What feature is essential for nighttime buoy identification?

The feature that is essential for nighttime buoy identification is the integration of lights. Buoys equipped with lights are crucial for visibility during low-light conditions, such as at night or in foggy weather. These lights are often designed to flash or have specific patterns that convey important navigational information to mariners. The presence of a light makes it easier for vessels to identify the buoy's position and its significance, ensuring safe navigation and helping to prevent collisions.

Reflective surfaces and sound signals play roles in navigation, but they are not as effective during nighttime when visibility is poor. Reflective surfaces may assist in reflecting existing light sources, while sound signals might provide an auditory cue but do not aid visual identification. Anchoring systems are vital for keeping buoys in place but do not contribute to nighttime identification. Thus, integrated lights are the most significant feature for ensuring buoys are visible and identifiable at night.