The form and stability of alluvial riverbeds, and their effects on macroinvertebrate communities across Great Britain

Thomas, Rhodri James ORCID: https://orcid.org/0000-0003-2841-9682 2018. The form and stability of alluvial riverbeds, and their effects on macroinvertebrate communities across Great Britain. PhD Thesis, Cardiff University. Item availability restricted.

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Abstract

The sustainable functioning of macroinvertebrate communities forms the basis of many of the vital ecosystem services provided by rivers, yet these communities are amongst the most stressed on the planet and predictions show these stresses increasing in the future. At a conceptual level, macroinvertebrate community composition is inextricably linked to the riverbed sediment in which they reside, although evidence of these links is largely confined to descriptive or small-scale studies. Robust predictions of the response of these communities to future change are urgently needed but this first requires a better understanding of the interaction between physical and ecological processes across larger spatial and temporal scales. Using national scale monitoring data for rivers across Great Britain, this study tested the ability of simple process-based models to predict physical habitat features (e.g. bars), before investigating their ability to describe spatial and temporal trends of invertebrate community function, composition and response to physical perturbation. The simple nature of the approaches used in this study, which combine basic geomorphological models with traditional ecological metrics and functional traits, presents an opportunity to develop tools that allow river managers to base decisions on quantifiable measures of physical process instead of expert opinion. Overall, the results provided evidence of an implicit link between freshwater community composition, function, and the spatial variation in physical processes. Traditional and functional measures of community diversity showed a response to changing bed material calibre and stability across large spatial scales, consistent with other studies of habitat stability in rivers and other ecosystems. Despite this, there was limited evidence of temporal variability in communities due to riverbed disturbance, perhaps because water quality continued to suppress the physical habitat signal. Further work is required to isolate the effect of riverbed disturbance from other controlling mechanisms.

Item Type:	Thesis (PhD)
Date Type:	Completion
Status:	Unpublished
Schools:	Biosciences Earth and Environmental Sciences
Uncontrolled Keywords:	Freshwater invertebrates rivers sediment disturbance
Funders:	President's Research Scholarship
Date of First Compliant Deposit:	16 May 2018
Last Modified:	03 Nov 2022 11:27
URI:	https://orca.cardiff.ac.uk/id/eprint/111456

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