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
05:30 PM
IMPACT OF ICE QUALITY ON RADIATIVELY DRIVEN CONVECTION DURING SEASONAL ICE COVER ON LAKES (8427)
Primary Presenter: Benjamin Smith, University Wisconsin-Madison (bjsmith28@wisc.edu)
Lakes that experience seasonal ice cover are not quiescent during ice-on due to the buoyancy driven flows within the water column. As winter progresses into spring, an increase of solar radiation through the ice generates currents that can transport nutrients into the water column triggering early growth of phytoplankton which can lead to blooms during or soon after ice cover. Prior to freezing, the lake conditions dictate the quality of the ice, for example, calm conditions will lead to highly transparent black ice, whereas variable conditions will lead to opaque white ice. Further, as the planet undergoes climate change, warmer average temperatures are resulting in thinner ice cover, thus, it is important to investigate how this change in ice quality impacts lake circulation which further dictates other biophysical processes. To tackle this, solar radiation is incorporated to the incompressible Navier-Stokes equations via the Beer-Lambert law which are then numerically solved on an initially thermally stratified domain. A fixed ice boundary with no melting is assumed in order to investigate the impact of ice quality as light starts to consistently penetrate the water column as in spring. It is found that ice quality impacts the flow in a meaningful way, for example, black ice reduces the duration of time for the onset of convection and enhances mixing compared to white ice as more light is allowed to propagate and transfer thermal energy into the water column.
05:30 PM
Using contemporary and past winter lake monitoring to identify the impact of warmer winter temperatures on lake diatom communities (8436)
Primary Presenter: dominique maier, University of Vermont (dominique.b.maier@gmail.com)
Previous research has indicated that lake diatom communities in both the water column and sediment records may be strongly influenced by winter conditions and may provide a proxy of past winter climate. Winters in the northeastern United States and Sweden are highly variable and changing rapidly, making them useful sites to test this hypothesis. To assess the effects of warmer winter air temperatures on lake diatom communities across the northern hemisphere, many biological, chemical, and physical catchment and in-lake drivers must be studied in space and time. Long term monitoring studies for different lake types with different mixing regimes are useful to identify effects of warmer and colder winters but often do not include critical parameters such as ice thickness, under ice light quality as they are difficult and dangerous to measure and are rarely included in standardized winter sampling. A combined approach of long-term monitoring programs in Vermont paired with observations of local community members, state employees, farmers, and fishermen will help to generate a more comprehensive view on the importance of different drivers, and particularly their timing for a potential change in lake productivity due to warmer winter air temperatures.
05:30 PM
OXYGEN, TEMPERATURE, AND NUTRIENT DYNAMICS IN A MESOTROPHIC LAKE DURING THE UNPRECEDENTED WARM WINTER OF 2023-2024 (7775)
Primary Presenter: Olivia Sowa, Oakland University (oliviasowa@oakland.edu)
Evidence is mounting that lakes are more productive in the winter than originally thought. However, our knowledge of winter abiotic and biotic dynamics in lakes remains rudimentary. With the climate changing rapidly and northern lakes warming faster than others, it is critical to understand winter lake dynamics. Here, we examined the drivers of oxygen dynamics in Tree Top Pond, a mesotrophic lake in Southeast Michigan, USA, during the unprecedented warm winter of 2023-2024. From December 2023 until February 2024, the air temperature was on average 2 to 4 °C warmer than the long-term average. We measured vertical dissolved oxygen and temperature dynamics at 15-minute intervals from November 17, 2023, until mid-April 2024. Additionally, we collected sub-monthly to monthly water samples for dissolved and total nitrogen (N), phosphorus (P), particulate C, N, P, and chlorophyll a. We did not collect nutrient and chlorophyll samples during periods of ice cover due to unsafe conditions. So far, our data indicate that the lake had periods of inverse stratification before ice-on, which affected oxygen dynamics. During inverse stratification, the lower strata dissolved oxygen concentrations decreased rapidly, likely due to high respiration rates. We identified variable spatial, vertical, and temporal dynamics of dissolved and total N and P, particulate C, N, and P, and chlorophyll a indicating variability in the productivity and nutrient recycling within the lake. Overall, our preliminary results will help fill existing knowledge gaps on the drivers of winter productivity.
