Changes in Seagrass Cover on Success and Parmelia Banks, Western Australia Between 1965 and 1995

Changes in seagrass cover on Success and Parmelia Banks, Western Australia between 1965 and 1995 were mapped from aerial photography using changes in the distribution and size of phototonal categories. Aerial photography from 1965, 1972, 1982 and 1995 was used to determine the temporal and spatial changes in seagrass distribution. Aerial photography was rectified using photogrammetric techniques, and manually interpreted at a scale of 1:10 000 to determine the extent of seagrasses and unvegetated sands. The 1995 data were also ground-truthed to determine the seagrass species assemblages. The mapping of seagrass cover using phototones is only feasible for species of seagrasses with a dense leaf canopy. The species that fit this criteria, and that have high cover on Success and Parmelia Banks, are Amphibolis antarctica, Amphibolis griffithii, Posidonia australis, Posidonia sinuosa and Posidonia coriacea.