ECOHYM (the Ecological Connectivity Hypoxia Model) revealed the daily and annual dynamics of the vertical biochemical-physical oxygen production and consumption rate in the tidal flat quantitatively, based on the validation from two perspectives: (1) the whole estuary, composed of temporal-spatial mutual linkage of the central bay-tidal and benthic-pelagic ecosystems (holistic approach) and (2) each biochemical and physical processes (elemental approach). The benthic oxygen consumption caused by biochemical production during daytime was higher than nighttime due to oxygen production of photosynthesis of benthic algae. This photosynthesis makes the benthic system sometimes an oxygen source for the pelagic system during daytime, although the benthic system is always an oxygen sink during night time.
