Macrophytes and suspension-feeding invertebrates modify flows and fine sediments in the Frome and Piddle Catchments, Dorset (UK)

Wharton, Geraldene; Cotton, Jacqueline A.; Wotton, Roger S.; Bass, Jon A. B.; Heppell, Catherine M.; Trimmer, Mark; Sanders, Ian A.; Warren, Luke L.. 2006 Macrophytes and suspension-feeding invertebrates modify flows and fine sediments in the Frome and Piddle Catchments, Dorset (UK). Journal of Hydrology, 330. 171-184. 10.1016/j.jhydrol.2006.04.034

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Abstract/Summary

This research investigated the ecosystem engineering by in-stream macrophytes, dominated by Ranunculus spp., and associated suspension-feeding blackfly larvae (Diptera: Simuliidae) for five reaches in the Frome and Piddle catchments, Dorset (UK) over one annual growth cycle (2003). This paper focuses on the modification of flow velocities and the trapping of fine sediment (particles <2 mm in diameter) by in-stream macrophytes and the processing of dissolved organic matter (DOM), fine particulate organic matter (FPOM) and fine inorganic particles into faecal pellets by blackfly larvae attached to the leaves of Ranunculus plants. In-stream macrophyte growth was extensive, with maximum percentage cover of 80% recorded in September and October 2003. The macrophyte cover significantly altered flow patterns and flow velocities within and between the macrophyte stands. The reduced flow velocities within the plants promoted sediment trapping, reaching volumes of 0.085 m3 of fine sediment trapped per metre square of vegetation at one site. The effective particle sizes of the sediments trapped within Ranunculus stands were dominated by the 250–500 μm fraction from March to July 2003 whereas a higher proportion of smaller fractions occurred from October to December. Faecal pellets were highly abundant in the sediments trapped within Ranunculus stands (up to 2.2 × 108 faecal pellets per m2) and their dimensions (total size range 25–400 μm) fall within the dominant size fraction of the trapped sediments. Our findings demonstrate the need to consider the biogenic component of the fine sediments in chalk streams in future studies of sediment and nutrient dynamics.

Item Type:	Publication - Article
Digital Object Identifier (DOI):	10.1016/j.jhydrol.2006.04.034
Programmes:	CEH Programmes pre-2009 publications > Water
UKCEH and CEH Sections/Science Areas:	_ River Ecology
ISSN:	0022-1694
Additional Keywords:	chalk rivers, ecosystem engineering, fine sediment, river flows, macrophytes, suspension feeders
NORA Subject Terms:	Biology and Microbiology Ecology and Environment Hydrology
Date made live:	15 May 2008 09:23 +0 (UTC)
URI:	https://nora.nerc.ac.uk/id/eprint/2943

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