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Effects of disturbance intensity and frequency on bacterial community composition and function.

Berga M, Székely AJ, Langenheder S - PLoS ONE (2012)

Bottom Line: Increases in disturbance strength resulted in gradually stronger changes in bacterial community composition and functions.In the disturbance frequency experiment, effects on the different functions were more consistent and recovery was not observed.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.

View Article: PubMed Central - PubMed

Affiliation: Department of Ecology and Genetics/Limnology, Uppsala University, Uppsala, Sweden. merce.berga@ebc.uu.se

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.

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Changes in the average slope of significant substrate guilds in the intensity experiment (Experiment 2).Values plotted are the mean values ± standard deviation, after the disturbance (A–D) and at the end of the experiment (E–G). Mean values of controls are represented as dashed lines (- -) and standard deviations as dotted lines (···). Tukey's homogenous groups are represented by a, b and c.
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pone-0036959-g006: Changes in the average slope of significant substrate guilds in the intensity experiment (Experiment 2).Values plotted are the mean values ± standard deviation, after the disturbance (A–D) and at the end of the experiment (E–G). Mean values of controls are represented as dashed lines (- -) and standard deviations as dotted lines (···). Tukey's homogenous groups are represented by a, b and c.

Mentions: In experiment 2 amino acids and carboxylic acids were the guilds that contained significant substrates directly after the disturbance. The average slope of amino acids differed between treatments (F: 4.899, p<0.05) being highest at the highest frequency (Fig. 6A). The slope of carboxylic acids was significantly increased by applying a disturbance, since all the levels of disturbance frequency showed higher slopes than the control (F: 6.861, p≤0.01; Fig. 6B). At the end the average slope of carbohydrates, carboxylic acids and the polymers differed significantly between treatments (Fcarbohydrates: 11.308, p<0.01; Fcarboxylic acids: 4.134, p<0.05 and Fpolymers: 5.587, p<0.05), showing an increase with increasing frequency, with exception of the carboxylic acids that peaked in the 2x treatment and had in general rather low rates compared to the control (Fig. 6C–E).


Effects of disturbance intensity and frequency on bacterial community composition and function.

Berga M, Székely AJ, Langenheder S - PLoS ONE (2012)

Changes in the average slope of significant substrate guilds in the intensity experiment (Experiment 2).Values plotted are the mean values ± standard deviation, after the disturbance (A–D) and at the end of the experiment (E–G). Mean values of controls are represented as dashed lines (- -) and standard deviations as dotted lines (···). Tukey's homogenous groups are represented by a, b and c.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3351442&req=5

pone-0036959-g006: Changes in the average slope of significant substrate guilds in the intensity experiment (Experiment 2).Values plotted are the mean values ± standard deviation, after the disturbance (A–D) and at the end of the experiment (E–G). Mean values of controls are represented as dashed lines (- -) and standard deviations as dotted lines (···). Tukey's homogenous groups are represented by a, b and c.
Mentions: In experiment 2 amino acids and carboxylic acids were the guilds that contained significant substrates directly after the disturbance. The average slope of amino acids differed between treatments (F: 4.899, p<0.05) being highest at the highest frequency (Fig. 6A). The slope of carboxylic acids was significantly increased by applying a disturbance, since all the levels of disturbance frequency showed higher slopes than the control (F: 6.861, p≤0.01; Fig. 6B). At the end the average slope of carbohydrates, carboxylic acids and the polymers differed significantly between treatments (Fcarbohydrates: 11.308, p<0.01; Fcarboxylic acids: 4.134, p<0.05 and Fpolymers: 5.587, p<0.05), showing an increase with increasing frequency, with exception of the carboxylic acids that peaked in the 2x treatment and had in general rather low rates compared to the control (Fig. 6C–E).

Bottom Line: Increases in disturbance strength resulted in gradually stronger changes in bacterial community composition and functions.In the disturbance frequency experiment, effects on the different functions were more consistent and recovery was not observed.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.

View Article: PubMed Central - PubMed

Affiliation: Department of Ecology and Genetics/Limnology, Uppsala University, Uppsala, Sweden. merce.berga@ebc.uu.se

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.

Show MeSH