Abstract

Coastal ecosystems are vulnerable to the effects of climate change, and commercially important organisms, such as the ascidia Pyura chilensis, are exposed to low salinities as a result of increasingly frequent and intense rainfall. However, information on the performance of P. chilensis under environmental stress is scarce. Therefore, the aim of the present investigation was to evaluate the effect of different salinities (30, 25, 20 and 15 psu) on the clearance, oxygen consumption and excretion rates, as well as the levels of oxidative stress (protein carbonyls) and the total antioxidant response of P. chilensis. The results indicate that there was a negative effect on oxygen consumption and clearance rates in individuals exposed to salinities of 20 and 15 psu. Excretion rate was not affected by low salinity. Protein carbonyl levels and total antioxidant response increased over time in the 25, 20 and 15 psu treatments. The negative effects of exposure to low salinity (< 25 psu) on physiological variables and the increase in oxidative stress indicators could lead to a reduction in P. chilensis fitness, which should be evaluated in future research. It is therefore necessary to deepen our understanding of the physiological and cellular responses of P. chilensis to different environmental conditions. © The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature 2025.