What is so special about mangroves?

The title question of this short paper has been addressed to me countless times by persons from all walks of life. The paper is a concise answer to the question; it might go halfway towards satisfying the questioners, but not more than halfway. This paper identifies the uniqueness of mangrove ecosystems in that they are created and sustained by a small number of rooted vascular plants in the intertidal area of the tropics. In addition to being a marginal ecosystem, a mangrove is unique in that, as an ecosystem it has various interactions with other ecosystems, both adjoining and remote in space and time. Another unique feature of mangroves is that, unlike most marginal ecosystems, they are highly productive and dynamic. Healthy mangrove ecosystems also have the peculiar ability to immobilize heavy metals.