Fig. 13.21 Deep-sea biogeographical regions characterized by distinctive benthic
species assemblages defined primarily from Russian sampling in the 1950s to 1980s.
(^) (After Vinogradova 1997.)
(^) Each region can be divided into provinces (shown in her figure by varied hatching),
the demarcation lines largely following mid-ocean ridges. Arctic abyssal fauna are
somewhat distinct, but Vinogradova found a stronger relation with the Atlantic
province than with the quite strongly distinctive subarctic Pacific one (“1A 1 ”). The
province pattern suggests that the dominant spatial barriers allowing allopatric
speciation in deep benthos are bathymetric and are, therefore, shaped quite differently
from biogeographical patterns in the plankton.
(^) Kussakin (1973) proposed that the Antarctic abyssal fauna, referring particularly to
isopods – his specialty, originated in cold shelf waters and expanded onto deeper
bottoms over time, at present reaching close to the limit of equatorward travel of
relatively unmixed Antarctic Bottom Water. A division of the circum-Antarctic
benthos into sectors has been offered by Griffiths et al. (2009) that is similar to
Vinogradova’s set, each sector south of one of the northward-extending oceans, but
with more provinces. If anyone can pull the scattered data together, identification of
provinces by an explicit, reproducible procedure (an algorithm) would be useful.
Hadal areas, outlined in Fig. 13.21, harbor communities distinct from those on
surrounding abyssal bottoms. Exceptions to hadal endemism are species shared
between at most two, closely adjacent trenches.
(^) Distributional work on continental shelves and slopes is more detailed, thanks to
better accessibility. There have been programs with more and more closely spaced
samples. For example, a study by Theroux and Wigley (1998) of macrofaunal
distributions on the New England shelf (Gulf of Maine, Georges Bank and southwest