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The impact of electrogenic sulfur oxidation on the biogeochemistry of coastal sediments: A field study
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Electro-active sediments distinguish themselves from other sedimentary environments by the presence of microbially induced electrical currents in the surface layer of the sediment. The electron transport is generated by metabolic activity of long filamentous cable bacteria, in a process referred to as electrogenic sulfur oxidation (e-SOx). Laboratory experiments have shown that e-SOx exerts a large impact on the sediment geochemistry, but its influence on the in situ geochemistry of marine sediments has not been previously investigated. Here, we document the biogeochemical cycling associated with e-SOx in a cohesive coastal sediment in the North Sea (Station 130, Belgian Coastal Zone) during three campaigns (January, March and May 2014). Fluorescence in situ hybridization showed that cable bacteria were present in high densities throughout the sampling period, and that filaments penetrated up to 7 cm deep in the sediment, which is substantially deeper than previously recorded. High resolution microsensor profiling (pH, H2S and O2) revealed the typical geochemical fingerprint of e-SOx, with a wide separation (up to 4.8 cm) between the depth of oxygen penetration and the depth of sulfide appearance. The metabolic activity of cable bacteria induced a current density of 25–32 mA m-2 and created an electrical field of 12–17 mV m-1 in the upper centimeters of the sediment. This electrical field created an ionic drift, which strongly affected the depth profiles and fluxes of major cations (Ca2+, Fe2+) and anions (SO42-) in the pore water. The strong acidification of the pore water at depth resulted in the dissolution of calcium carbonates and iron sulfides, thus leading to a strong accumulation of iron, calcium and manganese in the pore water. While sulfate accumulated in the upper centimeters, no significant effect of e-SOx was found on ammonium, phosphate and silicate depth profiles. Overall, our results demonstrate that cable bacteria can strongly modulate the sedimentary biogeochemical cycling under in situ conditions
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The impact of policy measures on profitability and risk in geothermal energy investments
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The development of geothermal energy is below the European National Renewable Energy Action Plans’ anticipated trajectory. High upfront investment costs and multiple sources of uncertainty result in a major investment risk, hampering the mobilization of required capital. To evaluate different policy measures, we developed a geological economic Monte Carlo simulation model that integrates both market and geological uncertainty and a firms’ option to abandon the geothermal project development after a first drilling is made. If the objective is to reduce the abandonment rate of geothermal projects, a heat premium comes forward as the most cost-efficient policy instrument. However, the risk that a project turns out unprofitable is not reduced and windfall profits do occur. In contrast, a recoverable loan reduces both the investment risk and the abandonment rate. An insurance scheme targets the investment risk as well. However, it also increases the abandonment rate and appears as the least cost-efficient policy measure. Considering the different policy performance indicators, a tax rebate is never preferred. Our results demonstrate the intricacies of choosing the correct policy measure, and the need to support such policy decisions with quantitative analyses.
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The impact of taphonomic processes on interpreting paleoecological changes in large lake ecosystems: Ostracodes in Lakes Tanganyika and Malawi
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RBINS Staff Publications
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The Impact of the Honeybee Apis mellifera on the Organization of Pollination Networks Is Positively Related with Its Interactive Role throughout Its Geographic Range
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Abstract: Studies at local spatial scales have shown that the generalist honeybee Apis mellifera L. can strongly affect the structural organization and properties of pollination networks. However, there is still little knowledge on how the connectivity of the honeybee within networks (i.e., interactive role) could affect pollination networks at a global scale. To fill this gap, we evaluated how the interactive role of A. mellifera could affect niche overlap, specialization, and robustness of pollination networks. We used 109 weighted pollination networks spread across about 94 degrees of latitude and 227 degrees of longitude. We developed a new standardized framework based on species removal to assess the impact of the honeybee on plant-pollinator networks. We found that when the honeybee was removed from the networks, plant species had less niche overlap (i.e., shared fewer interactions via their pollinators) and the networks became more specialized and more robust to species extinctions. Our findings indicate that A. mellifera’s effects on pollination networks vary geographically and could influence several ecological and evolutionary factors acting at local scales, including pollination services. We hope this contribution will stimulate new macroecological studies involving abundant and generalist species and their functional roles within ecological communities.
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RBINS Staff Publications 2022
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The importance of biological factors affecting trace metal concentration as revealed from accumulation patterns in co-occurring terrestrial invertebrates
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As physicochemical properties of the soil highly influence the bioavailable fraction of a particular trace metal, measured metal body burdens in a particular species are often assumed to be more reliable estimators of the contamination of the biota. To test this we compared the Cd, Cu and Zn content of three spiders (generalist predators) and two amphipods (detritivores), co-occurring in seven tidal marshes along the river Schelde, between each other and with the total metal concentrations and the concentrations of four sequential extractions of the soils. Correlations were significant in only one case and significant site x species interactions for all metals demonstrate that factors affecting metal concentration were species and site specific and not solely determined by site specific characteristics. These results emphasize that site and species specific biological factors might be of the utmost importance in determining the contamination of the biota, at least for higher trophic levels. A hypothetical example clarifies these findings. (C) 2003 Elsevier Ltd. All rights reserved.
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RBINS Staff Publications
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The importance of correct labelling of types: an example in Tortricidae (Lepidoptera) and its rectification
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RBINS collections by external author(s)
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The importance of habitat stability for the prevalence of sexual reproduction. Lake Baikal: a mirror in time and space for the understanding global change processes
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RBINS Staff Publications
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The importance of habitat stability for the prevalence of sexual reproduction. In: K. MINOURA (ed.), Lake Baikal: a mirror in time and space for understanding global change processes, Yokohama Symposium 1998
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RBINS Staff Publications
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The importance of relative humidity and trophic resources in governing ecological niche of the invasive carabid beetle Merizodus soledadinus in the Kerguelen archipelago
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RBINS Staff Publications 2016
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The in situ Glyptostroboxylon forest of Hoegaarden (Belgium) at the Initial Eocene Thermal Maximum (55 Ma)
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RBINS Staff Publications
