Impact of combined atmospheric and marine heatwaves on the filtration activity of the invasive Asian date mussel, Arcuatula senhousia.

The Asian date mussel, Arcuatula senhousia, originated from East Asia, is a highly invasive species that severely affects ecosystem functioning and biodiversity in various ecosystems in America and Europe. In recent decades, heatwave events have increased in severity and frequency, causing additional stress for intertidal organisms living in one of the most thermally challenging habitats. Therefore, understanding the impact of stressful environmental conditions on species' behavioural responses is essential for predicting the effects of biological invasions in the context of climate change. This study aimed to evaluate the response of A. senhousia filtration activity under two levels of realistic combined marine and atmospheric short-term heatwaves (strong and extreme), performed during spring and summer conditions. Although numerous intertidal organisms have been shown to suffer greatly from heatwaves, the results indicate that A. senhousia is able to withstand short-term heatwaves. The results showed that, for all intensities and seasons, heatwaves had no significant effect on the clearance rate. Although there was no distinct general trend regarding the influence of heatwaves on the behaviour of valve opening in spring, strong heatwave conditions significantly increased the valve gaping activity (e.g., increasing valve opening and time of active filtration) during the summer experiment without significant difference on the clearance rate. This highlights the importance of considering the season when attempting to understand and predict the impacts of heatwaves. Therefore, this species exhibits a high filtration rate as well as tolerance to heatwaves. However, future investigations should investigate if this resistance have an impact on the species growth and survival at a longer term. In the context of climate change, this species may have advantage over native ones, and its abundances may significantly rise, leading to important ecological consequences in terms of communities structures and habitat modifications.