Trade-offs between microbiome diversity and productivity in a stratified microbial mat

Abstract

Productivity is a major determinant of ecosystem diversity. Microbial ecosystems are the most diverse on the planet yet very few relationships between diversity and productivity have been reported as compared with macro-ecological studies. Here we evaluated the spatial relationships of productivity and microbiome diversity in a laboratory-cultivated photosynthetic mat. The goal was to determine how spatial diversification of microorganisms drives localized carbon and energy acquisition rates. We measured sub-millimeter depth profiles of net primary productivity and gross oxygenic photosynthesis in the context of the localized microenvironment and community structure, and observed negative correlations between species richness and productivity within the energyreplete, photic zone. Variations between localized community structures were associated with distinct taxa as well as environmental profiles describing a continuum of biological niches. Spatial regions in the photic zone corresponding to high primary productivity and photosynthesis rates had relatively low-species richness and high evenness. Hence, this system exhibited negative speciesproductivity and species-energy relationships. These negative relationships may be indicative of stratified, light-driven microbial ecosystems that are able to be the most productive with a relatively smaller, even distributions of species that specialize within photic zones.

Forfeiting the founder effect: turnover defines biofilm community succession

“…Homogenous selection appeared to act more strongly on the bacterial components of the community in later stages of succession when the biofilm community had presumably sampled the majority of taxa from the nearby environment. We note that founder speciesas well as other abundant taxa identified in this studywere identical or highly related to some of the most common taxa reported by previous studies performed in the Hot Lake ecosystem in different years (Bernstein et al 2017a, Lindemann et al 2013, Mobberley et al 2017, Moran et al 2014. This indicates that, although the phyla are shown to decrease during this 79-day succession period, these taxa are likely stable and persistent within the ecosystem.…”

“…The images also qualitatively show uptake of 13 C-label increases with the arrival of frequent diatom-like cell structures. While it is not surprising that microalgae act as primary producers, the finding does adds context to this unique hypersaline ecosystem where previous reports have mostly attributed primary production by cyanobacteria (Bernstein et al 2017a, Lindemann et al 2013, Moran et al 2014; but see (Bernstein et al 2017b). The importance of microalgae to the ecosystem is also supported by our identification of founder species, including photosynthetic eukaryotes (Charophyta or Pseudonitzchia) make up at least 40% of 18S OTUs in any given sample.…”

“…The microbial ecosystem was chosen because of a priori knowledge of seasonal community development presented in a previous study that ascertained a distinct mat-development period during summer months (June-August) (Lindemann et al 2013). The microbiome characterized from the mat during this growth period remained remarkably similar, in terms of members and relative abundance of taxa, across multiple related studies (Bernstein et al 2017a, Bernstein et al 2017b, Mobberley et al 2017, Moran et al 2014. Our first goal was to determine the structure and function (autotrophy and diazotrophy) of the community from the colonization period through to the season's typical maturation period.…”

Energetic and Environmental Constraints on the Community Structure of Benthic Microbial Mats in Lake Fryxell, Antarctica

“…These results are therefore consistent with PAR structuring communities largely by influencing the distribution of photoautotrophs. This trend of cyanobacteria in top layers and proteobacteria in underlying layers is found in other microbial mat ecosystems (Kunin et al 2008;Harris et al 2013;Bernstein et al 2017;Maier et al 2018) , raising the possibility that alpha diversity in microbial ecosystems is generally more dependent on the distribution of net primary producers than heterotrophs.…”

“…Species-energy theory is likely applicable to microbial ecosystems based on recent experimental work investigating the effects of increased carbon substrate availability on community composition and diversity in a groundwater system (Zhou et al 2014) . Other laboratory and field studies also suggest that microbial diversity increases with energy availability (Bernstein et al 2017) and [O 2 ] (Spietz et al 2015) . However, the actual energy available to a community is a complex function of both the biogeochemistry of the environment ( e.g.…”