Habitat suitability of crown-of-thorns starfish and Titan triggerfish and their response to climate change based on ensemble species distribution model

Abstract: The alterations in marine environments caused by global climate change have potential impacts on the suitable habitat zones for marine organisms. We utilized occurrence data for crown-of-thorns starfish (Acanthaster planci) and its key predator Titan triggerfish (Balistoides viridescens), along with environmental variables, to develop ensemble species distribution models by using seven algorithmic frameworks within the BIOMOD2 platform. These models predict current and future potential habitat suitability under various climate change scenarios. The results show that: 1) The committee averaging (CA) and weighted mean (WM) of probabilities ensemble species distribution model for crown-of-thorns starfish and Titan triggerfish show true skill statistic (TSS) and receiver operating curve (ROC) values are 0.96, 0.99 and 0.97, 0.99, respectively, which outperform the single models and provided accurate predictions of the spatial distribution patterns for both species. 2) Temperature and land distance are the primary factors influencing the spatial distribution of crown-of-thorns starfish, while temperature, dissolved oxygen and land distance are crical for Titan triggerfish. 3) The current potentially suitable habitats for both species are primarily located in the Great Barrier Reef of Australia, Indonesia, the South China Sea and the Red Sea. Titan triggerfish's potential suitable habitats are more extensive than those of crown-of-thorns starfish. Under future climate scenarios, both species' potential ranges are expected to broaden and migrate towards higher latitudes.