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Europe and Central Asia

Restoring Quarry Silt Lagoons for Migrant Waders - United Kingdom

 

Background

Aggregates sites have the potential to recreate lost wader habitat in lowland river basins, where it would otherwise have been abundant, through the maintenance of extensive soft-sediment or silt areas, which provide feeding and roosting habitat. A preliminary study has demonstrated that one likely barrier to greater use of silt lagoons by waders is the highly anoxic conditions that prevail below the surface which prevent establishment of sediment-living invertebrate communities. This project will use expertise in the ecology of wading birds, freshwater invertebrates and restoration sites to assess and improve the value of quarry silt lagoons for declining birds.
 
Location : Wykeham quarry in Yorkshire, England and numerous control and comparative sites in the UK and Netherlands
Size : ~150 ha
Mineral type : Gravel and sand
Habitat(s) created : Silt and mud banks, water fringe vegetation, freshwater lakes
Target species : Northern Lapwing, Redshank, other waders
Protected areas : None in immediate area
Organisations : Hanson UK, University of Hull Centre for Environmental and Marine Sciences, Scarborough Campus; RSPB and BirdLife International
 

Why is this project needed?

Silt lagoons in aggregates extraction sites represent an opportunity for habitat restoration targeted at wading birds. Much lowland wetland habitat in Europe has been lost through agricultural intensification and reclamation and populations of many species of wading birds have declined as a consequence.

The project focuses on species and habitats of relevance for the eastern Atlantic flyway with fieldwork carried out in the UK and the Netherlands. A silt lagoon restoration plan will be implemented as part of the project.

The project will be delivered by a PhD student undertaking field and desk research, supplemented by an MSc research project looking specifically at sites in the Netherlands.
 

Project objectives

The goal of this project is to explore opportunities for aggregate sites to add to wader habitat in the Eastern Atlantic flyway and to carry out experimental and observational studies on silt lagoons to develop processes for their effective restoration and subsequent use as wader habitat.
 

Public benefits

This project is mainly aimed at quarry restoration managers, mineral planners and restoration ecologists. By developing evidence based restoration techniques applicable at numerous sites, the project will contribute to wider conservation goals benefitting the ecosystems that support migratory birds and other organisms. These benefits will be widely shared by the outdoor enthusiasts and people working and living near mineral sites, thus helping restore a range of ecosystem services.

 

Research work planned

Map of sites of potential value to waders of silt lagoons

Aggregates sites within the eastern Atlantic flyway will be mapped and categorised by type from existing data sources. These will be combined with existing data on wader migration/movement routes to produce a ‘value map’ of potential restoration opportunities. This map will be used as the basis for site selection of field sites in the UK and the Netherlands. The final map will provide an additional evidence base for restoration proposals in mineral planning applications.

Observational study of sedimentation, temporal and spatial dynamics of invertebrate communities and wader habitat use at multiple quarry silt lagoon sites
A multi-site study of wader use and the sedimentary/ecological dynamics of silt deposition sites will be carried out over a 2 year period. The study will examine three sites (to be identified in early stages of the project) in the UK and three in the Netherlands.

Characterisation of ‘natural’ soft-sediment sites
Sediment samples will be taken from well-used wader feeding sites in the vicinity of the quarry sites in the UK and characterised by particle size, chemical composition and nutrient availability.

Experimental/trial field manipulation of sediment characteristics
Study plots at Wykeham quarry will have trial manipulations modifying sediment characteristics (including potentially seeding with invertebrates from nearby sites) on plots at the established silt lagoon site. These will be monitored over a full calendar year to assess change in sediment properties and the establishment of sediment invertebrates.

Field-scale restoration of silt lagoon (Wykeham Quarry, UK)
The derived knowledge will be used to implement a full-scale experimental/trial restoration at Wykeham quarry. The restoration will be monitored over the final 6 months of the project.
 

Project update

In the past few months we have been working on the task of mapping and assessing the state of all quarries in England and Wales using the Britpits database of mines and quarries. This database has over eleven thousand sand and gravel sites listed and PhD student Bryonie Fox has sorted the data, mapped it in a geographic information system (GIS) and located each site to assess its potential for restoration to habitat suitable for wading birds. She is then mapping the extent of each quarry site in order to evaluate the potential total resource that these sites might provide and how sites are distributed across the landscape. We have undertaken a preliminary spatial analysis of sites in North Yorkshire which has identified a corridor of ‘stepping stone’ sites between important areas for waders (Fig. 1), allowing us to differentiate between sites which would be high priorities for restoration to support waders and those which would be lower priorities. Repeating this analysis for our national datasets will give us a searchable map to help quarry managers and planners across the country assess whether their sites are in areas of high priority for restoration to support wader populations.

Fig 1: Priority of sand and gravel quarries in North Yorkshire for restoration to support waders: Larger, darker coloured points are highest priority. Arrows represent hypothetical landscape connections between major areas of wader habitat.

As migrating birds are now starting to move away from breeding sites and prepare for migration or movement to overwintering areas we are beginning surveys at quarry sites which currently support waders in order to understand how birds are using existing sites.