Environ Exp Biol (2020) 18: 135–141

Size structure and preyed corals of Acanthaster planci (crown-of-thorns sea star) in Lungui Island, Dimataling, Southern Philippines

Abstract

Outbreaks of Acanthaster planci are one of the major contributors to coral reef degradation, particularly in Indo-Pacific region. Correct assessment of its impact on coral reef ecosystems requires an understanding to its biology and ecology. This present study was conducted to determine the abundance, size structure and preyed corals of A. planci in Lungui Island, Dimataling, Southern Philippines. Four replicates of 50 × 4 m belt transects were laid in each of three sampling stations. A total of 112 A. planci individuals were recorded, whose body sizes varied significantly between the three stations (H = 3.401; p = 0.0180 at α = 0.05) ranging from 120 to 270 mm. All detected A. planci individuals were observed foraging on corals. Five preyed coral genera were identified through morphology-based identification, where Pocillopora was the most preyed coral genus, foraged by 28.57% of total A. planci individuals. Although the number of A. planci individuals in Lungui Island has not reached the outbreak threshold level, its presence in the area should not be overlooked. In fact, this raises a need for continuous monitoring of its population level in these local reef areas of the coastal waters of Dimataling, Southern Philippines.