770 research outputs found
Thoré & Merckx, 2023 (Journal of Fish Biology)
No full textDatasets (egg deposition of breeding pairs in long and wide data format, habitat choice, and egg deposition of social groups), including R script and corresponding read-me file for Thoré, E., & W. Merckx. 2023. Substrate colour guides turquoise killifish's (Nothobranchius furzeri) choice of preferred spawning habitat. Journal of Fish Biology. https://doi.org/10.1111/jfb.15392 </p
Water repellence and soil aggregate dynamics in a loamy grassland soil as affected by texture
No full textDe Gryze, S.; Jassogne, L.; Bossuyt, H.; Six, J.; Merckx, R
Data for Water deficit and potassium affect carbon isotope composition in cassava bulk leaf material and extracted carbohydrates
No full textThis repository contains data and scripts to reproduce results that are presented in the manuscript: Van Laere, J., Merckx, R., Hood-Nowotny, R., Dercon, G. (2023) Water deficit and potassium affect carbon isotope composition in cassava bulk leaf material and extracted carbohydrates. Front. Plant Sci. 14:1222558 doi: 10.3389/fpls.2023.122255
Moth abundance changes and consequent bottom-up effects on birds in boreal forests
No full textAbstract
Many insect populations are declining, although the exact details of the magnitude and geographic spread of these declines are still unknown. Considering how insects are vital for the functioning of terrestrial ecosystems, evidence of widespread declines has raised concern about cascading effects across trophic levels. The boreal forests of Finland, sources of high-quality long-term monitoring data, offer an ideal setting to expand insect abundance research and explore how climate and environmental change affect insect populations and their trophic interactions. My aim is to investigate (I) how the biomass of moths has changed over time and which ecological and life-history traits could explain these trends, (II) whether moth biomass has a bottom-up effect on insectivorous forest birds at the functional group level, and (III) whether such bottom-up effects can be detected at the species level. I used state-of-the-art joint dynamic species distribution models (JDSDMs) to address the aims. My results suggest that: (I) there has been no decline in the total biomass of moth functional groups across Finland in the past 27 years. Instead, biomass remained stable for most groups, while several were increasing. There was also considerable geographical variation in abundance trends. (II) Abundance fluctuations of insectivorous forest birds were positively associated with fluctuations in moth biomass, particularly among early-season moths in the north-boreal zone, where seasonal constraints on breeding are most pronounced. These bottom-up effects were observed for birds that were residents or long-distance migrants. The strength of these associations declined towards the south, indicating regional variation in the strength of trophic interactions. (III) At the species level, moth bottom-up effects on birds were generally weak and inconsistent, with a few weak but biologically meaningful patterns emerging in the north-boreal zone. The unexpectedly weak bottom-up effects indicate that forest birds may possess greater foraging flexibility and resilience than previously assumed, enabling them to cope with fluctuations in specific prey resources. This dissertation emphasizes how integrating long-term biodiversity datasets can reveal community-level trophic interactions and provide new opportunities for understanding the effects of global change on ecosystem functioning. Original papers Yazdanian, M., Kankaanpää, T., Itämies, J., Leinonen, R., Merckx, T., Pöyry, J., Sihvonen, P., Suuronen, A., Välimäki, P., & Kivelä, S. M. (2023). Ecological and life‐history traits predict temporal trends in biomass of boreal moths. Insect Conservation and Diversity, 16(5), 600–615. https://doi.org/10.1111/icad.12657 https://doi.org/10.1111/icad.12657 Self-archived version Yazdanian, M., Kankaanpää, T., Merckx, T., Huikkonen, I., Itämies, J., Jokimäki, J., Lehikoinen, A., Leinonen, R., Pöyry, J., Sihvonen, P., Suuronen, A., Välimäki, P., & Kivelä, S. M. (2024). Evidence for bottom‐up effects of moth abundance on forest birds in the north‐boreal zone alone. Ecology Letters, 27(12), e14467. https://doi.org/10.1111/ele.14467 https://doi.org/10.1111/ele.14467 Self-archived version Yazdanian, M., Kankaanpää, T., Merckx, T., Huikkonen, I. M., Itämies, J., Jokimäki, J., Lehikoinen, A., Leinonen, R., Pöyry, J., Sihvonen, P., Suuronen, A., Välimäki, P., & Kivelä, S. M. (2024). Assessment of bottom-up effects of moths on population dynamics of forest birds. Manuscript in preparation. Tiivistelmä
