ECOLOGY OF SHALLOW LAKES Shorter blooms expected with longer warm periods under climate change: an example from a shallow meso- eutrophic Mediterranean lake Gary Free . Mariano Bresciani . Monica Pinardi . Steef Peters . Marnix Laanen . Rosalba Padula . Alessandra Cingolani . Fedra Charavgis . Claudia Giardino Received: 20 May 2021 / Revised: 20 October 2021 / Accepted: 20 November 2021 Ó The Author(s) 2021 Abstract Satellite data from the Climate Change Initiative (CCI) lakes project were used to examine the influence of climate on chlorophyll-a (Chl-a). Non- parametric multiplicative regression and machine learning were used to explain Chl-a concentration trend and dynamics. The main parameters of impor- tance were seasonality, interannual variation, lake level, water temperature, the North Atlantic Oscilla- tion, and antecedent rainfall. No evidence was found for an earlier onset of the summer phytoplankton bloom related to the earlier onset of warmer temper- atures. Instead, a curvilinear relationship between Chl- a and the temperature length of season above 20°C (LOS) was found with longer periods of warmer temperature leading to blooms of shorter duration. We suggest that a longer period of warmer temperatures in the summer may result in earlier uptake of nutrients or increased calcite precipitation resulting in a shortening of the duration of phytoplankton blooms. The current scenario of increasing LOS of temperature with climate change may lead to an alteration of phyto- plankton phenological cycles resulting in blooms of shorter duration in lakes where nutrients become Guest editors: Jose ´ L. Attayde, Renata F. Panosso, Vanessa Becker, Juliana D. Dias & Erik Jeppesen / Advances in the Ecology of Shallow Lakes G. Free (&) Á M. Bresciani Á M. Pinardi Á C. Giardino Institute for Electromagnetic Sensing of the Environment, National Research Council, Via Bassini 15, 20133 Milan, Italy e-mail: free.g@irea.cnr.it M. Bresciani e-mail: bresciani.m@irea.cnr.it M. Pinardi e-mail: pinardi.m@irea.cnr.it C. Giardino e-mail: giardino.c@irea.cnr.it S. Peters Á M. Laanen Water Insight, Marijkeweg 22, 6709 PG Wageningen, The Netherlands e-mail: peters@waterinsight.nl M. Laanen e-mail: laanen@waterinsight.nl R. Padula Á A. Cingolani Á F. Charavgis ARPA UMBRIA, Via Pievaiola, 207/B-3 Loc. S. Sisto, 06132 Perugia, Italy e-mail: r.padula@arpa.umbria.it A. Cingolani e-mail: a.cingolani@arpa.umbria.it F. Charavgis e-mail: f.charavgis@arpa.umbria.it 123 Hydrobiologia https://doi.org/10.1007/s10750-021-04773-w