Globally consistent reef habitat maps

Now we sea Globally consistent reef habitat maps

By Chris Roelfsema and Chantel Say, Remote Sensing Research Centre, The University of Queensland

The world’s first globally consistent coral reef habitat maps are now freely available. Habitat maps describing the geomorphic zonation and benthic composition for every shallowwater coral reef around Australia can now be accessed via the Allen Coral Atlas. Additionally, Great Barrier Reef specific maps are available through the Reef Knowledge System powered

by the Reef Integrated Monitoring and Reporting Program (RIMReP).

A team at the University of Queensland’s Remote Sensing Research Centre led the development and implementation of the habitat mapping process. This global mapping approach was based on original work conducted by the team during pilot studies funded by the Great Barrier Reef Foundation and the Great Barrier Reef Marine Park Authority for mapping the Great Barrier Reef (GBR). These pilot studies led to the creation of the geomorphic zonation, benthic cover and predicted coral type maps. These are known as the GBR10 GBRMP maps, which can be accessed via the GBRMPA reef knowledge system. The methods used for the GBR10 GBRMP maps are fine tuned specifically for the GBR and only includes the reefs within the GBR marine park. These methods have been adapted by the Allen Coral Atlas in order to achieve a globally consistent map for the world’s reefs.

The Allen Coral Atlas is an international collaboration between experts in the fields of reef science and earth observation, who officially launched the world’s first globally consistent coral reef habitat map in September 2021.

This scientific tool for reef science includes both a mapping and monitoring component, set to revolutionise reef conservation and management around the world.

The Atlas’ coral monitoring tool uses the world’s first satellite-based global reef monitoring system for coral bleaching and turbidity. The bleaching detection system identifies the brightening of corals by detecting changes in the spectral signature of coral when analysing satellite imagery which coincide with a ‘bleaching warning’ from the National Oceanic and Atmospheric Administration Coral Reef Watch. These data are now vital, with modelling predicting that 70 to 90% of the world’s coral reefs will be lost by 2050 due to ocean warming, pollution and acidification. Additionally, by having created a suite of habitat maps, which all use the same globally consistent classification scheme for every reef around the world means comparisons can easily be made between all Australian shallow-water tropical coral reefs.

The methods used to create both the GBR10 GBRMP and Allen Coral Atlas map products combine satellite images, reference data and physical attributes (depth, bathymetry and waves), to train and validate semi-automated machine learning classifiers and object-based clean-up protocols.

A brief comparison between the two approaches:

The GBR10 GBRMP maps predominantly used data specifically fine tuned, calibrated and validated for the GBR. For instance, the field data protocol and sampling method was designed and executed for the GBR. These maps used Sentinel 2 satellite imagery surface reflectance and derived absolute water depth data (Mean Sea Level) by EOMAP ltd and 19 different wave climate parameters, based on SWANN modelling (Callaghan et al 2015).

The Allen Coral Atlas maps did not have the resources to fine tune the data collection for specific areas on earth but rather focused efforts more broadly across large regions globally. As a result, and in combination with COVID-19 restrictions, field data was gathered from the global reef community. Specifically, 1000 scientists and organisations from around the world were approached, which resulted in the collation of over 500 datasets. These datasets were then translated in over 600,000 geomorphic and 1 million benthic reference data points for the training of the classifier and the validation of the maps. Additionally, the Atlas maps are based on the higher resolution Planet Dove imagery which was tailored to be used globally.

Both the GBR10 GBRMP and the Allen Coral Atlas habitat maps are publicly available to download and are valuable resources for Australian’s coral reef research.

The Allen Coral Atlas data download directions for any shallow reef in the world:

1. You will need to create a free login and sign in on www.allencoralatlas.org in order to download data from the Atlas. Downloads will be sent to the email address associated with your Allen Coral Atlas account.

2. You can download data either by selecting an entire region for download from the “Mapped/Monitored Areas” dropdown menu or selecting an area of interest using the Polygon Tool.

2a. To download an entire region (e.g. Eastern Africa & Madagascar), navigate to the “Mapped/Monitored Areas” dropdown menu, find and select and select the region of interest (e.g. titled “Eastern Africa & Madagascar”). The option to see the stat card and download the area will appear next to the region name.

2b. To download a specific area, start by selecting the Polygon Tool on the left side panel. Use the tool to digitise around the area of interest. Double click to complete the polygon, which will result in a stats card to appear. Note, if the area is over 100km2, you will be prompted to save it. However, it is recommended to save areas even if they are smaller than 100km2 using the "Save Area" button, as an area must be saved before it can be downloaded. Additionally, you will be able to revisit all saved areas by navigating to the “My Areas” in the top toolbar. The option to see the stat card and download the area will also appear beside the saved area in the drop down.

