Data

Video surveys of long spined sea urchin (Centrostephanus rodgersii) barrens habitat, eastern Tasmania

Australian Ocean Data Network
Johnson, Craig, Prof.
Viewed: [[ro.stat.viewed]] Cited: [[ro.stat.cited]] Accessed: [[ro.stat.accessed]]
ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Adc&rfr_id=info%3Asid%2FANDS&rft_id=https://metadata.imas.utas.edu.au/geonetwork/srv/eng/catalog.search#/metadata/6d88abe0-8e7a-11dc-94b1-00188b4c0af8&rft.title=Video surveys of long spined sea urchin (Centrostephanus rodgersii) barrens habitat, eastern Tasmania&rft.identifier=https://metadata.imas.utas.edu.au/geonetwork/srv/eng/catalog.search#/metadata/6d88abe0-8e7a-11dc-94b1-00188b4c0af8&rft.description=The spatial extent of C. rodgersii barrens was estimated by surveying rocky reef habitat with a towed underwater video system. Sampling took place at 13 regions along the east coast of Tasmania, each comprising 3 subsites. Substrate and habitat type were recorded using video analysis, with 4 categories of urchin barren habitat recognised (see below for definitions).Maintenance and Update Frequency: notPlannedStatement: Sampling took place at 13 regions along the east coast of Tasmania, each comprising 3 subsites. At each subsite two video transects were conducted perpendicular to the shore and two transects were conducted parallel with the shore. The perpendicular transects covered depths from 1 to 45 m, while parallel transects were within a depth range of 15 to 20 m. In most cases, perpendicular tows spanned the width of reef from the shore to the reef fringe/sand edge. Parallel tows were conducted for 20-30 minutes or approximately 1 km in length (straight-line distance from tow start point), but tow speed varied depending on weather conditions and reef topography. Thus, at each site, ca. 6-7 km of inshore rocky reef was surveyed for barren habitat using this method, with the entire survey covering > 80 km of reef. Substratum types were resolved as either unclassified reef if the substratum type was unclear (usually where macroalgal cover prevented a clear view of the substratum) or, where the substratum could be discerned, flat rock with little apparent relief, boulder reef, cobble, gravel, pebble, or sand. Habitat types denoted either C. rodgersii barrens, or habitat dominated by particular canopy-forming species. Habitat was classified as sea urchin barrens when the understorey was completely denuded, and the overstorey occupied 10 m, while the other 3 categories are different types of patchy incipient barrens, where a patch was defined as a section of reef that was not continuously barren for 10 m. Type 2 barrens was defined as patchy barren where barrens covered > 40% of the bottom; Type 3 barrens defined patchy barrens in which barrens occupied between 20 - 40% cover; while Type 4 barrens referred to patchy barren where barren cover was < 20% cover.Statement: The video camera system was a scaled down version of the system developed by Barker et al. (1999). The camera was mounted inside a positively buoyant protective cage with an attached chain to provide stability and ensure that the camera and frame floated 1-2 m above the sea floor. This system enabled towing the camera across rocky reef with rough topographic relief so that the camera remained a similar distance off the sea floor regardless of depth, providing a field of view ca. 3-4 m wide depending on surge and topography. The camera system was linked to (1) an onboard video recorder to capture the image, date, time, position and depth; (2) a real time monitor; and (3) computer which logged the depth under the boat (from an electronic depth sounder) and position (from a GPS) of the vessel at 4 s intervals, and comments input by the operator. Note that data on depth and position related to the boat, while the camera was on a tow line 40-55 m behind the boat. In the laboratory, the video footage was examined in detail to classify habitat types, which was recorded against the logged data. In this way, the total distance of each video transect tow, and the proportion of each transect that was classified as C. rodgersii barrens and other habitat types was estimated from the logged GPS coordinates. In the event of poor GPS signals (e.g. at base of large cliffs), position was back-calculated by interpolating between fixes determined from good satellite coverage. GPS used datum WGS84. Note GPS inaccuracy may have resulted if datum type unknowingly changed etc (e.g. some points may appear on land, however subsite names may also give an indication as to actual location).