Archive | 2019
Microbial abundance and enzyme activity in sediments of the rapid-pool-benchland systems in the natural Duliu River of China
Abstract
River ecosystems have been greatly impaired by negative human activities. It is important to understand the relationships among the river structure, microbial abundance and enzyme activity of natural rivers for the restoration of impaired river ecosystems. The repeatedly occurring rapid-pool-bench land system (RPBS) is deemed a basic unit of natural river structure. Microbial abundance and enzyme activity in sediments of the RPBS are key processes that regulate a variety of ecological functions. However, detailed studies relating to a RPBS are scarce. We selected nine RPBSs in the Duliu River in China and studied the microbial abundance, enzyme activity, nutrients and heavy metals as influencing factors in the sediments of these RPBSs using the plate counting method, colorimetric methods, and atomic absorption spectrometry. The RPBSs were significantly different in microbial abundance, enzyme activity, nutrients and heavy metals. Bacteria, ammonifiers, actinomycetes, fungi, and denitrifying bacteria in the sediments of the pools of these RPBSs showed the greatest abundances. The number of bacteria was significantly larger than that of four other microbial groups. Total nitrogen had significant effects on microbial abundance. Catalase in bench lands, as well as phosphatase, urease and dehydrogenase in pools, exhibited high levels of activity and were significantly correlated with microbial abundances. Enzyme activity was substantially affected by N, Pb and As. The habitat heterogeneity represented by RPBSs altered the microbial abundance and enzyme activity, which regulated different ecological functions. The restoration of degraded rivers to include RPBSs is beneficial to diverse ecosystem functions.