Hormosira banksii beds on inter-tidal platforms are areas that are significant to the surrounding flora and fauna. These areas are sensitive and subject to damage by human interaction and adverse weather and tidal conditions. As these beds sometimes only cover a small area or are in remote locations it can be difficult to monitor the Hormosira banksii coverage. Aerial photography can cover large distances, provide the spatial resolution required when analysing small areas, with the advantage of being quick and cheap. This study investigates the use of medium format air photography to map Hormosira banksii coverage of an intertidal rock platform.

Aerial photographs of Victoria's coastline were taken from a light aircraft using 70mm Hasselblad cameras. The imagery consisted of contemporaneous colour and colour infrared photographs. Cheviot Beach in Point Nepean National Park, Australia, was used as the base line study site for detecting Hormosira banksii. Extensive ground truth data were used in conjunction with the aerial photographs to identify the Hormosira banksii on Cheviot Beach. This methodology was then applied to four other sites determine the effectiveness of the methodology to identify Hormosira banksii on geographically separated sites. Finally, this methodology was applied to a series of Cheviot Beach data to determine the ability of this methodology to map and monitor change in a Hormosira banksii bed over time.

Port Phillip Bay is a tidal embayment of approximately 1,950 square kilometres on the southern coast of Australia. It is an almost enclosed saucer shaped depression with a large tidal delta at its southern end, and is separated from Bass Strait to the south by a narrow entrance. In areas of large human population such as Port Phillip Bay, great pressures are put on the marine environment. It is because of these pressures that this study of southern Port Phillip was undertaken.

The main aim of this thesis is to examine the extent to which biological factors are correlated with the geology of the substrate, and the oceanographic factors at nine sites in southern Port Phillip Bay. The oceanographic factors include aspects such as tidal exposure, storm exposure and depth. The technique used to study these phenomena was to employ several methods of remotely sensed and in situ, or sea truth, data collection. Satellite imagery was the initial data source, with sidescan sonar and underwater video imaging also collected. A semi-submersible vessel and a remotely operated vehicle were utilised for the visual data collection.

The results from this project show that the seafloor environment of southern Port Phillip Bay is responsive to a complex interaction of depth, substrate and oceanographic exposure, with no one factor being completely predictive. No single data collection technique would be adequate as an environmental mapping tool, but a combination of data from different platforms allowed comprehensive mapping of the shallow seafloor environment.