Mussels, <i>Perna canaliculus</i> , as biosensors for climate change: concurrent monitoring of heart rate, oxygen consumption and gaping behaviour under heat stress

ABSTRACT The green‐lipped mussel, Perna canaliculus , is an important aquaculture species in New Zealand. Recently, the industry has been increasingly challenged by stressors associated with climate change. Predicting its response to climate change requires more than single‐parameter measurements, as mussels show various physiological and behavioural adaptations. In this study, heart rate (HR), respiration rate (), and relative gaping magnitude (RGM) of P. canaliculus were measured simultaneously under increasing temperature from 17°C to 30°C at a rate of 1°C every 20 min over seven hours. HR, and RGM responded differently to acute temperature increase. HR peaked at 26°C, while continued to rise until 30°C, and RGM spiked beyond 28°C. These integrated responses suggest the mussels’ upper thermal limit is around 26°C, higher than typical seawater temperatures of 20°C seen during summer heatwaves, indicating a significant thermal safety margin. Only HR and were positively correlated, but this relationship was disrupted at higher temperatures due to higher inter‐individual variabilities of those physio‐behavioural responses. Variations in such responses have potential in identifying more thermally tolerant mussel lines within selective breeding programmes that ultimately may help produce mussels tolerant of a warming future.