Protein and carbohydrate contents related to varying light levels and chlorophyll-a in selected freshwater and marine phytoplankton

This study investigated correlations between chlorophyll-a (CHLa) and certain biomass parameters (protein and two forms of carbohydrates) under the influence of light intensity. These findings are applicable to the estimation of metabolizable biomass in water bodies, which is important for understanding the nutritional value of phytoplankton and their impact on aquatic food webs. Furthermore, these determined biomass relationships can also assist in the prediction of the generation of anoxia during and following algal blooms. That is, one could relate the standing crop of metabolizable organic matter (proteins and carbohydrates) to existing conditions of water depth, currents, dissolved oxygen trends and other parameters. Results from this study indicate that protein, colloidal carbohydrates, and storage carbohydrate concentrations in phytoplankton can be broadly estimated by multiplying chlorophyll-a amounts (pg/cell or mg/L) by 202.6, 17.7, and 144.9, respectively. The methodology presented can therefore serve as a means of approximating the standing crop of metabolizable phytoplankton organic matter (viz. protein and two forms of carbohydrates).