A model of the development of a periphyton community: resource and flow dynamics

An ecological model of periphyton dynamics was designed to approach the dev elopment of a periphyton community under the effects of surrounding nutrien t concentration and light intensity. The model simulated the vertical heter ogeneities of biomass, light irradiance, and nutrients within the periphyto n mat. To determine the competition for resources between species, a Monod- type relationship was used to relate external nutrient concentration to per iphyton uptake rate, and 'Liebig's law of the minimum' was used to combine light and nutrient effects on growth rate and tension strength of the algal cell. The effect of the periphyton community to the vertical distribution of water velocity was also numerically investigated. To confirm the validit ies, the developed model was verified using several cases: the external con centration was constant or was varied with different diffusion coefficients . Reasonable responses of the periphyton community to the ambience nutrient concentrations, light intensity and, in turn, temporal variation of nutrie nts during the development of a periphyton community strongly encouraged fu rther application of the model. Variation in the water velocity in a vertic al direction intensively contributed to the results of the model. (C) 2001 Elsevier Science B.V. All rights reserved.