LIZARD ISLAND
Subtidal Seagrass Mapping Results
Data collection: CYWP, CSIRO and Dingaal Traditional Owners
Map planning, Data Analysis: CYWP
Data Collection Protocols: Seagrass-Watch
Map creation: Seagrass-Watch
- Lizard Island © CYWP
LIZARD ISLAND
Subtidal Seagrass Mapping Results
Data collection: CYWP, CSIRO and Dingaal Traditional Owners
Map planning, Data Analysis: CYWP
Data Collection Protocols: Seagrass-Watch
Map creation: Seagrass-Watch
- Lizard Island © CYWP
Some
field facts
How to use map viewer
On the Contents (dark) toolbar, click 
(Legend).
The legend displays information about each layer that is visible at the current map scale.
Not all layers contain legend information.
In Map Viewer, on the Contents (dark) toolbar (found on the left), select 
(Layers) to display all the different map Layers.
The legend displays information about each layer that is visible at the current map scale. Not all layers contain legend information.
On the Contents (dark) toolbar, click (Legend). The legend displays information about each layer that is visible at the current map scale. Not all layers contain legend information.
You do not need to show all map layers in the legend. For example, if the map focuses on seagrass distribution and extent for a region/country, you may want the legend to show only spotcheck symbols and not seagrass species and other reference data included in the map.
To hide a layer in the legend, do the following:
- Open the map with the legend in which you want to hide a layer.
- On the Contents (dark) toolbar, click Layers .
- Browse to the layer you want to hide (turn off) or show (turn on).
- The layer visibility can then be turned on (Show layer
) or off (Hide layer 
) by clicking the eye symbol on the list.
Simply move your mouse over a dot on the map and click on a Dot.
This will then bring up data and images from field
Using the mouse wheel makes it easy to zoom and pan anytime you like without changing the tool you are currently using.
These shortcuts work in data view and layout view. In layout view, they apply to the page by default. You can hold down the SHIFT key and perform any shortcut to apply it to the data frame instead of the page (the active data frame in the case of rolling the mouse wheel, or the data frame you clicked in the case of clicking or dragging the mouse wheel).
| Mouse wheel action | ArcMap navigation function |
|---|---|
| Rolling wheel back and forth | Zooms in and out |
| Holding down CTRL and rolling | Zooms in and out but with finer increment; used for small adjustments |
| Clicking mouse wheel (or middle mouse button) | Centers map at location where you clicked |
| Holding down mouse wheel (or middle mouse button) and dragging | Pans |
| Holding down CTRL and clicking mouse wheel | Centers and zooms in at location you clicked |
| Holding down CTRL and dragging with the mouse wheel | Zooms in |
Lizard Island Subtidal seagrass mapping results
A total of 199 mapping points were examined across the Lizard Island. Of these 111 points (55.8%) had seagrass present and 88 points (44.2%) had not.
Total seagrass cover ranged from 0.03 to 72.3%, with an overall mean of 8.1% (± 1.3 SE).
Four seagrass species were identified, with the most frequently encountered being Halodule uninervis, Thalassia hemprichii, Halophila ovalis and Cymodocea serrulata (39.6%, 36.2%, 25.9% and 2.4 average cover, respectively).
A total of thirteen individual seagrass meadows were mapped, covering 229.22 hectares in total. Eight meadows were delineated using a combination of point interpolation (Inverse Distance Weighting), bathymetry contours, and visual interpretation of PlanetScope satellite imagery (3 m resolution, captured on 17 February 2025). The remaining three meadows were mapped using 50 m buffers around verified seagrass presence points. This buffer-based method was applied where presence points occurred in isolation, with no nearby supporting observations to justify interpolation or imagery-driven mapping.
The biggest meadow identified was 73.7 hectares situated to the western side of the island. However, it is representative of a typical deep sparse meadow composed in majority of Halophila ovalis in low densities (average of 2% cover) with most spot-checks around 10m depth. The exact boundaries of such subtidal meadows are difficult to delineate accurately, and the lack of additional mapping points further offshore means that the estimated extent should be considered approximate, with an overall low confidence.
The second largest meadow mapped was 59.6 hectare and located in shallow waters within the southern reef lagoon. It supported a mixed community of four seagrass species, with Thalassia hemprichii contributing the highest proportion of cover (53.5%), followed by Halodule uninervis (29.3%), Halophila ovalis (12.5%), and Cymodocea serrulata (4.9%). Overall in this meadow seagrass cover averaged 6.7% across the spot-check points. This meadow is characteristic of a shallow subtidal reef-lagoon habitat typical of the Great Barrier Reef.
Across the remaining six meadows, species composition was dominated by combinations of Halodule uninervis,Halophila ovalis, and Thalassia hemprichii. These meadows exhibited a wide range of seagrass cover, from very sparse assemblages (<3% cover) in reef top areas to moderately dense patches exceeding 25% average cover in sheltered sandy lagoonal zones being the reef.
