Ecological responses to environmental variability in wet and dry chalk streams: towards better temporary stream monitoring and management

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Hayes, C. ORCID: 0000-0002-2357-1346, 2022. Ecological responses to environmental variability in wet and dry chalk streams: towards better temporary stream monitoring and management. PhD, Nottingham Trent University.

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Abstract

Temporary streams are those which stop flowing, and which typically dry, and form 52% of the global river network. Temporary streams are subjected to human impacts such as climate change, over-abstraction and channel modifications. Despite these threats, many studies do not fully characterise terrestrial species, or focus on aquatic macroinvertebrate responses to hydromorphology in perennial systems or responses to intermittence itself. Our lack of understanding means we cannot accurately assess the ecological health of temporary streams, and thus cannot effectively manage these ecosystems to protect, and potentially restore, their biodiversity. Therefore, this study aimed to analyse macroinvertebrate and dry-phase plant and invertebrate community responses to variability in habitat conditions, particularly those indicative of human impact.

The study sites were in temporary chalk streams in southern England, predominantly with agricultural and urban land use. An Environment Agency dataset was used to analyse macroinvertebrate community responses to hydromorphological conditions across a range of flow regimes (perennial to intermittent), characterised by a standardised habitat survey method. Dry-phase plant communities were surveyed using a modified version of a UK standard regulatory method to incorporate terrestrial species, and dry-phase invertebrate communities were sampled using pitfall traps, with environmental conditions characterised at each site.

Macroinvertebrates responded predominantly to flow and vegetation, with communities at intermittent sites particularly responding to the latter. These responses indicate that manging intermittent sites to restore flow and vegetation complexity could improve community resilience. Dry-phase invertebrates responded to vegetation (e.g. structural complexity), which was indicative of land use, in addition to sediment composition and moisture. Dry-phase plant communities responded to nutrient concentrations, despite a strong influence of sediment moisture, with metrics including plant dominance and grass richness increasing with increasing phosphorus concentrations. These results could inform biomonitoring methods and management practices to assess and protect ecosystem health regardless of in-channel flow conditions.

Item Type:	Thesis
Creators:	Hayes, C.
Date:	March 2022
Rights:	This work is the intellectual property of the author. You may copy up to 5% of this work for private study, or personal, non-commercial research. Any re-use of the information contained within this document should be fully referenced, quoting the author, title, university, degree level and pagination. Queries or requests for any other use, or if a more substantial copy is required, should be directed in the owner(s) of the Intellectual Property Right.
Divisions:	Schools > School of Science and Technology
Record created by:	Linda Sullivan
Date Added:	21 Mar 2023 14:44
Last Modified:	21 Mar 2023 14:44
URI:	https://irep.ntu.ac.uk/id/eprint/48573