Charles S. Yentsch

A method for the determination of phytoplankton chlorophyll and phaeophytin by fluorescence

Abstract The concentration of chlorophyll, principally chlorophyll a , and after acidification phaeophytin, is measured in 85% acetone extracts using a sensitive fluorometer. The method is very sensitive in the 10 fluorescence units are equal to 0·001 O.D. 665 mμ 10 cm . The maximum variation is 15%. The method is highly suitable for routine analysis at sea or in the laboratory.

The influence of phytoplankton pigments on the colour of sea water

Abstract By summing the absorbency of phytoplankton pigments with that of pure water, the absorption of the blue portion of the spectrum is markedly increased. As the concentration of phytoplankton pigments increases, the diminution of blue light gradually shifts the wave length of maximum transmission toward the green. At the concentration of phytoplankton pigments normally found in the open ocean, the red chlorophyll band has little influence on water colour. Inadequancies in present methods for detection of absorption bands in natural waters is attributed to wide band widths of filters used in submarine photometers. Poor spectral curves applicable to colour analysis in particulate systems are obtained by conventional spectrophotometric techniques because a large portion of the scattered light never reaches the photo-detector. Improvements for spectral analysis are suggested.

Distribution of chlorophyll and phaeophytin in the open ocean

Abstract Measurements of chlorophyll and phaeophytin have been made in the Indian and Atlantic Oceans by the method of Yentsch and Menzel (1963). The vertical profiles of these pigments show distinctive features which can be related to the quantity of light penetrating the water column and vertical mixing. The importance of light in the prevention of the formation of phaeophytin is shown by the observations that when in prolonged darkness marine phytoplankton cultures form phaeophytin. When cultures and natural particulate matter containing large amounts of phaeophytin are returned to light of moderate intensity, phaeophytin disappears and chlorophyll is produced. Sources and pathways of phaeo-pigment formation in the planktonic environment are discussed.