uu.seUppsala University Publications
Change search
Link to record
Permanent link

Direct link
BETA
Berga, Mercé
Alternative names
Publications (9 of 9) Show all publications
Comte, J., Berga, M., Severin, I., Logue, J. B. & Lindström, E. S. (2017). Contribution of different bacterial dispersal sources to lakes: Population and community effects in different seasons. Environmental Microbiology, 19(6), 2391-2404
Open this publication in new window or tab >>Contribution of different bacterial dispersal sources to lakes: Population and community effects in different seasons
Show others...
2017 (English)In: Environmental Microbiology, ISSN 1462-2912, E-ISSN 1462-2920, Vol. 19, no 6, p. 2391-2404Article in journal (Refereed) Published
Abstract [en]

The diversity and composition of lake bacterial communities are driven by the interplay between local contemporary environmental conditions and dispersal of cells from the surroundings, i.e. the metacommunity. Still, a conceptual understanding ofthe relative importance of the two types of factors is lacking. For instance, it is unknown which sources ofdispersal are most important and under which circumstances. Here, we investigated the seasonal variation in the importance of dispersal from different sources (mixing, precipitation, surface runoff and sediment resuspension) for lake bacterioplankton community and population dynamics. For that purpose, two small forest lakes and their dispersal sources were sampled over a period of 10 months.The influence of dispersal on communities and populations was determined by 454 sequencing of the 16S rRNA gene and Source Tracker analysis. On the community level direct effects of dispersal were questionable from all sources. Instead we found that the community of the preceding sampling occasion, representing growth of resident bacteria, was of great importance. On the population level, however, dispersal of individual taxa from the inlet could be occasionally important even under low water flow. The effect of sediment resuspension and precipitation appeared small.

National Category
Oceanography, Hydrology and Water Resources
Identifiers
urn:nbn:se:uu:diva-323624 (URN)10.1111/1462-2920.13749 (DOI)000404007700024 ()28401636 (PubMedID)
Funder
Swedish Research Council, 2009-5172Wenner-Gren FoundationsCarl Tryggers foundation Knut and Alice Wallenberg FoundationScience for Life Laboratory - a national resource center for high-throughput molecular bioscienceSwedish National Infrastructure for Computing (SNIC), b2010008
Available from: 2017-06-08 Created: 2017-06-08 Last updated: 2018-01-13Bibliographically approved
Berga, M., Zha, Y., Székely, A. J. & Langenheder, S. (2017). Functional and Compositional Stability of Bacterial Metacommunities in Response to Salinity Changes. Frontiers in Microbiology, 8, Article ID 948.
Open this publication in new window or tab >>Functional and Compositional Stability of Bacterial Metacommunities in Response to Salinity Changes
2017 (English)In: Frontiers in Microbiology, ISSN 1664-302X, E-ISSN 1664-302X, Vol. 8, article id 948Article in journal (Refereed) Published
Abstract [en]

Disturbances and environmental change are important factors determining the diversity,composition, and functioning of communities. However, knowledge about how naturalbacterial communities are affected by such perturbations is still sparse. We performeda whole ecosystem manipulation experiment with freshwater rock pools where weapplied salinity disturbances of different intensities. The aim was to test how thecompositional and functional resistance and resilience of bacterial communities,alpha- and beta-diversity and the relative importance of stochastic and deterministiccommunity assembly processes changed along a disturbance intensity gradient.We found that bacterial communities were functionally resistant to all salinity levels (3, 6, and 12 psu) and compositionally resistant to a salinity increase to 3 psu andresilient to increases of 6 and 12 psu. Increasing salinities had no effect on local richnessand evenness, beta-diversity and the proportion of deterministically vs. stochasticallyassembled communities. Our results show a high functional and compositional stabilityof bacterial communities to salinity changes of different intensities both at localand regional scales, which possibly reflects long-term adaptation to environmentalconditions in the study system.

