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CERF Underwater Video and Stills from Carnarvon Shelf

Note: This metadata describes the dataset in accordance with the ANZLIC (Australia New Zealand Land Information Council) Core Metadata Guidelines Version 2.


Dataset citation

ANZLIC unique identifier: ANZCW0703015196

Title: CERF Underwater Video and Stills from Carnarvon Shelf


Custodian

Custodian: Geoscience Australia

Jurisdiction: Australia


Description

Abstract:

Geoscience Australia carried out a marine survey on Carnarvon shelf (WA) in 2008 (SOL4769) to map seabed bathymetry and characterise benthic environments through co-located sampling of surface sediments and infauna, observation of benthic habitats using underwater towed video and stills photography, and measurement of ocean tides and wave-generated currents. Data and samples were acquired using the Australian Institute of Marine Science (AIMS) Research Vessel Solander. Bathymetric mapping, sampling and video transects were completed in three survey areas that extended seaward from Ningaloo Reef to the shelf edge, including: Mandu Creek (80 sq km); Point Cloates (281 sq km), and; Gnaraloo (321 sq km). Additional bathymetric mapping (but no sampling or video) was completed between Mandu creek and Point Cloates, covering 277 sq km and north of Mandu Creek, covering 79 sq km. Two oceanographic moorings were deployed in the Point Cloates survey area. The survey also mapped and sampled an area to the northeast of the Muiron Islands covering 52 sq km. TheGA0308_Carnarvon_SOL4976 folder contains video footage and still images. The MS databse, the Excel files are video characterisation datasets: Carnarvon_video data (export).mdb; all_substrata_tx.xls (transect level); all_substrata_patch.xls (patch level); all_benthos_tx.xls (transect level); all_benthos_patch.xls (patch level); Carnarvon_QAQC_VIDEOlog.doc (QAQC document); Attribute_metadata.xls (attribute definition). Underwater towed-video footage abd still images represent the raw data. Video characterisation datasets include percent cover of substrata and benthic taxa characterised at two spatial scales: transect scale (mean values per transect) and patch scale (mean values for each patch type within a transect).

ANZLIC search words:

  • GEOSCIENCES Mapping
  • MARINE

Spatial domain:

locality map

Geographic extent name: AUSTRALIA EXCLUDING EXTERNAL TERRITORIES - AUS - Australia - Australia

Geographic extent polygon: 111 -11, 124 -11, 124 -23, 111 -23, 111 -11,

Note: The format for each Geographic extent name is: Name - Identifier - Category - Jurisdiction (as appropriate) See GEN Register

Geographic bounding box:
North bounding latitude: -11 °
South bounding latitude: -23 °
East bounding longitude: 124 °
West bounding longitude: 111 °

Data currency

Beginning date: 2009-02-23

Ending date: 2009-02-23


Dataset status

Progress: Complete

Maintenance and update frequency: Not Known


Access

Stored data format:
DIGITAL - xls Microsoft Excel spreadsheet Excel
Available format type:
DIGITAL - xls Microsoft Excel spreadsheet Excel

Access constraints:

This material is released under the Creative Commons Attribution 3.0 Australia Licence.

Free Data Download

Data quality

Lineage:

The distribution of seabed habitats and associated assemblages were visually characterised from underwater tow-video footage from the immediate nearshore to just beyond the shelf break in three survey areas (Mandu, Pt Cloates, and Gnaraloo). At each station within the three survey areas, a single towed-video transect was undertaken using the AIMSs towed-video system, deployed from the stern of the RV Solander and towed for a distance of approximately 500 m. An operator used a remote-controlled winch to maintaining an altitude of 0.5 to 2 m above the seabed. The towed-camera system housed a forward-facing video camera and down-facing stills camera and their associated lights. Using the forward-facing video camera, video was transmitted to the surface via coaxial cable where video footage was recorded to mini DV tapes, and copied to digital format. The vertically mounted stills camera took digital photographs of the benthos every two seconds. The original mini DV tapes and still images are archived at AIMS-WA while digital copies are housed at GA and AIMS. The ships GPS position (i.e. UTC date and time, depth, latitude and longitude) was encoded to the audio track (called timecode) of the video footage for each video transect (although 8 transects failed to have GPS positions encoded) using Geocoder and following AIMS protocols. Underwater video footage and still images were collected from 122 stations from water depths of 13-125 m, although video quality varies among transects and some still images were not of suitable quality for analysis. 112 transects (those with gps timecode) were post-processed to provide characterisations of seabed habitats and benthic assemblages. Percent cover estimates were recorded for a single frame every 15 seconds along the transect. Due to the oblique angle of the video footage the observer recorded the percent coverage across the bottom 2/3 of the frame for each substratum type, and benthic taxa. Due to the positional uncertainty of the video data (approx. 30 m), these data were then used to calulate mean values of percent cover for each transect (transect scale, approx. 500m) and for patches within transects (patch-scale, generally 30 m or greater).

Positional accuracy:

There is a position accuracy/uncertainty of 30 m (multidirectional). The gps location of transects was recorded using the RV solanders GPS system (ie Shipboard navigation). Using ship board navigation means that there is some uncertainty as to the position of the towed-video system behind the ship. There is an estimated 30 m multidirectional uncertainy in position, based on the offset between a feature in the video relative to the location of the same feature in the bathymetry. This positional uncertainty can not be assumed to be directly behind the ship as current and winds often place the towed-video system at an angle to the ship.

Attribute accuracy:

Benthic organisms were identified to lowest possible taxonomic category, for example broad taxonomic groups (e.g. sponges, octocorals, hard corals), genera (Kebab sponges) and species (e.g. piebald holothurian). Taxonomic Identifications of taxa seen in the video footage were provided by Andrew Heyward (hard corals), octocorals (Katharina Fabricius), sponges (Chris Battershill and Christine Schonberg), mixed taxa (Matthew McArthur), and species identification books. All video data were carefully QA and QC. Data quality and data control was checked for errors and inconsistencies by two different operators, all data errors and subsequent changes to the dataset were recorded in a QA and QC video log (file name: Carnarvon_QAQC_VIDEOlog.doc), which can be found at the following location: Carnarvon_Shelf\Ningaloo(AIMS-GA)\BE Data\data delivery. These attributes are defined in the MS Access database under lookup tables (e.g. lkup_benthos, lkup_substrata) and have been exported as an excel file: Attribute_metadata.xls. You can also refer to definitions.xls for the definitions of the attributes and their values.

Logical Consistency:

All model outputs data have been visually checked for artefacts and spurious data. Tests

conducted to ensure data are reliable and valid.

Completeness:

Complete


Contact information

Contact organisation: Commonwealth of Australia (Geoscience Australia) (GA)
Contact position: Manager Client Services
Mail address: Cnr Jerrabomberra Ave and Hindmarsh Dr
Mail address: GPO Box 378
Locality: Canberra
State: ACT
Country: Australia
Postcode: 2601
Telephone: 02 6249 9966
Facsimile: 02 6249 9960
Electronic mail address: sales@ga.gov.au

Metadata information

Metadata date: 2013-03-08


Additional metadata

Metadata reference XHTML: http://www.ga.gov.au/meta/ANZCW0703015196.html

Metadata reference XML: http://www.ga.gov.au/meta/ANZCW0703015196.xml

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Authors:Geoscience Australia
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