Productivity refers to the cycling of nutrients and energy. Photosynthesis, which is the process where organisms produce sugars (energy) from sunlight and carbon dioxide, occurs in the upper layers of the ocean.
This primary productivity provides the basic food for all ocean ecosystems. Photosynthetic plankton are eaten by zooplankton, which are consumed by filter feeders such as kuku, which are consumed by fish and so on. Other producers can also take advantage of the decomposing marine life that sinks to the seafloor, digesting and releasing nutrients to continue in their cycles. Some biogenic habitats are among the most productive habitats on Earth – comparable to tropical rainforests.
However, not all forms of productivity rely on photosynthesis. For example, on deepsea hydrothermal vents where sunlight cannot reach, the primary producers are microbes that use a different technique to generate sugars. Instead of sunlight, they use the often-toxic chemicals seeping from the deepsea vents. These hydrothermal vents are among the most productive deepsea ecosystems.
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Copyright: Department of Conservation
