Trophic structure and functional diversity reveal pelagic-benthic coupling dynamic in the coastal ecosystem of Daya Bay, China

•Pelagic-benthic coupling related to trophic interaction was studied.•Both pelagic and benthic communities were largely influenced by pelagic production.•Seasonal variation of pelagic food caused trophic cascade and affected coupling.•Trait-based functional diversity in Daya Bay was also influenced by seasonality.