Brief description
The distribution of seagrass and associated benthic communities was mapped between the 29 July and 29 August 1997 on the reef and lagoon at Low Isles, Great Barrier Reef. For this survey, a total of 349 benthic survey points were examined by observers walking or free‐diving at survey points positioned approximately 50 m apart along a series of transects. To assist with mapping meadow boundaries, an additional 177 points were assessed and a 1:12,000 rectified aerial photo was commissioned (26th August 1997). A differential handheld global positioning system (GPS) was used to locate each point assessed. 127.8 ±29.6 hectares of seagrass was mapped.Lineage
Statement: Seagrass and associated benthic community data was derived by haphazardly placing 3 quadrats (0.25m**2) at each survey point. Seagrass above ground biomass (standing crop, grams dry weight (g DW m**-2)) was determined within each quadrat using a non-destructive visual estimates of biomass technique and the seagrass species present identified. In addition, the cover of all benthos was measured within each of the 3 quadrats using a systematic 5 point method. For each quadrat, frequency of occurrence for each benthic category was converted to a percentage of the total number of points (5 per quadrat). Data are presented as the average of the 3 quadrats at each point. Polygons of discrete seagrass meadow/habitat type boundaries were created using the on-screen digitising functions of ArcGIS (ESRI Inc.), differentiated on the basis of colour, texture, and the geomorphic and geographical context. The resulting seagrass and benthic cover data of each survey point and for each seagrass meadow/habitat type was linked to GPS coordinates and saved as an ArcMap point and polygon shapefile, respectively.
Statement: The boundary of each meadow/habitat type was primarily mapped in the field by observers assessing 526 ground truthed points. A georeferenced aerial photograph was used as a secondary source of information to aid in determining the boundaries of each meadow/habitat type. Bathymetry (elevation below Mean Sea Level) measured at each point assessed and from Ellison (1997) supplemented information used to determine boundaries, particularly in the subtidal lagoon. The on‐screen digitising functions of ArcGIS (ESRI Inc.) were used to create polygons of discrete meadow/habitat types (i.e. COMMUNITY), differentiated on the basis of 349 survey point data (see Low_Isles_1997_BenthicDataSites), the bathymetric contours and the imagery colour, texture, and the geomorphic and geographical context. An ‘estimate of reliability’ (R) of the areal extent (hectares) of each meadow was also calculated based on the errors associated with GPS fixes for survey points and digitising/rectifying the aerial photograph. Each column header title includes the following data:
COMMUNITY description of seagrass meadow/habitat type (dominant seagrass species, features and sediment type)
MDW_ID unique number for each seagrass meadow/habitat type
Ha____R area of polygon in hectares for each seagrass meadow/habitat type with error (±) estimate of Reliability (based on positional accuracy)
East_WGS84 Eastings in meters (UTM Zone 55 South)
Nth_WGS84 Northings in meters (UTM Zone 55 South)
Long_WGS84 Decimal Degrees
Lat_WGS84 Decimal Degrees
COMMUNITY description of seagrass meadow/habitat type (dominant seagrass species, features and sediment type)
MDW_ID unique number for each seagrass meadow/habitat type
Ha____R area of polygon in hectares for each seagrass meadow/habitat type with error (±) estimate of Reliability (based on positional accuracy)
East_WGS84 Eastings in meters (UTM Zone 55 South)
Nth_WGS84 Northings in meters (UTM Zone 55 South)
Long_WGS84 Decimal Degrees
Lat_WGS84 Decimal Degrees
text: westlimit=145.3; southlimit=-16.60; eastlimit=145.8; northlimit=-16.10
Subjects
ANGIOSPERMS (FLOWERING PLANTS) |
AQUATIC ECOSYSTEMS |
Abundance of biota |
BIOLOGICAL CLASSIFICATION |
Biological Sciences |
BIOSPHERE |
Benthic habitat |
Biotic taxonomic identification |
EARTH SCIENCE |
Ecology |
Environmental Science and Management |
Environmental Sciences |
Environmental Management |
Environmental Sciences Not Elsewhere Classified |
Great Barrier Reef |
MARINE HABITAT |
MONOCOTS |
Marine and Estuarine Ecology (Incl. Marine Ichthyology) |
Other Environmental Sciences |
PLANTS |
SEAGRASS |
biota |
diver |
human |
reef |
seagrass |
User Contributed Tags
Login to tag this record with meaningful keywords to make it easier to discover
Other Information
(Original metadata record [PANGAEA catalogue])
doi :
https://doi.pangaea.de/10.1594/PANGAEA.858945
global : 4739e4b0-4dba-4ec5-b658-02c09f27ab9a
Identifiers
- global : b2dbc96b-6737-41ab-b6fd-8fcf1b957ad0
