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High numbers of Trichodesmium and diazotrophic diatoms in the southwest Indian Ocean

By Alex J. Poulton, Mark C. Stinchcombe and Graham D. Quartly

Abstract

We observed high cell numbers of large (>50?m) nitrogen-fixing phytoplankton to the south and to the east of Madagascar in February 2005. The distribution of the diazotrophic taxa we found was markedly different: Trichodesmium was most abundant (500-1000 trichomes L-1) in the waters at the southern tip of Madagascar, while diazotrophic diatoms (125-500 cells L-1) were found to be abundant to the southeast of Madagascar. From these cell numbers, using literature values of nitrogen-fixation per cell, we estimate potential rates of nitrogen-fixation for Trichodesmium (south of Madagascar) of 1-5 mmol N m-2 d-1 and for diazotrophic diatoms (east of Madagascar) of 0.4-2.4 mmol N m-2 d-1. These cell-based estimates highlight the potential for significant nitrogen-fixation in the southwest Indian Ocean. High numbers of diazotrophic diatoms in subtropical waters to the east of Madagascar may have important implications for the biogeochemistry of the austral phytoplankton blooms that occur in this area

Topics: GC, QH301
Year: 2009
OAI identifier: oai:eprints.soton.ac.uk:66227
Provided by: e-Prints Soton

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Citations

  1. (2004). (Available at http://eprints.soton. ac.uk/42070)
  2. (2001). A major seasonal phytoplankton bloom in the Madagascar Basin,
  3. (2004). A possible plankton wave in the Indian Ocean,
  4. Bidigare (1999a), Temporal variations in diatom abundance and downward vertical flux in the oligotrophic North Pacific gyre,
  5. (2004). Biomass and primary productivity of the cyanobacterium, Trichodesmium spp.,
  6. (1966). Computation of phytoplankton number, cell volume, cell surface and plasma volume per litre from microscopic counts, Off. of Nav.
  7. (1995). Ecosystem changes in the North Pacific subtropical gyre attributed to the 1991–92 El Nin ˜o,
  8. (2006). Eddies around Madagascar: The retroflection re-considered,
  9. (1999). Extensive bloom of a N2-fixing symbiotic association in the tropical Atlantic Ocean,
  10. (1994). Fluorometric analysis of chlorophyll a in the presence of chlorophyll b and phaeopigments,
  11. (2008). Global distribution of summer chlorophyll blooms in the oligotrophic gyres,
  12. Karl (1999b), Diatom fluxes to the deep sea in oligotrophic North Pacific gyre at Station
  13. (1990). Laboratory cultivation and preliminary characterisation of the nitrogen-fixing Rhizosolenia-Richelia symbiosis,
  14. (2003). Large-scale latitudinal distribution of Trichodesmium spp. in the Atlantic Ocean,
  15. (1992). Marine nitrogen-fixing diatom-cyanobacteria symbioses, in Marine Pelagic Cyanobacteria: Trichodesmium and Other Diazotrophs, edited by
  16. (2005). Nitrogen fixation by Trichodesmium spp.: An important source of new nitrogen to the tropical and subtropical North Atlantic Ocean, Global Biogeochem.
  17. (1994). Regional Oceanography: An Introduction, Pergamon,
  18. (1996). Role of Trichodesmium spp. in the productivity of the subtropical North Pacific Ocean,
  19. (2006). RRS Discovery cruise D288: The Madagascar Experiment (MadEx),
  20. (2008). Summer phytoplankton blooms in the oligotrophic North Pacific Subtropical Gyre: Historical perspective and recent observations,
  21. (2005). The conundrum of marine N2 fixation,
  22. (1974). The distribution and significance of Richella intracellularis Schmidt in the North Pacific Central Gyre,
  23. (2005). The effect of growth rate, phosphorus concentration, and temperature on N2 fixation, carbon fixation, and nitrogen release in continuous cultures of Trichodesmium IMS101,
  24. (2000). Total organic nutrients in Drake Passage,
  25. (2007). What causes the sporadic phytoplankton bloom southeast off

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