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The effect of climate change on population abundances are less studied than those on species ranges. This is partly because population abundance data are harder to obtain. Nonetheless, abundance is an interesting variable to study. A species may change in abundance before there are changes in its range; therefore, we may detect climate change impacts on abundance that are not apparent if we just look at range edges. The aim of our study was to study the impacts of climate change on long-term abundance trends, using a broad range of species from all environmental realms. We included time-series data from 22 different communities since the 1980s, including 6 marine datasets collected from the North Sea (phytoplankton, benthic invertebrates and fish). Our test was based on the prediction that warm-adapted species should increase (or decrease less) than cold-adapted ones within each community under climate change. We used the population data to estimate species’ population trends and compiled distribution data (e.g., from GBIF and OBIS) to estimate species’ temperature preferences. We found a mixture of population trends in almost all datasets: many species have decreased, but many species have also increased. On average, temperature preference was positively related to population trends. Although some of the cold-adapted terrestrial species had decreased, more commonly warm-adapted terrestrial species had increased. We found weaker relationships in the marine and freshwater datasets although warm-dwelling marine fish have increased. Attributing changes in species’ abundance to particular drivers is tricky because populations are exposed to many drivers at the same time. By relating population trends to species characteristics (temperature preferences), we show how it is possible to detect the particular effects of climate change on species’ abundances, and how this is useful for comparative analysis of climate change impacts across environmental realms.
Full reference: Diana E. Bowler, Christian Hof, Peter Haase, Ingrid Kröncke, Oliver Schweiger, Rita Adrian, Léon Baert, Hans-Günther Bauer, Theo Blick, Rob W. Brooker, Wouter Dekoninck, Sami Domisch, Reiner Eckmann, Frederik Hendrickx, Thomas Hickler, Stefan Klotz, Alexandra Kraberg, Ingolf Kühn, Silvia Matesanz, Angelika Meschede, Hermann Neumann, Robert O’Hara, David J. Russell, Anne F. Sell, Moritz Sonnewald, Stefan Stoll, Andrea Sundermann, Oliver Tackenberg, Michael Türkay, Fernando Valladares, Kok van Herk, Roel van Klink, Rikjan Vermeulen, Karin Voigtländer, Rüdiger Wagner, Erik Welk, Martin Wiemers, Karen H. Wiltshire & Katrin Böhning-Gaese. 2017. Cross-realm assessment of climate change impacts on species’ abundance trends. Nature Ecology & Evolution 1: 0067 (doi:10.1038/s41559-016-0067)