Spatial Waves or Synchronicity of Outbreaks of Crown-of-thorns Starfish on the Great Barrier Reef?: A Bayesian Message From Large Scale Data

Large scale outbreaks of crown-of-thorns starfish have been observed on the Great Barrier Reef system since the mid-1960s. A popular and plausible explanation for the spread of these outbreaks asserts that their primary locus is in the Northern sector, and that they subsequently spread southwards in a wave of outbreaks, via larval transport in the East Australian current (Kenchington, 1977). In this paper we develop Bayesian statistical methods to analyse the large scale survey data on starfish outbreaks over the period 1966 to 1989, with a view to testing this hypothesis. These methods are specifically designed to cope with the large uncertainties inherent in the data. Our conclusion is that the evidence more strongly supports geographical synchronicity of outbreaks, rather than travelling waves, a conclusion which reinforces the theoretical work of Bradbury et al. (1990), van der Laan & Bradbury (1990), and van der Laan & Hogeweg (1992).