P. Raimbault et M. Pujopay, ACTIVATION OF NITRATE UPTAKE DUE TO PHOSP HATE ADDITION IN THE WATERSOF THE TROPICAL ATLANTIC-OCEAN, Comptes rendus de l'Academie des sciences. Serie 3, Sciences de la vie, 316(8), 1993, pp. 740-744
The utilization of a sensitive automatic method for nitrate analysis h
as been applied to study the influence of phosphate on nitrate uptake
in surface seawater samples collected in an oligotrophic area (Tropica
l Atlantic Ocean). The deck-incubation experiments performed during mo
re than 24 h showed a strong phosphate-stimulation of the nitrate cons
umption after a delay of 12 to 24 h. The nitrate uptake is increased b
y a factor of 3 to 6. The experiments described here demonstrate that
: (1) planktonic organisms that take up the nitrate are phosphorus-def
icient in this oligotrophic area ; (2) phosphorus may be a limiting fa
ctor for the new production ; (3) phosphorus takes an important part i
n the nitrogen dynamics in the ocean.