Human Disturbances Might Cause Dangerous Gas Bubbles to Form in Deep-Diving Whales
Whales have evolved for millions of year for a life in the ocean, and breath-hold dive to obtain food. As air breathing mammals they have to return to the surface to replenish the oxygen used for metabolism. However, the air in the lungs also contains nitrogen, a gas that is taken up but not used by the body. As the whale dives the pressure increases and more nitrogen is taken up as the pressure increases the number of gas molecules that can enter the liquid, called solubility of gases. When the whale returns to the surface and the pressure is decreasing the solubility decreases and the gas is returned to the lungs. If the whale spends too much time in the zone where nitrogen is taken up at elevated pressure, bubbles may form during ascent similar to what happens when you open a soda bottle. The bubbles can cause many different problems inside the body and even cause death. Whales normally do not experience bubbles that cause problems. In recent years scientists have discovered that when whales are disturbed by humans their dive behavior or physiology may change in ways that increase the risk of formation of bubbles that could cause trauma and even death. A better understanding of the mechanism how the behavior and physiology may cause bubbles may help scientist develop tools that can prevent these problems in whales.