Disentangling the structure of an Antarctic plankton food web in bloom and non-bloom conditions

Despite the fundamental role of phytoplankton in Antarctic marine ecosystems, the trophic dynamics among planktonic organisms remain largely unexplored. This study aims to fill this gap by examining the trophic structure and dynamics of the Potter Cove plankton community under phytoplankton blooming and non-blooming conditions using a network-based approach. For the comparison between the two contrasting conditions, a bloom and a non-bloom season were chosen from the 30-year time series available, and interaction strength was added to the food web models of those specific years. Under the bloom condition, more trophic species of higher trophic level and with higher interaction strength were present, indicating greater food availability for higher trophic levels compared to the non-bloom condition. Under the non-bloom condition, microzooplankton organisms were of greater importance in transmitting energy to the higher trophic levels. This research provides a better understanding of the energy flow within the Antarctic plankton community and the importance of microzooplankton, enhancing our ability to predict the impacts of environmental change, including climate change, on polar marine ecosystems.