accelerate the soft sediment deposition behind the structure and increase the bed level. This type of morphological changes may provide opportunities for mangrove planting. The study also showed that eco-engineered oyster reefs can support a high density of macro-benthos in reef areas, sessile macrofauna (oysters, barnacles, sea anemones etc.) on surface of reef substrates, large number of motile macro-invertebrates in reef system that attract transient nektons. The oyster breakwater reefs clearly has the potential to improve ﬁshery production by providing high quality habitat and prey to a variety of commercially and ecologically important ﬁshes, shrimps and crabs. Despite of having these benefits and opportunities, oyster breakwater reefs also have some limitations. Oysters need to settle, survive and grow at the designated place i.e. substrates in order to achieve long-term, persistent structures and self-sustainable reefs. This depends on the habitat characteristics of the site in the first place. Not all sites are equally suitable for oyster settlement survival and growth. Selection of the right site for creating oyster reefs is crucial. Therefore, we developed a HSI model that showed to be helpful in identifying potential sites (Chapter 2). The site can be further critically evaluated by a DEB model to understand seasonal dynamics in predicting oyster growth and reproduction (Chapter 4). Particularly, burial by sediment can cause significant loss of reef habitat. It can be avoided by increasing the heights of reef substrates based on the characteristics of the site. Additional constraints are the vulnerability of oysters for diseases and predation. Oyster drills (Urosalpinx spp.) and stone crabs (Myomenippe spp.) were found as meso-predators in the investigated sites, but their effects on oyster population need to be investigated.
The intertidal rock oyster, S. cucullata can be ecologically engineered by providing hard substrates to settle on, that offers a kick-start for reef formation at places where they were lost or are desirable for coastal protection. Reef formation and development is however strongly dependent on the local environmental conditions governing oyster recruitment, survival and growth dynamics. These conditions can be highly dynamic, for example during the monsoon season. S. cucullata shows abilities to adapt to these conditions by regulating their physiological activities. The study shows that the S. cucullata populations are able to sustain in many estuarine areas along the southeast coast of Bangladesh as they can cope with the monsoonal climate. This makes them suitable for the role as eco-engineers for coastal protection. The study showed that artificial substrates can be used to develop self-sustaining oyster populations that contribute to coastal protection. Furthermore, oyster breakwater reefs dissipate the wave energy that reduces the hydrodynamic pressure on the foreshore of the primary dike and thus reduce the dike maintenance cost. Integration of oyster reefs with other ecosystems can add more benefits. Even it can enhance the possibility of doing oyster culture by enhancing larval supply in the area. Moreover, coexisting with other ecosystems viz., salt marsh and mangrove along with oyster breakwater reefs in the intertidal zone can act as bio-shield to prevent erosion and reduce the effect of cyclonic storm surges in the region. Therefore, oysters provide a great chance for Bangladesh to utilize them for the benefit of coastal people and environment.
Atmospheric boundary layer dynamics from balloon soundings worldwide: CLASS4GL v1.0
Wouters, Hendrik ; Petrova, Irina Y. ; Heerwaarden, Chiel C. Van; Vilà-Guerau de Arellano, Jordi ; Teuling, Adriaan J. ; Meulenberg, Vicky ; Santanello, Joseph A. ; Miralles, Diego G. - \ 2019
Geoscientific Model Development 12 (2019)5. - ISSN 1991-959X - p. 2139 - 2153.
