Factors affecting the composition, diversity, and function of bacterial communities in mangrove soils

Abstract

Mangroves are intertidal coastal forests that provide many important ecosystem services, such as carbon storage, coastal protection, and habitat provision for fish and shellfish. Due to tidal inundation, they have unique soil habitats which are characterised by high salinity and anoxic conditions. Compared to terrestrial forests, relatively little is known about the diversity, composition, and functions of mangrove soil bacterial communities. In this thesis, I sought to advance our understanding of how mangrove soil bacterial communities vary spatially across the intertidal zone, identify the main factors that account for these distribution patterns, and determine how they respond to environmental change, with a focus on elevated nutrient levels. Through a combination of field studies and experiments, I demonstrate that site-specific environmental gradients in abiotic factors associated with intertidal zonation are of more importance than biotic factors associated with plant species or genetic identity in shaping the distribution of bacterial communities in mangroves. In laboratory and field experiments, I demonstrate that nitrogen and/or phosphorus addition can drive changes in the diversity, composition and function of soil bacterial communities, but that response is site dependant. Further, my laboratory experiment found functional changes in extracellular enzyme activity in response to nitrogen addition, suggesting that further investigations into potential functional changes in field conditions are warranted. Overall, I have been able to advance our knowledge of the factors controlling bacterial community compositions in mangroves, and demonstrate that environmental changes, such as elevated nutrients, can induce changes in soil functions.

Date of Award	31 Dec 2019
Original language	English
Awarding Institution	The University of Manchester
Supervisor	Richard Bardgett (Supervisor) & Clare Robinson (Supervisor)