Research papers featuring WWT Steart Marshes

Since its inception, WWT Steart Marshes continue to host an abundance of research activity, including academic studies and several PhD projects.

WWT strongly encourages research activity at Steart Marshes and the neighbouring Bridgwater Bay, recognising that these sites act as open laboratories that provide robust evidence for wetland superpowers, as well as demonstrating exemplar site design and community engagement.

On this page, you can find a list of published research outputs relating to Steart Marshes and Bridgwater Bay. This includes academic research articles, PhD theses, book chapters and conference papers on a wide variety of saltmarsh research topics.

How to use this page

You can browse the list of publication titles below, that each state the lead researcher or author of the work. Select "More Information" to view further details about the publication, including the research affiliation, date, and type of publication (thesis, book chapter, article etc.). Below the table, you can view the abstract or summary detailing the background, research context and general findings of the study. Publication details are given for research articles, under the heading "Further details" including the journal title, volume and page numbers.

The accessibility of the publication is described under "Access". Many of the publications are publicly accessible and the full text is available to directly view or download at the links provided. A small number of the publications are not currently publicly available, but those that have been added to platforms such as ResearchGate can be directly requested from the authors by following the link to the article page and selecting "Request full-text". Please note that you may need to register for a ResearchGate account and log-in to make a request.

How to create a saltmarsh: understanding the roles of topography, redox and nutrient dynamics

Peter Lawrence

Affiliation	Publication type	Date
MMU	PhD thesis	2018

Abstract/summary of findings

The restoration of saltmarsh is critical given the importance of the habitat and the degradation and losses it faces. However, success of saltmarsh restoration has been limited, particularly in replacing plant communities, despite like-for-like replacement being a legal requirement. Previous research found elevation in the tidal frame and sediment redox potential are important drivers of vegetation communities, and are different between restored and natural marshes. However, elevation and sediment redox potential together are insufficient to explain differences in plant communities. Topographic features are thought to alter redox potential-elevation relationships, though its role in plant communities is not currently known. Nutrient concentrations can also impact vegetation, however we lack evidence as to the typical concentrations in natural saltmarsh or restored sites, and how close these are to detrimental levels. This thesis explores these environmental properties in restored and natural saltmarshes, and how they may interact to drive plant communities. Results indicated that nutrients were highly variable both spatially and temporally. In contrast to expectations, there was a negligible effect of former land-use on surface soil development in a newly developing marsh. Instead of land-use, a combination of sedimentation and elevation appears to be the strongest predictor of nutrient properties, thus a better understanding of incoming sediment and elevation changes may lead to improved predictions of likely soil development. The results from nutrient analysis also indicated that globally saltmarshes are typically Phosphate enriched and thus the management of N input at natural saltmarshes should be avoided. Restored marshes have different topographic characteristics (flatter, wetter and more often concave). A lack of topography existed on both site and local scales, resulting in more homogenous plant communities (again at, sites and local-scales). Natural plant diversity was driven by elevation, local topography and redox, whereas on MR sites it was almost entirely driven by redox potential. The results show that more topographic manipulation is required to aid community convergence with natural diversity, and thus replicate natural conditions in restored saltmarshes.

Access: PhD thesis available to download from MMU's online repository.

Link: repository.mmu.ac.uk

Ecosystem services assessment at Steart Peninsula, Somerset UK

Lia Vieria da Silva et al.

Affiliation	Publication type	Date
WWT, Imperial College London, University of the West of England	Article	2014

Abstract/summary of findings

A systemic valuation was undertaken of marginal changes in ecosystem services assessed as likely to result from the Steart Coastal Management project, some in monetary terms and others semi-quantified. The Steart Coastal Management project entails allowing seawater once again to inundate formerly defended farmland, including modifications to the landform of to assist the re-creation of a range of wetland habitats on the Steart Peninsula. Primary drivers for the project include habitat creation and management of coastal flooding, although implications for a range of other connected services need also to be taken into account. Ecosystem services for which a market exists (typically traded goods with associated use values) were valued using market prices. For non-traded services, this study relied substantially on the economic valuation technique of "value transfer". Despite having to rely on some wide but transparently stated assumptions, a conservative, yet considerable, net annual benefit range of £491,155 to £913,752 was deduced. Research gaps that limited our ability to quantify and/or value several ecosystem services were identified.

Further details: Journal: Ecosystem Services, Volume 10, Pages 19-24

Access: Article available to download on ResearchGate.

