2020/11/24 by Andreas Fahlman, Bruno Cozzi, Mercy Manley +4 · 1 citation
Environmental Science · Neuroscience · Earth and Planetary Sciences · #Marine animal studies overview #Neuroscience of respiration and sleep #Ocean Acidification Effects and Responses
paper · pdf · doi:10.3389/fphys.2020.604018
openalex publication_date 2020/11/24 · openalex created_date 2020/12/07 · openalex updated_date 2026/07/23
Previous reports suggested the existence of direct somatic motor control over heart rate ( f H ) responses during diving in some marine mammals, as the result of a cognitive and/or learning process rather than being a reflexive response. This would be beneficial for O 2 storage management, but would also allow ventilation-perfusion matching for selective gas exchange, where O 2 and CO 2 can be exchanged with minimal exchange of N 2 . Such a mechanism explains how air breathing marine vertebrates avoid diving related gas bubble formation during repeated dives, and how stress could interrupt this mechanism and cause excessive N 2 exchange. To investigate the conditioned response, we measured the f H -response before and during static breath-holds in three bottlenose dolphins ( Tursiops truncatus ) when shown a visual symbol to perform either a long (LONG) or short (SHORT) breath-hold, or during a spontaneous breath-hold without a symbol (NS). The average f H (i f Hstart ), and the rate of change in f H (di f H /dt) during the first 20 s of the breath-hold differed between breath-hold types. In addition, the minimum instantaneous f H (i f Hmin ), and the average instantaneous f H during the last 10 s (i f Hend ) also differed between breath-hold types. The di f H /dt was greater, and the i f Hstart , i f Hmin , and i f Hend were lower during a LONG as compared with either a SHORT, or an NS breath-hold ( P < 0.05). Even though the NS breath-hold dives were longer in duration as compared with SHORT breath-hold dives, the di f H /dt was greater and the i f Hstart , i f Hmin , and i f Hend were lower during the latter ( P < 0.05). In addition, when the dolphin determined the breath-hold duration (NS), the f H was more variable within and between individuals and trials, suggesting a conditioned capacity to adjust the f H -response. These results suggest that dolphins have the capacity to selectively alter the f H -response during diving and provide evidence for significant cardiovascular plasticity in dolphins.