Investigating bottlenose dolphin physiology using near-infrared spectroscopy

Area of Science:

• Marine Biology
• Physiology
• Biophysics

Background:

• Cetacean diving physiology is not fully understood.
• Limited data exists on hemodynamic responses during dives.

Purpose of the Study:

• To investigate bottlenose dolphin hemodynamics during various aquatic activities.
• To apply a novel approach combining NIRS and kinematics.

Main Methods:

• Near-infrared spectroscopy (NIRS) and kinematic measurements were used.
• Measurements were taken during voluntary breathing, diving, and free swimming.
• Hemodynamic changes in oxygenated hemoglobin (HbO) and deoxygenated hemoglobin (HbR) were monitored.

Main Results:

• Oxygenated hemoglobin (HbO) increased post-respiration and decreased before the next breath.
• Deoxygenated hemoglobin (HbR) remained stable during short dives but decreased during prolonged breath-holds.
• Tissue Saturation Index (TSI) decreased by up to 8.9% during extended breath-holds.

Conclusions:

• The combined NIRS and kinematic approach provides new insights into cetacean diving physiology.
• This method is a significant step towards in-situ measurements in wild populations.