Eukaryotic Phytoplankton Functional Diversity: Dynamics of Phytoplankton in Upwelling Systems

The rate, magnitude and fate of primary production is dependent on the kind of phytoplankton that assimilates carbon. The majority of blooms and upwelling events are dominated by single celled organisms, mainly diatoms, presumably because they have the genetic potential and the physiological capabilities which result in the ability to grow faster in these environmental conditions. It is also well known that key metabolic genes, such as the assimilatory nitrate reductase (NR) and rbcL, the gene encoding the large subunit of ribulose-1,5-bisphosphate carboxylase/oxygenase, encode functions that are important in eukaryotic phytoplankton.  We suspect that their expression and regulation will shed light on the success of diatoms during bloom formation and upwelling events. Using a clone library and sequencing approach based on NR and rbcL genes, we have already shown that the Monterey Bay in California (upwelling environment) and the Western English Channel in the Atlantic Ocean (spring bloom environment) are dominated by diatom like sequences. In addition, diverse rbcL sequences from members of the Haptophyceae, Dinophyceae and Pelagophyceae were detected in these environments. The clone libraries exhibited both cosmopolitan and endemic ecological patterns from both the environments. The importance of diatoms and other eukaryotic phytoplanktons (as revealed by this and other studies) in bloom and upwelling environments depends on the genetic level of regulation and response within their environment. Using gene expression and microarrays based on key genes such as nitrate reductase we want to discover the basis of why diatoms are uniquely successful in upwelling and bloom environments. 

Ward Lab Participants: Punysaloke Bhadury and Anita Adhitya

Figure 1: Diversity of phytoplankton communities based on nitrate reductase phylogeny from Monterey Bay and Western English Channel.