313
had 20 attached coccoliths. Independent estimates of carbon per cell and per coccolith indicate
that the total fixation of carbon into organic matter and into calcite was about the same.
In cultures of E. huxleyi coccoliths are formed as rapidly as one per hour during the light
period (Westbroek et al., 1983; Fig. 8) so that the production rate might be as high as
10 cell· 1 d- 1 under natural conditions at temperate latitudes. However, without appropriate
information on changes in cell abundance with time and on losses of coccoliths due to sinking,
10'
A
10'
.!;
10'
ci
Z
10'
10'
GROWTH CURVE' E. huxleyl Clone SSE
C~IIS1ml •
':Slml •
........ --.
10
12
16
18
Day
Cal ci fi cat ion and Photosynthet i cRates
6e-7'.-_--::-_ _ _ _ _ _ _ _ _ _ _ ~
5e-7
~ 4e-7
'"
u
~ Je-7
::>.
•
Calciflcation
•
Photosynthesis
10
12
14
16
18
20
Day
Figure 8. A. Changes in cell and coccolith densities during growth in fl50 medium of a batch culture of E.
huxleyi (clone SSE from the Gulf of Maine). B. Changes in rates of photosynthesis and calcification for
the same culture, as determined from assimilation rates for 14C02 in the light period. (From Balch et
al., 1991).