The redox potential characteristics of saltmarsh sediments and their influence on the restoration of perennial halophytes in coastal realignment

Skelly, Denis (2015) The redox potential characteristics of saltmarsh sediments and their influence on the restoration of perennial halophytes in coastal realignment. Doctoral thesis, University of East Anglia.

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Sediment anoxia and associated low redox potential (Eh) are important influences on
the distribution of saltmarsh plants. Nevertheless, the detailed variation of Eh in
space and time is poorly understood, especially on managed realignment (MR)
saltmarshes where anoxia may be a significant constraint on the establishment of
characteristic perennial halophytes. This thesis examines the distribution of Eh in
natural and MR saltmarshes of North Norfolk and Lincolnshire, UK and its
implications for Armeria maritima, Limonium vulgare, Plantago maritima and
Triglochin maritima, species important in general saltmarsh (GSM) communities.
Detailed measurements of Eh were made using arrays of fixed electrodes and a field
datalogger, at different sites/seasons/sediment depths, over tidal cycles, and in relation
to microtopography (including on an existing experiment with manipulated
microtopography). Laboratory apparatus was devised to examine responses of
halophytes to controlled Eh in water culture.
Relationships between vegetation and Eh proved complex. Prolonged low-Eh
episodes occurred both at MR and natural GSM sites, particularly in summer. Atriplex
portulacoides and Puccinellia maritima tended to dominate where low-Eh episodes
were more transient, generally near drainage channels or at higher elevations. Atriplex,
Armeria and Plantago previously planted in experimental plots survived poorly at low
Eh, while Limonium and Triglochin showed higher survival. In cultivation, Atriplex
tolerated anoxia for only two weeks, and low Eh did not impose any additional stress.
In contrast, Triglochin survived the ten-week duration of the experiment even at low
Thus laboratory results suggested mechanistic bases to explain those in the field.
Although MR and GSM sediments can exhibit similar Eh measurements, they may
differ with respect to redox capacity; MR sediments sites with high reduction
capacities may exert additional stresses that could limit colonisation. Conversely,
consistently high Eh could also limit colonisation on MR sites by promoting vigorous
competitive growth of Atriplex and Puccinellia.

Item Type: Thesis (Doctoral)
Faculty \ School: Faculty of Science > School of Biological Sciences
Depositing User: Users 2259 not found.
Date Deposited: 22 Jun 2016 11:58
Last Modified: 22 Jun 2016 11:58

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