Brief description
In 2006, transect surveys were conducted at sites in eastern inshore Tasmanian waters at depths and habitats typical of those where abalone are commercially fished. Surveys focused on four areas of the Tasmanian coastline including St Helens, Bicheno and Dunalley on the east coast and the Actaeons region on the south-east coast; with at least 10 reefs sampled in each region.Lineage
Maintenance and Update Frequency: notPlanned
Statement: At each survey site a 100-m transect was deployed from the boat along the 6–8 m depth contour (2-3m at a few Dunnalley sites. Five 20 m2 quadrats were positioned at 20-m intervals along the transect and in each quadrat the number of H. rubra and other large mobile grazers (e.g. sea urchins) was recorded. Total H. rubra abundance was split into two separate categories of ‘cryptic’ and ‘emergent’ based on the location of individual animals. Cryptic H. rubra were defined as those hidden in cracks and crevices, while emergent H. rubra occupied exposed reef surfaces. Abundance of canopy-forming algae in each quadrat was also estimated by classifying cover of different species according to the following categories: 1 = 0–10%;
2 = 11–30%; 3 = 31–50%; 4 = 51–75%; 5 = 76–100%.
Abundance of understorey organisms (including algae and sessile invertebrates) was assessed in terms of percentage cover. Percentage cover was estimated with a 0.25 m2 ‘subquadrat’ using a point intercept method. The subquadrat was divided with a grid of 49 evenly spaced intersections and was laid flat on the reef during algal assessment. Algae occurring under each intercept and one corner of the subquadrat were recorded, to give a total of 50 intersections per subquadrat. Five randomly positioned subquadrats were assessed in this way for each 20 m2 quadrat. Organisms were identified in situ to the highest taxonomic resolution possible. For canopy algae identification to species level was possible; however, it was necessary to allocate other species to species complexes or guilds (e.g. crustose coralline algae, foliose red algae, sessile invertebrates).
Further environmental correlates measured, included relative wave exposure.
Notes
CreditFisheries Research & Development Corporation FRDC 2004/013
Purpose
The purpose of this data collection is identify reef-scale patterns in algal understory change in relation to changes in abalone abundance.
The purpose of this data collection is identify reef-scale patterns in algal understory change in relation to changes in abalone abundance.
Created: 03 07 2007
Data time period: 05 05 2006 to 03 08 2006
text: westlimit=147; southlimit=-44.0; eastlimit=148.5; northlimit=-40.5
text: uplimit=8; downlimit=2
Subjects
Agricultural and Veterinary Sciences |
AGRICULTURAL AQUATIC SCIENCES |
AGRICULTURE |
AQUATIC ECOSYSTEMS |
Abalone abundance |
Aquatic Ecosystem Studies and Stock Assessment |
Biological Sciences |
BIOSPHERE |
Blacklip abalone |
EARTH SCIENCE |
Ecology |
Fisheries |
Fisheries Sciences |
Fisheries Sciences Not Elsewhere Classified |
Haliotis rubra |
Marine Habitat |
Marine and Estuarine Ecology (Incl. Marine Ichthyology) |
Oceans | Marine Biology | Marine Invertebrates |
Substratum type |
biota |
canopy forming algae coverage |
crustose coralline algae |
crustose coralline algae coverage |
ecosystem changes |
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Identifiers
- global : 6070de80-44a3-11dc-8cd0-00188b4c0af8
