Journal: Ecosphere

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Publisher

ESA

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ISSN

2150-8925

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2017 - 201912020 - 20241
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Publications 1 - 2 of 2
  • Large river floodplain as a natural laboratory: non‐native macroinvertebrates benefit from elevated temperatures
    Item type: Journal Article
    Paillex, Amael; Castella, Emmanuel; Zu Ermgassen, Philine; et al. (2017)
    Ecosphere
    Water temperature is known to influence individual animal metabolism, development, and reproduction. However, in situ studies aiming to demonstrate the link between water temperature and community structure in complex ecosystems such as large river floodplains are still rare. In particular, we have little indication about how an increase in temperature affects the density of native and invasive species within a community. Large river floodplains cover a varied range of environmental conditions, are rich in species, and therefore potentially useful ecosystems to study the effect of water temperature at the community level. Moreover, as freshwater communities are increasingly impacted by global warming and biological invasions, an improved understanding of the possible interaction between these drivers would be beneficial. First, we studied during two years the thermal heterogeneity of 36 sites in a large river (Rhone) floodplain. Second, we compared the thermal regimes of sites having different levels of hydrological connectivity with the main river channel. Third, we studied the combined and separated effects of the thermal regime and the hydrological connectivity on the presence and densities of native and non-native species of macroinvertebrates. The studied large river floodplain covered a wide range of thermal regimes, with some sites displaying a yearlong constant temperature of about 10°C, whereas others experienced thermal amplitude of over 25°C. The thermal regime was independent of the level of hydrological connectivity of the sites. The increase in hydrological connectivity had a significant and positive effect on the richness of non-native species within sites. The thermal regime had a positive influence on the density of non-native species but no effect on the total density of native taxa within communities. This study showed that large river floodplains possess a wide range of thermal conditions and that the increase in water temperature can have a positive influence on the presence of non-native populations of macroinvertebrates. This study provides a first set of empirical results to establish models predicting the effect of increasing temperatures on the establishment of non-native and native species in a complex ecosystem and underline the problem of biological invasions under climate change.
  • The dependence of forecasts on sampling frequency as a guide to optimizing monitoring in community ecology
    Item type: Journal Article
    Daugaard, Uriah; Merkli, Stefanie; Merz, Ewa; et al. (2024)
    Ecosphere
    Facing climate change and biodiversity loss, it is critical that ecology advances so that processes, such as species interactions and dynamics, can be correctly estimated and skillfully forecasted. As different processes occur on different time scales, the sampling frequency used to record them should intuitively match these scales. Yet, the effect of data sampling frequency on ecological forecasting accuracy is understudied. Using a simple simulated dataset as a baseline and a more complex high-frequency plankton dataset, we tested how different sampling frequencies impacted abundance forecasts of different plankton classes and the estimation of their interactions. We then investigated whether plankton growth rates and body sizes could be used to select the most appropriate sampling frequency. The simple simulated dataset showed that the optimal sampling frequency scaled positively with growth rate. This finding was not repeated in the analyses of the plankton time series, however. There, we found that a reduction in sampling frequency worsened forecasts and led us to both over- and underestimate plankton interactions. This suggests that forecasting can be used to determine the ideal sampling frequency in scientific and monitoring programs. A better study design will improve theoretical understanding of ecology and advance policy measures dealing with current global challenges.
Publications 1 - 2 of 2