7824ba8cc3487aea5987410c83c9e362 English dataset Cornwall Inshore Fisheries and Conservation Authority Data Officer Cornwall IFCA Research Team enquiries@cornwall-ifca.gov.uk pointOfContact 2024-07-23 MEDIN Discovery metadata standard 2.3.8 urn:ogc:def:crs:EPSG::4326 2021 Cornwall Inshore Fisheries and Conservation Authority (IFCA) and the University of Exeter Fal and Helford Special Area of Conservation Acoustic Survey of the seagrass beds 2021-09-03 publication 2021_CIFCA_MX_FAH_Seagrass Cornwall Inshore Fisheries and Conservation Authority (Cornwall IFCA) were contracted by the University of Exeter to map the extent of the seagrass within the Fal and Helford Special Area of Conservation (SAC). The contract includes joint intellectual property (IP) of all data collected. In 2020, Cornwall Council declared a climate emergency and set new targets to achieve carbon net zero by 2030. To achieve carbon neutrality, a climate change action plan was produced. The project was commissioned to consider how specialist evidence and development of nature recovery plans can be used in the marine environment to help deliver Cornwall Councils carbon neutral and environmental growth goals. The seagrass was mapped “to gather specialist evidence for restoration plans and blue carbon accounts to guide the delivery of practical measures to maximise marine nature recovery and carbon drawdown by eelgrass in the Fal and Helford estuaries” (Cornwall Council, 2021). The aim of the survey was to map the extent and coverage of the seagrass beds within the Fal and Helford SAC using a Biosonics MX Scientific Echosounder. In total 407 MX tows were completed of which 403 were included in the analysis. Research Team Cornwall IFCA Cornwall Inshore Fisheries and Conservation Authority enquiries@cornwall-ifca.gov.uk originator Research Team Cornwall IFCA Cornwall Inshore Fisheries and Conservation Authority enquiries@cornwall-ifca.gov.uk custodian asNeeded Marine Environmental Data and Information Network NDGO0005 Habitats and biotopes GEMET - INSPIRE themes, version 1.0 2008-01-06 revision Habitat extent SeaDataNet P021 parameter discovery vocabulary 2009-11-16 revision Data is freely available for research or commercial use providing that the originators are acknowledged (Cornwall IFCA and University of Exeter) in any publications produced and permission must be sought if the data will be reproduced in full or part or if used in any analyses. otherRestrictions No restrictions to public access English biota Charting Progress 2 Sea Areas 2009-06-18 creation Western Channel and Celtic Sea ICES Rectangles 2009-05-01 creation 29E4 SeaDataNet vertical extent keywords 2010-01-01 revision water column -5.1365 -5.0057 50.0667 50.1780 2021-05-18 2021-08-16 2.1000 23.3000 Jenkin, A., Sturgeon S and Trundle, C. 2021.Acoustic survey of the seagrass beds within the Fal and Helford Special Area of Conservation Field Report. Cornwall Inshore Fisheries and Conservation Authority (Cornwall IFCA), Hayle. Research Team Cornwall IFCA Cornwall Inshore Fisheries and Conservation Authority enquiries@cornwall-ifca.gov.uk distributor dataset MEDIN data guideline for sidescan sonar (SSS) data 2012-04-30 publication See the referenced specification true Historic survey data of seagrass within the Fal and Helford SAC were download using the latest marine data release provided by Natural England and EMODnet and a 40 m buffer was created around each bed. These positions were uploaded onto HYPACK MAX Version 2019 software. For each polygon, survey lines were created depending on the aspect of each individual bed so that the survey lines ran perpendicular where possible to the coastline following the Environment Agency methodology of subtidal seagrass monitoring for the Water Framework Directive (WFD) (Environment Agency, 2019). Each survey line ran further than the known extent of each bed to capture any changes to the bed extent since they were last surveyed. The survey lines were set up with 20 m line spacing. Acoustic data was acquired using a MX Aquatic Habitat Echosounder (Appendix 2). The echosounder lets you simultaneously acquire submerged aquatic vegetation (including seagrass), substrate and bathymetry data using Visual Acquisition by BioSonics (Version 6.4) software. The transducer was deployed over the port side of the vessel via a pole mounted on the side which can be deployed for survey operations. Acoustic data was collected in nine survey areas to map the extent of the beds. Remote access software was used on all laptops to enable the home based Scientific officers to independently operate the MX Echosounder controls and HYPACK. Microsoft Teams was also used throughout each survey day to enable the home-based officers to maintain continuous communication with the survey crew aboard the vessel. On arrival at each bed, a Valeport Swift Sound Velocity Profiler was deployed to measure the Conductivity, Temperature, and Depth (CTD). Once recovered to deck the data was downloaded using Valeport Data log X2 software and the temperature and salinity values from the bottom depth were input into the Visual Acquisition software. A folder for each survey area was created prior to the deployment of the MX and data was recorded with date and time stamps for each file e.g. 20210701_125251. A target was created in HYPACK to indicate the start of line (SOL); this was repeated at the end of line (EOL). The speed over ground was aimed to be at a constant of 4.5 knots so that the pings from the MX were at a consistent distance. In areas where it was hard to decipher if patchy seagrass was present, a sport action HD camera or Remotely Operated Vehicle (ROV) were deployed to verify the acoustic signature. A target was created in HYPACK to indicate SOL and EOL and the footage was reviewed once the camera was recovered to the deck. MX SOL and EOL positions, targets for verification and video tow SOL and EOL positions were recorded in the Lat/Long WGS84 projection taken from a single GPS, Hemisphere V500 GNSS system on Tiger Lily VI. HYPACK targets were extracted as a .txt file format and opened in Microsoft Excel (comma delimited). The video files and raw MX files (.DT4 and .RTPX) were transferred from the PC to a WD Passport for transport and storage at the end of each survey day. The log sheets were worked on from the shared network drive and saved at the end of each day. A total of 407 lines were completed and a total of 403 lines were included in the data analysis. All lines for each bed were loaded into Visual Aquatic by BioSonics software in a batch, then analysed individually. Quality assurance (QA) was carried out for tows individually and the bottom line and plant line were manually adjusted where there were errors. The plant line was adjusted when anything other than seagrass present such as algae (kelp beds on rock, areas of long seaweed such as Sargassum muticum and areas of low lying weed such as algal turf. Once each line was corrected, the post processing information was recorded in the survey log. The analysed data were exported from Visual Aquatic as a .csv file which records the data as an average of every ten pings. The data was copied to Microsoft Excel pasted to columns with corrected headers including latitude, longitude, date, time and notes. This was saved as a .xls file and imported into MapInfo Professional Advanced (Version 17.0.4) to create points. A theme was added to the points data for the plant height (m) and the plant coverage (%). A polygon was drawn around each survey area clipped to the point at the start and end of each tow. A raster was created using the natural neighbour function for plant height (m) and plant coverage (%). The settings for the raster were distance: 20 m, smoothing: 0, clipped to polygon for each survey area, cell size: user suggested and interpolated along edges. Advanced colour was used to define the colour scales. Plots were created for points of plant height (m), percentage cover (%) of seagrass, contour plot of plant height (m) and the contour plot of percentage cover of seagrass (%).