Hydrosphere Contents

5. Aquatic Habitats

The ocean bottom environment is unique

The ocean bottom environment supports a unique ecology, which in the absence of sunlight, relies on hydrogen sulphide, emitted from hydrothermal vents. Large communities inhabit the deep ocean floor. At the base of the trophic levels are bacteria, which utilise the dissolved chemicals in the hot vent water to obtain energy. Without sunlight they survive through chemosynthesis, instead of photosynthesis, by utilising the hydrogen sulphide and carbon dioxide.

The ocean bottom has many important mineral reserves, including manganese oxide nodules, magnesium and sulphide deposits. Mining of these minerals generates a lot of controversy over whether the potential gain from the resources is worth the sacrifice of the ocean bottom environments. This is further complicated by the issue of who should have the mining rights over the resources, and whether they should be a common heritage for all people.

The ocean bottom water environment

Why is the ocean bottom environment unique?