How do prevailing winds affect the location of coral cays?

Prevailing winds play a critical role in the formation and positioning of coral cays by influencing the movement of sediment across a coral reef platform.

Sand cays typically develop on the leeward side of a reef—the side protected from the direct force of prevailing winds. The process occurs as follows:12

• Sediment Transport: Debris and sediment are broken off from the reef, particularly from the windward slopes, by wave action.12
• Deposition: These materials are swept across the reef platform by currents and waves generated by the prevailing winds.12
• Accumulation: The sediment is deposited in areas where water velocity is abruptly reduced, which is most commonly the more sheltered leeward end of the reef.2

While sand cays generally form opposite the direction of the prevailing winds, some cays consisting of coarser material, such as chunks of dead coral, may form on the windward edge of the reef platform. Once deposited, these accumulations can be stabilized by the formation of beach rock and the growth of vegetation, though they remain vulnerable to erosion and destruction by severe storms.12