4f4c4942-4343-5764-6473-313130303634 English Natural Resources Wales (NRW) Maes-y-Ffynnon, Penrhosgarnedd, Bangor, Gwynedd, LL57 2DW, Wales enquiries@naturalresourceswales.gov.uk http://naturalresources.wales/?lang=en 2024-05-31T09:39:45.335Z NRW 1.0 wel British National Grid (EPSG::27700) Initial hydroacoustic mapping of macrophyte communities in the southern end of Llyn Tegid Initial hydroacoustic mapping of macrophyte communities in the southern end of Llyn Tegid Mapio hydroacwstig cychwynnol o gymunedau macroffytau ym mhen deheuol Llyn Tegid, Initial hydroacoustic mapping of macrophyte communities in the southern end of Llyn Tegid, 2008-02-29 NRW_DS110064 This dataset is made up of the results of a hydroacoustic survey to map the extent of submerged macrophyte communities and major substrate types in the southern end of Llyn Tegid. The objectives of the present part of the project were to use hydroacoustics to map the current extent of submerged macrophyte communities and major substrate types in the southern end of Llyn Tegid and to present the findings of such work at the Countryside Council for Wales Marine and Freshwater Workshop 2007. This works was undertaken as a small work package added during the summer of 2007 to a much larger project concerned with the hydroacoustic survey and translocation of the gwyniad (Coregonus lavaretus). This dataset is made up of the results of a hydroacoustic survey to map the extent of submerged macrophyte communities and major substrate types in the southern end of Llyn Tegid. The objectives of the present part of the project were to use hydroacoustics to map the current extent of submerged macrophyte communities and major substrate types in the southern end of Llyn Tegid and to present the findings of such work at the Countryside Council for Wales Marine and Freshwater Workshop 2007. This works was undertaken as a small work package added during the summer of 2007 to a much larger project concerned with the hydroacoustic survey and translocation of the gwyniad (Coregonus lavaretus). Snowdonia National Park Authority National Park Office, Penrhyndeudraeth, Gwynedd, LL48 6LF, Wales parc@snowdonia-npa.gov.uk http://www.eryri-npa.gov.uk/ Natural Resources Wales (NRW) Maes-y-Ffynnon, Penrhosgarnedd, Bangor, Gwynedd, LL57 2DW, Wales enquiries@naturalresourceswales.gov.uk http://naturalresources.wales/?lang=en Snowdonia National Park Authority National Park Office, Penrhyndeudraeth, Gwynedd, LL48 6LF, Wales parc@snowdonia-npa.gov.uk http://www.eryri-npa.gov.uk/ Natural Resources Wales (NRW) Maes-y-Ffynnon, Penrhosgarnedd, Bangor, Gwynedd, LL57 2DW, Wales enquiries@naturalresourceswales.gov.uk http://naturalresources.wales/?lang=en CEH Lancaster Lancaster Environment Centre, Library Avenue, Bailrigg, Lancaster, Lancashire, LA1 4AP enquiries@ceh.ac.uk http://www.ceh.ac.uk/index.html Natural Resources Wales (NRW) Maes-y-Ffynnon, Penrhosgarnedd, Bangor, Gwynedd, LL57 2DW, Wales enquiries@naturalresourceswales.gov.uk http://naturalresources.wales/?lang=en sd">Species distribution Species distribution GEMET - INSPIRE themes, version 1.0 GEMET - INSPIRE themes, version 1.0 2008-06-01 geonetwork.thesaurus.external.theme.httpinspireeceuropaeutheme-theme Llyn Tegid macrophyte surveys macrophytes hydroacoustic marine and freshwater inventory NRW Thesaurus NRW Thesaurus 2023-12-31 geonetwork.thesaurus.local.theme.converted_nrw-keywords There are no access restrictions on this data. NRW may release, publish or disseminate it freely. no limitations © 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. English biota SeaVoX Vertical Co-ordinate Coverages SeaVoX Vertical Co-ordinate Coverages 2021-01-06 Wales (WLS) GWYNEDD - GWYNEDD -3.71531809 -3.53148748 52.83947505 52.95625105 2007-08-13 