The diversity and drivers of bacterial assemblages in the euphotic zone from coastal seas to the open ocean

Bird, Kimberley (2018) The diversity and drivers of bacterial assemblages in the euphotic zone from coastal seas to the open ocean. Doctoral thesis, University of East Anglia.

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Abstract

Marine bacteria are ubiquitous in the world’s oceans, contributing significantly to food webs and global biogeochemical cycles. Characterising the distribution and drivers of bacterial diversity is key to understanding their important roles in the marine ecosystem. This thesis characterised the diversity and drivers of bacterial communities in the euphotic zone from 1 mm to 250 m below the sea surface, covering a range of marine environments from the coastal and shelf seas to the open ocean, including biogeochemically important habitats such as the sea surface microlayer. Bacterioplankton communities vary seasonally and over local and global scales, in response to prevailing environmental characteristics. Using a multidisciplinary approach, interrogating 16S rRNA gene high-throughput sequence data with co-occurring physicochemical metadata has revealed that, in addition to the major overarching drivers of temperature and primary production, physical processes such as atmospheric deposition, mixing, and stratification can also influence the composition of bacterial communities and their vertical distribution in the water column. Enrichments of ecologically important bacteria such as Alteromonas sp. and Trichodesmium sp. in the sea surface microlayer have potential to influence the availability of resources arriving into the open ocean from the atmosphere. Using 16S rRNA transcripts to characterise active bacterioplankton communities has revealed that bacterioplankton activity is decoupled from abundance throughout the Atlantic Ocean, and may be influenced by the dominant primary producers. Furthermore, by combining culture-based techniques with functional amplicon sequencing, the physiological effects of CO-oxidation on the model bacterioplankton R. pomeroyi and a diversity of CO-oxidising bacterioplankton among the ecologically important Marine Roseobacter Clade in a temperate coastal environment have been identified. This thesis improves our understanding of bacterial ecology in the world's oceans, and demonstrates how holistic approaches to studying marine bacteria in the environment used in combination with molecular tools, can give a view of marine ecosystem function.

Item Type: Thesis (Doctoral)
Faculty \ School: Faculty of Science > School of Environmental Sciences
Depositing User: Gillian Aldus
Date Deposited: 17 Oct 2019 09:44
Last Modified: 17 Oct 2019 09:44
URI: https://ueaeprints.uea.ac.uk/id/eprint/72633
DOI:

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