2015 Natural England Dee Estuary SAC Condition Assessment
MRNE021400000002
Survey name: 2015 Natural England Dee Estuary SAC Condition Assessment This is a collation of surveys to gather data and evidence from a variety of marine environments. The survey purposes vary and include recommended Marine Conservation Zone (rMCZ) Phase I or II verification surveys, condition assessments, surveys of features of Natura 2000 sites (Special Area of Conservation, Special Protection Area), Intertidal surveys, Benthic grab surveys and others. All surveys are carried out to specified standards and follow established methodologies. Attribution statement: © Natural England copyright. Contains Ordnance Survey data © Crown copyright and database right [year]. Attribution statement: Attribution statement: © Natural England copyright. Contains Ordnance Survey data © Crown copyright and database right [year].
dataset
https://data.nbn.org.uk/Datasets/GA001574
protocol: WWW:DOWNLOAD-1.0-http--download
name:
description: Natural England Access to Evidence Catalogue
57ebd6a8-08d0-46c6-9253-547c27854df6
eng
http://www.opengis.net/def/crs/EPSG/0/27700
environment
OpenData
NEbatch3
Habitats and biotopes
publication
2015-08-30
-3.27
-3.04
53.44
53.27000000000001
http://data.ordnancesurvey.co.uk/doc/country/england
30/08/2015
16/09/2015
creation
2016-09-30
publication
2016-09-30
notPlanned
"The Dee Estuary is located on the north-west British coastline between the Wirral Peninsula in England and north-east Wales. It covers an area of 14,000 ha and is one of the largest estuaries in the UK. The importance of natural habitats and wild species features within the Dee Estuary European Marine Site (EMS) has been recognised through the designation of Marine Protected Areas (MPAs) according to national and European legislation or other international agreements. The Dee Estuary EMS is comprised of the marine components of the Dee Estuary/Aber Dyfrdwy Special Area of Conservation (SAC) (Habitat Directive), Special Protected Area (SPA) (Birds Directive) and Ramsar site under the Convention of Wetlands of International Importance. The entire Dee Estuary/Aber Dyfrdwy (13,680 Ha) and the associated features of interest were notified in 1984 as a Site of Special Scientific Interest (SSSI) (Wildlife and Countryside Act 1981).primary task of this study was to undertake dedicated survey work during the autumn of 2015 in order to derive high quality survey data on existing biotopes and supporting physical attributes to inform condition monitoring of Annex I habitat mudflats and sandflats not covered by seawater at low tide (H1140) (EUNIS code A2). Additional evidence from surface scrape samples (contaminants) and anthropogenic pressure information was collected to assist with assessment of change against historical evidence for each sub-feature with a preliminary condition assessment recommendation.The sedimentary littoral sub-features targeted during the surveys were: Intertidal mud and sand flats, Intertidal muddy sand biotopes and Intertidal mud biotopes. dAttributes that, subject to natural variation, should be used in the condition monitoring of the Dee Estuary SAC include measures of sub-feature extent, sediment character and distribution and community composition of characteristic biotopes. In addition a parallel evaluation was conducted on the presence of key benthic prey items for designated bird species bar-tailed godwit (Limosa lapponicacommon tern (Sterna hirundoand little tern (Sterna albifronsas well as for intertidal feeders and wading bird species of the regularly occurring migratory birds and wintering assemblage. dThe sampling strategy was based on a flexible stratified survey design informed by existing biotope distribution, aerial imagery and local knowledge of the team delivering the project. Field survey methods incorporate a combination of qualitative Phase I and quantitative WFD-compatible Phase II (0.01 m2 hand corer) approaches. The survey was designed and implemented using a stratified transect-based approach with vertical transects identified within three predefined estuary sectors (outer New Brighton, middle West Kirby, and inner- Heswall) targeting the three sedimentary littoral sub-features of focus for this surveysize distribution in the Phase II coring samples indicated the presence of finer fractions and more well sorted sediments in the inner Dee Estuary compared to areas further out and the entire outer Dee sector which were dominated by sandy shores. Sediment contaminants analyses indicated that organic analytes were within the limits of the Canadian Interim marine Sediment Quality Guidelines (ISQG) for all but one site in the Heswall estuarine sector. This sample was collected just next to an outfall in the creek that runs behind the saltmarsh. Several inorganic analytes (mercury, chromium, copper, lead and zinc) exceeded the guidelines in the Heswall sector. Chromium and arsenic was found over the recommended sediment thresholds in the West Kirby sector. Arsenic was the only element exceeding the guidelines in the New Brighton sector. No sample was found to exceed the Probable Effect Levels (PEL) for any of the reported analytes. total of 10 intertidal soft sediment biotopes (EUNIS level 4 & 5) were identified across the transects surveyed. Most biotopes (eight in total), were identified to EUNIS level 5 or better (three sub-biotopes were recorded) and two areas were assigned to biotope complexes (EUNIS level 4). The main habitats of the Dee Estuary SAC were characterised by littoral sand (LSa, 83.1% cover) followed by littoral mud (LMu, 15.8%). A small proportion of sites that bordered the intertidal exposed area during the large spring tides used for survey were assigned to sublittoral sand (SSa). Dominant biotope complexes were medium-fine (MoSa, 16.0%), fine (FiSa, 28.5%) and muddy sand (MuSa, 37.6%). Sandy mud (MEst, 15.2%) areas and littoral mud (UEst, 0.7%) areas were only recorded in the Heswall sector (inner estuary). Extensive areas of saltmarsh (LS.LMp.Sm) were found in the Heswall sector seaward from transects 0-4. This biotope complex was composed of mature and pioneer marsh and featured a complex morphology with numerous channels and creeks connecting sand and mud areas fronting the saltmarsh with upper vegetated areas found above the tidal limit. Finally, two additional broad habitat areas were recorded at the top of some transects, mixed coarse sediments and rock substrata.of taxa and number of individuals was greatest along the inner estuary sector transects with an average 10.75 taxa and 662 individuals per station (all 3 replicates combined). Species diversity decreased at the middle estuary and outer estuary sectors by 1.49 and 3.08 species, respectively. On average, total abundance halved at the middle estuary and decreased 15-fold at the outer estuary. The trend is likely to reflect the large amount of Peringia ulvae and Nematoda recorded within mud and muddy sand biotopes sampled at inner and middle estuarine sectors.only clear evidence of anthropogenic pressures within the EMS was the collection of Ensis spp. (razor clams) at one transect in the New Brighton to Hoylake sector.comparison was carried out between historical evidence and new data obtained in 2015, in an attempt to assess any change in habitat type that may have occurred since these studies were undertaken. It was not possible to make direct comparisons as different survey methods were used and quantitative data were not available for the full extent of the SAC area. Instead the assessment of the attributes extent, sediment character and community composition was done on available descriptions of life forms previously recorded and general character of the main three estuarine areas focus of this work. preliminary assessment considers that the following conservation objectives (CO) have been met: d{to maintain the extent of intertidal mudflats and sandflats;reduction potential of sediments (depth of black anoxic layer) should not deviated significantly from the baseline;level of contaminants in sediments should comply with Probable Effects Levels (PEL); anddistribution of muddy sand and mud biotopes in the muddy sand habitat should not deviate significantly from an established baseline. dThe taxon Dolichopodidae (larva), recorded in samples WKC1a,b and c and HWC4a, could not be entered into Marine recorder since it is not in the current Marine recorder taxon list (version 5.40). as such data fir this taxon has been provided in a seaprate import spreadhseet to be added to the data once the Marine Recorder taxon list has been updated. d"
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