"prosopis juliflora", a type of mesquite known as mexican thorn, was introduced by bbc engineers to bind the dry top soil when they arrived in 1966 to construct a shortwave relay station. it has thrived on the barren lava of the island – an estimated 38,000 bushes existed by 2016. its spread has been destructive to other species, and current encroachment on the edges of beaches threatens those that use this space, such as the green turtle. its hardy taproots can extend to 30 metres deep. local authorities are considering means of controlling or eradicating it.