Anglesey Invasive Species, Non-native Species and Sabellaria spinulosa Survey 2016
One of the aims of this survey was to collect data on Invasive Non-Native Species particularly in relation to Holyhead Deep. This disposal site receives dredged disposal material mainly from Holyhead Port, which is in close proximity to Holyhead Marina where there are known records of non-native species. Sabellaria spinulosa (Ross Worm) reef is designated by the Oslo/Paris Convention (for the Protection of the Marine Environment of the North-East Atlantic) as an threatened and declining habitat and a component of Annex I Reef. Individuals and crusts of Sabellaria spinulosa are recorded commonly around Wales but the presence of reef has rarely been confirmed. Previous commercial surveys off north and west Anglesey have indicated the presence of Sabellaria spinulosa reef. This survey, therefore, also aimed to verify these records and give an indication of extent of the habitat. The principal objective was to undertake a taxonomic analysis of video and still images from survey work undertaken around north and west Anglesey in October 2016. The survey area extended from Point Lynas west to Church Bay and out to sites on the Skerries, West Anglesey Reef and Holyhead Deep. The collection of underwater video using a high definition digital drop-down camera and stills for this survey was undertaken by the coastal survey vessel RV Mersey Guardian in October 2016. The video dataset encompassed 25 tows, comprising over eight hours of video in total. A total of 3759 still images taken at approximately seven second intervals were collected simultaneously with the video tows. The entire video/ set of stills from each tow were reviewed prior to detailed assessment and recording, and the boundaries between habitats (biotopes) or habitat complexes noted. The species and substratum in each tow section or 'sample' was then recorded, and habitats assigned. A total of 35 samples were derived across the 25 survey stations, with Ross Worm reef recorded in 34 of the 35 samples. Substantial reef over 10cm high was found at nine survey stations with the most diverse Ross worm reef habitat occurring on a stony reef of cobbles among pebbles off Wylfa. No non-native species were recorded during the survey. In particular there was concern that the Carpet Squirt (Didemnum vexillum) might occur at some of the sites receiving dredge material from Holyhead Port but it was not identified in any of the imagery. This species has recently been reported in natural habitats off the north Kent coast. Relatively little litter was seen in the video, mostly fragments of monofilament , pieces of plastic and cloth. Some toppled Ross worm reef was noted at single sites off Cemlyn and Church Bay. Two of the three sites in Holyhead Deep receiving dredge material from Holyhead Port appeared to be siltier than the near shore survey locations.
- Identification
- Extent
- Distribution
- Quality
- Keywords
- Spatial Reference System
- Content
- Constraints
- Maintenance
- Metadata
Identification
- Identifier
- NRW_DS118982
- Alternative Title
-
- NRW 2016 North Anglesey INNS and Sabellaria video and still image analysis
- Arolwg Rhywogaethau Goresgynnol, Rhywogaethau Estron a Sabellaria spinulosa, Ynys Môn 2016
- 2016 NRW Anglesey INNS and Sabellaria survey
- Metadata Language
- English
- Lineage
-
The survey area extended from Point Lynas west to Church Bay and out to sites on the Skerries, West Anglesey Reef and Holyhead Deep. The camera equipment used for the survey was a sledge mounted C-Tecnics High definition CT3009 camera providing full 1080i HD recording (1920 x 1080). This was obliquely mounted on a sledge accompanied by two C-Tecnics CT4004 LED Lamps each of approximately 1100 lumens, accompanied by two C-Tecnics Laser lights (CT4005 - subsea Laser Modules) and two lasers set 10cm apart to provide a visual scale on the resulting video footage. The video unit had its own integrated depth sensor. The video feed was relayed to the surface unit via a 200m umbilical where realtime GPS positional data and other information were over-laid on the video footage and recorded on the surface unit's computer hard drive. The drop down sledge was also equipped with a RovTech Seacam 18megapixel auto stills camera with an 18 mm lens, twin strobes and battery pack. This was a self-contained system that was set to take pictures at predefined intervals (for this study the stills camera interval varied from 6 to 10 seconds). The camera was set to start recording before the sledge was placed in the water and continued to take images at the predefined interval until it was brought back on board. Images were then downloaded between each camera tow and saved to a computer hard drive. The drop down video survey method followed the MESH (Mapping European Seabed Habitats) standard protocols (Coggan et al., 2007) as closely as possible. Drops were carried out during a neap tide and where possible during the period either side of slack water. Even on a neap tide, given the depth of some of the survey locations and the fast running currents in the area, it was difficult to position the video tow so that it passed exactly through the survey location, although every effort was made to get as close as possible.