Hyönteispopulaatioiden on maailmanlaajuisesti havaittu taantuneen voimakkaasti. Koska hyönteiset suorittavat kriittisiä toimintoja maaekosysteemeissä, havainnot niiden laajamittaisesta vähenemisestä ovat herättäneet huolta mahdollisista trofiatasojen välisistä kerrannaisvaikutuksista. Tästä huolimatta tiedot hyönteisrunsauksien pitkäaikaismuutoksista tai niiden vaikutuksista ovat puutteellisia jopa hyönteistuntemukseltaan edistyksellisessä pohjolassa. Suomen boreaalisista metsistä kerättyjen pitkien seuranta-aineistojen avulla voidaan tutkia ilmaston- ja ympäristönmuutosten vaikutuksia hyönteisrunsauksiin ja hyönteisten rooleihin ravintoverkoissa. Tutkin (I) miten yöperhosten biomassa on muuttunut viime vuosikymmeninä, sekä mitkä ekologiset- tai elinkierto-ominaisuudet selittävät lajienvälisiä eroja runsausmuutoksissa; (II) säätelevätkö yöperhosryhmien runsausvaihtelut metsälintujen pesimätiheyksiä, kun tarkastellaan lintuja joko niiden lajiominaisuuksien perusteella ryhmiteltyinä, tai (III) lajikohtaisesti. Käytin yhteisöekologian uusimpia ja väkevimpiä työkaluja, dynaamisia lajien yhteisesiintymismalleja (JDSDM). Tulosteni mukaan (I) minkään tutkimani yöperhosryhmän kokonaisbiomassa ei ole vähentynyt koko Suomen mittakaavassa viimeisten 27 vuoden aikana. Perhosryhmien sisällä tiheysmuutoksissa oli kuitenkin suurtakin maantieteellistä vaihtelua. (II) Yöperhosten, ja etenkin kasvukauden alussa toukkana esiintyvien lajien runsausvaihtelut selittivät seuraavan vuoden lintujen pesimätiheyksiä varsinkin pohjoisboreaalisella metsävyöhykkeellä. Yöperhosravinnon saatavuus vaikutti etenkin paikkalintujen sekä pitkänmatkan muuttajien pesimätiheyksiin. Vaikutusten heikkeneminen siirryttäessä eteläisemmille vyöhykkeille osoittaa maantieteellistä muuntelua ravintoverkkovuorovaikutusten voimakkuuksissa. (III) Yöperhosravinnon saatavuuden vaikutukset yksittäisten lintulajien pesimätiheyksiin olivat pääasiassa heikkoja ja epäjohdonmukaisia, muutamia pohjoisboreaalisella alueella havaittuja biologisesti mielekkäitä yhteyksiä lukuun ottamatta. Voimakkaiden yhteyksien puuttuminen voi tarkoittaa, että metsälinnut saattavat olla ravinnonhankinnassaan joustavampia kuin on yleisesti ajateltu, mikä helpottaisi niitä selviämään tiettyjen saaliseläinten runsausnotkahduksista. Tämä väitöstutkimus korostaa kuinka yhdistelemällä seuranta-aineistoja voimme paljastaa, miten lajienväliset vuorovaikutukset vaikuttavat eliöyhteisöjen muuttumiseen maailmanlaajuisten ympäristömuutosten seurauksena. Osajulkaisut Yazdanian, M., Kankaanpää, T., Itämies, J., Leinonen, R., Merckx, T., Pöyry, J., Sihvonen, P., Suuronen, A., Välimäki, P., & Kivelä, S. M. (2023). Ecological and life‐history traits predict temporal trends in biomass of boreal moths. Insect Conservation and Diversity, 16(5), 600–615. https://doi.org/10.1111/icad.12657 https://doi.org/10.1111/icad.12657 Rinnakkaistallennettu versio Yazdanian, M., Kankaanpää, T., Merckx, T., Huikkonen, I., Itämies, J., Jokimäki, J., Lehikoinen, A., Leinonen, R., Pöyry, J., Sihvonen, P., Suuronen, A., Välimäki, P., & Kivelä, S. M. (2024). Evidence for bottom‐up effects of moth abundance on forest birds in the north‐boreal zone alone. Ecology Letters, 27(12), e14467. https://doi.org/10.1111/ele.14467 https://doi.org/10.1111/ele.14467 Rinnakkaistallennettu versio Yazdanian, M., Kankaanpää, T., Merckx, T., Huikkonen, I. M., Itämies, J., Jokimäki, J., Lehikoinen, A., Leinonen, R., Pöyry, J., Sihvonen, P., Suuronen, A., Välimäki, P., & Kivelä, S. M. (2024). Assessment of bottom-up effects of moths on population dynamics of forest birds. Manuscript in preparation. Academic dissertation to be presented with the assent of the Doctoral Programme Committee of Technology and Natural Sciences of the University of Oulu for public defence in the OP-Pohjola auditorium (L6), Linnanmaa, on 22 August 2025, at 12 noonAbstract
