title: A phenomenological approach shows a high coherence of warming patterns in dimictic aquatic systems across latitude.
abstract: To predict the coherence in local responses to large-scale climatic forcing among aquatic systems, we developed a generalized approach to compare long-term data of dimictic water bodies based on phenomenologically defined hydrographic events. These climate-sensitive phases (inverse stratification, spring overturn, early thermal stratification, summer stagnation) were classified in a dual code (cold/warm) based on threshold temperatures. Accounting for a latitudinal gradient in seasonal timing of phases derived from gradients in cumulative irradiation (2.2 days per degree latitude), we found a high spatial and temporal coherence in warm-cold patterns for six lakes (84 %) and the Baltic Sea (78 %), even when using the same thresholds for all sites. Similarity to CW-codes for the North Sea still was up to 72 %. The approach allows prediction of phase-specific warming trends and resulting instantaneous or time-delayed ecological responses. Exemplarily, we show that warming during early thermal stratification controls food-web-mediated effects on key species during summer.
authors.affiliation: Institute of Hydrobiology, Technische Universität Dresden, 01062 Dresden, Germany.
authors.forename: Annekatrin
authors.initials: A
authors.lastname: Wagner
authors.affiliation: Institute of Hydrobiology, Technische Universität Dresden, 01062 Dresden, Germany.
authors.forename: Stephan
authors.initials: S
authors.lastname: Hülsmann
authors.affiliation: Neunzehnhain Ecological Station, TU Dresden, 09514 Lengefeld, Germany.
authors.forename: Lothar
authors.initials: L
authors.lastname: Paul
authors.affiliation: Institute of Zoophysiology, Westfälische Wilhelms-Universität Münster, 48143 Münster, Germany.
authors.forename: Rüdiger J
authors.initials: RJ
authors.lastname: Paul
authors.affiliation: Institute of Hydrobiology, Technische Universität Dresden, 01062 Dresden, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Petzoldt
authors.affiliation: Neunzehnhain Ecological Station, TU Dresden, 09514 Lengefeld, Germany.
authors.forename: René
authors.initials: R
authors.lastname: Sachse
authors.affiliation: Institute of Hydrobiology, Technische Universität Dresden, 01062 Dresden, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Schiller
authors.affiliation: Institute of Zoophysiology, Westfälische Wilhelms-Universität Münster, 48143 Münster, Germany.
authors.forename: Bettina
authors.initials: B
authors.lastname: Zeis
authors.affiliation: Institute of Hydrobiology, Technische Universität Dresden, 01062 Dresden, Germany.
authors.forename: Jürgen
authors.initials: J
authors.lastname: Benndorf
authors.affiliation: Institute of Hydrobiology, Technische Universität Dresden, 01062 Dresden, Germany.
authors.forename: Thomas U
authors.initials: TU
authors.lastname: Berendonk