Marine organisms play crucial roles in many bio-geochemical processes that sustain the biosphere, and provide a variety of products and functions which are essential to mankind’s well-being, including the production of food and natural substances, the assimilation of waste and regulation of the world’s climate. The rate and efficiency of any processes that marine organisms mediate, as well as the range of goods and services that they provide, are determined by interactions between organisms and interactions between organisms and their environment; and therefore by biodiversity.