Time-Frequency Analysis Reveals That Seaweed Farming Enhances Phytoplankton Resilience Under ENSO Events

Abstract

The El Niño-Southern Oscillation (ENSO), a key driver of interannual climate variability, significantly influences marine phytoplankton dynamics. Rising sea surface temperatures (SST) have further stimulated the occurrence of phytoplankton blooms, potentially increasing the role of seaweed farming in regulating phytoplankton communities. However, the impact of seaweed farming on the resilience of phytoplankton to ENSO events is still poorly understood. Here, using integrated in situ monitoring data from a high-yield seaweed farm in China, combined with satellite chlorophyll (Chl) data and time-frequency analysis, we find that seaweed farming regulates phytoplankton blooms and their periodic fluctuations, attenuating SST-driven growth patterns. We find that seaweed harvesting induces short-term phytoplankton growth. Seaweed farming enhances the teleconnection between phytoplankton and ENSO, but its regulation of phytoplankton mitigates the stimulation of phytoplankton blooms by increased SST, allowing them to exhibit a more regular and stable SST-driven pattern. These findings suggest that moderately expanded seaweed farming can be a scalable, nature-based solution for enhancing coastal ecosystem resilience to ENSO.