The effect of sediment characteristics and a fine sediment pulse on invertebrate distributional patterns

Bunting, George (2019) The effect of sediment characteristics and a fine sediment pulse on invertebrate distributional patterns. PhD thesis, University of Worcester.

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Abstract

The amount of fine sediment entering river systems has increased dramatically
in the last century and this has been recognised as a leading cause of ecological
degradation and water quality impairment. In order to monitor and manage this
problem more effectively further research is needed in to the quantitative,
mechanistic relationships between the amount of fine sediment delivery in to river
systems and the response of the lotic freshwater community. At present, this lack
of information is problematic for environmental managers and regulators as they
attempt to meet the challenges posed by this issue.
This thesis aimed to address this research gap by using stream mesocosms to
investigate the response of invertebrates to a fine sediment pulse. It was unique
in considering the effect of prior exposure to increased fine sediment deposition,
whilst examining the response of benthic, hyporheic and drifting invertebrates
concurrently. The research also set out to assess the effectiveness of fine
sediment biomonitoring approaches, comparing them with more traditional
metrics, it also investigated the power of a functional trait approach to
discriminate fine sediment stress.
The results detailed in this thesis demonstrate that biomonitoring approaches
have the ability to identify fine sediment stress more effectively than traditional
taxonomic metrics (e.g. abundance and taxonomic richness), particularly when
applied to invertebrate communities which are relatively tolerant of fine sediment
stress. This was one of the first studies to identify the effects of prior fine sediment
deposition on the response of invertebrates to a fine sediment pulse, finding that
this factor plays an important role in their response, providing important evidence
which may be used to better tailor our fine sediment management strategies.
Examining, in tandem, the effects of a fine sediment pulse on invertebrate drifting
behavior and their use of the hyporheic zone identified taxa-specific responses
to fine sediment which will be useful to further refine our understanding of the
mechanistic relationship between increased amounts of fine sediment and invertebrate
communities.
This information will help to inform the refinement of
functional trait databases, which has been identified by the work in this thesis as
one of the major factors limiting their effective use.

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