ABSTRACT
The marine environment encompasses the saline waters of the world’s oceans, seas, and coastal estuaries. This is a vast body of water, in places extending to depths of 10 kilometers or more, and is home to a broad array of interrelated biological systems. These systems ultimately rely on primary producers (phytoplankton and other photosynthetic marine organisms that convert sunlight to energy), which form the base of the marine food chain. Primary production supports microscopic zooplankton, crustaceans, fish, marine mammals (such as whales), and reptiles (such as turtles), as well as a host of other organisms. Marine ecosystems also support terrestrial (land-based) organisms, such as sea birds, seals, penguins, polar bears, and humans. Approximately one-quarter of humans’ dietary protein is derived from the marine environment. Overfishing and exploitation of marine resources by humans have already had a major impact on the abundance and health of marine ecosystems, but climate change is expected to exacerbate this ongoing decline in marine biodiversity.1
