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Benthic Habitat Mapping Lifuka Island. Aseri Baleilevuka OCEANS & ISLANDS PROGRAM SOPAC-SPC. What is habitat mapping?. A habitat map is basically a map of the different features of the ocean floor.
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Benthic Habitat Mapping Lifuka Island Aseri Baleilevuka OCEANS & ISLANDS PROGRAM SOPAC-SPC
What is habitat mapping? • A habitat map is basically a map of the different features of the ocean floor. • Marine habitat mapping is the synthesis of physical and biological data necessary delineate the distribution and extent of marine biota and their habitats. • Marine habitat maps helps us recognise the importance of marine habitats as sources of beach sediments. Purpose for the Lifuka project: • To use as base maps to determine the composition of the island sediment system. • Adds to the foundation of essential baseline information that can inform the development and design of appropriate adaptation options for Lifuka.
Habitat Mapping Process Field Data Collection and Analysis • Ground truthing - field data collection (Drop camera videos & subsurface photographs) • Control point survey • Videos & Snorkeling Photos analysis • Satellite image data processing Benthic Habitat Mapping Production • Expert knowledge, Manual delineation • Unsupervised classification (ArcGIS v9.3)
Ground truthing: Drop camera videos Still photo camera Video surface console • SeaViewer under water video camera
Ground truthing: Snorkel photos UQ-BRSG Drybag containing GPS camera Position of photos determined by synchronizing GPS & photo time using GPicSync software Resulting kml file
Reference Image Points survey • To minimize mis-registration between field data and image, control points are measured using Trimble R8 system.
Videos & Snorkeling Photos Analysis • Screenshots of drop camera videos taken (change in habitat/every 30s). • Classification scheme developed. • Used to label each snorkelling photo and video screenshot with a mapping category. • Lat and long for each photo is noted. • 33 videos – 310 photos • snorkel - 303 photos • 607 photos • Local knowledge Lifuka fishermen interpret habitats csv file of photo log opened in QGIS and saved as shapefile output
Photo classification examples Live coral Seagrass Rubble Algae
Satellite Image processing • Multi-spectral high resolution World View 2 imagery (50cm x 50cm pixels) acquired on 10 June 2011. • Reduced from 64 to 24 bit for processing • Global Mapper software used for adjusting contrast and geometrically correcting raster image. • Image rectified with reference points from Trimble R8 • Output: • TO_Lifuka_WV2_10JUN2011_24bit_adjusted_contrast_rectified.tif
Habitat map production • The National Oceanic and Atmospheric Administration (NOAA) habitat classification scheme is used – based on 3 attributes: geographic “zones”, geomorphological structure and biological cover.
Habitat Map of Zone Types • Manually delineated using NOAA‘s description of zones • Digitized in ArcGIS v9.3 at a scale of 1:2,500
Habitat Map of Structure Types • Manually delineated using NOAA’s description of structure types • Digitized in ArcGIS v9.3 at a scale of 1:5,000
Mapping of Biological cover • Unsupervised classification in ArcGIS v9.3 • Island and area of no data masked • Iso Cluster tool used to create 20 spectral classes • Maximum likelihood tool to perform EQUAL priori classification on image using signature file produced above
Habitat Map of Biological cover • classes produced used to inform and direct definitions of biological cover as described by the NOAA classification. • Videos and snorkelling photographs as guide, categories defined. • Digitized in ArcGIS v9.3 at a scale of 1:2,500
Other methods and softwares tested • Training shapefile of 200 polygons (digitized in ArcGIS v9.3) • Segmentation using Berkeley Image Segmentation software in conjunction with WEKA data mining software (Open source) • NOAA’s Habitat Digitizer Extension to ArcView • Supervised classification in ArcGIS v9.3
Acknowledgements • Habitat mapping project conducted by the whole Marine Survey team (Ocean & Islands Program, SOPAC - SPC) • NOAA’s Centre for Coastal Monitoring and Assessment (CCMA) • The University of Queensland (Biophysical Remote Sensing Group)