ORIGINAL PAPER Chrysophyte cyst-inferred variability of warm season lake water chemistry and climate in northern Poland: training set and downcore reconstruction I. Herna ´ndez-Almeida • M. Grosjean • W. Tylmann • A. Bonk Received: 16 December 2013 / Accepted: 14 October 2014 / Published online: 26 October 2014 Ó Springer Science+Business Media Dordrecht 2014 Abstract Chrysophyte cyst assemblages from sedi- ment trap and surface sediment samples of 50 lakes in northern Poland were related to environmental vari- ables using multivariate numerical analyses (DCA, CCA). Water electric conductivity, total nitrogen, total phosphorous, turbidity, and cation and anion compo- sitions (Ca 2? , HCO 3 - ) accounted for significant and independent variations in the chrysophyte cyst assem- blages. The first canonical axis was related to the gradient of Ca 2? while the second axis was correlated with total nitrogen. A quantitative transfer function was then developed to estimate Ca 2? (log 10 trans- formed) from modern chrysophyte cyst assemblages using weighted-averaging regression with classical deshrinking. The bootstrapped regression coefficient (R 2 boot ) was 0.68, with a root-mean square error of prediction of 0.143 (log 10 units). The calibration model was applied to a varved sedimentary sequence (AD 1898–2010) from Lake _ Zabin ´skie, Masurian Lakeland (NE Poland). Observational data from this lake show that the Ca 2? variability in the epilimnion depends on the efficiency of Ca 2? scavenging by CaCO 3 precipitation in early summer, which in turn is a function of water column stratification, temperature and the wind regime from late spring to early fall. The spring-fall wind regime drives the water column mixing. In Lake _ Zabin ´skie, cyst-inferred warm-season lake water Ca 2? concentrations are significantly negatively correlated with calcite precipitation (CaCO 3 concentrations in sediments; R =- 0.49, p adj \ 0.001; AD 1898–2010; 3-year filtered), and cyst-inferred lake water Ca 2? concentrations are significantly correlated with zonal wind speed (m s -1 ) (R = 0.50; p adj \ 0.001; AD 1898–2010; 3-year filtered). This study demonstrates that chryso- phyte cyst assemblages in Polish lakes respond to hydrochemical factors driven by climate variability. Keywords Chrysophyte cyst  Westerly winds  Varves  Transfer functions  Poland Electronic supplementary material The online version of this article (doi:10.1007/s10933-014-9812-4) contains supple- mentary material, which is available to authorized users. I. Herna ´ndez-Almeida (&)  M. Grosjean Institute of Geography, University of Bern, Erlachstrasse 9a, 3012 Bern, Switzerland e-mail: ivan.hernandez@giub.unibe.ch M. Grosjean e-mail: grosjean@giub.unibe.ch I. Herna ´ndez-Almeida  M. Grosjean Oeschger Centre for Climate Change Research, University of Bern, Falkenplatz 16, 3012 Bern, Switzerland W. Tylmann  A. Bonk Department of Geomorphology and Quaternary Geology, Institute of Geography, University of Gdansk, Gdan ´sk, Poland e-mail: geowt@ug.edu.pl A. Bonk e-mail: a.bonk@ug.edu.pl 123 J Paleolimnol (2015) 53:123–138 DOI 10.1007/s10933-014-9812-4