The coupling between soil, vegetation and atmosphere is thought to be crucial in the development and intensification of weather extremes, especially meteorological droughts, heat waves and severe storms. Therefore, understanding the evolution of the atmospheric boundary layer (ABL) and the role of land–atmosphere feedbacks is necessary for earlier warnings, better climate projection and timely societal adaptation. However, this understanding is hampered by the difficulties of attributing cause–effect relationships from complex coupled models and the irregular space–time distribution of in situ observations of the land–atmosphere system. As such, there is a need for simple deterministic appraisals that systematically discriminate land–atmosphere interactions from observed weather phenomena over large domains and climatological time spans. Here, we present a new interactive data platform to study the behavior of the ABL and land–atmosphere interactions based on worldwide weather balloon soundings and an ABL model. This software tool – referred to as CLASS4GL (http://class4gl.eu, last access: 27 May 2018) – is developed with the objectives of (a) mining appropriate global observational data from ∼15 million weather balloon soundings since 1981 and combining them with satellite and reanalysis data and (b) constraining and initializing a numerical model of the daytime evolution of the ABL that serves as a tool to interpret these observations mechanistically and deterministically. As a result, it fully automizes extensive global model experiments to assess the effects of land and atmospheric conditions on the ABL evolution as observed in different climate regions around the world. The suitability of the set of observations, model formulations and global parameters employed by CLASS4GL is extensively validated. In most cases, the framework is able to realistically reproduce the observed daytime response of the mixed-layer height, potential temperature and specific humidity from the balloon soundings. In this extensive global validation exercise, a bias of 10.1 m h−1, −0.036 K h−1 and 0.06 g kg−1 h−1 is found for the morning-to-afternoon evolution of the mixed-layer height, potential temperature and specific humidity. The virtual tool is in continuous development and aims to foster a better process understanding of the drivers of the ABL evolution and their global distribution, particularly during the onset and amplification of weather extremes. Finally, it can also be used to scrutinize the representation of land–atmosphere feedbacks and ABL dynamics in Earth system models, numerical weather prediction models, atmospheric reanalysis and satellite retrievals, with the ultimate goal of improving local climate projections, providing earlier warning of extreme weather and fostering a more effective development of climate adaptation strategies
Amazonian rainforest tree mortality driven by climate and functional traits
Aleixo, Izabela ; Norris, Darren ; Hemerik, Lia ; Barbosa, Antenor ; Prata, Eduardo ; Costa, Flávia ; Poorter, Lourens - \ 2019
Nature Climate Change 9 (2019)5. - ISSN 1758-678X - p. 384 - 388.
Tree mortality appears to be increasing in moist tropical forests 1 , with potentially important implications for global carbon and water cycles 2 . Little is known about the drivers of tree mortality in these diverse forests, partly because long-term data are lacking 3 . The relative importance of climatic factors and species functional traits as drivers of tropical tree mortality are evaluated using a unique dataset in which the survival of over 1,000 rainforest canopy trees from over 200 species has been monitored monthly over five decades in the Central Amazon. We found that drought, as well as heat, storms and extreme rainy years, increase tree mortality for at least two years after the climatic event. Specific functional groups (pioneers, softwoods and evergreens) had especially high mortality during extreme years. These results suggest that predicted climate change will lead to higher tree mortality rates, especially for short-lived species, which may result in faster carbon sequestration but lower carbon storage of tropical forests.
40 years of change on the coral reefs of Curaçao and Bonaire
Bakker, Desiderius Marinus de - \ 2019
Wageningen University. Promotor(en): H.J. Lindeboom; E.H. Meesters, co-promotor(en): F.C. van Duyl. - Wageningen : Wageningen University - ISBN 9789463434041 - 191
Tropical coral reefs are among the most species-rich and productive ecosystems on earth. They cover only 0.1-0.5% of the ocean floor, but provide a home to almost a third of all fish species and other marine biota. Just like with tropical rainforests, the terrestrial counterpart of these reefs, 3-dimensional complexity underlies this unique biodiversity. On coral reefs, such structural complexity is mainly provided by scleractinian corals. In the interest of growth and protection, these organisms deposit large amounts of limestone, which provides the rigid foundation for the reef. In this way, corals facilitate complex ecosystem functioning and offer shelter and substratum to an exceptional diversity of species. In addition, millions of people depend on these coral reefs, for goods and services such as nourishment (fishing), coastal protection, tourism and recreation. In spite of this, coral reefs are at present under substantial pressure as a consequence of increased human activities. Large-scale global processes such as climate change have a severe impact on these delicate systems, while at the same time a variety of stressors including overfishing, coastal development and pollution substantially reduce reef resilience on a local scale. In this thesis I describe various aspects of the ecological degradation that coral reefs in the Caribbean have undergone since the early 1970s, as a result of factors associated with continuous human population growth (e.g. pollution, overfishing, climate change). The focus of the presented work lies on the coral reefs surrounding Curaçao and Bonaire (southern Caribbean).
This chapter serves as an introduction explaining the importance of coral reefs and focusses on the main threats that these delicate ecosystems face today. Specifically, it emphases the history and current status of coral reefs in the wider Caribbean region. The main research topics of this thesis are presented, which revolve around the spatio-temporal dynamics of benthic sessile reef communities and the impact that reef degradation and shifts in community composition have on the carbonate budget of the studied reefs.
