The ice‐cover period in lakes is increasingly recognized for its distinct combination of physical and biological phenomena and ecological relevance. Knowledge gaps exist where research areas of hydrodynamics, biogeochemistry and biology intersect. For example, density‐driven circulation under ice coincides with an expansion of the anoxic zone, but abiotic and biotic controls on oxygen depletion have not been disentangled, and while heterotrophic microorganisms and migrating phytoplankton often thrive at the oxycline, the extent to which physical processes induce fluxes of heat and substrates that support under‐ice food webs is uncertain. Similarly, increased irradiance in spring can promote growth of motile phytoplankton or, if radiatively driven convection occurs, more nutritious diatoms, but links between functional trait selection, trophic transfer to zooplankton and fish, and the prevalence of microbial versus classical food webs in seasonally ice‐covered lakes remain unclear. Under‐ice processes cascade into and from the ice‐free season, and are relevant to annual cycling of energy and carbon through aquatic food webs. Understanding the coupling between state transitions and the reorganization of trophic hierarchies is essential for predicting complex ecosystem responses to climate change. In this interdisciplinary review we describe existing knowledge of physical processes in lakes in winter and the parallel developments in under‐ice biogeochemistry and ecology. We then illustrate interactions between these processes, identify extant knowledge gaps and present (novel) methods to address outstanding questions.

Climate change is reducing winter ice cover on lakes; yet, the full societal and environmental consequences of this ice loss are poorly understood. The socioeconomic implications of declining ice include diminished access to ice-based cultural activities, safety concerns in traversing ice, changes in fisheries, increases in shoreline erosion, and declines in water storage. Longer ice-free seasons allow more time and capacity for water to warm, threatening water quality and biodiversity. Food webs likely will reorganize, with constrained availability of ice-associated and cold-water niches, and ice loss will affect the nature, magnitude, and timing of greenhouse gas emissions. Examining these rapidly emerging changes will generate more-complete models of lake dynamics, and transdisciplinary collaborations will facilitate translation to effective management and sustainability.

Shifts in hydroclimatic regimes associated with global climate change are affecting the timing and duration of winter ice‐cover in temperate and high‐latitude lakes. Less is known on how associated changes in ice quality potentially affect under‐ice ecological processes and related biogeochemistry, particularly in shallow lake systems. This experimental study examined how differing surface ice‐cover types (slushed white ice, unmanipulated ice formation [black], snow‐on‐ice) affected under‐ice light and oxygen regimes and associated chlorophyll a concentrations, and water quality parameters using a combination of aboveground mesocosms and natural ponds over two consecutive winter seasons. In both systems, light transmission under white ice did not differ significantly from black but was significantly greater than snow‐on‐ice. Measures of light extinction coefficients taken at the ice‐water interface in the experimental ponds increased for black, white, and snow‐on‐ice, respectively, with all values being above thresholds for autotrophic activity. Under‐ice dissolved oxygen levels in all mesocosm ice treatments increased continually over time with increasing day length, peaking prior to ice off. Accumulated DO levels were aligned with observed chlorophyll a concentrations, with peaks early after ice onset, and decreases as winter progressed though patterns differed between years. No significant differences were observed in mean chlorophyll a levels in snow‐removed treatment ponds, regardless of whether white or black ice was present while the snow‐on‐ice ponds displayed consistently lower levels. This study highlights the complexities and importance of using manipulative experimental approaches to advance our understanding of how alterations in surface ice‐cover quality affect under‐ice hydro‐ecological processes.

This systematic review examines peer-reviewed literature (2014–2024) on aquatic health research in Alberta’s Bow River Basin to assess the inclusion of Indigenous Knowledge and collaboration in Western scientific studies. Despite growing recognition of the value of Indigenous ways of knowing, such as holistic stewardship and place-based practices, our analysis of 69 regional publications reveals minimal meaningful co-creation with Indigenous communities. Most studies relied on disciplinarily siloed, quantitative endpoints (e.g., water quantity modelling), with only one study explicitly co-developing research methods and outcomes with Indigenous partners (Siksika Nation). A parallel review of National Sciences and Engineering and Research Council grants (2020–2024) showed relative increases in approvals for community-based research, yet corresponding peer-reviewed outputs remain scarce. This disparity highlights some potential systemic barriers to meaningful collaboration, such as rigid academic timelines and tokenistic “integration” of Indigenous Knowledge. Key recommendations include mandatory Indigenous data stewardship training, flexible funding structures to support relationship-building, and recognition of nontraditional research deliverables. The findings underscore the urgent need for equitable partnerships that center Indigenous voices from project inception to dissemination, ensuring culturally relevant and sustainable water management in the Bow River Basin and more broadly.

This study measures the presence of bacteria‐sediment associations (BSAs) in an alpine, glacier‐fed watershed in the Southern Coast Mountains of British Columbia, Canada. The impact of BSAs on the creation of flocculated particles and their settling velocity are quantified using a laser transmissometer. Results from the study indicate that BSAs are present in the watershed and vary over both space and time. The percentage of bacteria associated with sediment particles was found to range from < 1% to 40%. Major sources of planktonic bacteria such as agricultural land and wastewater treatment outflow co‐occur with large decreases in the BSA ratio. Laboratory analysis demonstrates that an increase in the concentration of bacteria was associated with a decrease in the volume concentration of small particles, and a decrease in both estimated density and measured settling velocity for particles in larger size classes; consistent with flocculated particles of increasing complexity arising from combinations of primary particles and/or BSAs. Paleoenvironmental reconstructions using laminated lake sediments in alpine, glacier‐fed systems benefit from a fuller understanding of the geomorphologic processes by which they formed. While bacteria are noted to enhance formation of flocculated particles in laboratory systems, their impact upon geomorphic processes in natural systems have yet to be fully explored. © 2018 The Authors. Earth Surface Processes and Landforms published by John Wiley & Sons Ltd.

Winter lake ice conditions are undergoing rapid changes because of alterations in global and regional hydroclimatic conditions. The traditional understanding of lake ice growth and evolution through a winter period is the downward progression of ice until air temperatures rise and melt, and breakup ensues. A unique meteorological condition of substantial mid-winter warming in the foothills of the Canadian Rockies allowed for the identification of a phenomenon where a liquid water layer was trapped between ice layers near the surface of a lake. Phytoplankton analysis identified that the interstitial water layer had a bloom of motile phytoplankton belonging to the order Chlamydomonadales . Stable isotopes suggest the upward movement of pelagic water in combination with landscape runoff contributed to the formation of the interstitial water layer. This study provides new insights and illustrates the complexities involved in understanding the physicochemical and biological mechanisms involved in shaping the winter ecology, as well as subsequent ice-free periods, of lakes under a changing climate.