The missing middle – Investigating a North American metalimnetic cyanobacteria layer
Start Date
25-5-2022 3:30 PM
End Date
25-5-2022 3:45 PM
Abstract
While the majority of cyanobacteria research and bloom reports pertain to surficial events, research centred on subsurface cyanobacteria remains understudied. Metalimnetic cyanobacteria layers (MCL) are a subsurface phenomenon forming distinct depth stratum, often going unreported due to their inconspicuous nature, particularly in a North American context. Sunfish Lake (Ontario, Canada) represents a North American lake known for hosting an MCL. Here, we (1) reconstructed long-term cyanobacteria records to establish the changing risk of cyanobacteria blooms; and (2) investigated the spatial distribution of cyanobacteria and toxin-producing potential with real-time monitoring. The sediment record at Sunfish Lake revealed an unprecedented abundance of cyanobacteria in modern times (i.e., 1980s onwards), coinciding with increasingly warmer and wetter climatic conditions in the region. Real-time monitoring (2017) revealed an MCL and subsequent toxin analysis showed that peak toxin production (anabaenopeptin and microcystin) coincided with the MCL. Our findings provide (1) evidence for climate-driven shifts in cyanobacteria abundance and that even incremental alterations in climate signals over short temporal scales can push freshwater lakes towards cyanobacteria dominance; (2) importance of comprehensive monitoring to avoid “missing the middle” due to potential health risks at greater depths.
The missing middle – Investigating a North American metalimnetic cyanobacteria layer
While the majority of cyanobacteria research and bloom reports pertain to surficial events, research centred on subsurface cyanobacteria remains understudied. Metalimnetic cyanobacteria layers (MCL) are a subsurface phenomenon forming distinct depth stratum, often going unreported due to their inconspicuous nature, particularly in a North American context. Sunfish Lake (Ontario, Canada) represents a North American lake known for hosting an MCL. Here, we (1) reconstructed long-term cyanobacteria records to establish the changing risk of cyanobacteria blooms; and (2) investigated the spatial distribution of cyanobacteria and toxin-producing potential with real-time monitoring. The sediment record at Sunfish Lake revealed an unprecedented abundance of cyanobacteria in modern times (i.e., 1980s onwards), coinciding with increasingly warmer and wetter climatic conditions in the region. Real-time monitoring (2017) revealed an MCL and subsequent toxin analysis showed that peak toxin production (anabaenopeptin and microcystin) coincided with the MCL. Our findings provide (1) evidence for climate-driven shifts in cyanobacteria abundance and that even incremental alterations in climate signals over short temporal scales can push freshwater lakes towards cyanobacteria dominance; (2) importance of comprehensive monitoring to avoid “missing the middle” due to potential health risks at greater depths.