Chapter II describes changes in the composition of benthic sessile coral communities on the basis of a 40-year time series. In 1973, Prof. dr. Rolf Bak photographed 16 sections of coral reef on the reef slopes of Curaçao and Bonaire, each measuring 9 m2. Since then, these sections were photographed almost annually. To date, this is the longest running time series on coral reefs in the world, dating from before the mass-mortality of the branched Acropora corals and the Diadema antillarum sea urchins in the 1980s and the major bleaching events in 1998, 2005 and 2010. Quadrats were positioned at four locations along a depth gradient at 10, 20, 30 and 40 meters, respectively. Where the pre-1980 reef configurations are still characterized by exceptionally high cover of scleractinian corals we subsequently see a shift towards a dominance of fleshy macroalgae and algal turf assemblages. These fast-growing opportunistic organisms appear to thrive in the altered reef environment. Reduced herbivory and increased nutrient loads have rapidly provided these algae a competitive advantage over the already weakened corals and calcifying algae. The observed gradual decline in coral to an average cover of less than 10% inherently means a substantial loss of the fundament that underpins the striking biodiversity on these reefs. The rigidity provided by corals can by no means be accommodated by soft-bodied algae. Notably, this chapter describes the manifestation of a novel player that, since the early 2000s, is gaining a foothold on these reefs: benthic cyanobacterial mats. These thick red-brown bacterial assemblages are dominated by cyanobacteria and have become one of the prominent components on these reef. They are comparable to the toxic planktonic cyanobacteria that bloom in freshwater lakes during summertime. Similar to these assemblages, cyanobacterial mats on reefs are known to have a wide variety of negative effects on reef communities including the inhibition of larval settlement, acting as pathogens, smothering other organisms, and creating an anoxic environment. A striking conclusion of this chapter is that the observed path of reef degradation occurs at least down to 40 m depth. Considering the ongoing increase of anthropogenic impact on the coral reef environment, the rise of cyanobacterial mats in combination with algae and sponges is hypothesized to represent the next alarming step in the degradation of coral reefs.
In this chapter, shifts in the composition of coral species assemblages are described on the basis of the same time series as presented in the previous chapter. Whereas Chapter II described the trajectories of change of the various sessile organisms, this chapter focusses specifically on the different types of scleractinian corals. Although virtually all coral species declined in cover and abundance over the course of the studied period, a community shift was observed towards dominance of opportunistic species. While the historically prominent framework-building species of the Orbicella and Acropora genera have largely been diminished in the quadrats, species such as Madracis mirabilis, Porites astreoides, Pseudodiploria strigosa (formerly Diploria strigosa), and Agaricia lamarcki appear to possess life-history traits that allow them to better cope with the increasingly more hostile marine environment. Their persistence might make these opportunistic species modest ‘winners’ in the present-day coral assemblage. Yet, their overall cover declined over the past decades as well. A major concern is that these ‘weedy’ corals cannot equal the calcification rates of Orbicella and Acropora species, neither can they produce comparable architectural relief. Indeed, the gross calcium carbonate production of these reefs decline, on average, by 67% over the studied time period.
On a healthy reef there is a subtle balance between calcification and erosion, which results in the deposition of calcium carbonate and ultimately net reef accretion. Current global and local disturbance, however, is affecting this balance at increasingly more sites, often pushing it towards net destruction of the limestone structures that form the foundation of these reefs. In addition to a general decline in the abundance of carbonate producing organisms (corals, calcifying algae) (Chapter II and Chapter III), we also see that various bioeroding organisms appear to thrive under the current reef conditions. On many reefs in the Caribbean, excavating sponges are the dominant organisms to bore into the coral skeleton. They do this by chemically dissolving limestone in combination with the mechanical removal of limestone fragments (chips). These sponges are found to increase in both abundance and eroding capacity as a result of pollution, ocean acidification and surface water heating. Nonetheless, to date relatively little is known about these organisms. In this chapter various methods, including a flow-through incubation method are presented to quantify erosion rates of the six most prominent bioeroding sponges existing on the reefs of Curaçao. Markedly, the flow-through incubation methodology prevented the accumulation of waste and the depletion of oxygen, resulting in more accurate estimates for chemical erosion. Considerable interspecific variation was observed in the capacity of the various sponges to mechanically remove CaCO3 chips and chemically dissolve coral substrate. This observed interspecific variability could evidently be related to specific life-history traits such as the adopted boring strategy (i.e. gallery-forming, cavity-forming or network-working) and presence or absence of symbiotic zooxanthellae. Similarly, a distinct diurnal pattern was observed, where species that have high zooxanthellae densities have higher erosion rates at daytime. Such a pattern was absent in species with a low abundance or complete absence of zooxanthellae.
