Larval dispersal simulations: correlation with the crown-of-thorns starfish outbreaks database

Abstract

The work reported in this paper is a further development of results from a research programme whose principal objective is to achieve an understanding of the large-scale population dynamics of Acanthaster planci. The research is based on the development and use of numerical models of hydrodynamics and resulting larval dispersal throughout a large portion of the Great Barrier Reef. It is chiefly concerned with the large-scale statistical patterns of larval dispersal, the central hypothesis being that passive hydrodynamic dispersal plays an important role in the recruitment process. The present aim is to examine more closely than has been done before the consistencies between the modelling results and the database of recorded observations of crown-of-thorns starfish outbreaks. Reefs in the Cairns and Central Sections of the Great Barrier Reef Marine Park that were recorded as carrying active outbreaks during the period 1979-89 were used as sources in a programme of intensive simulations of Acanthaster larval dispersal under forcing by the wind, tidal action and the East Australian Current. The resulting broad-scale patterns of larval dispersal were found to be in strong qualitative agreement with the observed spatial and temporal distribution of adult Acanthaster populations. Statistical analysis of the results revealed a strong positive correlation between potential recruitment on surveyed reefs, as estimated by the dispersal simulations, and the observed presence of outbreak populations on those reefs. The correlation was particularly strong when different cross-shelf zones were considered separately.