05:30 PM
ZOOBENTHIC MACROINVERTBRATE COMMUNITY RESPONSES TO ICE BREAK UP IN SUBALPINE LAKE HABITATS OVER 15 YEARS (7855)
Primary Presenter: Elizabeth Mast, University of Nevada, Reno (emast@nevada.unr.edu)
Winter conditions and ice dynamics govern lake ecosystem processes during the ice-free season in polar and temperate freshwater systems. Lake ice cover duration is increasingly variable and declining due to climate warming. As lake ice conditions change, the impacts of ice on lake benthic processes during subsequent ice-free seasons remain poorly documented despite the significance of these habitats to whole lake function. In this study, we examined the connections between ice off date, lake physical and chemical traits in the ice-free season, and zoobenthic macroinvertebrate diversity in a subalpine lake (Castle Lake, CA, USA). Zoobenthos were collected during three periods (early, mid, and late summer) from four nearshore-littoral and three profundal lake habitats over 15 years and identified to family. Ice off dates were highly variable, ranging from Julian days 51 to 178. We identified 30 families, dominated by 3 taxa (Chironomidae, Oligochaeta, Pisidium) during the sampling period, with richness ranging between 1 to 13 taxa. Preliminary analyses suggest zoobenthic diversity is highly variable across lake habitats across years and ice-out dates, supporting potential resiliency in community structure over space and time. Our results suggest dominant zoobenthic taxa have the capacity to withstand significant environmental variability under changing ice conditions.
05:30 PM
SEASONAL DYNAMICS OF PHYTOPLANKTON NUTRIENT LIMITATION IN A HYPEREUTROPHIC RESERVOIR (7912)
Primary Presenter: Kloe Atwood, Miami University (atwoodk2@miamioh.edu)
In some areas, rainfall events are increasing in frequency and intensity, particularly in winter and spring seasons. Rising air temperatures also reduce ice cover in northern lakes and may raise lake temperature during the winter These changes impact aquatic ecosystems, affecting internal dynamics like lake stratification and external factors such as watershed nutrient inputs. Although recent studies highlight that phytoplankton can be active during the ‘non-growing season’, we know little about how altered precipitation or temperature regimes influence these communities. For example, it is unclear whether these non-growing season phytoplankton are nutrient-limited and how they respond to nutrient pulses. We performed weekly nutrient limitation bioassays in a Midwestern US hypereutrophic reservoir for one year with four treatment groups (control, +Nitrogen (N), +Phosphorus (P), and +NP). We found substantial differences between the control and treatment groups. Phytoplankton transited from P to NP/N limitation in late summer, potentially due to reduced precipitation and nutrient loading. Outside the growing season, algae remained nutrient-limited into the winter, demonstrating continued activity. Phytoplankton biomass remained high until factors, such as hydraulic flushing or extreme cold temperatures, decreased abundance/prevented growth. Results highlight that algae can be nutrient-limited during the non-growing season and show the influence of precipitation and temperature on algal dynamics in a lake transitioning from winters with seasonal ice cover to open waters.
