From a Ecological point of view: Most of the life in the ocean is foiund in coastal areas, where sufficient light hits the sea bed. The oceans are pretty devoid of life, except for single celled phyto & zooplankton. The limiting factor is ususally the availability of Nitrates and Phosphates, and light, which doesn't penetrate more tha 100m or so at maximium. Deep ocean life survives purely on corpses raining down from above, ad is really rare, except aroud volcanic vents.
Mid-ocean ridges usually have thermal vents which provide energy that powers ecosystems. These areas seem to be pretty diverse. But they're very deep & difficult to find.
The most productive areas are coastal upwellings, where water comes up from the deep oceas (and is loaded with nutrients) into the photic zone (where light penetrates). These areas are hugely productive. One example is off the coast of Peru.
Coral reefs are hugely productive, rivalling rainforests for biodiversity. However they're mainly a surface phenomenon - they don't extend more than about 30m deep because the light runs out. I've heard that deep water coral reefs have been found in the North Sea, but I don't know any details.
The other really productive areas are the edges of polar icecaps. When the ice melts in summer, huge amounts of trapped phytoplankton & nutriennts are released. This leads to a short lived explosion in productivity. Swarms of Krill can contain densities of several per cubic centimetre, while extending for several tens of kilometres. They support baleen whales, penguins etc.
So, I'd suggest:
Ocean beds: 3
Continental Shelf: 5
Coastal: 7
Mid Ocean Ridges: 5
Polar Oceans: 3 - 9 in summer
Coral Reefs: 9
Coastal Upwellings: 8-9 (there are only about six of these on earth, so they'd be pretty
rare, but pretty large - possibly several maritime provinces in size). Also subject to
periodic fluctuations - the El Nio effect, in which the source level drops to 6.
Fishing would reduce the source levels of these provices. Assume that 50% of the population of a coastal province support themselves by fishing and 100% of the population of a small island - eg. provinces in Mairada.
By Neil Barnes
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