General biological features of the South Atlantic
Biogeography (2)

A major goal of biogeographic surveys is producing one or a few maps which reflect adequately the distribution of life and life-related processes. Indeed, when discussing biogeography in the pelagic realm of the World Ocean, the first image that comes to mind is the above-mentioned classical system of belt-like polar to equatorial zones stretching across the globe. However, this picture changes radically if primary production, or the abundance of life — rather than distinct species assemblages — are considered. Compare (Gb1) with (Gb3b).

The distribution of endemics, of specific diversities, of particle size, of export production, etc. will each yield a different map, all of which are relevant to biogeography. Actually, one should probably think of biogeography as a multilayered system of maps, each layer representing a different property and/or addressing a different aspect of the biota (Boltovskoy, in press). However, such a multilayered system is not amenable to summarizing in one or even a few simple and straightforward schemes that satisfactorily represent a significant proportion of the traits of pelagic life. The divisions illustrated in (Gb1) are, therefore, a compromise solution to this maze of conflicting maps. For example, specific inventories of the Tropical Oceanic domain may not differ greatly from those of the Central Gyre (Gb1), yet they do have quite dissimilar primary production values, zooplanktonic biomass, phytoplankton:zooplankton biomass relationships, etc. (Table Gb1).