Respiration of the sea urchin Mesocentrotus nudus in response to large temperature fluctuations.

Some subtidal habitats may experience extremely large diel temperature fluctuations. To explore the potential of subtidal animals to regulate their metabolic processes, we investigated how the oxygen consumption rate (MO2 ) of the sea urchin Mesocentrotus nudus changes in response to extreme temperature fluctuations by mimicking temperature variations recorded at Dokdo Island, Republic of Korea. We compared the MO2 of urchins before and after a temperature fluctuation. MO2 was positively correlated with temperature. There was no change in the mean MO2 values even after exposure to fluctuating temperature. There was no significant difference in mean MO2 between large and small temperature fluctuations. These results indicate that the metabolic activity of M. nudus might be well-adapted to extreme temperature fluctuations. However, given that the temperature coefficient (Q10 ) values decreased with increasing temperature and Q10 values during the temperature decrease was higher than those during temperature increase, temperature rise may still act as a stressor for these animals.