The survey was conducted by the Cape York Water Partnership in collaboration with CSIRO and Dingall Traditional Owners.
Data collection: CYWP, CSIRO and Dingaal Traditional Owners
Map planning, Data Analysis: CYWP
Data Collection Protocols: Seagrass-Watch
Map creation: Seagrass-Watch
A total of 199 mapping points were examined across the Lizard Island
How the data was collected
Seagrass meadows around Lizard Island were surveyed in February 2025 using subtidal drop-camera methodology. Mapping points were positioned using a restricted random sampling design to ensure spatially representative coverage of intertidal and shallow subtidal habitats.
At each mapping point, observers collected 50 × 50 cm photoquadrats (2–3 per site) and recorded visual estimates of above-ground seagrass percent cover, species composition, macroalgal cover and epiphyte load, following standardised Seagrass-Watch protocols.
A differential handheld global positioning system (GPS) was used to locate each mapping point (accuracy ±3m).
Seagrass meadows around Lizard Island were surveyed in February 2025
Partnership
Working in Partnership to collate a rich but dispersed seagrass distribution information into an easily searchable, viewable and fully customisable map-based view for seagrass meadows of Lizard Island
Data collection: CYWP, CSIRO and Dingaal Traditional Owners
Map planning, Data Analysis: CYWP
Data Collection Protocols: Seagrass-Watch
Map creation: Seagrass-Watch
All images copyright Cape York Water Partnership
Lizard Island Subtidal seagrass mapping results
A total of 199 mapping points were examined across the Lizard Island. Of these 111 points (55.8%) had seagrass present and 88 points (44.2%) had not.
Total seagrass cover ranged from 0.03 to 72.3%, with an overall mean of 8.1% (± 1.3 SE).
Four seagrass species were identified, with the most frequently encountered being Halodule uninervis, Thalassia hemprichii, Halophila ovalis and Cymodocea serrulata (39.6%, 36.2%, 25.9% and 2.4 average cover, respectively).
A total of thirteen individual seagrass meadows were mapped, covering 229.22 hectares in total. Eight meadows were delineated using a combination of point interpolation (Inverse Distance Weighting), bathymetry contours, and visual interpretation of PlanetScope satellite imagery (3 m resolution, captured on 17 February 2025). The remaining three meadows were mapped using 50 m buffers around verified seagrass presence points. This buffer-based method was applied where presence points occurred in isolation, with no nearby supporting observations to justify interpolation or imagery-driven mapping.
The biggest meadow identified was 73.7 hectares situated to the western side of the island. However, it is representative of a typical deep sparse meadow composed in majority of Halophila ovalis in low densities (average of 2% cover) with most spot-checks around 10m depth. The exact boundaries of such subtidal meadows are difficult to delineate accurately, and the lack of additional mapping points further offshore means that the estimated extent should be considered approximate, with an overall low confidence.
The second largest meadow mapped was 59.6 hectare and located in shallow waters within the southern reef lagoon. It supported a mixed community of four seagrass species, with Thalassia hemprichii contributing the highest proportion of cover (53.5%), followed by Halodule uninervis (29.3%), Halophila ovalis (12.5%), and Cymodocea serrulata (4.9%). Overall in this meadow seagrass cover averaged 6.7% across the spot-check points. This meadow is characteristic of a shallow subtidal reef-lagoon habitat typical of the Great Barrier Reef.
Across the remaining six meadows, species composition was dominated by combinations of Halodule uninervis,Halophila ovalis, and Thalassia hemprichii. These meadows exhibited a wide range of seagrass cover, from very sparse assemblages (<3% cover) in reef top areas to moderately dense patches exceeding 25% average cover in sheltered sandy lagoonal zones being the reef.
The survey was conducted by the Cape York Water Partnership in collaboration with CSIRO and Dingall Traditional Owners.
How the data was collected
Seagrass meadows around Lizard Island were surveyed in February 2025 using subtidal drop-camera methodology. Mapping points were positioned using a restricted random sampling design to ensure spatially representative coverage of intertidal and shallow subtidal habitats.
At each mapping point, observers collected 50 × 50 cm photoquadrats (2–3 per site) and recorded visual estimates of above-ground seagrass percent cover, species composition, macroalgal cover and epiphyte load, following standardised Seagrass-Watch protocols.
A differential handheld global positioning system (GPS) was used to locate each mapping point (accuracy ±3m).
Data collection: CYWP, CSIRO and Dingaal Traditional Owners
Map planning, Data Analysis: CYWP
Data Collection Protocols: Seagrass-Watch
Map creation: Seagrass-Watch
Partnership
Working in Partnership to collate a rich but dispersed seagrass distribution information into an easily searchable, viewable and fully customisable map-based view for seagrass meadows of Lizard Island
Data collection: CYWP, CSIRO and Dingaal Traditional Owners
Map planning, Data Analysis: CYWP
Data Collection Protocols: Seagrass-Watch
Map creation: Seagrass-Watch
All images copyright Cape York Water Partnership