Day-night variation of cohesive sediment stability


Friend, P.L., Lucas, C.H. and Rossington, S.K (2005) Day-night variation of cohesive sediment stability. Estuarine Coastal and Shelf Science, 64, (2-3), 407-418. (doi: 10.1016/j.ecss.2005.03.006).

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Description/Abstract

Surface sediment properties related to cohesive sediment stability were measured over 8 consecutive day- and night-time emersion periods at three upper intertidal sites on a mudflat in August 2003, during the transition from spring to neap tides. Significant differences between day- and night-time critical erosion shear stress (τc) and chlorophyll a were found. A high degree of temporal and spatial variability existed between the sediment properties. During the first half of the study period, a rhythmic day–night variation occurred between τc, chl a, colloidal-S- and EDTA-extracted carbohydrate. During the second part of the study, the magnitude of variation of these parameters diminished. Results showed that sediments were more stable during the day than at night. Differences between day- and night-time sediment stability were related not only to diatom migration, but also to wave energy during preceding immersion periods. No significant relationships existed between τc and either chl a, or colloidal-S- or EDTA-extracted carbohydrate sediment content. It is suggested that tidal phasing, in terms of both the time during the day at which low water spring and neap tides occur, as well as the duration of the emersion period, control the biomass dynamics. The tidal phasing effect is expected to be more pronounced on a cohesive intertidal flat where low water spring tides occur at noon and midnight. The results of this study will be of use in time-dependent estuarine models.

Item Type: Article
Related URLs:
Keywords: cohesive sediment stability, day–night, spring–neap, microphytobenthos, Hydrobia ulvae, chlorophyll a, colloidal-S, EDTA, carbohydrate, Southampton Water
Subjects: Q Science > QE Geology
Divisions: University Structure - Pre August 2011 > School of Ocean & Earth Science (SOC/SOES)
ePrint ID: 17305
Date Deposited: 22 Aug 2005
Last Modified: 27 Mar 2014 18:07
URI: http://eprints.soton.ac.uk/id/eprint/17305

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