Zonation of the marine environment
Introduction Organisms are not evenly distributed in the global ecosystem but follow many different abiotic and biotic features that govern their distribution and zonation. Figure. 21 presents a diagrammatic representation of the terms which are used to describe different parts of the sea bed as well as the corresponding approximate depths. It is interesting here to observe the globally common pattern concerning continental shelf and continental slope. The continental shelf formation is due to a series of causes such as:
Beyond the continental shelf which usually reaches down to 200 metres the sea bottom presents a much steeper incline called the continental slope which extends down to the bottom of the ocean basins to a depth of 3000-6000 metres.
This morphology pattern of the sea bottom has various consequences as far as its physical and chemical characteristics are concerned and therefore also in respect of the organisms which live there. Thus a specific terminology is used to denote the zonation of the marine environment (Figure 22) both for the pelagic and the benthic categories. The pelagic division occurs horizontally (i.e. in relation to the distance from the coast) and is divided into two categories: |