Assessing a robust ensemble-based Kalman filter for efficient ecosystem data assimilation of the Cretan Sea

► The H-infinity filter is implemented for the first time in a complex ecological model. ► The H-infinity filter should help Operational Ecology for better forecasting since it reduces the forecast error for a longer period. ► The H-infinity filter helps the model (ERSEM ecosystem model) to better describe the processes of the Cretan Sea ecosystem.