英语翻译We develop a six-compartment model consisting of phospho

英语翻译
We develop a six-compartment model consisting of phosphorus,detritus,phytoplankton,zooplankton,planktonivorous fish and pisciphagous fish.In this model,we study the implications that the body sizes of phytoplankton and zooplankton have on the system dynamics.We use ascendency as a goal function or indicator of system performance.Ascendency quantifies growth and development of an ecosystem as a product of total system throughflow and the mutual information inherent in the pattern of internal system flows.Different physiological rate parameters of phytoplankton and zooplankton are assessed by means of allometric relationships applied to their body sizes.We let the phytoplankton body size range from 10 μm3 to 107 μm3 and the zooplankton body size range from 10 μm3 to 104 μm3 in volume.We also investigate the effects of phosphorus input conditions,corresponding to oligotrophic,mesotrophic and eutrophic systems on system dynamics.Ascendency (to be maximized over phytoplankton and zooplankton sizes) was computed after the system had reached a steady state.Since it always was a seasonal cycle,and the ascendency followed this behavior,we averaged the ascendency over 365 successive days (duration of one year) in the oscillatory phase.Under all types of nutrient conditions,the smallest phytoplankton size yielded the maximal values of the ascendency,while the corresponding zooplankton size varied.Under oligotrophic conditions,a phytoplankton size of 10 μm3 combined with a zooplankton size of 101.25 μm3 to give the maximum value of the ascendency.Under mesotrophic and eutrophic conditions,maxima were obtained for zooplankton sizes 102.26 μm3 and 103.20 μm3,respectively.