Coverage showing the distribution of seagrass, mangrove and saltmarsh Botany Bay derived from recent aerial photographs.

Aerial photographs from 1995 at 1:16 000 scale were used to map mangrove, saltmarsh and seagrass in Botany Bay. Vegetation boundaries were digitised from images created by scanning and rubbersheeting the photographs with ground control points and were checked by field surveys undertaken in June and July 1998. The area of each vegetation type was calculated in IDRISI GIS software and recently transferred to ERDAS IMAGINE format.

AMG coordinates obtained from a +/-1m DGPS and 1:10 000 orthophotomaps were used to resample classified images to a 2m grid with RMS errors of between 2.55 and 5.37 for individual images.

Vegetation boundaries were identified on aerial photographs and the boundaries were confirmed in the field and the species identification checked. Families or in some case species of vegetation were mapped in the following categories: Zostera capricorni, Sparse Zostera, Posidonia australis, Mixed Posidonia (indicating presence of P. australis and Z. capricorni and/or Halophila spp.), Mixed Halophila (indicating presence of Halophila spp and Z. capricorni and/or P. australis which occurs on the southern shore only.) saltmarsh (all species combined), mangroves (all species combined) and Kelp (all species combined). Kelp was mapped incidentally and does not represent the full extent of this group of aquatic plants within Botany Bay.

All cells within the Grid are coded for the given attributes.

Classification to species level is complete for seagrass only. Kelp was mapped incidentally and does not represent the full extent of this group of aquatic plants within Botany Bay.

Similar data was collected and mapped in 1985 in nondigital format and published in West, R.J., Thorogood, C.A. Walford, T.R. and Williams, R.J. (1985) An estuarine inventory for New South Wales, Australia. N.S.W. Department of Agriculture, Fisheries Bulletin No. 2, 140 pp.

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