- Additional Information
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Baldock, L. and Goudge, H. (2017), North Anglesey INNS and Sabellaria video and still image analysis, NRW Evidence Report 206 pp 61, NRW, Bangor.
- Dataset Reference Date (Publication)
- 2017-06-30
Extent
Extent
- Geographic Extent
- Irish Sea
- Geographic Extent
- Caernarfon Bay
- Geographic Extent
- Menai Strait
))
Vertical Extent
- Medin Extent Keyword
-
circalittoral
Vertical Extent
- Minimum value (metres)
- -19
- Maximum value (metres)
- -84.6
- Vertical CRS
- urn:ogc:def:datum:EPSG::5100 Sea Level depth is unadjusted and does not take into account tidal height
Distribution
- Format Type and Description
-
-
Database
()
- Specification
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[A] Report in PDF Format - held in the DMS [B] Raw video files in .ASF format [C] Still images in .JPG format [D] Survey logs as .XLSM and .TXT format [E] Track GPS data in Arc .SHP and MapInfo .TAB format [G] Marine Recorder Survey [MRCCW32600000002] [H] Field Notes, scanned and stored as .PDF format
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Database
()
Quality
Data quality
- Quality Scope
- Dataset
- Lineage
-
The survey area extended from Point Lynas west to Church Bay and out to sites on the Skerries, West Anglesey Reef and Holyhead Deep. The camera equipment used for the survey was a sledge mounted C-Tecnics High definition CT3009 camera providing full 1080i HD recording (1920 x 1080). This was obliquely mounted on a sledge accompanied by two C-Tecnics CT4004 LED Lamps each of approximately 1100 lumens, accompanied by two C-Tecnics Laser lights (CT4005 - subsea Laser Modules) and two lasers set 10cm apart to provide a visual scale on the resulting video footage. The video unit had its own integrated depth sensor. The video feed was relayed to the surface unit via a 200m umbilical where realtime GPS positional data and other information were over-laid on the video footage and recorded on the surface unit's computer hard drive. The drop down sledge was also equipped with a RovTech Seacam 18megapixel auto stills camera with an 18 mm lens, twin strobes and battery pack. This was a self-contained system that was set to take pictures at predefined intervals (for this study the stills camera interval varied from 6 to 10 seconds). The camera was set to start recording before the sledge was placed in the water and continued to take images at the predefined interval until it was brought back on board. Images were then downloaded between each camera tow and saved to a computer hard drive. The drop down video survey method followed the MESH (Mapping European Seabed Habitats) standard protocols (Coggan et al., 2007) as closely as possible. Drops were carried out during a neap tide and where possible during the period either side of slack water. Even on a neap tide, given the depth of some of the survey locations and the fast running currents in the area, it was difficult to position the video tow so that it passed exactly through the survey location, although every effort was made to get as close as possible.
Keywords
Keywords
Keywords
Keywords
- SeaDataNet Parameter Discovery Vocabulary
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- Seabed photography
- Habitat characterisation
- Habitat extent
- Zoobenthos taxonomic abundance
- Type
- Theme
Citation
- Date (Revision)
- 2021-01-06
Spatial Reference System
Content
Content Information
NRW Profile
Custom Elements
- NRW Related Title
-
North Anglesey INNS and Sabellaria video and still image analysis
Constraints
Constraints
Limitations on Public Access and Use
- Restriction type
- Other restrictions
Access Constraints Directive
- Limitations
- no limitations
Access Constraints Text
- Other constraints
-
There are no access restrictions to this data. NRW may release, publish or disseminate it freely.
Use Constraints
- Use constraints type
- Other restrictions
- Other constraints
-
© CNC/NRW Data may be re-used under the terms of the Open Government Licence providing it is done so, acknowledging both the source and NRW's copyright. It is the recipient's responsibility to ensure the data is fit for the intended purpose.
Metadata
Metadata
- File Identifier
- 4f4c4942-4343-5764-6473-313138393832 XML
- Metadata Language
- English
- Resource type
- Dataset
- Metadata Date
- 2024-05-31T09:37:33.991Z
- Metadata Standard Name
- NRW
- Metadata Standard Version
-
1.0