Biological response of Costa Rica Dome phytoplankton to Light, Silicic acid and Trace metals.
The Costa Rica Dome (CRD) is a unique open-ocean upwelling system, with picophytoplankton dominance of phytoplankton biomass and suppressed diatoms, yet paradoxically high export of biogenic silica. As a part of Flux and Zinc Experiments cruise in summer (June-July 2010), we conducted shipboard incubation experiments in the CRD to examine the potential roles of Si, Zn, Fe and light as regulating factors of phytoplankton biomass and community structure. Estimates of photosynthetic quantum yields revealed an extremely stressed phytoplankton population that responded positively to additions of silicic acid, iron and zinc and higher light conditions. Size-fractioned Chlayielded the surprising result that picophytoplankton, as well as larger phytoplankton, responded most to treatments with added silicic acid incubated at high incident light (HL + Si). The combination of Si and HL also led to increases in cell sizes of picoplankton, notably inSynechococcus. Such a response, coupled with the recent discovery of significant intracellular accumulation of Si in some picophytoplankton, suggests that small phytoplankton could play a potentially important role in Si cycling in the CRD, which may help to explain its peculiar export characteristics.
Lamont Doherty Earth Observatory at Columbia University, Palisades , New York, NY 10964 , USA.
Joaquim I
JI
Goes
Lamont Doherty Earth Observatory at Columbia University, Palisades , New York, NY 10964 , USA.
Helga do Rosario
HD
Gomes
Department of Oceanography , University of Hawaii at Manoa , Honululu, HI 96822 , USA.
Karen E
KE
Selph
Scripps Institution of Oceanography , University of California at San Diego , 9500 Gilman Dr, La Jolla, CA 92093 , USA.
Michael R
MR
Landry
Synechococcus; light; microphytoplankton; nanophytoplankton; picophytoplankton; silicic acid