Chlorophyll a: Determination by spectroscopic methods.

Abstract

Chlorophyll a is the principal pigment in plants. As a biomass indicator of aquatic microalgae which support food webs in the sea, it is probably the most frequently measured biochemical parameter in oceanography.

This document describes a procedure for the routine determination of chlorophyll a in sea water for use by ICES Member Countries. It has been developed from a review of current methodology for measuring chlorophyll a undertaken by the Working Group on Phytoplankton Ecology (WGPE) and the Marine Chemistry Working Group (MCWG). This work was led by A. Aminot (MCWG) and F. Rey (WGPE) and both groups based their discussions around a recently published work on this topic (Jeffrey, Mantoura, and Wright, 1997). The present document represents the consensus between the two groups.

This document draws attention to critical points of chlorophyll a determination and reviews recommendations concerning the use of this pigment as a biomass marker. In addition, it proposes a standard procedure for chlorophyll a determination. Although many points in the procedure can apply to any other method, the document is devoted to the determination of chlorophyll a in discrete samples, after extraction and spectroscopic measurement of the pigments.

It is not presently possible or desirable to recommend a single method for measuring chlorophyll a in seawater samples. Instead, a procedure incorporating three spectroscopic analytical methods is proposed. Apart from these alternatives, all other steps in the procedure are similar.