PARENT SESSION
Oral Session # 95: Predator - Prey Ecology III: Aquatic Systems.
Presiding: J Vonesh
Friday, August 8. 8:30 AM to 12:00 PM, SITCC Meeting Room 201.

The effects of predation risk on social coral reef fish at Lizard Island, Great Barrier Reef.

Abdulla, Ameer^{*,1, 2, 3}, Connolly, Sean^{2, 4}, ¹ CRC Reef Research Centre, Townsville, Queensland, Australia² Centre for Coral Reef Biodiversity, Townsville, Queensland, Australia³ School of Tropical Environment Studies and Geography, Townsville, Queensland, Australia⁴ School of Marine Biology and Aquaculture, Townsville, Queensland, Australia

ABSTRACT- Little emphasis has been placed on non-lethal effects (risk) of predators that may influence prey behaviour and fitness in marine environments. This study investigated such non-fatal interactions, which have the potential to affect the fitness of coral reef fish. Observational data collected from Lizard Island reefs on the Great Barrier Reef (GBR) show a correlation between predator abundance and group size of habitat-associated prey. We adopted a foraging model that predicts predators will significantly reduce the growth of a prey individual at low prey density, but will have a smaller effect at higher densities. We tested these predictions in the field using experimental manipulations of group densities of Pomacentrus moluccensis, a tropical reef damselfish, and a system of artificial coral reefs and cages at Lizard Island. Results indicate that the risk of predation affects both the behaviour and growth rate of the prey. This suggests that suppression of growth due to predation risk may affect population dynamics of adult coral reef fish by regulating the rate of individuals reaching reproductive maturity and/or by increasing the probability of size-selective mortality on juveniles.

Key words: coral reefs, fitness, predation risk, group size