Particulate light absorption and the prediction of phytoplankton biomass and planktonic metabolism in northeastern Spanish aquatic ecosystems

Examination of particulate light absorption and microplankton metabolism in 36 northeastern Spanish aquatic ecosystems, ranging from alpine rivers to inland saline lakes and the open Mediterranean Sea, revealed the existence of general relationships between particulate light absorption and the bioma ss of phytoplankton and microplankton metabolism. The particulate absorptio n spectra reflected a dominance of nonphotosynthetic, likely detrital, part icles in rivers and a dominance of phytoplankton in coastal lagoons. There was a strong relationship between the light absorbed by phytoplankton and t he chlorophyll a (Chl a) concentration of the systems, which indicated an a verage (+/- SE) Chl a specific absorption coefficient of 0.0233 +/- 0.0020 m(2).mg Chl a(-1) for these widely diverse systems. Chl a concentration was a weaker predictor of the total particulate light absorption coefficient, pointing to an important role of nonphytoplanktonic particles in light abso rption. Gross production was very closely related to the light absorption c oefficient of phytoplankton, whereas community respiration was strongly cor related with the total particulate light absorption coefficient, indicating the optical signatures of sestonic particles to be reliable predictors of planktonic biomass and metabolism in aquatic ecosystems.