Reducing the arbitrary: fuzzy detection of microbial ecotones and ecosystems – focus on the pelagic environment

Author(s)
Antoine Bagnaro, Federico Baltar, Gretchen Brownstein, William G. Lee, Sergio E. Morales, Daniel W. Pritchard, Christopher D. Hepburn
Abstract

Background

One of the central objectives of microbial ecology is to study the distribution of microbial communities and their association with their environments. Biogeographical studies have partitioned the oceans into provinces and regions, but the identification of their boundaries remains challenging, hindering our ability to study transition zones (i.e. ecotones) and microbial ecosystem heterogeneity. Fuzzy clustering is a promising method to do so, as it creates overlapping sets of clusters. The outputs of these analyses thus appear both structured (into clusters) and gradual (due to the overlaps), which aligns with the inherent continuity of the pelagic environment, and solves the issue of defining ecosystem boundaries.
Results

We show the suitability of applying fuzzy clustering to address the patchiness of microbial ecosystems, integrating environmental (Sea Surface Temperature, Salinity) and bacterioplankton data (Operational Taxonomic Units (OTUs) based on 16S rRNA gene) collected during six cruises over 1.5 years from the subtropical frontal zone off New Zealand. The technique was able to precisely identify ecological heterogeneity, distinguishing both the patches and the transitions between them. In particular we show that the subtropical front is a distinct, albeit transient, microbial ecosystem. Each water mass harboured a specific microbial community, and the characteristics of their ecotones matched the characteristics of the environmental transitions, highlighting that environmental mixing lead to community mixing. Further explorations into the OTU community compositions revealed that, although only a small proportion of the OTUs explained community variance, their associations with given water mass were consistent through time.
Conclusion

We demonstrate recurrent associations between microbial communities and dynamic oceanic features. Fuzzy clusters can be applied to any ecosystem (terrestrial, human, marine, etc) to solve uncertainties regarding the position of microbial ecological boundaries and to refine the relation between the distribution of microorganisms and their environment.

Organisation(s)
Functional and Evolutionary Ecology
External organisation(s)
University of Otago, Manaaki Whenua - Landcare Research, Te Rūnanga o Ngāi Tahu
Journal
Environmental Microbiome
Volume
15
No. of pages
14
ISSN
2524-6372
DOI
https://doi.org/10.1186/s40793-020-00363-w
Publication date
08-2020
Peer reviewed
Yes
Austrian Fields of Science 2012
106021 Marine biology
Keywords
ASJC Scopus subject areas
Applied Microbiology and Biotechnology, Genetics, Microbiology
Sustainable Development Goals
SDG 14 - Life Below Water
Portal url
https://ucris.univie.ac.at/portal/en/publications/reducing-the-arbitrary-fuzzy-detection-of-microbial-ecotones-and-ecosystems--focus-on-the-pelagic-environment(d42be76c-2197-4c00-baa4-2173e30dd298).html