Many insect populations are declining, although the exact details of the magnitude and geographic spread of these declines are still unknown. Considering how insects are vital for the functioning of terrestrial ecosystems, evidence of widespread declines has raised concern about cascading effects across trophic levels. The boreal forests of Finland, sources of high-quality long-term monitoring data, offer an ideal setting to expand insect abundance research and explore how climate and environmental change affect insect populations and their trophic interactions. My aim is to investigate (I) how the biomass of moths has changed over time and which ecological and life-history traits could explain these trends, (II) whether moth biomass has a bottom-up effect on insectivorous forest birds at the functional group level, and (III) whether such bottom-up effects can be detected at the species level. I used state-of-the-art joint dynamic species distribution models (JDSDMs) to address the aims. My results suggest that: (I) there has been no decline in the total biomass of moth functional groups across Finland in the past 27 years. Instead, biomass remained stable for most groups, while several were increasing. There was also considerable geographical variation in abundance trends. (II) Abundance fluctuations of insectivorous forest birds were positively associated with fluctuations in moth biomass, particularly among early-season moths in the north-boreal zone, where seasonal constraints on breeding are most pronounced. These bottom-up effects were observed for birds that were residents or long-distance migrants. The strength of these associations declined towards the south, indicating regional variation in the strength of trophic interactions. (III) At the species level, moth bottom-up effects on birds were generally weak and inconsistent, with a few weak but biologically meaningful patterns emerging in the north-boreal zone. The unexpectedly weak bottom-up effects indicate that forest birds may possess greater foraging flexibility and resilience than previously assumed, enabling them to cope with fluctuations in specific prey resources. This dissertation emphasizes how integrating long-term biodiversity datasets can reveal community-level trophic interactions and provide new opportunities for understanding the effects of global change on ecosystem functioning.Tiivistelmä
Hyönteispopulaatioiden on maailmanlaajuisesti havaittu taantuneen voimakkaasti. Koska hyönteiset suorittavat kriittisiä toimintoja maaekosysteemeissä, havainnot niiden laajamittaisesta vähenemisestä ovat herättäneet huolta mahdollisista trofiatasojen välisistä kerrannaisvaikutuksista. Tästä huolimatta tiedot hyönteisrunsauksien pitkäaikaismuutoksista tai niiden vaikutuksista ovat puutteellisia jopa hyönteistuntemukseltaan edistyksellisessä pohjolassa. Suomen boreaalisista metsistä kerättyjen pitkien seuranta-aineistojen avulla voidaan tutkia ilmaston- ja ympäristönmuutosten vaikutuksia hyönteisrunsauksiin ja hyönteisten rooleihin ravintoverkoissa. Tutkin (I) miten yöperhosten biomassa on muuttunut viime vuosikymmeninä, sekä mitkä ekologiset- tai elinkierto-ominaisuudet selittävät lajienvälisiä eroja runsausmuutoksissa; (II) säätelevätkö yöperhosryhmien runsausvaihtelut metsälintujen pesimätiheyksiä, kun tarkastellaan lintuja joko niiden lajiominaisuuksien perusteella ryhmiteltyinä, tai (III) lajikohtaisesti. Käytin yhteisöekologian uusimpia ja väkevimpiä työkaluja, dynaamisia lajien yhteisesiintymismalleja (JDSDM). Tulosteni mukaan (I) minkään tutkimani yöperhosryhmän kokonaisbiomassa ei ole vähentynyt koko Suomen mittakaavassa viimeisten 27 vuoden aikana. Perhosryhmien sisällä tiheysmuutoksissa oli kuitenkin suurtakin maantieteellistä vaihtelua. (II) Yöperhosten, ja etenkin kasvukauden alussa toukkana esiintyvien lajien runsausvaihtelut selittivät seuraavan vuoden lintujen pesimätiheyksiä varsinkin pohjoisboreaalisella metsävyöhykkeellä. Yöperhosravinnon saatavuus vaikutti etenkin paikkalintujen sekä pitkänmatkan muuttajien pesimätiheyksiin. Vaikutusten heikkeneminen siirryttäessä eteläisemmille vyöhykkeille osoittaa maantieteellistä muuntelua ravintoverkkovuorovaikutusten voimakkuuksissa. (III) Yöperhosravinnon saatavuuden vaikutukset yksittäisten lintulajien pesimätiheyksiin olivat pääasiassa heikkoja ja epäjohdonmukaisia, muutamia pohjoisboreaalisella alueella havaittuja biologisesti mielekkäitä yhteyksiä lukuun ottamatta. Voimakkaiden yhteyksien puuttuminen voi tarkoittaa, että metsälinnut saattavat olla ravinnonhankinnassaan joustavampia kuin on yleisesti ajateltu, mikä helpottaisi niitä selviämään tiettyjen saaliseläinten runsausnotkahduksista. Tämä väitöstutkimus korostaa kuinka yhdistelemällä seuranta-aineistoja voimme paljastaa, miten lajienväliset vuorovaikutukset vaikuttavat eliöyhteisöjen muuttumiseen maailmanlaajuisten ympäristömuutosten seurauksena
