Mangroves are a group of halophytic (salt tolerant) trees and shrubs growing in brackish to saline tidal waters of tropical and sub-tropical coastlines (Kauffman and Donato, 2011, p 1). These plants have developed a number of morphological adaptations that allow them to survive the saline conditions of the tidal environment, including aerial roots and salt excretion glands. Mangroves may occur as isolated patches of vegetation of limited height, or may form dense canopies of trees 30–40 metres in height (FAO, 2007, p 15).