What causes outbreaks of crown-of-thorns starfish?
No one knows the answer to this question. Nor is it known whether outbreaks are caused by a single factor or a group of factors. Currently two hypotheses concerning the cause(s) of outbreaks have received most attention from scientists. One invokes natural causes; runoff from high land masses after periods of dry weather creates phytoplankton (algal) blooms which provide food for the larvae and enhance their survivorship. The other suggests that outbreaks are a result of man’s interference since he has (inadvertently?) removed the main predators of the starfish (see 18). Both hypotheses are based on correlating one set of data (on the occurrence of outbreaks) with another (eg. occurrence of cyclones and very heavy rains). As yet there is no proof that the occurrence of outbreaks is directly caused by the processes that these two hypotheses invoke (ie. runoff or removal of predators). Other hypotheses have been put forward to account for the occurrence of outbreaks which involve the eff
