Over the past several decades, aquatic systems have experienced significant alterations in ice phenology and winter weather, and more dramatic changes are expected in the future. Understanding the rapidly increasing magnitude of change and its consequences requires investment in research across diverse bodies of water and the diverse winter conditions they experience, as well as the physical, biological, and chemical aspects of the systems. This session invites presentations focused on any of these aspects, with the goal being to bring together diverse approaches and knowledge bases to advance understanding of the influence of changing winters on inland waters. In this session, we encourage field scale, laboratory, modeling, and predictive studies that investigate both basic and applied questions relating to changing winter conditions. We encourage submissions by early career researchers as well as by researchers from BIPOC, LGBTQIA+, and other historically excluded identities.
Lead Organizer: Isabella Oleksy, University of Colorado Boulder (isabella.oleksy@colorado.edu)
Co-organizers:
Ana Morales, University of Vermont (ana.morales@uvm.edu)
Trista Vick-Majors, Michigan Tech University (tjvickma@mtu.edu)
Presentations
02:00 PM
Shorter ice duration and changing phenology influence under-ice lake thermal dynamics (8177)
Primary Presenter: Isabella Oleksy, University of Colorado Boulder (bellaoleksy@gmail.com)
Temperate lakes worldwide are losing ice cover but the implications for under-ice thermal dynamics are poorly constrained. Using a 90-year record of ice phenology from a temperate and historically dimictic lake, we examined trends, variability, and drivers of ice phenology and under-ice temperatures. The onset of ice formation decreased by 23 days century-1 which can be largely attributed to warming air temperatures. Ice-off date has become substantially more variable with spring air temperatures and cumulative February through April snowfall explaining over 80% of the variation in timing. As a result of changing ice phenology, total ice duration contracted by a month and more than doubled in inter-annual variability. Using weekly under-ice temperature profiles for the most recent 36 years, we found that shorter ice duration decreased winter inverse stratification and extended the spring mixing period. We illustrate the limitations of relying on discrete ice clearance dates in our assumptions around under-ice thermal dynamics by presenting high-frequency under-ice observations in two recent winters: one with intermittent ice cover and a year with slow spring ice clearance.
02:15 PM
Declining lake ice safety in response to warming climates (8082)
Primary Presenter: Joshua Culpepper, York University (jaculp@yorku.ca)
Millions of people rely on lake ice for safe winter recreation. Warming air temperatures impact the phenology (timing of formation and breakup) and quality (ratio of black to white ice) of lake ice cover, both critical components of ice safety. As ice cover duration decreases and ice quality changes in a warming world, the period of safe ice use will similarly diminish. We use a large ensemble modeling approach to predict ice thickness throughout the winter period in the Northern Hemisphere. We focus on the period of ice cover as it transitions from an unsafe thickness (≤ 10 cm) to a safe thickness (≥ 10 cm) for general use (i.e., walking). We find that the period of transition from unsafe to safe ice cover is growing longer, while the total duration of safe ice cover is getting shorter. The transition period of unsafe ice increases by 4.97 ± 3.67 days in a 4 °C warmer world, assuming 100% black ice. Diminished ice quality further limits safe ice conditions. The unsafe transition period increases by an average of 19.8 ± 8.84 days and 8.75 ± 6.63 days for the ice formation and breakup periods, respectively in a 4 °C warmer world assuming 100% white ice conditions. This work highlights the need to understand both lake ice phenology and quality to better assess safe lake ice use during the formation and melt periods.
02:30 PM
Sampling frequency requirements for detecting phenological mismatch in physical conditions and biological communities. (8370)
Primary Presenter: Gretchen Gerrish, University of Wisconsin Madison (ggerrish@wisc.edu)
Mechanistic documentation of trophic mismatch in aquatic systems due to early and late ice off requires high frequency sampling and substantial effort in collecting and quantifying physical and biological information. And, the required time scale of sampling varies depending on the life span of a parameter or organism. We will use the North Temperate Lakes Long Term Ecological Research data in comparison with three years of higher frequency ecosystem measurements to guide discussion on how we can empirically capture predation changes, food limitation, and temperature constraints on growth and food web interactions.
