What is one sign of low air supply that divers should monitor during a night dive?

Monitoring the breathing rate and the effort required to inhale is crucial for divers during a night dive, especially as a sign of low air supply. When air becomes limited, divers may start to experience changes in their breathing pattern. A decreased breathing rate or difficulty inhaling can indicate that the diver is nearing the end of their air supply, which can lead to panic or dangerous situations if not addressed promptly.

In contrast, increased buoyancy control is not directly indicative of an air supply issue and is more related to the diver's skill level and experience in managing their buoyancy. Improved visibility typically does not correlate with air supply, as visibility can be influenced by water conditions rather than the diver's air tank. Lastly, while increased heart rate can be a physiological response to various factors including anxiety and exertion, it is not a reliable sign specifically pointing to low air supply. Therefore, monitoring the breathing rate is a key indicator for ensuring safety during dives, especially at night when conditions can be more challenging.