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

3.3. Relationships between environmental parameters and zoobenthos communities The RDA plot illustrates the relationship between zoobenthos and various environmental fac- tors (Fig 3A). Blue arrows represent environmental factors, with their direction and length indicating the gradient and strength of influence on zoobenthos. The overall permutation test (P = 0.001) confirms that these environmental factors significantly impact the zoobenthos community. Salinity, represented as a comprehensive index of cationic and anionic concentra- tions, plays a crucial role in shaping these communities. Higher salinity levels are associated with families such as Naididae, Aphanolaimidae, Aeolosomatidae, and Polycystididae, suggest- ing these families prefer nutrient-rich, saline environments. Conversely, Limnocharidae and Hyocopridae prefer areas with low salinity and higher oxygen levels. Additionally, a random forest regression analysis was utilized to determine the relative importance of various environ- mental factors influencing zoobenthos (Fig 3B). Each point on the graph represents the impor- tance score of a specific factor, with higher scores indicating a greater influence on the presence, abundance, or health of these organisms. The trend in the graph indicates that cer- tain environmental factors, particularly salinity, significantly shape the distribution and abun- dance of different zoobenthic families in aquatic ecosystems. The NMDS plot shows the β diversity of zoobenthic communities across different salinity

conditions (Fig 3C). Statistical analysis confirms significant differences between high and low salinity groups (PERMANOVA: F = 5.873, P = 0.001). The metaMDS stress value of 0.162 indicates a good representation of the data. The low salinity group (blue) is distinct and pri- marily located in the lower left quadrant, while the high salinity group (red) is separate and sit- uated in the upper region. The median salinity group (cyan) is positioned between the low and high groups, indicating a transitional community structure. Fig 3D illustrates the α diversity of zoobenthos, measured by Shannon’s diversity index, under three different salinity conditions. Fig 2. Zoobenthic community compositions (A) and population statistics (B) across different sampling sites in the Yellow River Estuary Coastal Wetland. The circos plot displays the 20 most abundant zoobenthic families. In the petal plot, values within the petals represent the number of zoobenthic families unique to each sample, and the sum of the value outside the petal and the core value indicates the total number of families. https://doi.org/10.1371/journal.pone.0315346.g002 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 8 / 19