HOT-75 COMMEMORATIVE SCIENCE SYMPOSIUM

A Comparison of HPLC Pigment Signatures and Electron Microscopic Observations for Oligotrophic Waters of the North Atlantic and North Pacific Oceans

Robert Bidigare¹, Mikel Latasa¹, Robert Andersen² and Maureen Keller²

¹School of Ocean and Earth Science and Technology, University of Hawaii, Honolulu, HI 96822

²Bigelow Laboratory for Ocean Sciences, West Boothbay Harbor, ME 04575

The use of HPLC pigment analysis has become a primary tool for investigating the taxonomic composition of natural phytoplankton populations. This approach was developed using the pigment characteristics of select phytoplankton species in culture. In this study, we compare, for the first time, the taxonomic composition based upon HPLC pigment signatures with direct electron microscopic identifications from samples collected from the North Atlantic and North Pacific Oceans (Hydrostation S and Station ALOHA, respectively). Electron microscopic observations provided direct identification of specific taxonomic groups and these observations generally agreed with inferred taxonomic identities based upon HPLC pigment analysis. The general agreement of the two methods, although not perfect, suggests that HPLC data provide a good first approximation concerning the taxonomic composition of the phytoplankton. At both locations, the eukaryotic ultraplankton was similar in taxonomic composition, at least at the class level, and the Prymnesiophyceae and the newly described Pelagophyceae were the two most abundant groups of eukaryotes. We conclude that in our study, electron microscopic observations and HPLC data for eukaryotic algae are reasonably similar, and we suggest that pigment analysis can be used as a means for approximating the taxonomic composition of the phytoplankton.