3. If you have the stat card open, you can download the data by navigating across from the ‘Stats’ tab to the ‘Download data’ tab. Here, you will be provided with multiple download options.

These options include which data layers you would like to download: Visual Planet Dove Imagery (2018, 2019, 2020; raster, Geotiff), Benthic and geomorphic Map (raster JSON, vector- shapefile), Quarterly Turbidity (raster, GEOTIFF), Bathymetry - composite data (raster, GEOTIFF)

4. If you agree to the data license terms, you will then be able to hit the "Prepare Download" button. When the data package is ready, the data will be sent to you as an email for download. The data package will be available for download for 30 days.

The GBR10 GBRMP data download directions for the shallow reefs of the GBR marine park :

1. Go to the GBRMPA knowledge system website at https://reefiq.gbrmpa.gov.au/ ReefKnowledgeSystem or go direct to Step 2 below.

2. Download the GBR10 GBRMP via following hyperlinks: Benthic, Geomorphic, Depth and Sentinel 2 image mosaic (Raster GeoTiff). 3. Alternatively, you can copy the webservice address from each of the four data sets and use that in your GIS environment.

For additional information and resources:

• Visit the Allen Coral Atlas • Watch the video – Powered By Planet

Data, Allen Coral Atlas Completes Map of all the World’s Coral Reefs • Read the UQ News piece –

‘Momentous’ mapping project completed, helping to save the world’s reefs • Read the media release from the

Minister for the Environment –

‘Technology breakthrough sheds new light on Great Barrier Reef’

References: 1. Kennedy, E. V., Roelfsema, C. M., Lyons, M. B., Kovacs, E. M., Borrego-Acevedo, R., Roe, M., Phinn, S. R., Larsen, K., Murray, N. J., Yuwono, D., Wolff, J., & Tudman, P. (2021). Reef Cover, a coral reef classification for global habitat mapping from remote sensing. Scientific Data, 8(1), 196. https://doi.org/ 10.1038/s41597-021-00958-z 2. Li, J., Knapp, D. E., Lyons, M., Roelfsema, C., Phinn, S., Schill, S. R., & Asner, G. P. (2021). Automated Global Shallow Water Bathymetry Mapping Using Google Earth Engine. Remote Sensing, 13(8), 1469. https://www.mdpi.com/ 2072-4292/13/8/1469 3. Lyons, M. B., Roelfsema, C. M., Kennedy, E. V., Kovacs, E. M., Borrego-Acevedo, R., Markey, K., Roe, M., Yuwono, D. M., Harris, D. L., Phinn, S. R., Asner, G. P., Li, J., Knapp, D. E., Fabina, N. S., Larsen, K., Traganos, D., & Murray, N. J. (2020). Mapping the world's coral reefs using a global multiscale earth observation framework. Remote Sensing in Ecology and Conservation, 6(4), 557-568. https:// doi.org/https://doi.org/10.1002/rse2.157 4. Roelfsema, C. B.-A., Rodney; Canto, Robert; Harris, Daniel; Kennedy, Emma; Kovacs, Eva; et al. (2021a). Benthic and Geomorphic Reference Data for Global Coral Reef Mapping. figshare. Collection. https://doi.org/https://doi.org/10.6084/ m9.figshare.c.5233847.v4 5. Roelfsema, C. M., Lyons, M., Murray, N., Kovacs, E. M., Kennedy, E., Markey, K., BorregoAcevedo, R., Ordoñez Alvarez, A., Say, C., Tudman, P., Roe, M., Wolff, J., Traganos, D., Asner, G. P., Bambic, B., Free, B., Fox, H. E., Lieb, Z., & Phinn, S. R. (2021b). Workflow for the Generation of ExpertDerived Training and Validation Data: A View to Global Scale Habitat Mapping [Methods]. Frontiers in Marine Science, 8(228). https://doi.org/10.3389/ fmars.2021.643381

The Reef Knowledge System Accessing Great Barrier Reef specific data

Available data includes benthic and geomorphic maps, satellite imagery and depth data. Key features available for each dataset include:

A

A brief overview of the data followed by a more in-depth description.

B

The downloadable data.

C

A URL which can be used to add the data as a web service in a GIS environment.

THE AUSTRALIAN CORAL REEF SOCIETY

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