Declining Ice Duration and Changing Ice Quality Drive Key Under-Ice Ecological Changes in Wisconsin Lakes

Abstract

Lakes are rapidly losing ice cover. We expect that ice loss will have widespread ecological consequences, but these consequences are poorly understood, particularly over long temporal scales. Here, we ask: how do changing ice duration and ice quality influence under-ice photic depth, water temperatures, dissolved oxygen concentrations, and chlorophyll a concentrations? We analyzed winter data from 11 lakes across Wisconsin, USA, with time-series extending from 1982 to 2023. Shorter ice durations and less snow were associated with deeper photic depths, colder under-ice water temperatures, and higher dissolved oxygen saturations. Snow and ice conditions were significantly related to chlorophyll a concentrations; however, the relationship was mediated by nutrient concentrations. We suggest that the drivers of under-ice ecology are as complex as those of the open water season and advocate for the use of integrative models to understand the future of ice-covered lakes.