Simone Baldanzi1,2, Francisca Fernández1, Lucas Bravo-Guzman1, Anibal Sanchez1, Miriam Fernández2, Evie Weiters2, Karen Diele3, Marco Fusi4
1Universidad de Valparaíso, Chile - 2Pontificia Universidad Católica de Chile - 3Edinburgh Napier University, UK - 4Newcastle University, UK
Oxygen variability in coastal areas comprises both predictable patterns and stochastic fluctuations, creating a challenging signal-processing environment for marine species. In tropical habitats, due to strong photosynthetic activity of primary producers, daily fluctuations of dissolved oxygen (from oxygen-poor to supersaturated waters) can improve thermal tolerance of benthic species. Little is known, however, on the effects of dissolved oxygen fluctuations on temperate benthic species and there is a lack of experimental evidence worldwide. To begin to fill this gap, we exposed females of the kelp crab Taliepus dentatus to 10 days of acclimation to variable (daily fluctuations from hipo- to hyperoxia) vs constant conditions of dissolved oxygen, measuring animal metabolic activity (heartbeat), lactate and hemocyanin levels in the haemolymph. After acclimation, animals were exposed to 12 hours low temperature, hypoxia and low pH, simulating an upwelling event, and we determined their critical oxygen pressure (PO2crit) to test whether acclimation to daily fluctuations improved animal’s oxygen regulation after stress. During acclimation, we found higher levels of lactate in those females experiencing Código de campo cambiado daily fluctuations of oxygen, but only after 4 days of acclimation. The heartbeat of females exposed to fluctuating oxygen conditions showed a significant increase of frequencies compared to the heartbeat of those females acclimated to constant values. After acclimation no differences in the PO2crit were found between females acclimated to constant vs fluctuating conditions of oxygen, while after stress exposure, females acclimated to fluctuating conditions were better able to regulate oxygen (lower PO2crit). The results show that acclimation to oxygen fluctuations improves kelp crabs’ capacity to extract oxygen after experiencing an acute stress. We demonstrated that, for a temperate crab species, variability of oxygen can provide considerable physiological benefits, highlighting the importance of integrating ecologically relevant oxygen variability into experimental assessments of animal physiology.