proportional to the area occupied by a given depth in the world’s oceans. For example,
depths in the abyssal category occupy about 60% of the seafloor
(^) (After Hedgpeth 1957).
There are some rocky deep-sea sites, particularly at spreading centers, but most of
the ocean is underlain by sediment-covered bottom 2000 to 5500 m below the surface
productive layer. The extent to which both pelagic and benthic habitats have been
studied with respect to the organisms living in them and their ecology declines rapidly
as depth increases. While deep habitats are difficult to access and sample, they have
been studied and much is known about them.
A few Mathematical Reminders
I The Exponential Function
(^) This is, of course, basic mathematics, but, to refresh the concepts, we provide these
notes. The exponential function appears repeatedly in biological oceanographic
discourse. It appears repeatedly throughout science. It appears in analytical chemistry
as Beer’s Law, discussed above – the relationship between light absorption by a not
quite fully transparent medium of transmission and the length of the absorbing
column of medium. It appears in population dynamics, nuclear decay theory,
everywhere.
(^) Any function of the form y = ax can be termed exponential. We use the values of 10x
where x is an integer to give the place values in our usual number system:
(^) X 10 X 2 X