Biological response of Costa Rica Dome phytoplankton to Light, Silicic acid and Trace metals

TitleBiological response of Costa Rica Dome phytoplankton to Light, Silicic acid and Trace metals
Publication TypeJournal Article
Year of Publication2016
AuthorsGoes J.I, Gomes H.D, Selph K.E, Landry MR
JournalJournal of Plankton Research
Date Published2016/03
Type of ArticleArticle
ISBN Number0142-7873
Accession NumberWOS:000372874300009
Keywordsactive; atlantic-ocean; community structure; diatom growth; equatorial pacific; fluorescence; in-situ; Iron; light; marine-phytoplankton; microphytoplankton; nanophytoplankton; picophytoplankton; silicic acid; Synechococcus; upwelling dome

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 Chl a yielded 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 in Synechococcus. 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.

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