Detrended fluctuation analysis of bloom-forming phytoplankton based on weekly data of phytoplankton concentration

Phytoplankton blooms, regardless of their toxicity, represent major ecological events that reshape aquatic community dynamics. Understanding the temporal signatures and ecological niches of dominant taxa is essential to predict their behavior under shifting environmental conditions. This study investigates the temporal dynamics and ecological strategies of dominant phytoplankton taxa in Narragansett Bay using weekly time series data spanning two decades. Detrended Fluctuation Analysis was applied to assess short- and long-term self-affine correlations in species abundance and evaluated ecological niches using the Outlying Mean Index and subniches with Within Outlying Mean Indexes. The results reveal that taxa with higher short-term DFA exponents exhibit more persistent ecological behavior during rapid environmental changes. In contrast, higher long-term DFA exponents are associated with greater specialization and sensitivity to long-term environmental variability. Skeletonema spp., the most frequently blooming taxon, displayed anti-persistent long-term behavior, suggesting self-effect dynamics. Integrating Detrended Fluctuation Analysis with ecological niche modeling provides a useful method to differentiate phytoplankton strategies of bloom dynamics.