The island mass effect: a study of wind-driven nutrient upwelling around reef islands

Using the method of process-oriented modelling, this study explores wind-driven upwelling features around reef islands of the tropical Pacific Ocean. The three-dimensional hydrodynamic model is coupled to a nutrient-phytoplankton (NP) model to simulate the creation of phytoplankton blooms initiated by the wind-driven upwelling of nutrients into the euphotic zone. Findings demonstrate that short-lived wind events of 2-5 days in duration, which are typical of tropical regions, can lead to significant phytoplankton blooms near reef islands. This finding agrees with observational evidence. Comparison studies reveal that the total phytoplankton production increases for higher wind speeds, longer durations of wind events and larger reef islands, and that it decreases with stronger static stability of the pycnocline. Overall, our findings indicate that wind-driven nutrient upwelling supports the ecosystem functioning around larger tropical reef islands.