Shifts of sediment bacterial community and respiration along a successional gradient in a typical karst plateau lake wetland (China)

Abstract

Bacteria are important regulators of carbon cycling in lakes and are central to sediment ecosystem processes. However, the sediment microbial communities and their respiratory responses to the lake wetland succession are poorly understood. In this study, we collected sediment samples from four different succession points (the Potamogeton lucens zone, the Scirpus tabernaemontani zone, the Scirpus triqueter zone, and the Juncus effusus zone) in the Caohai Wetland of the Guizhou Plateau (China). The bacterial communities at these succession points were studied using a high-throughput sequencing approach. The sediment microbial respiration (SR) was measured using static chambers in the field and basal respiration (BR) was determined in the laboratory. The results show that the dominant bacterial taxa in the sediment was Proteobacteria (34.7%), Chloroflexi (17.8%), Bacteroidetes (7.3%), Acidobacteria (6.6%), and Cyanobacteria (6.1%). Principal coordinate analysis showed that the microbial community structure differs significantly at different sampling points along the successional gradient, indicating that the bacterial community structure is sensitive to the lake wetland succession. Different hydrological regimes and soil characteristics such as NH 4 + -N, Fe2+, Mn2+, and sediment organic carbon (SOC) content may be important factors responsible for the differences in the sediment microbial characteristics of the different successional stages in the Caohai wetland. Additionally, it was found that the SR increased significantly from the P. lucens zone to the J. effusus zone, but BR had the opposite response. The shifts in the bacterial community structure along the successional gradient may be the main reason for the observed differences in sediment respiration.