Incorporation of the intracellular elemental correlation pattern into simulation models of phytoplankton uptake and population dynamics

Abstract

Compelling evidence of complex statisticalrelationships among various elements contained withinphytoplankton cells has traditionally been ignored inmodels of algal nutrient uptake and populationdynamics. Here we present a new approach,incorporating a phytoplankton intracellular elementalcorrelation pattern into the existing dynamicsimulation model of a freshwater lake. Within thisapproach, uptake and cycling of elements that arelikely to become limiting during the simulation periodare described by ordinary differential equations.Dynamics of nutrients that are unlikely to becomelimiting are described either by differentialequations or, when more practicable, by multipleregressions on environmental variables and cell quotasof other elements. This allows an easy simultaneousconsideration of a wide range of elements.The model adopting the described approach wastested on a data set for Rostherne Mere, Cheshire, UK.It showed a good fit between observations andsimulations for all considered variables, includingthe population dynamics of Ceratium hirundinellaand Microcystis aeruginosa, the outcome ofinterspecific competition and changes inconcentrations within algal cells and in thesurrounding lake water. The approach could easily beimplemented in models of bioreactors, chemostatexperiments and aquatic ecosystems.