Adventures in symbiosis

Abstract

A research adventure is described in which the symbiosis of Hydra and Chlorella is modeled with a novel computer program. The model faithfully simulates equilibrium populations of hydra and algae, and is used to discern the parameters which govern the stability of the symbiosis and its breakdown resulting from eutrophication. The model reveals that amelioration of a nutrient limitation causes symbiotic Chlorella to reduce fitness of host cells, converting a stable mutualistic symbiosis into an unstable parasitic one. © 1989 by the American Society of Zoologists.