composition at the redox interface. The deeper community, dominated by nematodes,
is referred to as the “thiobios” (which includes anaerobic bacteria, of course).
Investigation of the necessary physiological adaptations is in progress, hampered of
course by the small size of the study subjects.
Abundance Versus Water-Column Depth
(^) Trends in faunal numbers and biomass with depth have been treated with statistical
sophistication by Rex and Etter (2010), using partial regression to standardize masses
of data from the literature to a fictional common suite of collector, sieve-mesh
opening and latitude. They provide figures with these comparisons from a wide range
of sites, and we show their comparisons between the east and west sides of the North
Atlantic (Fig. 13.12), which are statistically indistinguishable. Of course, the
standardization has the additional effect of moving plotted points well away from the
actual data. However, the general trend with increasing depth could be well
represented by almost any transect of samples crossing a continental shelf and slope,
extending to the abyss. A compendium (Rowe 1983) of Russian biomass vs. depth
results from the extensive cruise work of the Soviet era, mostly results from “okean”
grab samples, shows a similar trend (Fig. 13.13).
Fig. 13.12 Semi-log plots of (a) numbers of macrofauna vs. depth, and (b)
macrofaunal biomass vs. depth for samples from the east and west sides of the North
Atlantic. The regression lines (east heavier) are not significantly different.
(^) (After Rex & Etter 2010.)
Fig. 13.13 Biomass as wet weight vs. depth from Soviet era oceanographic studies.