Stable Seasonal and Annual Alpha Diversity of Benthic Diatom Communities Despite Changing Community Composition

Understanding microbial community dynamics in the alpine cryosphere is an important step toward assessing climate change impacts on these fragile ecosystems and meltwater-fed environments downstream. In this study, we analyzed microbial community composition, variation in community alpha and beta diversity, and the number of prokaryotic cells and virus-like particles (VLP) in seasonal snowpack from two consecutive years at three high altitude mountain summits along a longitudinal transect across the European Alps. Numbers of prokaryotic cells and VLP both ranged around 104 and 105 per mL of snow meltwater on average, with variation generally within one order of magnitude between sites and years. VLP-to-prokaryotic cell ratios spanned two orders of magnitude, with median values close to 1, and little variation between sites and years in the majority of cases. Estimates of microbial community alpha diversity inferred from Hill numbers revealed low contributions of common and abundant microbial taxa to the total taxon richness, and thus low community evenness. Similar to prokaryotic cell and VLP numbers, differences in alpha diversity between years and sites were generally relatively modest. In contrast, community composition displayed strong variation between sites and especially between years. Analyses of taxonomic and phylogenetic community composition showed that differences between sites within years were mainly characterized by changes in abundances of microbial taxa from similar phylogenetic clades, whereas shifts between years were due to significant phylogenetic turnover. Our findings on the spatiotemporal dynamics and magnitude of variation of microbial abundances, community diversity, and composition in surface snow may help define baseline levels to assess future impacts of climate change on the alpine cryosphere.

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Ecological memory mitigates negative impacts of disturbance on biomass production in benthic diatom metacommunities

10.1101/2020.07.23.217448 ◽

2020 ◽

Author(s):

Friederike G. Engel ◽

Birte Matthiessen ◽

Rosyta Andriana ◽

Britas Klemens Eriksson

Keyword(s):

Benthic Diatom ◽

Species Pool ◽

Intertidal Flat ◽

Ecological Communities ◽

Response Diversity ◽

Extreme Heat Events ◽

Ecological Memory ◽

Mechanical Disturbance ◽

Diatom Communities ◽

Negative Impacts

AbstractDisturbance events to coastal habitats such as extreme heat events, storms, or floods have increased in magnitude and frequency in recent years due to anthropogenic climate change and the destruction of habitats. These events constitute a major threat to many ecological communities and global biodiversity. Disturbance history influences ecosystem response to novel disturbances such that communities that have previously been exposed to disturbances should be more resilient to new disturbances compared to previously sheltered communities. This principle is defined as ecological memory. Resilience should also increase with access to a larger species pool, because a larger species pool increases species and response diversity of a community. One possibility of increasing the local species pool is connectivity via adequate dispersal between habitat patches with different species compositions in metacommunities. In a laboratory experiment, we exposed benthic diatom communities of different origin to a mechanical disturbance, simulated dispersal in half of the communities, and measured their chlorophyll a concentration over time. The local diatom communities originated from different locations on an intertidal flat that varied in hydrodynamic exposure history. Hydrodynamic exposure disturbs the sediment, and thereby determines sediment properties and the composition of intertidal diatom communities. In the experiment, disturbance negatively affected chlorophyll a concentration across all treatments. However, the response to disturbance depended on the ecological memory of the communities; the more exposed areas the communities originated from, the less negative was the effect of the mechanical disturbance. Interestingly, dispersal did not mitigate the negative impacts of disturbance in any of the communities. Our results highlight the importance of ecological memory for ecosystem functioning and demonstrate the limitations of patch connectivity to alleviate the impacts of disturbance events in metacommunities.

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Soil microbes and oxygen influence the changes in bacterial community composition during swine carcass decomposition

10.21203/rs.3.rs-211559/v1 ◽

2021 ◽

Author(s):

Michelle Miguel ◽

Seon Ho Kim ◽

Sang Suk Lee ◽

Yong Il Cho

Keyword(s):