2007-08-31 Initial hydroacoustic mapping of macrophyte communities in the southern end of Llyn Tegid Documents Raw data derived from the echo sounder is stored in *.dt4 format (Visual Acquisition Version 5.0.4) proprietary software would be required to view or analyse this data. Data from the laboratory examination and analysis of output from the echo sounder and GPS used in the field were analysed with Sonar5-Pro Version 5.9.7 (24.09.2007). This data was supplied as Microsoft Excel files. This report has been produced as a Microsoft Word 2000 file(s) and as an Adobe Portable Document Format version. Commission Regulation (EU) No 1089/2010 of 23 November 2010 implementing Directive 2007/2/EC of the European Parliament and of the Council as regards interoperability of spatial data sets and services 2010-12-08 false Echo sounding was carried out using a BioSonics DT-X echo sounder with a 200 kHz splitbeam vertical transducer of beam angle 6.5 degrees operating under the controlling software Visual Acquisition Version 5.0.4. Throughout the surveys, data threshold was set at -130 dB, pulse rate at 5 pulses s-1, pulse width at 0.1 ms, and data recorded from a range of 0 m from the transducer. The system was deployed from a 4.8 m inflatable dinghy powered by a 25 horse power petrol outboard engine and moving at a speed of c. 1.1 m s-1, depending on wind conditions. The transducer was positioned c. 0.5 m below the surface of the water. Navigation was accomplished using a Garmin GPSMAP 60CSx Global Positioning System (GPS) with accuracy to less than 10 m, while a JRC Model DGPS212 GPS with accuracy to less than 5 m inputted location data directly to the hydroacoustic system where they were incorporated into the recorded hydroacoustic data files. Prior to the surveys, the hydroacoustic system had been calibrated using a tungsten carbide sphere of target strength (TS) -39.5 dB at a sound velocity of 1470 ms-1. Hydroacoustic surveys were undertaken between c. 20.29 and 21.34 hours on 13 August 2007 using 20 transects, each starting near the 10 m depth contour and running directly inshore to a depth of c. 1 m. Transects varied in length from c. 20 to 226 m depending on local bathymetry and hindrances to navigation in the form of semi-submerged fences or near-surface rocks. Echo sounding was carried out using a BioSonics DT-X echo sounder with a 200 kHz splitbeam vertical transducer of beam angle 6.5 degrees operating under the controlling software Visual Acquisition Version 5.0.4. Throughout the surveys, data threshold was set at -130 dB, pulse rate at 5 pulses s-1, pulse width at 0.1 ms, and data recorded from a range of 0 m from the transducer. The system was deployed from a 4.8 m inflatable dinghy powered by a 25 horse power petrol outboard engine and moving at a speed of c. 1.1 m s-1, depending on wind conditions. The transducer was positioned c. 0.5 m below the surface of the water. Navigation was accomplished using a Garmin GPSMAP 60CSx Global Positioning System (GPS) with accuracy to less than 10 m, while a JRC Model DGPS212 GPS with accuracy to less than 5 m inputted location data directly to the hydroacoustic system where they were incorporated into the recorded hydroacoustic data files. Prior to the surveys, the hydroacoustic system had been calibrated using a tungsten carbide sphere of target strength (TS) -39.5 dB at a sound velocity of 1470 ms-1. Hydroacoustic surveys were undertaken between c. 20.29 and 21.34 hours on 13 August 2007 using 20 transects, each starting near the 10 m depth contour and running directly inshore to a depth of c. 1 m. Transects varied in length from c. 20 to 226 m depending on local bathymetry and hindrances to navigation in the form of semi-submerged fences or near-surface rocks.