The influence of macrofauna on intertidal sediment stability and biogeochemical properties.

Hale, Rachel (2013) The influence of macrofauna on intertidal sediment stability and biogeochemical properties. Doctoral thesis, University of East Anglia.

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Macrofauna are known to have a significant effect on intertidal
sediment stability and biogeochemical properties. A series of manipulative in
situ mudflat studies at Breydon Water, Great Yarmouth, UK investigated the
effect of biodiversity on selected biogeochemical sedimentary properties
related to mudflat sediment stability including the sediment erosion threshold
and relative erosion rate, microphytobenthos biomass and health, sediment
particle size and size distribution, sediment water content, chlorophyll a and
b concentration, and colloidal carbohydrate concentration. Mudflat sediment
macrofaunal biomass was removed using cryo-defaunation and the
abundances of three common mudflat species Hediste diversicolor, Hydrobia
ulvae and Corophium volutator manipulated to examine different aspects of
macrofaunal biodiversity including species identity, density, biomass
distribution, and richness. An additional laboratory study enabled two and
three dimensional high resolution visualisation of fluid and particle mixing as
a result of organism sediment bioturbation.
Species identity was found to have a significant effect on sediment
properties. The three species have distinct bioturbatory actions with
consequences for sediment stability. In some circumstances a single
organism was found to have as great an effect on selected ecosystem
processes as a whole community. Variations in species density significantly
changed the effect of the species on the measured sedimentary processes.
Species richness effects were negatively interactive, with species mixtures
underyielding in comparison to their monoculture counterparts. Changes in
species biomass distribution and richness resulted in significant context
dependent changes to sediment properties, moderated by inter- and intraspecific
interactions. Species were also observed to exhibit a functional
abundance threshold, below which they did not contribute significantly to
ecosystem processes. Temporal and spatial variability observed in the
experiments emphasised the potential of environmental and abiotic factors to
also influence ecosystem processes. Investigating these subtle aspects of
biodiversity will be key in the determination of the relationship between
biodiversity and ecosystem processes.

Item Type: Thesis (Doctoral)
Faculty \ School: Faculty of Science > School of Environmental Sciences
Depositing User: Users 2259 not found.
Date Deposited: 11 Jun 2014 13:52
Last Modified: 11 Jun 2014 13:52

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