&rft.creator=Johnson, Craig, Prof. &rft.date=2007&rft.coverage=westlimit=148.30; southlimit=-41.00; eastlimit=148.40; northlimit=-40.90&rft.coverage=westlimit=148.30; southlimit=-41.00; eastlimit=148.40; northlimit=-40.90&rft.coverage=westlimit=148.30; southlimit=-41.300000000000004; eastlimit=148.40; northlimit=-41.20&rft.coverage=westlimit=148.30; southlimit=-41.300000000000004; eastlimit=148.40; northlimit=-41.20&rft.coverage=westlimit=148.30; southlimit=-41.60; eastlimit=148.40; northlimit=-41.50&rft.coverage=westlimit=148.30; southlimit=-41.60; eastlimit=148.40; northlimit=-41.50&rft.coverage=westlimit=148.20; southlimit=-41.90; eastlimit=148.30; northlimit=-41.80&rft.coverage=westlimit=148.20; southlimit=-41.90; eastlimit=148.30; northlimit=-41.80&rft.coverage=westlimit=147.90; southlimit=-42.90; eastlimit=148.00; northlimit=-42.80&rft.coverage=westlimit=147.90; southlimit=-42.90; eastlimit=148.00; northlimit=-42.80&rft.coverage=westlimit=148.30; southlimit=-42.20; eastlimit=148.40; northlimit=-42.10&rft.coverage=westlimit=148.30; southlimit=-42.20; eastlimit=148.40; northlimit=-42.10&rft.coverage=westlimit=148.30; southlimit=-42.400000000000006; eastlimit=148.40; northlimit=-42.30&rft.coverage=westlimit=148.30; southlimit=-42.400000000000006; eastlimit=148.40; northlimit=-42.30&rft.coverage=westlimit=148.10; southlimit=-42.70; eastlimit=148.20; northlimit=-42.60&rft.coverage=westlimit=148.10; southlimit=-42.70; eastlimit=148.20; northlimit=-42.60&rft.coverage=westlimit=147.30; southlimit=-43.10; eastlimit=147.40; northlimit=-43.00&rft.coverage=westlimit=147.30; southlimit=-43.10; eastlimit=147.40; northlimit=-43.00&rft.coverage=westlimit=147.30; southlimit=-43.40; eastlimit=147.40; northlimit=-43.30&rft.coverage=westlimit=147.30; southlimit=-43.40; eastlimit=147.40; northlimit=-43.30&rft.coverage=westlimit=147.90; southlimit=-43.20; eastlimit=148.00; northlimit=-43.10&rft.coverage=westlimit=147.90; southlimit=-43.20; eastlimit=148.00; northlimit=-43.10&rft.coverage=westlimit=147.70; southlimit=-43.30; eastlimit=147.80; northlimit=-43.20&rft.coverage=westlimit=147.70; southlimit=-43.30; eastlimit=147.80; northlimit=-43.20&rft.coverage=westlimit=147.00; southlimit=-43.60; eastlimit=147.10; northlimit=-43.50&rft.coverage=westlimit=147.00; southlimit=-43.60; eastlimit=147.10; northlimit=-43.50&rft.coverage=uplimit=45; downlimit=1&rft.coverage=uplimit=45; downlimit=1&rft_rights=Creative Commons Attribution-Share Alike 2.5 Australia License http://creativecommons.org/licenses/by-sa/2.5/au/&rft_rights=The citation in a list of references is: citation author name/s (year metadata published), metadata title. Citation author organisation/s. File identifier and Data accessed at (add http link).&rft_rights=The data described in this record are the intellectual property of the University of Tasmania through the School of Zoology and the Tasmanian Aquaculture and Fisheries Institute.&rft_subject=biota&rft_subject=25 211001&rft_subject=Centrostephanus rodgersii&rft_subject=SEA URCHINS&rft_subject=EARTH SCIENCE&rft_subject=BIOLOGICAL CLASSIFICATION&rft_subject=ANIMALS/INVERTEBRATES&rft_subject=ECHINODERMS&rft_subject=RANGE CHANGES&rft_subject=REEF HABITAT&rft_subject=BIOSPHERE&rft_subject=AQUATIC ECOSYSTEMS&rft_subject=INVASIVE SPECIES&rft_subject=Temperate Reef&rft_subject=Marine and Estuarine Ecology (incl. Marine Ichthyology)&rft_subject=BIOLOGICAL SCIENCES&rft_subject=ECOLOGY&rft_subject=Ecological Impacts of Climate Change&rft_subject=ENVIRONMENTAL SCIENCES&rft_subject=ECOLOGICAL APPLICATIONS&rft_subject=diver&rft_subject=Substratum type&rft_subject=Habitat type&rft_subject=Urchin barren zone&rft_subject=Algal species coverage&rft_subject=Abundance of biota&rft.type=dataset&rft.language=English Access the data
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The citation in a list of references is: citation author name/s (year metadata published), metadata title. Citation author organisation/s. File identifier and Data accessed at (add http link).

