Taxonomic and functional dissimilarities of soil bacterial communities are more related to environmental dissimilarity than geographic distance

The processes governing soil bacteria biogeography are still not fully understood. It remains unknown how the importance of environmental filtering and dispersal differs between bacterial taxonomic and functional biogeography, and whether their importance is scale-dependent. We sampled soils at 195 plots across the Tibet plateau, with distances among plots ranging from 20 m to 1 550 km. Taxonomic composition of bacterial community was characterized by 16S amplicon sequencing, and functional community composition by qPCR targeting 9 functional groups involved in N dynamics. Twelve climatic and soil characteristics were also measured. Both taxonomic and functional dissimilarities were more related to environmental dissimilarity than geographic distance. Taxonomic dissimilarity was mostly explained by soil pH and organic matter, while functional dissimilarity was mostly linked to moisture, temperature and N, P and C availabilities. The roles of environmental filtering and dispersal were, however, scale-dependent and varied between taxonomic and functional dissimilarities, with distance affecting taxonomic dissimilarity over short distances (<~300 km) and functional dissimilarity over long distances (>~600 km). The importance of different environmental predictors varied across scales more for functional than taxonomic dissimilarity. Our results demonstrate how biodiversity dimension (taxonomic versus functional) and spatial scale strongly influence the conclusions derived from bacterial biogeography studies.

Changes in Ciliate Communities Reveal Modification of Lake Functioning Over the Last Century

Ciliates are unicellular heterotrophic organisms that play a key role in the planktonic and benthic food webs of lakes, and represent a great potential as bioindicator. In this study, we used the top-bottom paleolimnological approach to compare the recent and past (i.e. prior to major anthropogenic impacts) ciliate communities of 48 lakes located along an elevation gradient using metabarcoding techniques applied on sedimentary DNA (sed-DNA). Our results show an overall decline in the β-diversity in recent time, especially in lowland lakes which are more strongly expose to local human pressure. Analyses of the functional groups indicate important restructuration of the trophic food web and changes that are consistent with several well documented environmental changes such as the widespread increase in deep water anoxia, changes in thermal stability and nutrient cycling. Our study demonstrates the potential offered by sed-DNA to uncover information about past ciliate communities on a wide variety of lakes and the potential of using ciliates as valuable indicators, integrating information from the pelagic to the benthic profundal (and littoral) zones. Through trait-based functional community approach, the ciliates provide additional valuable information on ecosystem functioning, thus offering more a holistic view on the long-term changes of aquatic ecosystems.

Water as a Social Generator: Activating social and water security in residential Kilbirnie

<p>Residential streets make up a large proportion of accessible public space while failing to facilitate community activity. These streets carry a relatively low volume of traffic, yet are standard in form. This factor in conjunction with the self-contained nature of houses in residential areas results in a lack of social capital in areas with a large amount of social potential. The suburbs of Kilbirnie on the Rongotai isthmus in Wellington have been selected as the site due to the potential of the streets; in particular due to their width and mono-functionality. The five sites that have been selected have potential far beyond their current use and are going to be used as a design case study to explore pre-emptive disaster design in conjunction with providing social amenities. The streetscape within the identified site is excessively wide with a large amount of on-street parking. This thesis argues that this extra, underutilised space has the potential to be adapted into an aesthetically pleasing, functional community amenity. The designs will break up the monotonous nature of the residential streets and create a hub for surrounding residents through the exploration of programme and form. The introduction of water storage infrastructure as a programme will pre-emptively service the suburb in the event of a disaster. The likelihood of the potable water supply being severed to both the Wellington CBD and to the Rongotai Isthmus and Miramar Peninsula is high due to the location of the service pipes in relation to the dominant fault lines in the suburb. The study proposes exploring programmes which challenge people’s perception of ownership of public land and amenity. Re-allocating and prioritising parts of street space to provide amenity for surrounding residents has the potential to initiate a change from monotone, mundane functionality into a hub of social activity, community building and disaster resilience. The design methodology uses precedents which employ techniques that can be used to challenge the norm and provide a design outcome which creates engaging residential spaces.</p>

Water as a Social Generator: Activating social and water security in residential Kilbirnie

