In March 2015, the winds and storm surge created by Cyclone Pam resulted in waves of 3 metres (9.8 ft) to 5 metres (16 ft) breaking over the reef of the outer islands caused damage to houses, crops and infrastructure. On Nui the sources of fresh water were destroyed or contaminated. The flooding in Nui and Nukufetau caused many families to shelter in evacuation centres or with other families. Nui suffered the most damage of the three central islands (Nui, Nukufetau and Vaitupu); with both Nui and Nukufetau suffering the loss of 90% of the crops. Of the three northern islands (Nanumanga, Niutao, Nanumea), Nanumanga suffered the most damage, with 60-100 houses flooded, with the waves also causing damage to the health facility. Vasafua islet, part of the Funafuti Conservation Area, was severely damaged by Cyclone Pam. The coconut palms were washed away, leaving the islet as a sand bar.
The loss of what caused the Vasafua islet to become  a sand bar due to Cyclone Pam?
coconut palms