Highlights
- Typhoon-induced nutrient surge triggered cascade effects in Zhanjiang Bay.
- Skeletonema costatum proliferated and decayed rapidly in eutrophic waters.
- Bloom collapse caused water acidification and oxygen depletion.
- A CNN-LSTM model achieved 73% relative accuracy in 6 h Chl-a rolling forecast.
Abstract
Typhoons can trigger biogeochemical cascade effects, including eutrophication, algal blooms, acidification, and dissolved oxygen (DO) depletion in the estuary-coast continuum, yet the underlying mechanisms remain poorly understood. This study employed a multidisciplinary observation approach, combining high-frequency in situ monitoring with field surveys, to capture the dynamics of the cascade during Typhoon “Yagi” (Sep 2024) in Zhanjiang Bay (ZJB). The analysis incorporated multivariate hydrological, meteorological, and physicochemical parameters, stable isotopes (δ15N-NO3−, δ18O-NO3−, δ18O-H2O, δD-H2O), and phytoplankton community characterization. Results showed that during the pre-algal bloom period, freshwater discharge, fluxes of dissolved inorganic nitrogen (DIN), and dissolved inorganic phosphorus (DIP) increased by factors of 8.7, 43.4, and 3.0, respectively, relative to the pre-typhoon stage, while salinity decreased by 9.7%. This nutrient surge exacerbated eutrophication, leading to a serious algal bloom eight days after the typhoon. Subsequent bloom decay triggered acidification and DO decline. Field investigations confirmed typhoon-driven freshwater input and algal blooms. Moreover, a deep learning model was developed for Chlorophyll-a forecasts, achieving 73% relative accuracy (RA) in rolling 6-hour forecasting. Typhoon-driven nutrient surge triggered the cascade: Skeletonema costatum bloomed under extreme thermohaline perturbation and decayed rapidly, leading to acidification and DO depletion. This study advances mechanistic understanding of typhoon-driven cascading effects in tropical coastal ecosystems, providing a scientific basis for the assessment of their ecological consequences and predictive coastal management strategies.
Long H., Zhang P., Zhang J., Gao M., Fan B., Hu Z., Li Z. & Chen R., 2026. Typhoon-induced cascade effects on hydrological and biogeochemical dynamics in estuary-coast continuum: insights from multidisciplinary observations and model forecasting in Zhanjiang Bay, China. Journal of Hydrology 664: 134610. doi: 10.1016/j.jhydrol.2025.134610. Article.
