An Analysis of the Threats to Fish Habitat in the Lower Yellow River due to River Channel Transformation

Abstract

River morphology plays a key role in shaping fish habitats. Changes in channel form can greatly affect habitat quality. This study examines how river morphology changes impact fish habitats in the Yellow River over time and space. The focus is on the Huayuankou and Jiahetan reaches, where the river has shifted from a braided to a meandering form. An ecological hydraulics model, combined with a fish habitat suitability model, was used to assess these effects under different flow conditions. The results show that this transformation has led to habitat fragmentation. Yellow River carp (Cyprinus carpio) species have lost habitat diversity and connectivity. Crucian carp (Carassius auratus) species have gained shallower, slow-flow areas but face other challenges. Flow homogenization and water quality decline have reduced habitat quality. Ecological restoration has helped improve conditions, but complex habitats remain limited. This study underscores the need to consider river morphology when managing fish habitats. Future restoration strategies should enhance habitat suitability for both large and Crucian carp (C. auratus). Both hydrological and morphological factors should be addressed to support aquatic biodiversity in regulated rivers.