To evaluate the implications of our results for marine systems, we also analyzed water temperature data of Marsdiep, a tidal inlet to the
Waddensea. The lake water temperature model fitted equally well to all four water bodies. Applying the water temperature model to the
period 1961–2006 showed an annual increase of 0.042 °C irrespective of lake size and depth.We extrapolated the consequences of lake
warming for the onset of growth of larval bream and the size of young-of-the-year bream at the end of the year using an existing fish
hatching and growthmodel. Bothmodelswere tested against data fromLake Tjeukemeer,which is intermediate in size compared to Lake
Zwemlust and Lake IJsselmeer. The main conclusions of this study are that