THE INFLUENCE OF EARLY SPRING SEASON CONDITIONS ON PELAGIC PHYTOPLANKTON AND CYANOBACTERIA RECRUITMENT FROM SEDIMENTS

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.

Primary Presenter: Maggie Voyles, Miami University (voylesm@miamioh.edu)

Authors:

Maggie Voyles, Miami University  (voylesm@miamioh.edu)

Lesley Knoll, Miami University  (knolllb@miamioh.edu)