Bacterial Community ◽

16S Rrna ◽

Community Composition ◽

Soil Microbes ◽

Close Association ◽

Bacterial Community Composition ◽

Alpha Diversity ◽

Decomposition Process ◽

Metagenomic Sequencing ◽

Unsterilized Soil

Abstract Background Carcass decomposition is influenced by various factors such as temperature, humidity, microorganisms, invertebrates, and scavengers. Soil microbes play a significant role in the decomposition process. In this study, we investigated the changes in the bacterial community during carcass decomposition in soil with an intact microbial community and soil which was sterilized decomposed with and without oxygen access using 16s rRNA metagenomic sequencing. Results Based on the 16S rRNA metagenomic sequencing, a total of 988 operational taxonomic units (OTUs) representing 16 phyla and 533 genera were detected. The bacterial diversity varied across the based on the alpha diversity indices. The bacterial composition in the unsterilized soil – aerobic condition (U_A) and unsterilized soil – anaerobic condition (U_An) set-ups have higher alpha diversity than the other burial set-ups. Beta diversity analysis revealed a close association in the samples according to the burial type and decomposition day. Firmicutes was the dominant phylum across all samples regardless of the burial type and decomposition day. The bacterial community composition changed throughout the decomposition process in all burial set-up. Meanwhile, the genus Bacillus dominated the bacterial community towards the end of decomposition period. Conclusions Our results showed that bacterial community composition changed during carcass decomposition and was affected by the soil and oxygen access, with microorganisms belonging to phylum Firmicutes dominating the community.

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Benthic diatom communities in boreal streams: community structure in relation to environmental and spatial gradients

Ecography ◽

10.1111/j.0906-7590.2004.03749.x ◽

2004 ◽

Vol 27 (3) ◽

pp. 330-342 ◽

Cited By ~ 136

Author(s):

Janne Soininen ◽

Riku Paavola ◽

Timo Muotka

Keyword(s):

Community Structure ◽

Benthic Diatom ◽

Spatial Gradients ◽

Boreal Streams ◽

Diatom Communities

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Assessing anthropogenic pressures on streams: A random forest approach based on benthic diatom communities

The Science of The Total Environment ◽

10.1016/j.scitotenv.2017.02.096 ◽

2017 ◽

Vol 586 ◽

pp. 1101-1112 ◽

Cited By ~ 19

Author(s):

Floriane Larras ◽

Romain Coulaud ◽

Edwige Gautreau ◽

Elise Billoir ◽

Juliette Rosebery ◽

...

Keyword(s):

Random Forest ◽

Benthic Diatom ◽

Anthropogenic Pressures ◽

Diatom Communities

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PSI-10 Establishing a foundation to harvest the potential of the microbiome in poultry production

Journal of Animal Science ◽

10.1093/jas/skz258.594 ◽

2019 ◽

Vol 97 (Supplement_3) ◽

pp. 293-294

Author(s):

Camila S Marcolla ◽

Benjamin Willing

Keyword(s):

Microbial Community ◽

Gut Microbiota ◽

Community Composition ◽

Relative Abundance ◽

Microbial Community Composition ◽

Alpha Diversity ◽

Poultry Production ◽

Microbiota Composition ◽

Microbial Composition ◽

The Impact

Abstract This study aimed to characterize poultry microbiota composition in commercial farms using 16S rRNA sequencing. Animals raised in sanitized environments have lower survival rates when facing pathogenic challenges compared to animals naturally exposed to commensal organisms. We hypothesized that intensive rearing practices inadvertently impair chicken exposure to microbes and the establishment of a balanced gut microbiota. We compared gut microbiota composition of broilers (n = 78) and layers (n = 20) from different systems, including commercial intensive farms with and without in-feed antibiotics, organic free-range farms, backyard-raised chickens and chickens in an experimental farm. Microbial community composition of conventionally raised broilers was significantly different from antibiotic-free broilers (P = 0.012), from broilers raised outdoors (P = 0.048) and in an experimental farm (P = 0.006) (Fig1). Significant community composition differences were observed between antibiotic-fed and antibiotic-free chickens (Fig2). Antibiotic-free chickens presented higher alpha-diversity, higher relative abundance of Deferribacteres, Fusobacteria, Bacteroidetes and Actinobacteria, and lower relative abundance of Firmicutes, Clostridiales and Enterobacteriales than antibiotic-fed chickens (P < 0.001) (Fig3). Microbial community composition significantly changed as birds aged. In experimental farm, microbial community composition was significant different for 7, 21 and 35 day old broilers (P < 0.001), and alpha diversity increased from 7 to 21d (P < 0.024), but not from 21 to 35d; whereas, in organic systems, increases in alpha-diversity were observed from 7d to 21d, and from 21d to 35d (P < 0.05). Broilers and layers raised together showed no differences in microbiota composition and alpha diversity (P > 0.8). It is concluded that production practices consistently impact microbial composition, and that antibiotics significantly reduces microbial diversity. We are now exploring the impact of differential colonization in a controlled setting, to determine the impact of the microbes associated with extensively raised chickens. This study will support future research and the development of methods to isolate and introduce beneficial microbes to commercial systems.

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