On Mon, 26 Jan 1998, Ed Stark wrote:
> Of course, a DM may also be perfectly justified in ruling that, for some
> reason, water sources are rare or do not exist–perhaps mebhaighl does not
> permeate the oceans like it does the land. And maybe the ocean floor just
> doesn’t give you the kick you need.
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 limitig 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.
Obviously, feel free to change stuff to suit your campaign.
neil