Variations in the Bacterial, Fungal, and Protist Communities and Their Interactions Within Sediment Affected by the Benthic Organism, Snail Bellamya purificata

Abstract

In aquatic benthic environments, benthic organisms have been found to regulate important biogeochemical characteristics and perform key ecosystem functions. To further explore the ecological impact of the snail Bellamya purificata's, presence on the benthic environment, we employed high-throughput sequencing technology to investigate its effects on the bacterial, fungal, and protist communities in sediment and their intrinsic interactions. Our findings revealed that B. purificata's presence significantly enhanced the diversity and evenness of the fungal community while simultaneously decreasing the diversity and richness of the protist community, and it also altered the composition and relative abundance of the dominant phyla across the bacterial, fungal, and protist communities. The snail B. purificata considerably altered the co-occurrence networks of the microbial communities, particularly by enhancing the intrinsic complexity of the protist community and by strengthening the interconnections among the protist, bacterial, and fungal communities. Notably, the proportions of specialists within the sediment bacterial, fungal, and protist communities declined due to the snail B. purificata. Its presence also notably expanded the habitat niche breadth for sediment bacteria and protists. In terms of community assembly, B. purificata shifted the fungal community assembly from being dominated by stochastic processes to being dominated by deterministic processes, whereas the protist community assembly shifted from deterministic processes to being dominated by stochastic processes. The mainly altered ecological processes in the fungal and protist assemblies were drift and homogenizing selection. Additionally, the presence of B. purificata resulted in a notable reduction in the sediment ON level and a significant increase in the ammonia, FA, and EN concentrations. Sediment properties, particularly FA and nitrate, were strongly correlated with microbial communities and were key contributors to changes in microbial community dynamics. These research findings not only broadened our understanding of the ecological impacts of B. purificata on benthic microbial communities but also highlighted its substantial potential in enhancing microbial community stability.

Keywords: Bellamya purificata; bacterial; fungal; microbial community; protist communities; sediment.

Figure 1

Impacts of snail Bellamya purificata presence on the diversity and composition of sediment bacterial community. (a) Differences in the bacterial Shannon, Simpson, Chao1, and Pielou_J induced within sediment between the BG and CG groups. (b) Differences in sediment bacterial communities demonstrated by PCoA (Principal Coordinates Analysis). (c) Composition of the top ten bacterial phyla in terms of relative abundance. (d) Bacterial phyla with considerable differences between the BG and CG groups. Distinct lowercase letters marked in the violin plots or box plots signify statistically significant differences (p < 0.05).

Figure 2

Impacts of snail Bellamya purificata presence on the diversity and composition of sediment fungal community. (a) Differences in the fungal Shannon, Simpson, Chao1, and Pielou_J induced within sediment between the BG and CG groups. (b) Differences in sediment fungal communities demonstrated by PCoA (Principal Coordinates Analysis). (c) Composition of the top ten fungal phyla in terms of relative abundance. (d) Fungal phyla with considerable differences between the BG and CG groups. Distinct lowercase letters marked in the violin plots or box plots signify statistically significant differences (p < 0.05).

Figure 3

Impacts of snail Bellamya purificata presence on the diversity and composition of sediment protist community. (a) Differences in the protist Shannon, Simpson, Chao1, and Pielou_J induced within sediment between the BG and CG groups. (b) Differences in sediment protist communities demonstrated by PCoA (Principal Coordinates Analysis). (c) Composition of the top ten protist phyla in terms of relative abundance. (d) Protist phyla with considerable differences between the BG and CG groups. Distinct lowercase letters marked in the violin plots or box plots signify statistically significant differences (p < 0.05).

Figure 4

Alterations in the interactions within and between bacteria, fungi, and protist communities across the BG and CG groups. (a) Co-occurrence networks representing the interactions within and between bacteria, fungi, and protist communities across the BG and CG groups. (b) The number of edges in the co-occurrence networks for bacteria, fungi, and protist communities across the BG and CG groups. (c) The number of nodes in the co-occurrence networks for bacteria, fungi, and protist communities across the BG and CG groups.

Figure 5

Impacts of snail Bellamya purificata presence on the environmental adaption and habitat niche breadth of sediment bacterial, fungal, and protist communities. (a) The habitat niche breadth of bacterial, fungal, and protist communities and their differences between BG and CG groups. (b) The dispersal ability of bacterial, fungal, and protist communities and their differences between BG and CG groups. (c) Proportion of generalist and specialist bacteria, fungi, and protist in the sediment of the BG and CG groups. Distinct lowercase letters marked in bar charts or box plots indicate remarkable differences between the BG and CG groups (p < 0.05).

Figure 6

Impacts of snail Bellamya purificata presence on the assembly processes of sediment bacterial, fungal, and protist communities. (a) Differences in the β-nearest taxon index (βNTI) value of the sediment bacterial, fungal, and protist assembly between the BG and CG groups. (b) Differences in the proportion of deterministic to stochastic processes in the assembly processes shaping bacterial, fungal, and protist communities between the BG and CG groups. (c) Proportions of ecological processes in the assembly processes of sediment bacterial, fungal, and protist communities across BG and CG groups. Distinct lowercase letters marked on the box plot indicate obvious differences between the BG and CG groups (p < 0.05).

Figure 7

Impacts of snail Bellamya purificata presence on the sediment properties including total nitrogen (TN, µg/g), organic nitrogen (ON, µg/g), fixed ammonium (FA, µg/g), exchangeable nitrogen (EN, µg/g), ammonium (µg/g), nitrate (µg/g), and nitrite (µg/g). Distinct lowercase letters marked on the box plot indicate obvious differences between the BG and CG groups (p < 0.05).

Figure 8

Associations between sediment properties and bacterial, fungal, and protist communities. (a) Correlations of the sediment properties with the bacterial, fungal, and protist communities assessed by distance-based redundancy analysis (db-RDA) across BG and CG groups. (b) Relative contributions of the soil properties to the changes in bacterial, fungal, and protist communities evaluated by aggregated boosted tree (ABT).