Mesocosm Experiments Reveal Global Warming Accelerates Macrophytes Litter Decomposition and Alters Decomposition-Related Bacteria Community Structure

Meng Pan,Tao Wang,Min Zhang,Penglan Shi,Bowen Hu,Jun Xu

doi:10.3390/w13141940

Abstract

Global climate change scenarios predict that lake water temperatures will increase up to 4 °C and extreme weather events, such as heat waves and large temperature fluctuations, will occur more frequently. Such changes may result in the increase of aquatic litter decomposition and on shifts in diversity and structure of bacteria communities in this period. We designed a two-month mesocosm experiment to explore how constant (+4 °C than ambient temperature) and variable (randomly +0~8 °C than ambient temperature) warming treatment will affect the submerged macrophyte litter decomposition process. Our data suggests that warming treatments may accelerate the decomposition of submerged macrophyte litter in shallow lake ecosystems, and increase the diversity of decomposition-related bacteria with community composition changed the relative abundance of Proteobacteria, especially members of Alphaproteobacteria increased while that of Firmicutes (mainly Bacillus) decreased.

Highlights

The earth is experiencing rapid climatic changes, the mean global surface temperature will rise by 2.6 ◦C to 4.8 ◦C by the end of this century under the IPCC RCP8.5 stimulation scenario, resulting in extreme weather events at higher frequency [1]
Our first hypothesis was confirmed, constant and variable warming stimulate the decomposition of aquatic macrophyte litter, especially in the early stage
Our previous research has shown that global warming will increase the growth and senescence of P. crispus, which will lead lakes to earlier turbid-stage in summer [7]

Summary

Introduction

The earth is experiencing rapid climatic changes, the mean global surface temperature will rise by 2.6 ◦C to 4.8 ◦C by the end of this century under the IPCC RCP8.5 stimulation scenario, resulting in extreme weather events at higher frequency [1]. The possibly consequent heatwaves and large temperature fluctuations will threaten global biodiversity and modify ecosystem functions, whose collapses will lead to feedbacks in global warming [2]. Aquatic macrophyte is an essential element of aquatic food web and plays an vital role in maintaining the function and biodiversity of lake ecosystem [3]. Recent research showed that warming accelerated the growth and senescence of P. crispus, which shortened the time for phase shifting of the lake from a clear to turbid state [7]; the decomposition of its residue in water may further cause secondary pollution [8]. Studies in the litter decomposition process are critical for understanding the states of lacustrine ecosystems under climate change

Methods

Results

Conclusion