Embedded Files
Gejla Toromani, Devon Popson, Dr. Rachael Morgan-Kiss
Gejla Toromani, Devon Popson, Dr. Rachael Morgan-Kiss
Department of Microbiology, Miami University
Department of Microbiology, Miami University
INTRODUCTION
INTRODUCTION
Lake Bonney, located in the McMurdo Dry Valleys of Antarctica, is a perennially ice-covered lake composed of two distinct basins: the East Lobe (ELB) and the West Lobe (WLB). Each lobe is stratified and largely isolated, with limited water exchange between them, resulting in distinct physical and chemical environments. The lake is permanently sealed by an ice cover approximately 3–5 meters thick, and its water column exhibits strong vertical stratification due to density differences driven by salinity, temperature, and chemical gradients. The food web in Lake Bonney is entirely microbial, making it a good model for exploring the processes of the microbial loop. A particularly significant stratified zone, known as the chemocline, occurs between 10 and 20 meters in depth and represents a transition zone of significant chemical and biological change.
Lake Bonney, located in the McMurdo Dry Valleys of Antarctica, is a perennially ice-covered lake composed of two distinct basins: the East Lobe (ELB) and the West Lobe (WLB). Each lobe is stratified and largely isolated, with limited water exchange between them, resulting in distinct physical and chemical environments. The lake is permanently sealed by an ice cover approximately 3–5 meters thick, and its water column exhibits strong vertical stratification due to density differences driven by salinity, temperature, and chemical gradients. The food web in Lake Bonney is entirely microbial, making it a good model for exploring the processes of the microbial loop. A particularly significant stratified zone, known as the chemocline, occurs between 10 and 20 meters in depth and represents a transition zone of significant chemical and biological change.
Green algae are a dominant group of primary producers in Lake Bonney and are found in high abundance at the chemocline, a critical ecological boundary where biological activity, nutrient availability, and microbial communities undergo sharp transitions. These organisms rely on stable environmental conditions, including light availability, temperature, and nutrient concentrations, all of which are susceptible to changes driven by climate variability.
Green algae are a dominant group of primary producers in Lake Bonney and are found in high abundance at the chemocline, a critical ecological boundary where biological activity, nutrient availability, and microbial communities undergo sharp transitions. These organisms rely on stable environmental conditions, including light availability, temperature, and nutrient concentrations, all of which are susceptible to changes driven by climate variability.
This study investigates long-term trends (2004–2023) in green algae abundance in both the East and West Lobes of Lake Bonney. Using data provided by the McMurdo Long-Term Ecological Research (LTER) program, we compare trends in green algae abundance at the chemocline across both lobes and analyze the influence of key climate-related variables: air temperature, water column temperature, and ice thickness.
This study investigates long-term trends (2004–2023) in green algae abundance in both the East and West Lobes of Lake Bonney. Using data provided by the McMurdo Long-Term Ecological Research (LTER) program, we compare trends in green algae abundance at the chemocline across both lobes and analyze the influence of key climate-related variables: air temperature, water column temperature, and ice thickness.
RESEARCH QUESTIONS
RESEARCH QUESTIONS
- Is the abundance of green algae within the chemocline of Lake Bonney changing over time?
- Which environmental variables (air temperature, water temperature, or ice thickness) appear to be driving these changes, if any?
Figure 1. Conceptual diagram of Lake Bonney showing vertical stratification and chemocline structure in the East and West Lobes.
METHODS
METHODS
RESULTS
RESULTS
Figure 2. Green algae abundance measured in the chemocline of (A) East Lake Bonney (ELB, 15–20 m depth) and (B) West Lake Bonney (WLB, 14–17m depth) from 2004 to 2023. Error bars indicate the standard deviation (SD) of the measurements. The asterisks show years for which green algae abundance is significantly different (p<0.05) from 2004 as determined by an ANOVA and Tukey test.
Figure 3. Average Water temperature measured in the chemocline of (A) East Lake Bonney (ELB, 15–20 m depth) and (B) West Lake Bonney (WLB, 14–17 m depth) from 2004 to 2023. Error bars indicate the standard deviation (SD) of the measurements.
Figure 4. The annual average ice thickness for (A) East Lake Bonney (ELB, red) and(B) West Lake Bonney (WLB, blue) from 2004 to 2023. Error bars show the standard error of the mean for each year.
Figure 5. Average air temperature measured near Lake Bonney from 2004 to 2022. Error bars indicate the standard deviation (SD) of the measurements.
Table 1. East Lobe (ELB) Regression Analysis Table. Regression coefficients for water temperature, ice thickness, and sampling year are displayed, with statistical significance indicated by the asterisks next to the p-values. The intercept is also provided. Air temperature data is excluded due to its lack of significant influence on green algae abundance in the East Lobe.
Table 2. West Lobe (WLB) Regression Analysis Table. Regression coefficients for water temperature, ice thickness, and sampling year are displayed, with significant results marked by the asteriks next to the p-values. The intercept is also included. Air temperature data is omitted because it did not significantly affect green algae abundance in the West Lobe.
