Marine Ecosystems
Marine ecosystems cover 70 per cent of the earth's surface and have an average depth of 3.750 m (the greatest known depth being 10,750 metres in the Marianas Trench). Marine ecosystem as you know is one of the largest reservoirs of water, living things and essential nutrients needed by both the marine and land organisms.
The total biomass in the marine ecosystems far exceeds that of all fresh water ecosystems put together.