The data described in this record are the intellectual property of the University of Tasmania through the School of Zoology and the Tasmanian Aquaculture and Fisheries Institute.

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Brief description

The spatial extent of C. rodgersii "barrens" was estimated by surveying rocky reef habitat with a towed underwater video system. Sampling took place at 13 regions along the east coast of Tasmania, each comprising 3 subsites. Substrate and habitat type were recorded using video analysis, with 4 categories of urchin barren habitat recognised (see below for definitions).

Lineage

Maintenance and Update Frequency: notPlanned
Statement: Sampling took place at 13 regions along the east coast of Tasmania, each comprising 3 subsites. At each subsite two video transects were conducted perpendicular to the shore and two transects were conducted parallel with the shore. The perpendicular transects covered depths from 1 to 45 m, while parallel transects were within a depth range of 15 to 20 m. In most cases, perpendicular tows spanned the width of reef from the shore to the reef fringe/sand edge. Parallel tows were conducted for 20-30 minutes or approximately 1 km in length (straight-line distance from tow start point), but tow speed varied depending on weather conditions and reef topography. Thus, at each site, ca. 6-7 km of inshore rocky reef was surveyed for barren habitat using this method, with the entire survey covering > 80 km of reef. Substratum types were resolved as either "unclassified reef" if the substratum type was unclear (usually where macroalgal cover prevented a clear view of the substratum) or, where the substratum could be discerned, "flat rock" with little apparent relief, "boulder reef", "cobble", "gravel", "pebble", or "sand". Habitat types denoted either C. rodgersii barrens, or habitat dominated by particular canopy-forming species. Habitat was classified as sea urchin barrens when the understorey was completely denuded, and the overstorey occupied <15% cover. We recognized four categories of sea urchin barrens habitat: Type 1 barrens denotes continuous barrens habitat in the camera field of view for > 10 m, while the other 3 categories are different types of "patchy" incipient barrens, where a patch was defined as a section of reef that was not continuously barren for 10 m. Type 2 barrens was defined as patchy barren where barrens covered > 40% of the bottom; Type 3 barrens defined patchy barrens in which barrens occupied between 20 - 40% cover; while Type 4 barrens referred to patchy barren where barren cover was < 20% cover.
Statement: The video camera system was a scaled down version of the system developed by Barker et al. (1999). The camera was mounted inside a positively buoyant protective cage with an attached chain to provide stability and ensure that the camera and frame floated 1-2 m above the sea floor. This system enabled towing the camera across rocky reef with rough topographic relief so that the camera remained a similar distance off the sea floor regardless of depth, providing a field of view ca. 3-4 m wide depending on surge and topography. The camera system was linked to (1) an onboard video recorder to capture the image, date, time, position and depth; (2) a real time monitor; and (3) computer which logged the depth under the boat (from an electronic depth sounder) and position (from a GPS) of the vessel at 4 s intervals, and comments input by the operator. Note that data on depth and position related to the boat, while the camera was on a tow line 40-55 m behind the boat. In the laboratory, the video footage was examined in detail to classify habitat types, which was recorded against the logged data. In this way, the total distance of each video transect tow, and the proportion of each transect that was classified as C. rodgersii barrens and other habitat types was estimated from the logged GPS coordinates. In the event of poor GPS signals (e.g. at base of large cliffs), position was back-calculated by interpolating between fixes determined from good satellite coverage. GPS used datum WGS84. Note GPS inaccuracy may have resulted if datum type unknowingly changed etc (e.g. some points may appear on land, however subsite names may also give an indication as to actual location).

Notes

Credit
Ling, Scott
Credit
Ross, Jeff, Dr
Credit
Funding: FRDC project 2001/044
Purpose
To determine the distribution of barrens habitat associated with the long spined sea urchin (Centrostephanus rodgersii) on the east coast of Tasmania.

Created: 30 10 2007

Data time period: 26 10 2001 to 17 08 2002

This dataset is part of a larger collection

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Subjects
25 211001 | ANIMALS/INVERTEBRATES | AQUATIC ECOSYSTEMS | Abundance of biota | Algal species coverage | BIOLOGICAL CLASSIFICATION | Biological Sciences | BIOSPHERE | Centrostephanus rodgersii | EARTH SCIENCE | ECHINODERMS | Ecological Applications | Ecology | Environmental Sciences | Ecological Impacts of Climate Change | Habitat type | INVASIVE SPECIES | Marine and Estuarine Ecology (Incl. Marine Ichthyology) | RANGE CHANGES | REEF HABITAT | SEA URCHINS | Substratum type | Temperate Reef | Urchin barren zone | biota | diver |

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Other Information
(DATA - *Large download: 20GB* Zip file containing raw video files from transects across all 13 regions [direct download])

uri : https://data.imas.utas.edu.au/attachments/6d88abe0-8e7a-11dc-94b1-00188b4c0af8/all_video_transects.zip

(README - Key to variable names used in data (.docx) [direct download])

uri : https://data.imas.utas.edu.au/attachments/6d88abe0-8e7a-11dc-94b1-00188b4c0af8/AnalysisLog.docx

(SUPPLEMENTARY INFO - GPS coordinates for sites and subsites (.xls) [direct download])

uri : https://data.imas.utas.edu.au/attachments/6d88abe0-8e7a-11dc-94b1-00188b4c0af8/GPS_coordinates_dive_transects_FRDC_____survey_2001_044.xls

(SUPPLEMENTARY INFO - Short sample clip showing video file quality [link])

uri : http://youtu.be/79eTl2ljVuE

Identifiers
  • global : 6d88abe0-8e7a-11dc-94b1-00188b4c0af8
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