Algal symbiosis: A mathematical analysis

Host and algal symbion growth can be described by an iterative model which incorporates utilization efficiencies of host and symbiont. This model predicts that, with input of organic matter to the host and at very low host and algal utilization efficiences coupled with efficient recycling of nutrients between the host and symbionts, production of organic matter by the system can be increased by 2–3 orders of magnitude over that of a system comprised of only autotrophs and heterotrophs. Energy available for growth and respiration by the host is 1–2 orders of magnitude over that available to a heterotroph without symbionts. Algal symbiosis is highly advantageous in oligotrophic environments where radiant energy is abundant, growth-limiting nutrients are scarce and only concentrated in organic matter, and much energy must be expended to capture that organic matter.