Keywords
adaptation, bacteria, community assembly, community composition, community function, disturbances, resistance, salinity
National Category
Oceanography, Hydrology and Water Resources Microbiology
Identifiers
urn:nbn:se:uu:diva-323601 (URN)10.3389/fmicb.2017.00948 (DOI)000402854900001 ()28642735 (PubMedID)
Funder
Swedish Research Council Formas
Available from: 2017-06-08 Created: 2017-06-08 Last updated: 2018-01-13Bibliographically approved
Berga, M., Östman, Ö., Lindström, E. S. & Langenheder, S. (2015). Combined effects of zooplankton grazing and dispersal on the diversity and assembly mechanisms of bacterial metacommunities. Environmental Microbiology, 17(7), 2275-2287
Open this publication in new window or tab >>Combined effects of zooplankton grazing and dispersal on the diversity and assembly mechanisms of bacterial metacommunities
2015 (English)In: Environmental Microbiology, ISSN 1462-2912, E-ISSN 1462-2920, Vol. 17, no 7, p. 2275-2287Article in journal (Refereed) Published
Abstract [en]

Effects of dispersal and the presence of predators on diversity, assembly and functioning of bacterial communities are well studied in isolation. In reality, however, dispersal and trophic interactions act simultaneously and can therefore have combined effects, which are poorly investigated. We performed an experiment with aquatic metacommunities consisting of three environmentally different patches and manipulated dispersal rates among them as well as the presence or absence of the keystone species Daphnia magnaDaphnia magnareduced both local and regional diversity, whereas dispersal increased local diversity but decreased beta-diversity having no net effect on regional diversity. Dispersal modified the assembly mechanisms of bacterial communities by increasing the degree of determinism. Additionally, the combination of the D. magna and dispersal increased the importance of deterministic processes, presumably because predator-tolerant taxa were spread in the metacommunity via dispersal. Moreover, the presence of D. magna affected community composition, increased community respiration rates but did not affect bacterial production or abundance, whereas dispersal slightly increased bacterial production. In conclusion, our study suggests that predation by a keystone species such as D. magna and dispersal additively influence bacterial diversity, assembly processes and ecosystem functioning.

National Category
Biological Sciences
Identifiers
urn:nbn:se:uu:diva-252430 (URN)10.1111/1462-2920.12688 (DOI)000358114300010 ()25367396 (PubMedID)
Funder
Swedish Research Council FormasThe Royal Swedish Academy of Sciences
Note

Funding: Bioinformatics Infrastructure for Life Sciences (BILS), Marie Curie Reintegration Grant, Olsson Borgh foundation 

Available from: 2015-05-07 Created: 2015-05-07 Last updated: 2017-12-04Bibliographically approved
Andersson, M., Berga, M., Lindström, E. S. & Langenheder, S. (2014). The spatial structure of bacterial communities is influenced by historical environmental conditions. Ecology, 95(5), 1134-1140
Open this publication in new window or tab >>The spatial structure of bacterial communities is influenced by historical environmental conditions
2014 (English)In: Ecology, ISSN 0012-9658, E-ISSN 1939-9170, Vol. 95, no 5, p. 1134-1140Article in journal (Refereed) Published
Abstract [en]

The spatial structure of ecological communities, including that of bacteria, is often influenced by species sorting by contemporary environmental conditions. Moreover, historical processes, i.e., ecological and evolutionary events that have occurred at some point in the past, such as dispersal limitation, drift, priority effects, or selection by past environmental conditions, can be important, but are generally investigated much less. Here, we conducted a field study using 16 rock pools, where we specifically compared the importance of past vs. contemporary environmental conditions for bacterial community structure by correlating present differences in bacterial community composition among pools to environmental conditions measured on the same day, as well as to those measured 2, 4, 6, and 8 d earlier. The results prove that selection by past environmental conditions exists, since we were able to show that bacterial communities are, to a greater extent, an imprint of past compared to contemporary environmental conditions. We suggest that this is the result of a combination of different mechanisms, including priority effects that cause rapid adaptation to new environmental conditions of taxa that have been initially selected by past environmental conditions, and slower rates of turnover in community composition compared to environmental conditions.

