Pigment Fluorescence Signatures as an Index to the Taxonomic Structure of Phytoplankton Communities.

摘要

The spatial distribution and taxonomic composition of phytoplankton communities are important determinants of the structure of marine ecosystems and the optical environment of the sea. In oceanic waters the dominant photoautotrophs are picoplankton cyanobacteria. Dominant photoautotrophs in coastal waters, in contrast, are frequently larger diatoms, dinoflagellates and prymnesiophytes. The optical environment of Case 2 waters is shaped by the absorption and scattering of the larger phytoplankton with pigment signatures and cell, or colonial, morphologies that are distinct from the oceanic picoplankton in Case 1 waters (Kirk, 1994). Biological oceanographers have developed a variety of methods to map the spatial distribution of taxonomic groups in natural plankton communities. The classical approach of microscopic enumeration of preserved samples is now supplemented by molecular biological and molecular phylogenetic techniques adapted from medical research (Long, 1998). Furthermore, the distinct pigment composition of individual phytoplankton taxonomic classes can be used as pigment 'biomarkers' to qualitatively map the abundance of phytoplankton classes with high performance liquid chromatography. Fluorescence characteristics of phytoplankton classes have also been utilized in both microscopic and flow cytometric methods to identify taxa in natural communities (Wood et al., 1985). These methods are, however, mainly applied to discrete samples collected at specific locations and depths. Since the optical, physical, chemical and biological properties in the ocean vary over a wide of temporal and spatial scales (Bidigare et al., 1992), in situ observations are needed at frequent intervals in time and space to determine relationships between the abiotic and biological processes.