02:45 PM
Stoichiometry through the seasons: an exploration of high elevation lake chemistry and ecology in southeastern Wyoming, USA (7741)
Primary Presenter: Casey Brucker, University of Wyoming (cbrucker@uwyo.edu)
High-elevation watersheds are valuable freshwater resources facing increasing anthropogenic disturbances and a rapidly changing climate. These compounding impacts cascade through the ecosystem leading to increased water temperatures and nutrients, modified hydrological regimes, and ultimately altered biological processes and biotic communities. Despite their value, little is known about year-round, high-elevation, water body conditions, specifically winter and ice-on conditions. We examined seasonal trends in water chemistry, seston stoichiometry, chlorophyll-A, and zooplankton stoichiometric composition and community structure in seven high elevation lakes (2180-3280 m) in the plains and montane habitats of southeastern Wyoming. Plains and montane lakes show distinct differences in salinity, ice phenology, hydrologic controls, geology, and vegetation, despite their close proximity (53 km radius) and, for some, their hydrologic connectivity. Connected lakes showed diverging water chemistry and seston nutrient composition during phases of hydrologic isolation. The four highest lakes had much longer ice-on periods, and showed that elevation was an important factor associated with surface temperature, specific conductivity, and pH variability. Seston and zooplankton productivity was still evident in most lakes throughout the ice-on period. The examination of seasonal changes in water, seston, and zooplankton stoichiometry has led to a better understanding of the importance of winter lake conditions, and unexpected insights into extreme events that can alter lake function.
03:00 PM
SUBSTANTIAL VARIATION IN ICE PHENOLOGY AND UNDER ICE CONDITIONS ACROSS BACKWATER LAKES OF A LARGE RIVER (8367)
Primary Presenter: Kathi Jo Jankowski, US Geological Survey (kjankowski@usgs.gov)
Winter can be a bottleneck for riverine organisms, but our understanding of the patterns and controls of winter conditions that support river food webs is limited. Further, large floodplain rivers often have a diversity of off channel areas that provide overwintering habitat and affect how winter conditions are expressed across the river landscape. To evaluate drivers of variability in winter conditions across the Upper Mississippi River (UMR), we combined long-term data analysis with winter field surveys in backwater lakes across three reaches of the UMR spanning a gradient of winter intensity and varying in depth and connectivity to the mainstem river. We quantified the timing and duration of ice and snow cover; continuous oxygen, temperature, and light under ice; and drivers of this variation. Ice duration varied by up to a month between the most northern and southern reaches and one to two weeks among sites within the same reach, indicating local factors mediated regional climate effects on ice dynamics. Oxygen and temperature conditions varied with lake depth and connectivity, and responded dynamically to changes in discharge and snow cover throughout the season. The highest daily fluctuation of oxygen, an indicator of under ice productivity, occurred in shallower, less-connected backwaters and during intermittent ice and snow cover at the edges of winter. These findings show that factors such as depth and connectivity affect ice and under ice conditions in rivers, emphasizing the importance of maintaining habitat diversity in river ecosystems as winters change.
03:15 PM
Nuanced connections between ice phenology and summer phytoplankton blooms (7846)
Primary Presenter: Claire Stevens, Trent University (clairestevens@trentu.ca)
Northern hemisphere lakes have experienced a decrease in the duration, spatial extent, and quality of lake ice over the past century. There have been recent advances in the understanding of how ice conditions can drive some summer processes, however much is unknown regarding how changes in ice conditions will affect the timing and severity of summer phytoplankton blooms. To investigate this knowledge gap, we examined a 20-year data set, consisting of ice phenology and coverage data and summer water quality information for Lake Erie. We found significant correlations between the duration of ice coverage and both chlorophyll concentration and phytoplankton community composition. Chlorophyll was negatively correlated with the duration of ice cover, and percent ice coverage in Lake Erie’s western basin. In the central basin, chlorophyll was negatively correlated with the date of ice-on. In both the central and western basin, chlorophyll was positively correlated with date of ice-off, ice duration, and percent ice coverage. Phytoplankton community composition was also related with ice phenology and we found that dinoflagellate biomass was negatively correlated with ice duration and percent ice coverage in the western basin. In the central basin, the average chlorophyte biomass and the yearly chlorophyte maxima were negatively correlated with the date of ice off. These connections may help to elucidate not only the role that winter conditions play in summer dynamics, but also how the loss of lake ice may shape the severity of phytoplankton blooms.
SS12A - Influence of Changing Winters on Inland Waters from Organisms to Ecosystems
Description
Time: 2:00 PM
Date: 3/6/2024
Room: Meeting Room MN