Chapter V describes the effect that decreasing calcification and increasing erosion have on the net production of calcium carbonate on the reefs of Bonaire. Net production and maximum reef accretion potential were determined on the basis of the ReefBudget approach for 115 locations on the shallow reef on the leeward side of Bonaire and Klein Bonaire. The balance is drawn up between the gross biogenic calcification and the gross biogenic erosion, which ultimately yields an estimate for the net carbonate production. For each site, the ReefBudget method was applied to the terrace zone (~ 5 m depth) and to the shallowest area of the reef slope (~ 10 m depth). The striking results indicate that many shallow reef sites display marginal growth or even net loss of carbonate substrate. The maximum reef accretion potential of the vast majority of the studied reef sites will, in their current configurations, not match the most optimistic projections for of future sea level rise (IPCC 2018: RCP2.6 scenario). Alarmingly, reefs with the lowest vertical accretion potential are found in regions characterized by a low coastline (often < 1 m above sea level), and include the coastal areas with highest human activity and development around Kralendijk (capital). The current absence of well-developed, rapidly accreting shallow reefs that would otherwise aid in reducing wave energy at the shoreline makes these regions more susceptible to inundation. The risk of flooding will be aggravated especially by the increased frequency and intensity of tropical storms, hurricanes and extreme swell events.
In Chapter VI, the new time series described in the previous chapter is used to address both the recent developments within the coral and fish community and the current status of the coral reefs and on the leeward side of Bonaire at remarkably high spatial resolution. A novel classification of present-day benthic reef habitats is proposed for reefs in the lower-terrace and drop-off zones. Four distinct benthic communities are classified within each zone, characterized by distinct configurations of both biotic and abiotic (e.g. sand, rubble) constituents. The majority of the eight newly described communities show little resemblance to pre-1980 configurations. Similarly, a thorough description of reef fish communities is provided for the two zones. Within fish communities, the focus lies on the current population status of herbivorous (parrotfish, surgeonfish and damselfish) and commercially important fish species (groupers and snappers). Their abundance and total biomass declined ubiquitously across the shallow reef of Bonaire. Both Chapters V and Chapter VI demonstrate that spatially a distinct gradient of ecological degradation exists on a fine spatial scale (the leeward fringing reef of Bonaire), from nearly pristine reefs in the north to reefs that are at the tipping point of full functional collapse (in front of Kralendijk). The data presented in these chapters further emphasize the negative anthropogenic impacts that locally threaten ecological functioning of coral reefs, but also hints towards stabilization of degradation and possible recovery when local conditions are favourable. The currently existing near-pristine reefs and the reefs to which the latter findings apply should be the ones we learn from to implement adequate management of local stressors.
In the final chapter the overall gloomy findings of this thesis are discussed thoroughly. The chapter ends with a positive note, namely that the coral reefs are not lost yet. Mainly the findings described in Chapter V and Chapter VI give a modest reason for hope, at least for the shallower reef zones. The presented work shows that nowadays, under the harsh global environment, it is still possible to maintain reefs that exist in relatively good conditions. The latter appears to be strongly correlated to favourable local conditions (both natural and anthropogenic) (see also Chapter II). These reefs should be studied in detail to reveal the processes underlying their notable ecological success. Furthermore, it is tentatively hypothesized that adequate local management at least in part, facilitated an apparent stabilizing trend observed on the shallow coral reefs around Bonaire. The observation that some of the least degraded reefs are found in marine reserves, where entrance for humans is prohibited, suggests that proper local nature policies indeed aid in making reefs more resilient to the large-scale global disturbance. The main message presented here is that Caribbean coral reefs have been heavily impacted over the past decades but that these reefs and the essential services they provide are not yet lost. Nonetheless, we will have to act now and intervene, on a global and local scale, in order to maintain relatively healthy reefs and improve the condition of severely impacted reefs!
Using Mobile Methods to Trace Networks and Connections: Environmental Migration in the Digital Age
Boas, I.J.C. - \ 2019
In: SAGE Research Methods Cases Part 2 Sage - ISBN 9781526466730
This case reflects on the use of mobile methods in a study of environmental migration. Environmental migration refers to the movement of people in the context of environmental impacts and changes (e.g., storms, droughts, sea-level rise). I studied how this phenomenon takes shape in the digital age. In the digital age, people may be increasingly connected and have more means to exchange information, shaping migrants’ mobility decisions. I conducted this research in Bangladesh and Kenya. Mobile methods concentrate on movement, connections, and networks, and are therefore a good fit for my study focused on migration and digital connectivity. Instead of staying in one or few places during fieldwork, the idea is to follow the connections, to move along with them, and to understand how movement and networking play out in practice. In this case, I reflect on the benefits and the difficulties of using mobile methods by discussing how I used them during my field research in Bangladesh. I stress the benefits of adopting an inductive approach to such research and the need to always be reflexive toward the application of a particular method. In that way, it is possible to adjust to empirical realities and thereby more strongly fulfil the set research objectives.