Link: www.researchgate.net

The Ecology and Distribution of Seabass in the Southwest UK

Tom Stanton

Affiliation	Publication type	Date
Plymouth University	PhD thesis	2016+

Abstract/summary of findings

Work carried out to survey seabass at managed realignment sites (including Steart). Asking "Do managed realignment sites provide equivalent habitat to natural saltmarsh?" Tested for differences between the fish community and diet and feeding success. Included 3 managed realignment sites plus natural saltmarsh. Fyke nets and seines deployed in both habitat types with 5 surveys in total. 16 species recorded, 9 of commerical interest and 1 of conservation interest (eel). Different fish communities were captured within managed realignment sites compared to natural saltmarsh. Average diversity of fish was higher within managed realignment sites compared to natural saltmarsh. Some grouping of seabass diet was observed due to habitat, suggesting they have a different diet on natural and realignmnt sites. MRAS do provide habitat for fish evidenced by high fish diversity, but the habitat is not currently equivalent to natural saltmarsh evidenced by different diets.

Access: PhD thesis available to download from Plymouth University's online repository.

Link: pearl.plymouth.ac.uk

Ecological community changes and ecosystem functioning during structured wetland development

Adam George

Affiliation	Publication type	Date
Bridgwater College, Oxford Brookes University	PhD thesis	2018+

Abstract/summary of findings

Abstract taken from ResearchGate: In my PhD project I am studying the ecological changes that take place on a saltmarsh creation scheme at Steart Marshes in Somerset, UK. The managed realignment scheme is run by the Wildfowl and Wetlands Trust (WWT). I am comparing the ecological starting state of the site before it was breached in September 2014 with the changes that take place now that it is under the influence of a tidal regime.

Access: PhD thesis available to download from Oxford Brokes online repository.

Link: radar.brookes.ac.uk

Suitability of compensatory saltmarsh habitat for feeding and diet of multiple estuarine fish species

Thomas Stamp

Affiliation	Publication type	Date
University of Plymouth	Article	2022

Abstract/summary of findings

Saltmarsh provides essential fish feeding and nursery habitat but has globally declined by 50%. We used a statistical block design to compare fish feeding activity within human‐engineered or "re‐aligned" saltmarsh to established saltmarsh. Linear and multivariate modelling highlighted that Thinlip Mullet (Chelon ramada) and European Bass (Dicentrarchus labrax) feeding rates were 16% and 31% lower within re‐aligned than established saltmarshes, whereas Gobies (Pomatoschistus spp.) fed at the same rate as in both habitats. Analysis of European bass and Goby gut contents highlighted that important detritivorous prey species were up to 85.6% lower in re‐aligned sites. Lower vegetation density may have negatively affected the feeding ecologies of fishes within re‐aligned sites. However, due to the ecological value and potential for further improvement or habitat development, continued assessment of the beneficial effects of re‐aligned sites for fisheries and net gain perspectives is needed.

Further details: Journal: Fisheries Management and Ecology, Volume 30, Pages 44-55.

Access: Open access article available to download from Wiley.

Link: onlinelibrary.wiley.com

Delivering large habitat restoration schemes: lessons from the Steart Coastal Management Project

James Scott, Nigel Pontee, Tim McGrath, Richard Cox, Matt Philips

Affiliation	Publication type	Date
CH2M, WWT, Environment Agency, Kier	Conference paper	2015

Abstract/summary of findings

The Steart Coastal Management Project is one of the largest managed realignment and habitat creation projects ever carried out in the UK. As compensation for disappearing habitat elsewhere in the Severn Estuary the Environment Agency (EA) has transformed 477 hectares of the Steart Peninsula into wildlife rich habitats whilst improving the flood defences and providing greatly improved provision for public access and community involvement. This complex scheme has faced and overcome numerous challenges including: community engagement, which turned opposition into support; development of a mosaic of habitat types; the design and construction of earthworks, which worked within the constraints of the site; the complete replacement of an extensive water management network; and the construction of a breach and exit channel. This paper outlines the key aspects of the project and documents the lessons that were learnt during the planning, design and construction phases of the project.

Further details: Conference: Coastal Management 2015, Changing Coast, Changing Climate, Changing Minds. At: Amsterdam, Netherlands

Access: Paper available to download on ResearchGate.

Link: www.researchgate.net

Rapid carbon accumulation at a saltmarsh restored by managed realignment exceeded carbon emitted in direct site construction

Hannah L Mossman, Nigel Pontee, Katie Born, Colin Hill, Peter J Lawrence, Stuart Rae, James Scott, Beatriz Serato, Robert B Sparke, Martin J P Sullivan, Rachel M Dunk

Affiliation	Publication type	Date
Manchester Metropolitan University, Jacobs Engineering Group Inc	Article	July 2005

