A MECHANISM TO MAINTAIN A DINOFLAGELLATE RED TIDE IN THE NERITIC WATERS OFALEXANDRIA (EGYPT)

A MECHANISM TO MAINTAIN A DINOFLAGELLATE RED TIDE
IN THE NERITIC WATERS OFALEXANDRIA (EGYPT)
CONJUNCTION OF THE DIEL VERTICAL MIGRATION OF

PROROCENTRUM TRIESTINUM WITH ITS INSITUAND IN

VITRO NUTRIENT UPTAKE KINETICS AND PHr1SED CELL

DIVISION

BY
WAGDY LABm* AND SAMIA KA1’lEL
*National Institute o/Oceanography and Fisheries. Kayet Bey, Alexandria (Egypt)
Key Words: Nutrients uptake kinetics, phased cell division, diel v~rtical migration
ABSTRACT
The ability of Prorocentrum triestinum to undergo diel vertical
migration crossing a distinct pycnocline, its relatively higher
migration ambit as well as growth rate and corresponding doubling
time represent crocialstrategic factors for its massive occurrence.
Aspects ofthe species reproduction facilitate the lise ofthe phased
cell division method Cells in different division stages were seen most
ofthe time. Yet, the main division gate extendedfor about -I-hrs before
sunrise and there was a lag time ofabout 3–1 hrs behind the formation
of cells with 2 nuclei and those paired together cells. The phased
division of P. triestinum ‘Occurred predominantly in the migrating
cells and there was a depth differentiation ofdivided cells.
The ability of this species to take up nitrate andphosphate in
darkness has been considered a special adaptation, which might work
in conjunction with the diel vertical migration to foster its
development in nature. In situ, > 60 % and 70 % ofnitrate and
phosphate over the bottom disappeared hetween midnight and early
morning of the next day, with the descent-partial ascent movement of