Heating up a cold subject: prospects for under-ice plankton research in lakes

Long-term patterns and drivers of ecosystem structure may be misunderstood if knowledge of an ecosystem is derived primarily from a single season, a situation common in many temperate lakes where the role of winter has been less studied. In lakes, avoidance of winter research has been especially pronounced for those that experience winter ice, but critical ecological processes can take place under ice. Even when obscured by snow, ice transmitting as little as 2% incident light can allow relatively high rates of photosynthesis, and winter trophic interactions may have year-round repercussions. Here, we offer a suite of research questions that require attention, in order to build a mature understanding of seasonal plankton dynamics in lakes. Specifically, we ask freshwater ecologists to consider the extent to which abundance and nutrition of winter primary productivity supports consumers under the ice, reorganizes food webs, and how long the effects of winter trophic dynamics extend throughout the year. In addition, we recognize some critical gaps in knowledge about physical and biogeochemical conditions at the time of ice-off. Worldwide shortening in ice duration lends imperative to under-ice studies, in order to more fully understand changes in ecosystem structure and function that may already be underway.