|The self-constrained Dommel River
Candel, J.H.J. ; Makaske, A. ; Kijm, Niels ; Kleinhans, M.G. ; Storms, J.E.A. ; Wallinga, J. - \ 2018
Decreasing lateral migration and increasing planform complexity of the Dommel River during the Holocene
Candel, J.H.J. ; Makaske, A. ; Kijm, Niels ; Storms, J.E.A. ; Wallinga, J. - \ 2018
In: The future river. - NCR (NCR 42-2018) - p. 32 - 33.
Introduction: Exclusion and Struggles for Co-Decision : from Part III - Exclusion and Struggles for Co-Decision
Vos, J.M.C. ; Perreault, Tom ; Boelens, R.A. - \ 2018
In: Water Justice / Boelens, R., Perreault, T., Vos, J., Cambridge : Cambridge University Press - ISBN 9781107179080 - p. 188 - 192.
Water justice is often sought in “good water governance.” Yet, what “good governance” means is not something that can be straightforwardly decided or linearly implemented: different stakeholders hold different power positions, have conflicting interests and deploy different valuation languages regarding water, land and livelihoods. Deliberative policy-making processes, including local communities’ participation in decision-making, are often presented as the tool to help craft inclusive, democratic water governance arrangements. However, here, a fundamental but commonly neglected or actively suppressed question is, “who participates in whose project”? Although water governance is about institutional configurations, regulations and policy-making and implementation, it is also about capabilities, powers and social struggle over access to resources, setting the agenda and discursively framing problems. Water justice, then, is not something that can easily be crafted through tinkering with governance arrangements, but requires struggles and continuous renegotiation as part of larger battles for justice and democracy. Water injustices often imply exclusion of vulnerable groups from access to clean water and affordable services, but also from representation in water-control decision-making. This exclusion can be based on gender, race, caste, class, ethnicity, religion, or political affiliation. Maria Rusca, Cecilia Alda-Vidal, and Michelle Kooy (Chapter 11) provide clear examples of this in their chapter on drinking water in Kampala. Joyeeta Gupta (Chapter 14) contends that privatizing irrigation water services may often exclude smallholders. Climate Justice Climate change also causes major distributive injustices. Droughts and floods tend to affect the poor more severely than the relatively rich (Adger, 2001; Ikeme, 2003; IPCC 2014; Ribot, 2010; Schneider and Lane, 2006). Skewed vulnerabilities in relation to effects of climate change lead to asymmetrical impacts (Gardiner and Hartzell-Nichols, 2012). This is even more unfair and imbalanced considering that the poor’s share in emission of greenhouse gases is much less than the gigantic emissions by the rich. A report commissioned by the World Bank (2008) estimates the impacted populations killed or left homeless per region by seven common chronic and sudden disasters that are increasingly related to climate change: droughts, extreme temperatures, floods, landslides, tidal surges and wind storms. Already millions of people are affected by floods in Southern and Eastern Asia and droughts in South America, South Asia and East Africa. Likewise, health effects of climate change affect the poor disproportionally (Costello et al., 2009)
Natural disasters and agricultural protection : A panel data analysis
Klomp, Jeroen ; Hoogezand, Barry - \ 2018
World Development 104 (2018). - ISSN 0305-750X - p. 404 - 417.
Agriculture - Natural disasters - Trade protection
We explore the impact of natural disasters on the degree of agricultural protection using data from 76 countries thereby covering more than 70 of the most traded agricultural commodities. Theoretically, the direction of this effect is not a priori directly clear as it balances the trade-off between protecting the economic interests of the domestic agricultural sector on the one hand and ensuring food availability for the society at large on the other. Our most important findings suggest that natural disasters generally raise agricultural trade controls to favor domestic farmers. These barriers are mainly provided by limiting imports in the aftermath of a natural event. However, the protection pattern differs among countries. To be more specific, floods and storms increase agricultural protection in high-income countries, while trade barriers in many LDCs are reduced during periods of extreme drought in an attempt to diminish food scarcity. Finally, it turns out that a large part of the change in agricultural protection caused by a natural disaster is explained by a number of commodity specific particularities (i.e., food vs. cash crops).
|Stream planform formation in peat-filled valleys
Candel, J.H.J. ; Makaske, A. ; Wallinga, J. ; Storms, J.E.A. - \ 2017