Rate of decomposition of crown-of-thorns starfish, Acanthaster planci, on the Great Barrier Reef

Brief description

The decomposition of 67 crown-of-thorns starfish was monitored in 2 m x 2 m permanent quadrats established at John Brewer Reef in September 1985 and Little Broadhurst Reef in December 1988.Approximately 2 months prior to the commencement of each study, the starfish were kept under starvation conditions in the laboratory to simulate the general state of health that would be expected at the end of outbreaks, when food usually is limited. The starfish were transported back to the reefs and killed by immersion in fresh water for 8 hours.Four quadrats were located amongst patch reefs along the north eastern perimeter of John Brewer Reef. Two of the quadrats were located on sand at 9 m depth while the other two were amongst a mixed coral assemblage (mainly Acropora spp.) at a depth of 3 m. All 4 quadrats were within 10 m of each other and ten starfish were placed randomly in each quadrat and monitored over 9 days. Three quadrats were located on the eastern perimeter of the lagoon at Little Broadhurst Reef. The quadrats were situated next to each other on sand at 9 m depth and 9 starfish were positioned randomly in each quadrat and monitored for 7 days.Quadrats were monitored for about 1 hour each time, normally 3 times during the day and once at night. Maps of each quadrat indicated the position of starfish and their state of decomposition. Changes in the position of starfish were noted as were any instances of predation or other activities which might affect the decomposition process. The main morphological features of some predators were noted for later identification as it was not possible to obtain photographs of these animals. This preliminary taphonomic study was undertaken to determine how long the remains of the crown-of-thorns starfish (Acanthaster planci) are recognisable in the field and the factors that are important in the decomposition process.

Lineage

Maintenance and Update Frequency: notPlanned

Notes

Credit
Moran, Peter J, Dr (Principal Investigator)