Plant pigments and light penetration in intertidal sediments

Abstract

1. Chromatographic analyses were used to determine the concentration of plant pigments in the sediments at four intertidal stations at Barnstable Harbor, Massachusetts, U.S.A. Two of the stations were sand flats exposed to relatively strong tidal currents and two were mud flats subject to weak currents. In general, highest concentrations of all pigments were found in the upper mm. Chlorophyll-a, chlorophyll-c and fucoxanthin concentrations decreased with depth but considerable quantities (20 to 50% of surface values) were found at 5 cm. Diatoxanthin, diadinoxanthin and carotene concentrations did not decrease with depth. Quantitative differences between the stations were noted. 2. With one exception, measurements of light attenuation through these sediments, were roughly correlated with mean particle size. 3. On one station, living diatoms were found as deep as 5 cm, but the vertical distribution of the pigments could not be explained by the diatom distribution.