Nearshore marine habitat mapping of the Norfolk Marine Park

Brief description

Parks Australia - Our Marine Parks Grants Round 2 Project: Nearshore marine habitat mapping of the Norfolk Marine Park (Grant Activity ID: 4-FIZ391E) The Norfolk Marine Park is the is the eastern-most Park in the Temperate East Network of Australian Marine Parks, located between the NSW coast and Norfolk Island. The Park encompasses 188,444 km² of ocean and ranges in depth from 0 m at the Norfolk Island high tide mark to more than 5,00 m off the edge of the Norfolk Ridge. The Park includes two key ecological features – the Norfolk Ridge, and the Tasman Front and associated eddy field – both of which are valued for their high productivity, aggregations of marine life, biodiversity, and endemism. Norfolk Marine Park supports a range of species, including those listed as threatened under the Environment Protection and Biodiversity Conservation (EPBC) Act (1999), and contains Biologically Important Areas for breeding, foraging, and migration of seabirds, marine turtles, and humpback whales. The objective of this project was to create the first marine habitat map for the nearshore shallow water surrounding Norfolk, Nepean, and Phillip Islands. This was conducted in collaboration with Norfolk residents to provide local knowledge input and to ground-truth the remotely-sensed habitat mapping. This high-level habitat map will be used for planning purposes, development applications, and EPBC Act referrals within the nearshore waters of the Norfolk Marine Park, where no specific zoning for recreational and commercial activities currently exists. The map provides a basis for any ongoing citizen-science-driven marine habitat impact and condition assessments, ecosystem monitoring, and to provide the Norfolk Island residents with ownership of any future zoning planning. The map can be further refined as more detailed information becomes available from subject matter experts in the future.

Lineage

Maintenance and Update Frequency: notPlanned

Statement: The Norfolk Marine Park survey was acquired by the Australian Government (Parks Australia) as part of Our Marine Parks Grant - Round 2 in 2022 and undertaken by Pendoley Environment Pty Ltd in collaboration with EOMAP Australia. The habitat mapping was conducted in five broad stages; 1. Initial high-level habitat classification using satellite imagery and specialised algorithms (by EOMAP). 2. Community consultation with local fishers, surfers, and divers at Norfolk Island to validate and refine the remote sensing habitat classifications. 3. Ground-truthing using towed video surveys conducted by a team based at Norfolk Island (led by Pendoley Environment). 4. Review and interpretation of field data to assess classification accuracy. 5. Remapping and refinement of the habitat classifications identified in the satellite imagery-derived map based on field validation. Initial habitat mapping was conducted by EOMAP over a ~70 km² Area of Interest around Norfolk, Phillip, and Nepean Islands. High-resolution (2 m) multispectral satellite imagery (WorldView-2/3, April 2018) was processed using EOMAP’s Modular Inversion and Processing System (MIP), which applies physics-based algorithms to correct for atmospheric effects and water column interference, enabling accurate separation of seabed reflectance. Mapping extended to depths of ~40 m, depending on local optical conditions. Habitat types were classified using EOMAP’s Seafloor Classification (SFC) method, which employs object-based image analysis to group contiguous pixels with similar spectral, shape, and textural characteristics into ecologically meaningful classes. Bathymetry data acquired by the Royal Australian Navy’s Laser Airborne Depth Sounder (LADS - LiDAR) in 2015–2016 were also incorporated to improve mapping accuracy. Following the initial satellite-derived habitat classification, community feedback was gathered through two public workshops on Norfolk Island. Local fishers, divers, and surfers reviewed printed habitat maps and provided qualitative observations, which informed the selection of field validation sites for a ground truthing survey conducted in October 2022. In October 2022, a ground-truthing survey was conducted using a towed video system comprising GoPro Hero 9 cameras and LED lights mounted on a custom dropper frame. The system was deployed from a vessel at selected locations across a range of depths and mapped habitat types. Cameras were operated in 4K video mode, recording for several minutes at each site while drifting approximately 1 m above the seafloor. Waypoints were logged using a depth sounder and GPS. Videos were reviewed to assign broad habitat type classes at each site. These observations were compared with the initial EOMAP satellite-derived classifications, and the habitat map was updated to reflect any necessary corrections based on field evidence. Selected images and video clips were prepared for public access and map integration.

Notes

Credit
Director of National Parks (Parks Australia), Pendoley Environment Pty Ltd