Yaringa and French Island Marine National Park habitat mapping

Deakin University and the Department of Primary Industries were commissioned by Parks Victoria (PV) to create two updated habitat maps for Yaringa and French Island Marine National Parks. The team obtained a ground-truth data set using in situ video and still photographs. This dataset was used to develop and assess predictive models of benthic marine habitat distributions incorporating data from World-View-2 imagery atmospherically corrected by CSIRO and LiDAR (Light Detection and Ranging) bathymetry. In addition, the team applied an unsupervised classification approach to an aerial photograph to assess the differences between the two remote sensors. This report describes the results of the mapping as well as the methodology used to produce these habitat maps. This study has provided mapping of intertidal and subtidal habitats of Yaringa and French Island MNPs at a 2 m resolution with fair to good accuracies (Kappa 0.40-0.75). These were combined with mangrove and saltmarsh habitats recently mapped by Boon et al. (2011) to provide compete-coverage habitat maps of Yaringa and French Island MNPs. The mapping showed that Yaringa MNP was dominated by mangroves, wet saltmarsh and dense Zostereaceae, covering 33%, 29% and 19%, respectively. Similarly, intertidal vegetation and subtidal vegetation (dominated by Zosteraceae) covered 26% and 25% of French Island MNP. However, as a result of turbidity and missing satellite imagery 27% of French Island MNP remains unmapped. The coupling of WV-2 and LiDAR reduced potential artefacts (e.g. sun glint causing white and black pixels known as the “salt and pepper effect”). The satellite classification appeared to provide better results than the aerial photography classification. However, since there is a two-year difference between the capture of the aerial photography and the collection of the ground-truth data this comparison is potentially temporally confounded. It must also be noted that there are differences in costs of the data, the spatial resolution between the two datasets (i.e. WV-2 = 2 m and the Aerial = 0.5 m) and the amount spectral information contained in the data (i.e. WV-2 = 8 bands and the aerial = 4 bands), which may ultimately determine its utility for a particular project. The spatial assessment using FRAGSTATs of habitat patches within Yaringa MNP provides a viable and cost effect way to assess habitat condition (i.e. shape, size and arrangement). This spatial assessment determined that dense Zosteraceae and NVSG habitat classes were generally larger in patch size and continuity than the medium/sparse Zosteraceae habitat. The application spatial techniques to time-series mapping may provide a way to remotely monitor the change in the spatial characteristics of marine habitats. This work was successful in providing new baseline habitat maps using a repeatable method meaning that any future changes in intertidal and shallow water marine habitats may be assessed in a consistent way with quantitative error assessments. In wider use, these maps should also allow improved conservation planning, fisheries and catchment management, and contribute toward infrastructure planning to limit impacts on Western Port.