Assessing thermal performance of an endemic ecosystem engineer from southeast Australia

Over the last decades, southeast Australia has experienced some of the fastest increases in ocean temperatures globally. Marine ectotherms are likely to be the more vulnerable group in this region, particularly endemic and broadcast-spawning species. Therefore, it is a priority to understand the vulnerability of such species to temperature, especially those with major effects on their ecosystems. Thermal performance curves are a valuable tool to predict the impact of global warming on survival, dispersal, and recruitment of ectotherms. These curves can differ among life history stages. However, most of the studies on species responses to temperature have focused on a single life stage, mainly adults. Furthermore, from the available studies using thermal performance curves at early life stages, few have considered the effects of plastic responses, and even fewer have determined performance in fluctuating temperatures. For most marine taxa, it remains unknown which life stage is most vulnerable to thermal stress, even though early life stages have shown to be most sensitive to other stressors, and can represent a major bottleneck for population persistence under stressful conditions. This project uses as a model the native marine tube worm, Galeolaria caespitosa: an ecosystem engineer that occurs on rocky shores of southeast Australia. By describing the thermal performance of early life stages (fertilisation, embryonic and larval development) and the factors that can modify thermal performance, this project aims to deliver insights into the capacity of important native ectotherms like Galeolaria to withstand the current and near-future thermal challenges that they face, and to inform predictions about population persistence.