A Model Explaining Successional Change in Standing Crop of Thermal Blue‐Green Algae

Abstract

The gross productivity and changes in the standing crop of both biomass and chlorophyll @a were measured during ecological succession in thermal blue—green algal community. The rate of gross production (Pg) in gC°m—2°h‐1 was directly related to the chlorophyll α (Chl) in mg°m—2 and independent of light intensity (Pg = 0.018 chl0,51). In turn we found a log—log relationship of chlorophyll α (mg°m—2) to biomass (x) in g°m—2 (Chl = 0.59 x1,40). The respiration rate (R) in gC°m—2°day—1 of the algal mat was directly proportional to the biomass (R = 0.0164 x). The increasing concentration of chlorophyll α per unit biomass as succession proceeded in these thermal ecosystems contrasted with the decreasing chlorophyll concentration noted in other ecosystems. The equations were combined into a nonlinear model, and algal growth during succession was predicted on the basis of algal density, free CO2 concentrations in the water, and day length. These predictions agreed closely with field data on biomass increase during succession.