Spatial pattern and environmental determinants of benthic diatom diversity in the middle and lower reaches of the Yellow River

Qingyang Guo¹Qin Zhu²Pengfei Peng³Qiuling Zhou¹Yong Ding¹Zhenchang Zhu^1*

• ¹Guangdong University of Technology, Guangzhou, China
• ²Southern Marine Science and Engineering Guangdong Laboratory - Guangzhou, Guangzhou, China
• ³South China Sea Marine Survey and Technology Center of State Oceanic Administration, Guangzhou, China

Benthic diatoms serve as critical bioindicators of freshwater ecosystem health due to their responsiveness to environmental shifts. However, previous studies have often overlooked the integrated effects of environmental, geographical, and anthropogenic factors on diatom diversity, especially in sediment-laden and highly heterogeneous rivers. This study examines the spatial patterns and environmental determinants of benthic diatom diversity in the middle and lower reaches of the Yellow River. It incorporates environmental, geographical, and anthropogenic factors to reveal their combined effects. Using data from 46 sampling sites, key water quality parameters, including total nitrogen (TN), total phosphorus (TP), and turbidity, were identified as primary drivers of diatom diversity. Structural equation modeling further demonstrated the mediating role of water quality, linking land use patterns and geographical gradients to diatom community structure. The middle reaches showed higher alpha diversity, attributed to moderate nutrient levels and stable hydrological conditions. In contrast, the lower reaches, affected by urbanization and nutrient enrichment, exhibited community homogenization and dominance by eutrophic taxa. By investigating multi-scale drivers of diatom diversity in a heterogeneous and human-impacted river system, this study proposes a framework for analyzing biodiversity patterns. It also offers insights for sustainable management of the Yellow River and comparable large river systems.