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

The alterations in marine environments caused by global climate change have potential impacts on the suitable habitat zones for marine organisms. Based on the occurrence data for crown-of-thorns starfish (Acanthaster planci) and its key predator Titan triggerfish (Balistoides viridescens), in addition with environmental variables, we developed 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 ensemble species distribution model of Committee Averaging (CA) and Weighted Mean of Probabilities (WM) for crown-of-thorns starfish and Titan triggerfish show that the true skill statistic (TSS) and receiver operating curve (ROC) values are 0.96, 0.99 and 0.97, 0.99, respectively, which outperforms the single model and provides 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.