Abstract
From a transect between Brazil and Newfoundland in April 1983, a summary description of the phytoplankton species is that diversity decreases northward as conditions alter from equilibrium to nonequilibrium. These conditions do not increase the southern species adapted to impoverished nutrient but do increase species unadopted to impoverished nutrient. Diversity is related to equilibrium and adaptation in this way: (1) species belonging to a very diverse group occur under equilibrium conditions and are adapted to impoverished nutrient (with three logical opposites to this general descriptive statement) (2) species adapted to impoverished nutrient occur under nonequilibrium conditions only if they do not belong to a very diverse group, (3) species occurring under equilibrium conditions are unadapated to impoverished nutrient only if they do not belong to a very diverse group, and (4) species occurring under nonequilibrium do not belong to a very diverse group and species (the same) unadopted to impoverished nutrient do not belong to a very diverse group either. General statements (1) through (4) describe completely and perfectly the species distributions discursively and incompletely described by the first two sentences.