National Category
Ecology Microbiology
Identifiers
urn:nbn:se:uu:diva-207181 (URN)10.1890/13-1300.1 (DOI)000336740500003 ()
Available from: 2013-09-10 Created: 2013-09-10 Last updated: 2017-12-06Bibliographically approved
Berga Quintana, M. (2013). Assembly Mechanisms in Aquatic Bacterial Communities: The Role of Disturbances, Dispersal and History. (Doctoral dissertation). Uppsala: Acta Universitatis Upsaliensis
Open this publication in new window or tab >>Assembly Mechanisms in Aquatic Bacterial Communities: The Role of Disturbances, Dispersal and History
2013 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Environmental conditions, biotic interactions, dispersal and history have been suggested to be important processes influencing the spatial distribution of organisms and thus to affect community assembly. Understanding how these processes influence community assembly is important, particularly because community diversity and composition are suggested to be relevant for ecosystem functioning. Moreover, bacteria are strongly contributing to nutrient and carbon cycle. Bacteria are highly abundant and ubiquitous, and thus it is relevant to study how they are assembled. This thesis aims to gain insight on the role of these processes on aquatic bacterial community assembly, diversity and functioning. The studies included in this thesis involve transplant and microcosm experiments performed in the lab as well as manipulation experiments and field surveys in a natural rock pool systems. Bacterial community composition was addressed by analysis of 16S rRNA gene and community functioning by measuring bacterial production, community respiration and the ability to use different carbon substrates. This thesis highlights that species sorting is a very important assembly mechanism for bacterial communities, but also finds that other processes such as dispersal and history contribute to the patterns observed. Dispersal caused rescuing effects compensating for losses of diversity; at the same time it increased the similarity between communities. Moreover, bacteria have shown a high level of functional plasticity when colonizing a new locality. Interestingly, past environmental conditions explained the structure of bacterial communities better than present-day environmental conditions. Disturbances and biotic interactions are also important in the assembly of communities. Disturbance caused temporary shifts in bacterial function and changes in composition, the magnitude of which depended on the intensity and the frequency of the disturbance. However, natural aquatic bacterial communities showed quite high resilience capacities. Competition can shift the proportion of generalists and specialists species whereas predation or trophic interactions have been found to decrease diversity and to modify the importance of stochasticity. Both caused alterations of community functioning. Finally, this thesis shows that the diversity-functioning relationship is context dependent. Further research should be directed to understanding the intensity and direction of changes in composition and how this affects the functionality of bacterial communities

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2013. p. 56
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 1071
Keywords
diversity, community composition, metacommunity
National Category
Ecology Microbiology
Identifiers
urn:nbn:se:uu:diva-207183 (URN)978-91-554-8749-2 (ISBN)
Public defence
2013-10-25, Friessalen, Evolutionary Biology Centre (EBC), Norbyvägen 18, Uppsala, 10:00 (English)
Opponent
Supervisors
Available from: 2013-10-02 Created: 2013-09-10 Last updated: 2014-01-23
Székely, A. J., Berga, M. & Langenheder, S. (2013). Mechanisms determining the fate of dispersed bacterial communities in new environments. ISME Journal, 7(1), 61-71
Open this publication in new window or tab >>Mechanisms determining the fate of dispersed bacterial communities in new environments
2013 (English)In: ISME Journal, ISSN 1751-7362, Vol. 7, no 1, p. 61-71Article in journal (Refereed) Published
Abstract [en]

Recent work has shown that dispersal has an important role in shaping microbial communities. However, little is known about how dispersed bacteria cope with new environmental conditions and how they compete with local resident communities. To test this, we implemented two full-factorial transplant experiments with bacterial communities originating from two sources (freshwater or saline water), which were incubated, separately or in mixes, under both environmental conditions. Thus, we were able to separately test for the effects of the new environment with and without interactions with local communities. We determined community composition using 454-pyrosequencing of bacterial 16S rRNA to specifically target the active fraction of the communities, and measured several functional parameters. In absence of a local resident community, the net functional response was mainly affected by the environmental conditions, suggesting successful functional adaptation to the new environmental conditions. Community composition was influenced both by the source and the incubation environment, suggesting simultaneous effects of species sorting and functional plasticity. In presence of a local resident community, functional parameters were higher compared with those expected from proportional mixes of the unmixed communities in three out of four cases. This was accompanied by an increase in the relative abundance of generalists, suggesting that competitive interactions among local and immigrant taxa could explain the observed functional overachievement. In summary, our results suggest that environmental filtering, functional plasticity and competition are all important mechanisms influencing the fate of dispersed communities.

National Category
Natural Sciences
Identifiers
urn:nbn:se:uu:diva-192014 (URN)10.1038/ismej.2012.80 (DOI)000313236000006 ()
Available from: 2013-01-24 Created: 2013-01-15 Last updated: 2014-01-23Bibliographically approved
Berga, M., Székely, A. J. & Langenheder, S. (2012). Effects of Disturbance Intensity and Frequency on Bacterial Community Composition and Function. PLoS ONE, 7(5), e36959
Open this publication in new window or tab >>Effects of Disturbance Intensity and Frequency on Bacterial Community Composition and Function
2012 (English)In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 7, no 5, p. e36959-Article in journal (Refereed) Published
Abstract [en]

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.