Van de Broek et al. (2016) Controls on soil organic carbon stocks in tidal marshes along a salinity gradient, Biogeosciences, supplementary data
No full textThis is supplementary data for the article Van de Broek M, Temmerman S., Merckx R., Govers G., 2016, Controls on soil organic carbon stocks in tidal marshes along an estuarine salinity gradient, Biogeosciences. For study site descriptions, material and methods and interpretation of this data we refer to this article
Hedgerow trees and extended-width field margins enhance macro-moth diversity: implications for management
No full textImproving the effectiveness of agri-environment schemes is essential for reversing declines in farmland biodiversity. Crucial to achieving this is identifying management options that are practical and beneficial to biodiversity, and understanding the influence of the surrounding landscape. We used data on abundance and species richness of farmland macro-moths, many of which are declining, and trait-based analyses on their feeding guild, mobility and conservation status, to explore local- and landscape-scale effects of two farmland features (extended-width field margins and hedgerow trees) and surrounding farmland intensification. Macro-moths were light trapped at 48 fixed sites on 16 farms, over 4 years, within a 1200-km2 area of lowland UK farmland. Sites belonged to one of four experimental groups that differed in their combinations of hedgerow tree presence and field margin width. Hedgerow trees and extended-width field margins locally increased species richness, but not abundance, of macro-moths, irrespective of each other's presence. Overall, species richness and abundance were not affected by agricultural intensification, as measured by the amount of arable land in the surrounding landscape. Sedentary moths showed double the species richness, but were half as abundant as mobile moths. Both groups responded positively to extended-width margin and hedgerow tree presence. The effect of hedgerow trees was particularly strong for shrub- and/or tree-feeding species. Analyses based on the conservation status of moths demonstrated that agricultural intensification lowered the species richness of nationally severely declining UK Biodiversity Action Plan priority species and the abundance of both nationally moderately declining and priority species. These effects were most pronounced at the 0·8-km radius scale. Synthesis and applications. Our results suggest that the presence of extended-width field margins and hedgerow trees, possibly promoted by agri-environment schemes targeting their implementation at relatively small spatial scales (0·8 km), may help mitigate negative effects of agricultural intensification on macro-moths. A wide range of other taxa feed on macro-moths and may therefore indirectly benefit from these features. Nevertheless, taxa differ widely in their mobility and measures mitigating biodiversity loss may need to be targeted at multiple spatial scales to maximize their effectiveness for multiple taxa. Our results suggest that the presence of extended-width field margins and hedgerow trees, possibly promoted by agri-environment schemes targeting their implementation at relatively small spatial scales (0·8 km), may help mitigate negative effects of agricultural intensification on macro-moths. A wide range of other taxa feed on macro-moths and may therefore indirectly benefit from these features. Nevertheless, taxa differ widely in their mobility and measures mitigating biodiversity loss may need to be targeted at multiple spatial scales to maximize their effectiveness for multiple taxa. © 2012 British Ecological Society
Diagnose en herstel van zwak responsieve bodems in West-Kenia
