Surveys of benthic habitats and zonation in Florence Bay, Magnetic Island, north Queensland

In April 1989, the marine habitat at Florence Bay, Magnetic Island was surveyed. Initially, manta tows (a snorkeller towed slowly behind a small boat) were made to provide an overview of the area to be surveyed. A series of survey points were established to allow the positions of all survey stations to be determined. A bathymetric map of the bay was also compiled based on 12 echo sounder traverses.A diver-operated underwater video camera was towed over 19 evenly spaced paths in order to assist interpretation of the bay's main biological features. Some of the transect footage was used with hand-held material to produce a video documentary of the bay's main features. A subset of the videotapes was sampled to determine the distribution and relative abundance of major benthic categories along the tow paths.Forty line transects, 20m in length, were used to estimate the cover of benthic organisms and substratum. Corals in the line transects were identified to species level and where necessary, a specimen was collected for taxonomic determination in the laboratory. The maximum diameter of each coral intercepted along each transect was estimated to obtain a size frequency distribution of corals. This research was undertaken to describe the physical and ecological structure of Florence Bay. This information was used to assess the potential impact that a resort would have on the marine ecosystem of the bay. Tasks identified were:1. to generate a bathymetric map of Florence Bay2. to characterize the hard bottom marine habitats of Florence Bay (the southern rocky shore, and the coral reef) with a focus on coral communities A survey of the marine benthic flora of Florence Bay was also conducted by Karen Edyvane and R. de Nys as part of this project.