On the decadal linkage of seagrass growth in southern Taiwan with the Pacific Meridional Mode

While decadal predictability is one of the key information demands on marine management and conservation endeavors, the lack of long-term observed records and complex climate variability challenges understanding it. Seagrass beds are not only important blue carbon sinks but also crucial habitats and feeding grounds for diverse marine organisms. This study uses in-situ data from 2001 to 2021 to investigate the primary decadal environmental control, the Pacific Meridional Mode, on seagrass growth in southern Taiwan. Two primary seagrass metrics, aboveground biomass and cover, were examined against various environmental and meteorological variables. Our initial findings reveal a significant correlation between PMM and seagrass growth. Aboveground biomass exhibits a robust negative correlation with PMM, while cover displays a weaker yet positive association. Further examination of regional climate dynamics unveils notable shifts in surface solar radiation, temperature, and rainfall concerning seagrass. Specifically, increased aboveground biomass coincides with reduced solar radiation, lower temperatures, and enhanced rainfall in southern Taiwan, resembling a negative PMM-like pattern. This pattern underscores the sensitivity of aboveground biomass to large-scale climatic fluctuations across the Pacific basin. Conversely, seagrass cover demonstrates opposing patterns compared to aboveground biomass but with less statistical significance. This suggests that cover growth is influenced by a broader array of factors, resulting in a more nonlinear response. In essence, our research underscores the vital role of PMM and regional climate conditions in shaping tropical seagrass growth, offering further insights for marine conservation efforts.