Biodiversity and distribution of zoobenthos in the ecological water replenishment area of the Yellow River estuary coastal wetland revealed by eDNA metabarcoding

These species demonstrate strong adaptability to fluctuating salinity levels, which is crucial in an environment like the Yellow River Delta, where salinity varies across different zones. Con- versely, families like Xyalidae and Chromadoridae are more sensitive to pH, preferring slightly alkaline environments [65,66]. These dynamics highlight the complex responses of zoobenthic communities to environmental fluctuations, suggesting their potential as bioindicators of salinity and other related stressors. At a more specific level, the effect of salinity on zoobenthic genera is influenced by the com- position of specific ions (e.g., Mg2⁺, Ca2⁺) (Fig 4). Elevated levels of these ions are essential for the health and diversity of certain taxa, such as Longipedia and Halicyclops, which show posi- tive correlations with Mg2⁺ and Ca2⁺ [67]. These ions support crucial physiological functions, such as bone and shell formation, enzyme activity, and osmotic regulation. Other genera, like Itaipusa, benefit from the protection and stability provided by ion-rich sediments [68]. In con- trast, changes in anion concentrations have a less pronounced impact on community struc- tures [67]. Genera such as Stronglostoma and Limnodrilus show positive correlations with TOC and NH₄⁺, indicating their preference for nutrient-rich environments that support decomposition and nutrient cycling [69–71]. Moerisia, on the other hand, exhibits a negative correlation with TOC due to its sensitivity to organic pollution [72]. 5. Conclusions

This study employed eDNA metabarcoding to reveal the biodiversity and distribution of zoo- benthos in the ecological water replenishment area of Yellow River Estuary Coastal Wetland. This method identified 174 zoobenthic families, offering a broader and more comprehensive understanding of the ecosystem compared to traditional morpho-taxonomic approaches. Environmental factors such as salinity, cations, and organic matter significantly influence the composition and distribution of zoobenthos. These findings emphasize the importance of using advanced molecular techniques to assess biodiversity and ecological health in coastal wetlands. They provide new insights into the ecological dynamics and environmental stressors affecting zoobenthic communities under ecological management. Supporting information S1 Fig. Taxonomy and list of the 10 most abundant zoobenthic families. The columns in the figure represent the taxonomic levels from left to right: Domain, phylum, class, order, and family. (TIF) S2 Fig. Network roles of analyzing module feature at genus level. Scatter plot of within- module connectivity (Zi) and among-module connectivity (Pi) showing the distribution of species based on their topological roles. Nodes are categorized into module hubs (Zi > 2.5 and Pi < 0.62), connectors (Zi < 2.5 and Pi > 0.62), network hubs (Zi > 2.5 and Pi > 0.62), and peripheral nodes (Zi < 2.5 and Pi < 0.62). (TIF) S1 Table. Longitude and latitude coordinates of sampling sites. (DOCX) S2 Table. Taxonomic list of identified zoobenthos. (DOCX) S1 Graphical abstract. (TIF) PLOS ONE

Biodiversity and zoobenthos distribution in yellow river estuary wetlands revealed by eDNA metabarcoding PLOS ONE | https://doi.org/10.1371/journal.pone.0315346 December 18, 2024 14 / 19