05:30 PM
THE INFLUENCE OF EARLY SPRING SEASON CONDITIONS ON PELAGIC PHYTOPLANKTON AND CYANOBACTERIA RECRUITMENT FROM SEDIMENTS (7914)
Primary Presenter: Maggie Voyles, Miami University (voylesm@miamioh.edu)
Cyanobacteria blooms are occurring more frequently and with more intensity in response to climate change. Further, the phenology of harmful algal blooms may be mediated by both pelagic cyanobacteria and the recruitment of cyanobacteria resting cells from sediments, which are influenced by abiotic factors like temperature, precipitation, nutrient availability, and light levels. These factors may shift the onset and longevity of harmful algal blooms as early season conditions change. We analyzed phytoplankton data from Acton Lake collected between 2012 to 2023. A strong negative relationship between emergence and early season temperature were observed (i.e., earlier emergence associated with warmer air temperature in the spring). Lab experiments were then conducted to investigate how light, temperature, and nutrient conditions influence pelagic cyanobacteria and cyanobacteria recruitment from sediments in Acton Lake in the spring. We observed that pelagic cyanobacteria increased significantly with increased temperature, increased nutrients, and low light conditions. Cyanobacteria recruitment in Acton Lake peaked at experiment day 6 in the light and nutrient addition treatment. Preliminary microscopy identifies Planktothrix as the dominant taxa in these samples. This indicates that early spring conditions may influence harmful algal blooms by altering pelagic communities and cyanobacteria recruitment dynamics.
05:30 PM
EFFECTS OF FRESHWATER FREEZING ON MICROBIAL HABITABILITY (8204)
Primary Presenter: Garrett Lukosavich, Michigan Technological University (gnlukosa@mtu.edu)
Bacteria play a crucial role in the transformation of organic carbon in freshwater lakes. Despite their fundamental involvement in organic matter biogeochemistry, most analyses have been conducted during warm periods dominated by open water. During winter nearly half of all freshwater lakes globally are subject to seasonal freezing, which directly influences the distribution of bacteria across snow-ice-water transects. Ice accretion for example has been shown to alter both the chemistry and distribution of organic matter in the water column, via the exclusion of aromatic components of dissolved organic carbon (DOC) from ice. On the other hand, evidence also shows that some bacteria are preferentially incorporated into the ice. The cross-season effects on habitability resulting from these processes remain unknown. To explore the consequences of seasonal freezing for microbial habitability within and beneath ice, we conducted a series of controlled freezing experiments on water collected from a North temperate freshwater lake. Samples were taken before and after freezing, then analyzed for changes in organic matter fluorescence, dissolved organic carbon (DOC) concentration, and cellular abundance. Results showed changes in the composition of dissolved organic material between time points, as indicated by excitation emission matrix spectroscopy. Significant differences in the concentrations of DOC between pre- and post freeze samples were also observed. Plans for future experiments include determination of the favorability of ice-DOC as a substrate for microbial growth.
05:30 PM
LIGHT AND NUTRIENT LIMITATION OF ICE-ASSOCIATED AND PLANKTONIC PHOTOAUTOTROPHS (7981)
Primary Presenter: Hong An Nguyen, Univerisity of Wisconsin - Stout (nguyenh8759@my.uwstout.edu)
Phytoplankton abundance under-ice is often lower than in the ice-free season but in eutrophic lakes primary producer biomass may remain elevated in the winter. Under-ice primary producers also have access to additional habitat in the form of the ice itself. Phytoplankton communities can vary due to light intensity and under-ice habitats. Despite high dissolved nutrients and lower light intensity under ice, winter primary producers can still exhibit nitrogen and phosphorus limitation in addition to light limitation. Diatoms are often important primary producers in winter and may experience silica-limitation. The goal of our study is to compare light and nutrient limitations of ice-associated and planktonic photoautotrophs. in a hypereutrophic reservoir. We conducted a 14-day under-ice experiment by deploying nutrient-diffusing substrates at the ice-water interface (ice-associated) and phytoplankton bags (planktonic). Both were amended with nitrogen (N), phosphorus (P), silica (Si), and N+P+Si nutrients. The light was manipulated by removing snow (high light) or leaving the snow (low light). Phytoplankton were light limited and ice-associated photoautotrophs were light inhibited. Phytoplankton were P-limited in low light treatments and not-limited in high light while ice-associated photoautotrophs were silica-limited in high light treatments. This study affirms that nutrient limitation and light limitation co-occur under ice and suggests differential light responses by planktonic and ice-associated photoautotrophs.
SS12P - Influence of Changing Winters on Inland Waters from Organisms to Ecosystems
Description
Time: 5:30 PM
Date: 4/6/2024
Room: Madison Ballroom D