<p>Residential streets make up a large proportion of accessible public space while failing to facilitate community activity. These streets carry a relatively low volume of traffic, yet are standard in form. This factor in conjunction with the self-contained nature of houses in residential areas results in a lack of social capital in areas with a large amount of social potential. The suburbs of Kilbirnie on the Rongotai isthmus in Wellington have been selected as the site due to the potential of the streets; in particular due to their width and mono-functionality. The five sites that have been selected have potential far beyond their current use and are going to be used as a design case study to explore pre-emptive disaster design in conjunction with providing social amenities. The streetscape within the identified site is excessively wide with a large amount of on-street parking. This thesis argues that this extra, underutilised space has the potential to be adapted into an aesthetically pleasing, functional community amenity. The designs will break up the monotonous nature of the residential streets and create a hub for surrounding residents through the exploration of programme and form. The introduction of water storage infrastructure as a programme will pre-emptively service the suburb in the event of a disaster. The likelihood of the potable water supply being severed to both the Wellington CBD and to the Rongotai Isthmus and Miramar Peninsula is high due to the location of the service pipes in relation to the dominant fault lines in the suburb. The study proposes exploring programmes which challenge people’s perception of ownership of public land and amenity. Re-allocating and prioritising parts of street space to provide amenity for surrounding residents has the potential to initiate a change from monotone, mundane functionality into a hub of social activity, community building and disaster resilience. The design methodology uses precedents which employ techniques that can be used to challenge the norm and provide a design outcome which creates engaging residential spaces.</p>

Environmental Filtering Influences Functional Community Assembly of Epibenthic Communities

Community assembly theory states that species assemble non-randomly as a result of dispersal limitation, biotic interactions, and environmental filtering. Strong environmental filtering likely leads to local assemblages that are similar in their functional trait composition (high trait convergence) while functional trait composition will be less similar (high trait divergence) under weaker environmental filters. We used two Arctic shelves as case studies to examine the relationship between functional community assembly and environmental filtering using the geographically close but functionally and environmentally dissimilar epibenthic communities on the Chukchi and Beaufort Sea shelves. Environmental drivers were compared to functional trait composition and to trait convergence within each shelf. Functional composition in the Chukchi Sea was more strongly correlated with environmental gradients compared to the Beaufort Sea, as shown by a combination of RLQ and fourth corner analyses and community-weighted mean redundancy analyses. In the Chukchi Sea, epibenthic functional composition, particularly body size, reproductive strategy, and several behavioral traits (i.e., feeding habit, living habit, movement), was most strongly related to gradients in percent mud and temperature while body size and larval development were most strongly related to a depth gradient in the Beaufort Sea. The stronger environmental filter in the Chukchi Sea also supported the hypothesized relationship with higher trait convergence, although this relationship was only evident at one end of the observed environmental gradient. Strong environmental filtering generally provides a challenge for biota and can be a barrier for invading species, a growing concern for the Chukchi Sea shelf communities under warming conditions. Weaker environmental filtering, such as on the Beaufort Sea shelf, generally leads to communities that are more structured by biotic interactions, and possibly representing partitioning of resources among species from intermediate disturbance levels. We provide evidence that environmental filtering can structure functional community composition, providing a baseline of how community function could be affected by stressors such as changes in environmental conditions or increased anthropogenic disturbance.

Molecular analyses of the diversity and function of the family 1 β-glucosidase-producing microbial community in compost

The diversity and transcription efficiency of GH1 family β-glucosidase genes were investigated in natural and inoculated composts using a DNA clone library and real-time qPCR. Compositional differences were observed in the functional community between both composting processes. Proteobacteria, Actinobacteria, Firmicutes, and Chloroflexi were the dominant phyla. Twenty representative β-glucosidase genes were quantitatively analyzed from DNA and RNA pools. Principal component analysis and Pearson’s correlation analysis showed that cellulose degradation is correlated with the composition and succession of functional microbial communities, and this correlation was mainly observed in Proteobacteria and Actinobacteria. Compared with inoculated compost, the functional microbial communities in natural compost with a low diversity index exhibited weak buffering capacity for function in response to environmental changes. This may explain the consistency and dysfunction of cellulose degradation and transcriptional regulation by dominant β-glucosidase genes. Except for the β-glucosidase genes encoding constitutive enzymes, individual β-glucosidase genes responded to environmental changes more drastically than the group β-glucosidase genes. Correlation results suggested that β-glucosidase genes belonging to Micrococcales played an important role in the regulation of intracellular β-glucosidase. These results indicated that the responses of functional microorganisms were different during both composting processes, and were reflected at both the individual and group levels.