Artificial river flow regulation triggered spatio-temporal changes in marine macrobenthos of the Yellow River Estuary

Abstract

The Water Sediment Discharge Regulation (WSR) in the Yellow River transports a vast quantity of freshwater and materials to the Bohai Sea within 20 days, significantly altering the ambient environment of the estuary. To elucidate the ecological impacts of this typically artificial flood event, we investigated the benthic habitats and macrobenthic biodiversity within the Affected Core Area (ACA) influenced by this discharge. Our results show that: (1) The discharge created an area with extreme environmental conditions, extending from the southern estuary to Laizhou Bay. This led to a rapid transformation of the habitat, as evidenced by a significant increase in turbidity, ammonium, and silicate levels. Among these factors, nitrogen nutrients and pH were the dominant drivers of environmental filtration, shaping the macrobenthos community structure; (2) The changing habitat triggered spatial shifts in macrobenthos abundance based on the distance from the estuary. Compared to the northern estuary, species composition and C-diversity in the southern area decreased significantly. These changes collectively established a short-term biodiversity front in the estuary region; (3) Community stability declined, as evidenced by a 24.20% reduction in niche width for generalist species and a 90.91% shift in specialist species. Furthermore, the connectivity between species decreased, and the average path length of the network increased, resulting in a more fragmented community structure. Notably, some ecological patches dominated by generalist species (e.g. Alpheus distinguendus) emerged. These findings enhance our understanding of marine ecological responses to artificial flood events within the context of global environmental changes.