DISCUSSION
DISCUSSION
- Green algae abundance has increased over time in both the East (ELB) and West (WLB) lobes, with notable spikes in 2010, 2014, 2016, and 2022.
- Ice thickness has gradually declined in both lobes, showing a borderline significant effect on green algae abundance.
- Water column temperature trends diverged: slight decrease in ELB and increase in WLB; it was a modest but significant predictor of algae abundance.
- Air temperature remained relatively stable from 2004–2023 and had no significant relationship with algae abundance.
- Overall, water temperature, ice thickness, and year are key drivers of variability in green algae, while air temperature is not a major factor.
CONCLUSIONS
CONCLUSIONS
This study investigated long-term trends in green algae abundance across both lobes of Lake Bonney in relation to climate-related factors. While air temperature remained relatively stable and showed no significant impact, water column temperature and ice thickness exhibited notable fluctuations and were mildly significant predictors of algal abundance. The year of sampling emerged as a strong contributing factor, indicating that green algae abundance is changing over time, though not in a clearly linear fashion. These results suggest that localized environmental factors and long-term shifts may be influencing lake stratification and ecosystem dynamics. Understanding these changes is essential for predicting the future health of polar freshwater systems under ongoing climate pressure.
This study investigated long-term trends in green algae abundance across both lobes of Lake Bonney in relation to climate-related factors. While air temperature remained relatively stable and showed no significant impact, water column temperature and ice thickness exhibited notable fluctuations and were mildly significant predictors of algal abundance. The year of sampling emerged as a strong contributing factor, indicating that green algae abundance is changing over time, though not in a clearly linear fashion. These results suggest that localized environmental factors and long-term shifts may be influencing lake stratification and ecosystem dynamics. Understanding these changes is essential for predicting the future health of polar freshwater systems under ongoing climate pressure.
FUTURE RESEARCH
FUTURE RESEARCH
Further investigation could explore additional factors such as salinity, light penetration, or nutrient concentrations to better understand drivers of green algae dynamics in Lake Bonney. Moreover, examining whether certain variables disproportionately affect one lobe over the other, and exploring the underlying causes, could offer insight into localized ecological responses to climate change. Applying multivariate or nonlinear statistical models may also reveal more complex relationships. Lastly, comparative studies with other Antarctic lakes could help provide context and help identify patterns across the McMurdo Dry Valleys.
Further investigation could explore additional factors such as salinity, light penetration, or nutrient concentrations to better understand drivers of green algae dynamics in Lake Bonney. Moreover, examining whether certain variables disproportionately affect one lobe over the other, and exploring the underlying causes, could offer insight into localized ecological responses to climate change. Applying multivariate or nonlinear statistical models may also reveal more complex relationships. Lastly, comparative studies with other Antarctic lakes could help provide context and help identify patterns across the McMurdo Dry Valleys.
ACKNOWLEDGEMENTS
ACKNOWLEDGEMENTS
This research was made possible through data provided by the McMurdo Dry Valleys Long-Term Ecological Research (LTER) Project, available via the McMurdo Dry Valleys website. I would like to extend my sincere thanks to my research mentor, Dr. Morgan-Kiss, for her invaluable guidance, and to Ms. Devon Popson, graduate student, for her support with statistical analysis and project development.
This research was made possible through data provided by the McMurdo Dry Valleys Long-Term Ecological Research (LTER) Project, available via the McMurdo Dry Valleys website. I would like to extend my sincere thanks to my research mentor, Dr. Morgan-Kiss, for her invaluable guidance, and to Ms. Devon Popson, graduate student, for her support with statistical analysis and project development.
REFERENCES
REFERENCES
- Lee et al., 2024. Microbial assemblages and associated biogeochemical processes in Lake Bonney, a permanently ice-covered lake in the McMurdo Dry Valleys, Antarctica. Environmental Microbiome, 19, 60. https://doi.org/10.1186/s40793-024-00605-1
- Takacs-vesbach, C.D., Priscu, J.C. 2025. Lake ice thickness and density measurements, McMurdo Dry Valleys, Antarctica (1989-2025, ongoing). Environmental Data Initiative. DOI: 10.6073/pasta/e72dc49d774796767884c535e864c915.
- Takacs-vesbach, C.D., Priscu, J.C. 2025. Conductivity, temperature, and depth (CTD) vertical profiles collected from lakes in the McMurdo Dry Valleys, Antarctica (1993-2023, ongoing). Environmental Data Initiative. DOI: 10.6073/pasta/004de32b27fc88954abdce0ff8a3bbb3.
- Dugan, H.A., P.T. Doran, and A.G. Fountain. 2025. High-frequency, hourly, and daily measurements from Lake Bonney Meteorological Station (BOYM), McMurdo Dry Valleys, Antarctica (1993-2025, ongoing) ver 22. Environmental Data Initiative. https://doi.org/10.6073/pasta/3e680ff4a17518b1f391a599552362cf
Page updated
Report abuse