Initial hydroacoustic mapping of macrophyte communities in the southern end of Llyn Tegid

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).

Identifier: NRW_DS110064

Alternative Title

Mapio hydroacwstig cychwynnol o gymunedau macroffytau ym mhen deheuol Llyn Tegid,
Initial hydroacoustic mapping of macrophyte communities in the southern end of Llyn Tegid,

Metadata Language: English

Lineage: 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.

Dataset Reference Date (Publication): 2008-02-29

Temporal Extent

Begin date: 2007-08-13

End date: 2007-08-31

Topic category

Biota

Owner

Snowdonia National Park Authority

National Park Office, Penrhyndeudraeth, Gwynedd, LL48 6LF, Wales

http://www.eryri-npa.gov.uk/

Owner

Natural Resources Wales (NRW)

Maes-y-Ffynnon, Penrhosgarnedd, Bangor, Gwynedd, LL57 2DW, Wales

http://naturalresources.wales/?lang=en

Originator

CEH Lancaster

Lancaster Environment Centre, Library Avenue, Bailrigg, Lancaster, Lancashire, LA1 4AP

http://www.ceh.ac.uk/index.html

Extent

Geographic Extent: Wales (WLS)

Geographic Extent: GWYNEDD - GWYNEDD

Map representing the geographic extent of the dataset

Format Type and Description

Documents Documents ()

Specification

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.

Data quality

Quality Scope: Dataset

Conformity: 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
Explanation
Degree: false

Lineage: 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.

Keywords

GEMET - INSPIRE themes, version 1.0

Species distribution

Type: Theme

Citation

Date (Publication): 2008-06-01

Code: geonetwork.thesaurus.external.theme.httpinspireeceuropaeutheme-theme

Keywords

NRW Thesaurus

Llyn Tegid
macrophyte surveys
macrophytes
hydroacoustic
marine and freshwater inventory

Type: Theme

Citation

Date (Publication): 2023-12-31

Code: geonetwork.thesaurus.local.theme.converted_nrw-keywords

Code: British National Grid (EPSG::27700)

Content Information

NRW Profile

Custom Elements

NRW Related Title: Initial hydroacoustic mapping of macrophyte communities in the southern end of Llyn Tegid

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 on 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

File Identifier: 4f4c4942-4343-5764-6473-313130303634 XML

Metadata Language: English

Resource type: Dataset

Metadata Date: 2024-05-31T09:39:45.335Z

Metadata Standard Name: NRW

Metadata Standard Version: 1.0

pointOfContact

Natural Resources Wales (NRW)

Maes-y-Ffynnon, Penrhosgarnedd, Bangor, Gwynedd, LL57 2DW, Wales

http://naturalresources.wales/?lang=en

Publishing Body

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Initial hydroacoustic mapping of macrophyte communities in the southern end of Llyn Tegid

Identification

Temporal Extent

Extent

Extent

Distribution

Quality

Data quality

Keywords

Keywords

Citation

Keywords

Citation

Spatial Reference System

Content

Content Information

NRW Profile

Custom Elements

Constraints

Constraints

Limitations on Public Access and Use

Access Constraints Directive

Access Constraints Text

Use Constraints

Metadata

Metadata

Publishing Body