The effects of acute carbon dioxide on behavior and physiology in Procambarus clarkii

Vertebrates and invertebrates show a similar response of rapid anesthesia with high levels of carbon dioxide. In this study, we use crayfish to examine both behavioral and physiological responses to increasing [CO ₂] to explain the rapid unresponsiveness and cessation of an autonomic response. Hypoxic and low pH environments that are induced by CO ₂ exposure were also examined, although neither produced the identified CO ₂ effects. In insects, low concentrations play a vital role in providing information for task performance such as food location through attraction cues, whereas high concentrations produce avoidance responses. We found behavioral responses in crayfish that demonstrate a strong repellent effect to high [CO ₂] and that the avoidance behavior decreases with lower [CO ₂]. There was not a preference and/or repellent behavioral response with 5% CO ₂, hypoxic or low pH environments. Mechanosensory stimulation showed that only at high [CO ₂] there is an unresponsiveness to stimuli within a 30min time period. Additionally, the autonomic bioindex of heart and ventilatory rates showed a complete cessation with high acute exposure within in the same time period for unresponsiveness to mechanosensory stimulation.