Phytoplankton pigment patterns in a temperate estuary: From unialgal cultures to natural assemblages

Abstract

Pigment analysis complemented with microscopic observations of live and preserved cells was used to gain insight into the composition of estuarine phytoplankton. Biological material, obtained from the Nervion River estuary, consisted of 37 species belonging to 15 phytoplankton classes and 10 field samples taken in 2004 in the context of a monitoring program and selected by the presence of species with pigments shared by different algal classes. Pigment diversity was highest among prymnesiophyceans, represented by five chemotaxonomic types, which differed by the distribution of the different chlorophylls (Chls) c and the acyloxyderivatives of the carotenoid fucoxanthin (Fuco). Dinoflagellates belonged to five pigment types including dinoflagellates with peridinin (Per) and others with pigments of diatoms, chlorophytes, haptophytes or cryptophytes. Four species of prasinophyceans were identified, one with prasinoxanthin (Pras), two with siphonaxanthin derivatives and the fourth with loroxanthin derivatives. The rest of the algal classes were represented by one chemotaxonomic group each. In field samples of mixed populations, the more specific pigments of the species sharing major pigments with other classes were undetectable. This study reveals the great diversity of pigment patterns present within several phytoplankton classes and the difficulty to infer the structure of phytoplankton assemblages in estuarine waters only from pigments. © The Author 2007. Published by Oxford University Press. All rights reserved.