Nutrient enrichment decreased the Cross-Taxon congruence across bacteria, fungi, and zoobenthos in sediment

Abstract

Eutrophication is a major problem currently affecting sediment biodiversity in different kingdoms. Surveys at different spatial scales have suggested that nutrient enrichment drove the congruence in biodiversity across different kingdoms. In this study, we examined the diversity indexes of bacteria, fungi, and zoobenthos in Dongting Lake, which is undergoing different trophic levels. The species richness and Shannon index of bacteria, fungi, and zoobenthos were all consistent with the intermediate disturbance hypothesis along the content of TN and TP, with the hysteresis of fungal group. Significant cross-taxon congruence was found in species richness between bacteria and zoobenthos, and Shannon index between bacteria and fungi. Also, the strength of congruence in biodiversity among bacteria, fungi and zoobenthos would decrease along nutrient enrichment. Multi- and single-kingdom networks found that bacterial group contained more nodes and edges compared to fungal and zoobenthos groups, and bacterial removal led to the lowest natural connectivity. And highest positive interaction proportion and lowest absolute value of natural connectivity slope were observed in zoobenthos group. These results highlighted the importance of bacteria as stabilizer in sediment ecosystem, and the most sensitive feature of zoobenthos to nutrient enrichment. Taken together, our results confirmed the cross-taxon congruence between multi-kingdoms, and the effectiveness of bacteria as a potential bioindicator of ecological change.