Biology
Permanent URI for this collection
Browse
Browsing Biology by Subject "Abrupt shifts"
Now showing 1 - 2 of 2
Results Per Page
Sort Options
Item Open Access Impacts of Climate Change and Multiple Stressors on Water Levels and Phytoplankton in Small Temperate Lakes Within the Great Lakes Region Over Three Decades(2020-05-11) Gaibisels, Katrina Meiri-Liis; Sharma, SapnaChanges in climate influence water quantity and water quality through hydrological processes, thermal regimes, and ice phenology. This thesis investigates the impacts of climate change and additional anthropogenic stressors on water quantity and quality in two study areas with minimal anthropogenic disturbance within the Great Lakes region. Between 1984 and 2014, water levels dropped by an average of 50 cm in northern Wisconsin lakes. We found that 49% of the variation in water levels was attributed to decreased precipitation, and 30% was attributed to warmer air temperatures. Water levels are projected to rise by an average of 44 cm by the year 2070. In south-central Ontario, phytoplankton dominance shifted from diatoms to chrysophytes between 1984 and 2013. Changes in lake chemistry and lake morphometry explained 60% of the variation in phytoplankton biomass. Understanding how multiple interacting stressors affect lakes will help improve ecosystem management strategies.Item Open Access Investigating Changes in Lake Ice Breakup Under Current and Future Climate Change(2019-07-02) Lopez, Lianna Stephanie; Sharma, SapnaChanges in climate profoundly influence the timing of lake ice breakup. We assessed: 1) potential future changes in lake ice breakup date in the Great Lakes Region and 2) historical linear changes and shifts in ice breakup across the Northern Hemisphere. We found that at the regional and global scales, warming air temperatures contributed to earlier ice breakup. In the Great Lakes region, ice breakup was forecasted to occur 13 days earlier on average by 2070. Across the Northern Hemisphere, we detected abrupt changes in ice breakup dates in the 1970s to the 2000s, coinciding with shifts in air temperature, precipitation and phase switches of climate oscillations. The structure and function of many lakes in the mid- and high latitudes are influenced by seasonal ice cover, and these ecosystems will likely undergo a variety of changes with earlier ice breakup and a shorter ice season.