Help: primary production

Henri-Michel Cauchie cauchie at
Tue Nov 21 13:50:02 EST 1995

Hi, I'm a PhD student and I'm working on the secondary production  in
sewage lagoons.

As I needed primary production data to analyse the seasonal succession of
plankton, I  used the
"dark and light bottle" method.However, (as I'm a zoologist), I  wander  if
all the steps  that I
followed are correct...

Step 1: I measured the variation of the oxygen content in bottles incubated
at 5 depth (Surface,
20 cm, 50 cm, 100 cm and 200 cm) during four hours around noon. Dark bottle
incubation was also
made during the same period.
During the incubation period, I also measured the total Irradiance
(Einstein by sqare meter).

Step 2:  The oxygen quantities (produced  by hour and by litre) were
converted into fixed carbon
(by hour and by litre) by multiplying by 0.375. (APHA 1985))

Step 3:  I calculated the production by hour and by square meter for the
whole water column by
integrating the production measured at the different depth

Step 4: I multiplied the production by hour and by square meters  by the
ratio  "Total Irradiance
during the day/Total irradiance during the incubation".

Any remarks, (even on the spelling or grammar !), are wellcomed.
Thank you very much in advance.

Henry-Michel CAUXHIE

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