Chapter 11
Biome and province analysis of the oceans
Longhurst’s Analysis
(^) Alan Longhurst was among the group (Abbott, Banse, Brown, Esaias, Longhurst,
McClain, McGowan, Pelez, Platt, Sathyendranath, and others) who took an early
interest in the information from images made with the first visible-wavelength
satellite radiometer, the CZCS, which was active from 1978 to 1986. In 1998, he
published a book, The Ecological Geography of the Sea (2nd edition, 2006),
attempting to define a geography of ecosystem types in the world’s oceans based on
chlorophyll and temperature images. He concluded that basically there are four
“biomes” in the world ocean. Biome is a term from terrestrial ecology, where we
recognize rainforest, desert, savannah, and other habitats as general biome types,
regardless of the specific organisms living in any given example. Longhurst suggested
a division of oceans into polar, westerlies, trades, and coastal zone biomes.
Immediately after defining them, however, he divided them into a substantial number
of “provinces”, zones that are more homogeneous physically and are “recognized” by
large sets of species as suitable habitats (Chapter 10). For example, at least the two
polar and all the westerlies biomes vary enough from each other that they must be
considered separately. It is also clear that the trades biome, in which Longhurst
included central gyre and equatorial areas, covers some fairly heterogeneous physics
and biology. He did obtain a division comparable to that indicated by the
distributional patterns of organisms (a source of information that he rather disparages)
by the “provincial” subdivision, ultimately arriving at a necessarily complex scheme
(Fig. 11.1). The general biogeographical observations reported in the previous chapter
match remarkably well with Longhurst’s provinces, a set of ocean sectors which the
satellite observations distinguish reasonably well. We will treat those as distinctive
habitats requiring individual analysis. We agree with Longhurst’s distinction of
coastal biomes, which again divide into many types, such as zones of upwelling or of
large river influx.
Fig. 11.1 The layout of pelagic provinces identified by Longhurst (2006) based
primarily on satellite chlorophyll mapping. Readers should decode the province