Interpretation of interannual variability in long-term aquatic ecological surveys

Type Article
Date 2020-05
Language English
Author(s) Cauvy-Fraunié Sophie1, Trenkel Verena2, Daufresne Martin3, Maire Anthony4, Capra Hervé5, Olivier Jean-Michel6, Lobry Jérémy7, Cazelles Bernard8, Lamouroux Nicolas5
Affiliation(s) 1 : Irstea Centre de Lyon-Villeurbanne, 89723, 5 rue la doua, Villeurbanne, France
2 : IFREMER - Centre de Nantes, 70611, Nantes, Pays de la Loire, France
3 : Irstea Centre d'Aix-en-Provence, 84233, Aix-en-Provence, Provence-Alpes-Côte d'Azur, France
4 : EDF R and D Site de Chatou, 151443, Chatou, Île-de-France, France
5 : Irstea Centre de Lyon-Villeurbanne, 89723, Villeurbanne, Rhône-Alpes , France
6 : Université Claude Bernard Lyon 1 Faculté des Sciences et Technologies, 200932, LEHNA, Villeurbanne, France
7 : Irstea Centre de Bordeaux, 84269, Cestas, Aquitaine, France
8 : ENS, 26909, Paris, Île-de-France, France
Source Canadian Journal Of Fisheries And Aquatic Sciences (0706-652X) (Canadian Science Publishing), 2020-05 , Vol. 77 , N. 5 , P. 894-903
DOI 10.1139/cjfas-2019-0146

Long-term ecological surveys (LTES) often exhibit strong variability among sampling dates. The use and interpretation of such interannual variability is challenging due to the combination of multiple processes involved and sampling uncertainty. Here, we analysed the interannual variability in ~30 years of 150 species-density (fish and invertebrate) and environmental-observation time series in four aquatic-systems (stream, river, estuary, and marine continental shelf) with different sampling efforts to identify the information provided by this variability. We tested, using two empirical methods, whether we could observe simultaneous fluctuation between detrended time series corresponding to widely acknowledged assumptions about aquatic population dynamics: spatial effects, cohort effects, and environmental effects. We found a low number of significant results (36, 9, 0% for spatial, cohort, and environmental effects), suggesting that sampling uncertainty overrode the effects of biological processes. Our study does not question the relevance of LTES for detecting important trends, but clearly indicated that the statistical power to interpret interannual variations in aquatic-species densities is low, especially in large systems where the degree of sampling effort is always limited.

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Cauvy-Fraunié Sophie, Trenkel Verena, Daufresne Martin, Maire Anthony, Capra Hervé, Olivier Jean-Michel, Lobry Jérémy, Cazelles Bernard, Lamouroux Nicolas (2020). Interpretation of interannual variability in long-term aquatic ecological surveys. Canadian Journal Of Fisheries And Aquatic Sciences, 77(5), 894-903. Publisher's official version : , Open Access version :