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Changes in invertebrate assemblage composition in benthic and hyporheic zones during a severe supraseasonal drought

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journal contribution
posted on 2015-04-24, 10:31 authored by Rachel Stubbington, A.J. Boulton, Sally Little, Paul WoodPaul Wood
Droughts are unpredictable disturbances characterized in streams by declining flow, reduced habitat availability, and deteriorating abiotic conditions. Such events typically reduce benthic invertebrate taxon richness and modify assemblage composition, but little is known about how hyporheic invertebrate assemblages respond to drought or how these responses relate to changes in benthic assemblages. We hypothesized that taxon richness (α diversity) and variability (as within-site β diversity) in benthic assemblage composition would decline as drought proceeded, whereas concurrent changes in hyporheic assemblages would be lower in this more stable environment. We predicted that benthic assemblage composition between sites would converge as epigean taxa were selectively eliminated, whereas between-site hyporheic β diversity would change little. We sampled benthic and hyporheic invertebrates concurrently from 4 sites along a groundwater-fed stream during the final stages of a severe supraseasonal drought punctuated by a record heat wave. Abiotic conditions in benthic habitats deteriorated as flow declined, but changes were less pronounced in the hyporheic zone. Benthic α diversity declined during drought, whereas hyporheic α diversity changed little. However, benthic within-site β diversity increased as the drought progressed because of localized variation in the abundance of common taxa. Temporal trends in hyporheic β diversity were less consistent. Benthic assemblages at individual sites became more similar, especially during the heat wave, reflecting low α diversity and abundance. Hyporheic assemblages changed markedly because of temporary increases in abundances of epigean and hypogean amphipods. These contrasting responses of benthic and hyporheic assemblages to drought should be recognized when developing management strategies for drought-impacted streams.

Funding

This research was supported by a Natural Environment Research Council Urgency Grant [grant number NE/E001769/1] entitled ‘The response of aquatic invertebrate fauna to supra-seasonal drought and drying in a largely perennial chalk stream’. The authors acknowledge the support of the Environment Agency of England and Wales and particularly Ian Humpheryes, Shelagh Wilson, and Kevin Grimmett. Meteorological data for Manston (Kent) were provided by the British Atmospheric Data Centre (BADC).

History

School

  • Social Sciences

Department

  • Geography and Environment

Published in

FRESHWATER SCIENCE

Volume

34

Issue

1

Pages

344 - 354 (11)

Citation

STUBBINGTON, R. ... et al, 2015. Changes in invertebrate assemblage composition in benthic and hyporheic zones during a severe supraseasonal drought. Freshwater Science, 34 (1), pp. 344 - 354.

Publisher

University of Chicago Press / © Society for Freshwater Science

Version

  • AM (Accepted Manuscript)

Publisher statement

This work is made available according to the conditions of the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0) licence. Full details of this licence are available at: https://creativecommons.org/licenses/by-nc-nd/4.0/

Publication date

2015

Notes

This article was accepted for publication in the journal, Freshwater Science [University of Chicago Press / © Society for Freshwater Science]. The definitive version is available at: http://dx.doi.org/10.1086/679467

ISSN

2161-9549

Language

  • en