Browsing by Autor "Monika Winder"

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Effects of the non-native Arapaima gigas on native fish species in Amazonian oxbow lakes (Bolivia)
(Public Library of Science, 2025) Danny Rejas; Monika Winder; Reinaldo Cholima; Thierry Oberdorff
The introduction of non-native fish species into new environments has raised global concerns due to potential ecological impacts on recipient ecosystems. A previous study focusing on the introduced fish species Arapaima gigas in Bolivian Amazon waters showed that its isotopic niche significantly overlapped with most co-occurring native fish species, suggesting potential competition. To evaluate this hypothesis, we extended here the investigation by comparing the trophic position and isotopic niche width of eleven abundant native fish species inhabiting both colonized and non-colonized floodplain lakes. We found lower trophic positions in colonized versus non-colonized lakes only for native piscivores, mostly driven by a shift towards increased dietary proportion of detritivorous fishes. Conversely, results showed that the isotopic niche width of most fish species analyzed (i.e. 10 over 11 species) did not significantly decrease in colonized compared to non-colonized lakes. Our overall results suggest potentially low competitive interactions between A. gigas and native fishes, with the notable exception of piscivorous species. We attribute our findings to the high abundance of available resources in Amazon oxbow lakes.
InSAR Ground Deformation and Pumping Energy Consumption Reveal Urban Water Security
(Wiley, 2026) Martin Marañon; Alfredo Durán; Rígel Rocha; Monika Winder; Carmen Ledo; M. P. Sanders; Alfredo Mendoza; Seifeddine Jomaa
Abstract Water resource assessments are critical for ensuring water security (WS), particularly in rapidly urbanizing regions with increasing water demand and limited water monitoring capabilities. Earth observations and indirect indicators of surface and groundwater changes are valuable tools for developing such assessments. This study examines WS by combining trends in pumping energy consumption and water‐induced ground deformation over time and space in the sprawling metropolitan region of Cochabamba, Bolivia. We integrate Interferometric Synthetic Aperture Radar data with pumping energy consumption records from an extensive well network in the period 2012 to 2022. Statistical analysis identifies four trends in energy consumption (increasing, decreasing, stable, and no consumption) and three in ground deformation (uplift, subsidence, and no change). Based on these trends, we define four WS scenarios: WS, Threatened Water Security, water insecurity (WI), and Reversible Water Insecurity. Results reveal predominant domestic groundwater use and an increasing trend in energy consumption by pumping. In more than 1000 of these wells, both unsustainable water use and subsidence occur, implying WI. This study demonstrates the potential of combining InSAR‐derived ground deformation and pumping energy consumption as a cost‐effective and scalable groundwater monitoring tool for WS assessments.
The introduced <i>Arapaima gigas</i> in the Bolivian Amazon: Trophic position and isotopic niche overlap with native species
(Wiley, 2023) Danny Rejas; Thierry Oberdorff; Steven Declerck; Monika Winder
Abstract Non‐native fish species may generate major ecological impacts on native assemblages. This study aims to assess the potential impact of the introduced Arapaima gigas on native fish assemblages in two oxbow lakes of the Bolivian Amazon. Stable isotope data were used to determine trophic position (TP) and isotopic niche overlap, to evaluate potential predation and competition interactions, respectively. Results suggest that A. gigas is more an omnivore than a top predator, as often claimed. Arapaima gigas occupied an intermediate TP between detritivore/herbivore and piscivore fish species and showed broader isotopic niche compared to most native species analysed. The isotopic niche of A. gigas significantly overlapped with most native fish species in one lake (i.e. Lake Mentiroso), while there was low niche overlap in the second (i.e. Lake Miraflores). Given its omnivorous tendencies, the predation impact of A. gigas on other fish species is likely less than currently claimed and likely varies with the food web structure of the ecosystem. More precise data on resource availability and use are necessary to infer whether niche overlap will have negative impacts on native fish species through potential competitive interactions. Increasing our understanding on the processes generating impact of these introductions on resident communities through food web ecology will pave the way for better resource management and conservation efforts.