Since the measurements started there is a clear trend of the first ice coming later and the ice thawing earlier, meaning the total time when the ice covers the lake gets shorter. As you can see in the diagramme the shorter ice period is connected to the warmer temperatures. A shorter time with ice means there is less time to build a thick ice layer which also leads to a faster thawing of the ice. Here the same effect comes in as we see with the decreased snow cover – the open water is darker than the ice and will warm up by the sun instead of reflecting the sun light (this is the albedo effect again). The lake has more time to warm up and thus getting warmer than before. Warmer water results in greater biological productivity (which increases the amount of CO2 exchanged with the atmosphere). For sure not all fish species will adapt to that.