Geographic Variation in Artificial Island Colonization Curves

Abstract

Colonization of identical marine—fouling—panel "islands" is compared at several shallow—water Northern Hemisphere localities in tropical, subtropical, temperate and subarctic regions. Because these sites differ in total number of species available for colonization, the equilibrium number of species on these islands predicted by an extension of the MacArthur—Wilson model is expected to differ as well. Initially the number of sessile species of marine invertebrates and algae accumulating on panels is inversely related to the availability of potentially colonizing species; in most cases this implies an inverse relation to latitude. By the end of the study equilibrium species number shows minimal differences between sites, appearing to converge on similar values at all localities. Thus, colonization curves are more peaked in species—rich regions such as the tropics than in poorer ones.