Differences in oxygen consumption and diel activity as adaptations related to microhabitat in Neotropical freshwater decapods (Crustacea)

This study evaluated oxygen consumption (MO₂) and diel activity in Aegla longirostri, Trichodactylus panoplus and Parastacus brasiliensis (three species of freshwater decapods that occur in sympatry), under two different conditions of O₂ availability, limited and constant; and searched for the existence of a relationship between these two variables. The Kruskal–Wallis test showed that in all the species, MO₂ was higher under constant O₂ availability; T. panoplus and P. brasiliensis showed an oxygen-dependent pattern, while A. longirostri showed higher MO₂ values and less variation in the values between the treatments, indicating a higher and more oxygen-independent metabolism. P. brasiliensis was more active in constant O₂. A. longirostri was more active in limited O₂ and did not show a clear diel activity in any case, showing behavioral changes when in unfavorable conditions. The Spearman's rank correlation analysis did not indicate any relationship between MO₂ and activity. These results indicate a higher metabolism in A. longirostri. The less demanding metabolisms of P. brasiliensis and T. panoplus allow these species to occupy environments that are unavailable to A. longirostri due to differences in dissolved-oxygen concentrations.