No full textAmong other soil fertility challenges, a poor response to fertilizer application persist in preventing the closure of crop yield gaps in western Kenya. This not only threatens the continuity of fertilizer use but becomes a setback to the achievement for the long awaited food security in the region. Therefore, this research seeks to unravel the drivers of poor responses to fertilizer NPK application and thereafter develop effective soil fertility packages for such soils. The research work is in two main phases: first is a diagnostic phase that (i) assess farmers' knowledge on the occurrence of poorly response soils using open-ended questionnaire and (ii) determines crop nutrient imbalances related to such soils using a multivariate diagnostic tool. Phase 2 involves (i) the development of fertilizer blends that would correct the nutrient imbalances identified in Phase 1, and (ii) the evaluation of their effectiveness through on-farm trials.status: Publishe
Plasmodium falciparum regulatory subunit of cAMP-dependent PKA and anion channel conductance
No full textMalaria symptoms occur during Plasmodium falciparum development into red blood cells. During this process, the parasites make substantial modifications to the host cell in order to facilitate nutrient uptake and aid in parasite metabolism. One significant alteration that is required for parasite development is the establishment of an anion channel, as part of the establishment of New Permeation Pathways (NPPs) in the red blood cell plasma membrane, and we have shown previously that one channel can be activated in uninfected cells by exogenous protein kinase A. Here, we present evidence that in P. falciparum-infected red blood cells, a cAMP pathway modulates anion conductance of the erythrocyte membrane. In patch-clamp experiments on infected erythrocytes, addition of recombinant PfPKA-R to the pipette in vitro, or overexpression of PfPKA-R in transgenic parasites lead to down-regulation of anion conductance. Moreover, this overexpressing PfPKA-R strain has a growth defect that can be restored by increasing the levels of intracellular cAMP. Our data demonstrate that the anion channel is indeed regulated by a cAMP-dependent pathway in P. falciparum-infected red blood cells. The discovery of a parasite regulatory pathway responsible for modulating anion channel activity in the membranes of P. falciparum-infected red blood cells represents an important insight into how parasites modify host cell permeation pathways. These findings may also provide an avenue for the development of new intervention strategies targeting this important anion channel and its regulation.INSERM-EPF
Surfactant protein B (SP-B) enhances the cellular siRNA delivery of proteolipid coated nanogels for inhalation therapy
No full textUNLABELLED: Despite the many advantages of small interfering RNA (siRNA) inhalation therapy and a growing prevalence of respiratory pathologies, its clinical translation is severely hampered by inefficient intracellular delivery. To this end, we previously developed hybrid nanoparticles consisting of an siRNA-loaded nanosized hydrogel core (nanogel) coated with Curosurf®, a clinically used pulmonary surfactant (PS). Interestingly, the PS shell was shown to markedly improve particle stability as well as intracellular siRNA delivery in vitro and in vivo. The major aim of this work was to identify the key molecular components of PS responsible for the enhanced siRNA delivery and evaluate how the complexity of the PS coat could be reduced. We identified surfactant protein B (SP-B) as a potent siRNA delivery enhancer when reconstituted in proteolipid coated hydrogel nanocomposites. Improved cytosolic siRNA delivery was achieved by inserting SP-B into a simplified phospholipid mixture prior to nanogel coating. This effect was observed both in vitro (lung epithelial cell line) and in vivo (murine acute lung injury model), albeit that distinct phospholipids were required to achieve these results. Importantly, the developed nanocomposites have a low in vivo toxicity and are efficiently taken up by resident alveolar macrophages, a main target cell type for treatment of inflammatory pulmonary pathologies. Our results demonstrate the potential of the endogenous protein SP-B as an intracellular siRNA delivery enhancer, paving the way for future design of nanoformulations for siRNA inhalation therapy. STATEMENT OF SIGNIFICANCE: Despite the therapeutic potential of small interfering RNA (siRNA) and a growing prevalence of lung diseases for which innovative therapies are needed, a safe and effective siRNA inhalation therapy remains non-existing due to a lack of suitable formulations. We identified surfactant protein B (SP-B) as a potent enhancer of siRNA delivery by proteolipid coated nanogel formulations in vitro in a lung epithelial cell line. The developed nanocomposites have a low in vivo toxicity and show a high uptake by alveolar macrophages, a main target cell type for treatment of inflammatory pulmonary pathologies. Importantly, in vivo SP-B is also critical for the developed formulation to obtain a significant silencing of TNFα in a murine LPS-induced acute lung injury model.sponsorship: PM is a doctoral fellow of the Research Foundation Flanders (FWO Vlaanderen) with financial support of the Flanders Innovation and Entrepreneurship Agency (VLAIO). LDB is a postdoctoral researcher of the Special Research Fund of Ghent University. LVH is a junior research assistant of the Department of Biomedical Molecular Biology of Ghent University. RG is an early stage researcher of the NANOMED project, which has received funding from the European Union's Horizon 2020 Research and Innovation Programme Marie Sklodowska Curie Innovative Training Networks (ITN) under grant number 676137. JPG, ME and BO acknowledge support of grants from the Spanish Ministry of Economy (BIO2015-67930-R) and the Regional Government of Madrid (S2013/MIT-2807). SDS and KR gratefully acknowledge FWO Vlaanderen (1517516), Ghent University (BOF12/GOA/014) and the Agency for Innovation by Science and Technology Flanders (IWT Vlaanderen) (SBO 140061). (Flanders Innovation and Entrepreneurship Agency (VLAIO), European Union's Horizon 2020 Research and Innovation Programme Marie Sklodowska Curie Innovative Training Networks (ITN)|676137, Spanish Ministry of Economy|BIO2015-67930-R, Regional Government of Madrid|S2013/MIT-2807, FWO Vlaanderen|1517516, Ghent University|BOF12/GOA/014, Agency for Innovation by Science and Technology Flanders (IWT Vlaanderen)|SBO 140061)status: Publishe
Scalable perovskite/CIGS thin-film solar module with power conversion efficiency of 17.8%
No full text© 2017 The Royal Society of Chemistry. All-thin film perovskite/CIGS multijunction solar modules, combining a semi-transparent perovskite top solar module stacked on a CIGS bottom solar module, are a promising route to surpass the efficiency limits of single-junction thin-film solar modules. In this work, we present a scalable thin-film perovskite/CIGS photovoltaic module with an area of 3.76 cm2and a power conversion efficiency of 17.8%. Our prototype outperforms both the record single-junction perovskite solar module of the same area as well as the reference CIGS solar module. The presented perovskite/CIGS thin-film multijunction solar module makes use of the "4-terminal architecture", which stacks the perovskite solar module in superstrate configuration on top of the CIGS solar module in substrate configuration. Both submodules apply a scalable interconnection scheme that can accommodate scale-up towards square meter scale thin-film multijunction solar modules. In order to identify the future potential of the presented stacked perovskite/CIGS thin-film solar module, we quantify the various losses in the presented prototype and identify the key challenges of this technology towards very high power conversion efficiencies.sponsorship: The authors thank the thin-film PV team at imec, i.e. Afshin Hadipour, Tamara Merckx and Griet Uytterhoeven for the continuous support with the fabrication of perovskite solar cells. The authors thank the ZSW team for supporting this study with the preparation of CIGS solar modules. The financial support of the Helmholtz Association's Initiative and Networking Fund for the Helmholtz Young Investigator Group of Ulrich Paetzold is highly acknowledged. This work has been supported by Solliance, a partnership of R&D organizations from the Netherlands, Belgium and Germany working on thin-film photovoltaic solar energy. The authors declare no competing financial interests. (Helmholtz Association, Solliance, a partnership of R&D organizations from the Netherlands, Belgium and Germany working on thin-film photovoltaic solar energy)status: Publishe
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