Abstract/summary of findings

Increasing attention is being paid to the carbon sequestration and storage services provided by coastal blue carbon ecosystems such as saltmarshes. Sites restored by managed realignment, where existing sea walls are breached to reinstate tidal inundation to the land behind, have considerable potential to accumulate carbon through deposition of sediment brought in by the tide and burial of vegetation in the site. While this potential has been recognised, it is not yet a common motivating factor for saltmarsh restoration, partly due to uncertainties about the rate of carbon accumulation and how this balances against the greenhouse gases emitted during site construction. We use a combination of field measurements over four years and remote sensing to quantify carbon accumulation at a large managed realignment site, Steart Marshes, UK. Sediment accumulated rapidly at Steart Marshes (mean of 75 mm yr-1) and had a high carbon content (4.4% total carbon, 2.2% total organic carbon), resulting in carbon accumulation of 36.6 t ha-1 yr-1 total carbon (19.4 t ha-1 yr-1 total organic carbon). This rate of carbon accumulation is an order of magnitude higher than reported in many other restored saltmarshes, and is somewhat higher than values previously reported from another hypertidal system (Bay of Fundy, Canada). The estimated carbon emissions associated with the construction of the site were ~2-4% of the observed carbon accumulation during the study period, supporting the view that managed realignment projects in such settings may have significant carbon accumulation benefits. However, uncertainties such as the origin of carbon (allochthonous or autochthonous) and changes in gas fluxes need to be resolved to move towards a full carbon budget for saltmarsh restoration.

Further details: Journal: PLOS ONE, Volume 17(11): e0259033.

Access: Open access article available to download from Plos One.

Link: journals.plos.org

Nearfield erosion at the Steart marshes (UK) managed realignment scheme following opening.

Nigel Pontee, Beatriz Serato

Affiliation	Publication type	Date
Jacobs Engineering Group Inc, University of Southampton	Article	11 July 2005

Abstract/summary of findings

The ingress and egress of water from managed realignment sites in macrotidal estuaries commonly causes erosion at the breaches and the formation of channels across the fronting intertidal areas. However, the rate of development of these features and their final dimensions have not been well documented. This case study paper details the development of the breach area and the erosional processes in the main and exit channels associated with the Steart Marshes managed realignment site in south west England. The paper shows type of data, along with its accuracy, which is currently available for this type of study. It uses a combination of UAV and LiDAR data that was collected as part of a monitoring campaign to record the development of scheme over a period of 3 years and 7 months following site opening. This data would normally reside within consultancy reports and thus be unavailable to the wider scientific community. The paper demonstrates that further work is needed to improve the prediction of erosion rates associated with managed realignment schemes. The monitoring data at Steart Marshes show the development of a large exit channel along the line of the former channel that led across the existing intertidal mudflats. The highest rates of erosion occurred in the first 3 months following opening. After this time rates declined markedly and, approximately 7 months after opening, the breach and exit channel region began to show periods of accretion as well as erosion. The non-linearity in erosion rates is similar to previously reported sites, but the rates of development were more rapid due to higher flow speeds generated by large tidal prism and the single breach design. Although the volume of the exit channel region appears to have stabilised, a secondary channel is starting to form, which suggests that further changes are likely. Within the site, further recession of the step feature is expected before a stable condition is reached. The paper documents these changes in more detail and draws out those behaviours that are likely to apply to other schemes.

Further details: Journal: Ocean & Coastal Management, Volume 172, Pages 64-81

Access: Not open access but the article can be requested from the author on ResearchGate at the link provided.

Link: /www.researchgate.net

Reserve Focus: WWT Steart Marshes, Somerset

A Branson

Affiliation	Publication type	Date
British Wildlife Publishing	Article	July 2005

Abstract/summary of findings

Creating and managing habitats is no easy task, yet the environmental benefits of wetlands and marshes are far-reaching. Andrew Branson explores the Steart Marshes and its wildlife.

Further details: Journal: British Wildlife, Volume 28(3), Pages187-192.

Access: Not open access, requires a subscription to British Wildlife to view.

Link: www.britishwildlife.com

People's perceptions towards the Steart Marshes Creation Project through stakeholder interviews and questionnaires

Robert McInnes, Mark Everard, Hiromi Yamashita

Affiliation	Publication type	Date
Ritsumeikan Asia Pacific University, University of the West of England (UWE), RM Wetlands & Environment Ltd	Book chapter	July 2005

Abstract/summary of findings

This book chapter documents the outcomes of public perceptions on the outcomes of a managed realignment scheme at Steart Marshes on the mouth of the River Parrett in Somerset, UK. This chapter explores the perceptions of local citizens through face-to-face interviews and questionnaire responses from the Steart Coastal Management Project in Somerset, UK. Both sampling approaches reveal interesting disconnects between how environmental organisations explained the benefits of the project to the public and how local people perceived the project from their perspectives.

Further details: Book: Coastal Wetlands Restoration, Pages 46-60.

Access: Not open access but the chapter can be requested from the author on ResearchGate at the link provided.

Link: www.researchgate.net/