Mitigation of Eutrophication in a Shallow Lake: The Influences of Submerged Macrophytes on Phosphorus and Bacterial Community Structure in Sediments

Juanjuan Wang,Tianyang Que,Xuliang Zhuang,Tsing Bohu,Siwen Zhang,Anna H Kaksonen,Xiaoqing Qian

doi:10.3390/su13179833

Abstract

Remediating water eutrophication is critical for maintaining healthy and sustainable development of lakes. The aim of this study was to explore the seasonal variation in phosphorus (P) speciation and bacterial community structure in sediments of Qin Lake (Taizhou, Jiangsu Province, China) associated with the growth of submerged macrophyte Vallisneria natans. The differences in sediment bacterial diversity and community structure between V. natans growing and control areas were analyzed over a period of one year. The results showed that V. natans growth reduced the total P and organic matter contents of the sediments and increased the bioavailable iron (Fe) and Fe-bound P contents. The α-diversity of sediment bacteria was significantly higher in the presence of V. natans than in the controls during the vigorous plant growth stage. In the presence of V. natans, there was a higher relative abundance of Proteobacteria and lower relative abundances of Chloroflexi and Acidobacteria. The Fe(II) content in the sediment had a larger influence on the spatial distribution of bacterial communities than sediment Fe-bound P, organic matter, and Fe(II) contents. V. natans growth could reshape sediment bacterial community structure in the shallow lake, which, in turn, enhanced P immobilization in the sediments and thereby improved the water quality.

Highlights

Nutrient overloading is a major cause of water eutrophication and water quality decline in shallow lakes
It was found that the growth of V. natans reduced the total P content and increased the percentage of Fe-bound P in the sediments
The NMDS analysis performed in this study revealed that the bacterial community composition of the sediments was markedly different between the Qin Lake areas with and without V. natans

Summary

Introduction

Nutrient overloading is a major cause of water eutrophication and water quality decline in shallow lakes. Eutrophication is always followed by rapid growth of phytoplankton and other microorganisms, which will deteriorate water quality and subsequently destroy the lake ecosystem. Eutrophication control is essential for maintaining healthy and sustainable development of lakes. Phosphorus (P) is a vital and limiting nutrient, and P concentrations can serve as an indicator of lake water quality [2]. Endogenous P in lakes mainly comes from the accumulation and recycling of P in sediments, which play an essential role in the P cycling of shallow lakes [3]. An excess of endogenous P severely affects lake water quality in the Sustainability 2021, 13, 9833.

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