Effects of Disturbance Intensity and Frequency on Bacterial Community Composition and Function

Mercè Berga,Silke Langenheder,Anna J Székely,Caroline P Slomp

doi:10.1371/journal.pone.0036959

Mercè Berga, Silke Langenheder + Show 2 more

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https://doi.org/10.1371/journal.pone.0036959

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Journal: PLoS ONE	Publication Date: May 14, 2012
Citations: 168	License type: CC BY 4.0

Affiliation: Uppsala University

Abstract

Disturbances influence community structure and ecosystem functioning. Bacteria are key players in ecosystems and it is therefore crucial to understand the effect of disturbances on bacterial communities and how they respond to them, both compositionally and functionally. The main aim of this study was to test the effect of differences in disturbance strength on bacterial communities. For this, we implemented two independent short-term experiments with dialysis bags containing natural bacterial communities, which were transplanted between ambient and ‘disturbed’ incubation tanks, manipulating either the intensity or the frequency of a salinity disturbance. We followed changes in community composition by terminal restriction fragment analysis (T-RFLP) and measured various community functions (bacterial production, carbon substrate utilization profiles and rates) directly after and after a short period of recovery under ambient conditions. Increases in disturbance strength resulted in gradually stronger changes in bacterial community composition and functions. In the disturbance intensity experiment, the sensitivity to the disturbance and the ability of recovery differed between different functions. In the disturbance frequency experiment, effects on the different functions were more consistent and recovery was not observed. Moreover, in case of the intensity experiment, there was also a time lag in the responses of community composition and functions, with functional responses being faster than compositional ones. To summarize, our study shows that disturbance strength has the potential to change the functional performance and composition of bacterial communities. It further highlights that the overall effects, rates of recovery and the degree of congruence in the response patterns of community composition and functioning along disturbance gradients depend on the type of function and the character of the disturbance.

Highlights

Disturbances are discrete events in time that cause changes in resources or in the physical environment and, influence community structure
Active bacterial community composition did not show significant changes with increasing disturbance intensity (Experiment 1) directly after the disturbance (ANOSIM: R: 0.2, p.0.05), even though the high salinity treatments were clearly separated from the control and the low salinity treatments (Fig. 1A)
It has been shown that bacterial communities are often affected by disturbances [17,37,38,39], but it is likely that these response patterns are influenced by the strength of a disturbance, such as its intensity and frequency

Summary

Introduction

Disturbances are discrete events in time that cause changes in resources or in the physical environment and, influence community structure. They are known to lead to changes in species richness [1,2] and to impair ecosystem functioning [3,4]. With the main focus on microbial community composition, a community can be resistant, i.e., withstand disturbances without any changes in composition [8]. It can be resilient, i.e.; recover from a disturbance-induced change and regain the original state [9]. Some studies have suggested that this relationship might depend on the level of the studied function [15,16]

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