National Category
Biological Sciences
Identifiers
urn:nbn:se:uu:diva-177625 (URN)10.1371/journal.pone.0036959 (DOI)000305339400046 ()
Available from: 2012-07-18 Created: 2012-07-17 Last updated: 2017-12-07Bibliographically approved
Shade, A., Peter, H., Allison, S. D., Baho, D. L., Berga, M., Bürgmann, H., . . . Handelsman, J. (2012). Fundamentals of microbial community resistance and resilience. Frontiers in Microbiology, 3, 417
Open this publication in new window or tab >>Fundamentals of microbial community resistance and resilience
Show others...
2012 (English)In: Frontiers in Microbiology, ISSN 1664-302X, Vol. 3, p. 417-Article in journal (Refereed) Published
Abstract [en]

Microbial communities are at the heart of all ecosystems, and yet microbial community behavior in disturbed environments remains difficult to measure and predict. Understanding the drivers of microbial community stability, including resistance (insensitivity to disturbance) and resilience (the rate of recovery after disturbance) is important for predicting community response to disturbance. Here, we provide an overview of the concepts of stability that are relevant for microbial communities. First, we highlight insights from ecology that are useful for defining and measuring stability. To determine whether general disturbance responses exist for microbial communities, we next examine representative studies from the literature that investigated community responses to press (long-term) and pulse (short-term) disturbances in a variety of habitats. Then we discuss the biological features of individual microorganisms, of microbial populations, and of microbial communities that may govern overall community stability. We conclude with thoughts about the unique insights that systems perspectives – informed by meta-omics data – may provide about microbial community stability.

Keywords
microbial ecology, disturbance, stability, sensitivity, structure-function, perturbation, community structure, time series
National Category
Ecology
Identifiers
urn:nbn:se:uu:diva-191088 (URN)10.3389/fmicb.2012.00417 (DOI)
Available from: 2013-01-09 Created: 2013-01-09 Last updated: 2013-01-09Bibliographically approved
Langenheder, S., Berga, M., Östman, Ö. & Székely, A. J. (2012). Temporal variation of beta-diversity and assembly mechanisms in a bacterial metacommunity. The ISME Journal, 6(6), 1107-1114
Open this publication in new window or tab >>Temporal variation of beta-diversity and assembly mechanisms in a bacterial metacommunity
2012 (English)In: The ISME Journal, ISSN 1751-7362, E-ISSN 1751-7370, Vol. 6, no 6, p. 1107-1114Article in journal (Refereed) Published
Abstract [en]

The turnover of community composition across space, beta-diversity, is influenced by different assembly mechanisms, which place varying weight on local habitat factors, such as environmental conditions and species interactions, and regional factors such as dispersal and history. Several assembly mechanisms may function simultaneously; however, little is known about how their importance changes over time and why. Here, we implemented a field survey where we sampled a bacterial metacommunity consisting of 17 rock pools located at the Swedish Baltic Sea coast at 11 occasions during 1 year. We determined to which extent communities were structured by different assembly mechanisms using variation partitioning and studied changes in beta-diversity across environmental gradients over time. beta-Diversity was highest at times of high overall productivity and environmental heterogeneity in the metacommunity, at least partly due to species sorting, that is, selection of taxa by the prevailing environmental conditions. In contrast, dispersal-driven assembly mechanisms were primarily detected at times when beta-diversity was relatively low. There were no indications for strong and persistent differences in community composition or beta-diversity between permanent and temporary pools, indicating that the physical disturbance regime is of relatively minor importance. In summary, our study clearly suggests that there are temporal differences in the relative importance of different assembly mechanisms related to abiotic factors and shows that the temporal variability of those factors is important for a more complete understanding of bacterial metacommunity dynamics.

Keywords
metacommunities, bacteria, assembly mechanisms, temporal, beta-diversity, productivity
National Category
Biological Sciences
Identifiers
urn:nbn:se:uu:diva-175601 (URN)10.1038/ismej.2011.177 (DOI)000304047800003 ()
Available from: 2012-06-13 Created: 2012-06-11 Last updated: 2017-12-07Bibliographically approved
Organisations

Search in DiVA

Show all publications