Biodiversity of plankton by species oscillations and chaos

Biodiversity has both fascinated and puzzled biologists(1). In aquatic ecos ystems, the biodiversity puzzle is particularly troublesome, and known as t he 'paradox of the plankton'(2). Competition theory predicts that, at equil ibrium, the number of coexisting species cannot exceed the number of limiti ng resources(3-6). For phytoplankton, only a few resources are potentially limiting: nitrogen, phosphorus, silicon, iron, light, inorganic carbon, and sometimes a few trace metals or vitamins. However, in natural waters dozen s of phytoplankton species coexist(2). Here we offer a solution to the plan kton paradox. First, we show that resource competition models(6-10) can gen erate oscillations and chaos when species compete for three or more resourc es. Second we show that these oscillations and chaotic fluctuations in spec ies abundances allow the coexistence of many species on a handful of resour ces. This model of planktonic biodiversity may be broadly applicable to the biodiversity of many ecosystems.