Phytoplankton pigments in relation to carbon content in phytoplankton communities

Abstract

Measurements of natural marine phytoplankton communities were carried out in a mesocosta experiment by means of pigment analysis by HPLC to identify phytoplankton composition, and using microscopic identification of species and measurement of cell volume to estimate the carbon content of the phytoplankton groups. The enclosures were manipulated with additions of nutrients and mussels and reduction of light to induce changes in the phytoplankton communities. The trophic status of the individual enclosures was illustrated by F(p) ratios defined as the diagnostic pigments for diatoms and dinoflagellates divided by the total concentration of all diagnostic pigments. The F(p) ratios were significantly correlated to F(c) ratios, defined as the carbon content of dinoflagellates and diatoms divided by total phytoplankton carbon, suggesting that the phytoplankton diagnostic pigments can be used as both a qualitative and quantitative indicator of the respective phytoplankton groups.