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International Journal of Marine Science 2014, Vol.4, No.18: 166-178
http://ijms.sophiapublisher.com
176
of mesocosm experiment, even the value of
photosynthesis rate were varied within location. The
result also showed that the length of incubation period
impacted significantly on photosynthesis rate for all
CO
2
treatments. There was a similar trend of
photosynthesis rate for all mesocosm experiment,
which were the longer incubation period was the
higher photosynthesis rate for all mesocosm
experiments. The lowest negative value of
photosynthesis rate was found at Barrang Lompo
mesocosm experiment account for -0.0019
gC/Cell/Day (Figure 10c) and the highest negative
value of photosynthesis rate was -0.714 gC/Cell/Day
at Barru mesocosm experiment for 1000 ppm CO
2
concentration at 48 hours incubation period (Figure
10a). The study finding that photosynthesis rate was
negative due to the growth rate for all mesocosm
experiments were negative. It showed that there was
not organic material was produced during the
incubation periods due to the effect of increasing CO
2
concentration.
However,
this
finding
was
contracdicted with previous research which showed
that increasing CO
2
concentration elevated
photosynthesis rate at monoculture species. The
contradicting of this finding possibly due to natural
comunity phytoplanktoan was subjected in this study.
Carbon-concentrating mechanisms enable most
marine phytoplankton species to accumulate in-
tracellular inorganic carbon either as CO
2
or HCO
3
−
or
both (Giordano et al., 2005). Largely because of these
mechanisms, most marine phytoplankton tested in
single-species laboratory studies and field population
experiments show little or no change in photosynthetic
rates when grown under high pCO
2
conditions
equivalent to
∼
760 µatm (Tortell et al., 1997; Hein
and Sand-Jensen, 1997; Burkhardt et al., 2001; Tortell
and Morell, 2002; Rost et al., 2003; Beardall and
Raven, 2004; Giordano et al., 2005; Martin and
Tortell,2006).
3.2.5 Calcification rate
Calcification involves the precipitation of CaCO
3
from
Ca
2+
and CO
3
2-
ions in solution. In most cases this
involves the generation of microenvironments that
allow supersaturation of CaCO
3
(Brownlee and Taylor,
2002). Our result found that there was a negative
value of calcification rate for all CO
2
treatments for
both incubation periods (Figure 11). In general, there
was a similar trend of calcification rate or all location
of mesocosm experiment. Calcification rate was
higher at 48 hours than 96 hours incubation period for
all CO
2
concentration. Our finding showed that
increasing CO
2
concentration decreased calcification
rate for both incubation periods. This finding also
showed that length period of incubation affected
significantly to calcification rate. The highest and the
lowest of calcification rate was 0.006 and -1.088
gC/Cell/Day, respectively (11a). Decrease in the rate
of calcification with increasing CO
2
concentration, as
derived from changes in the seawater alkalinity by
Delille et al. (unpubl.). Although differences in
[PIC]:[POC] ratios could also result from an effect of
CO
2
on cell growth and organic carbon production by
E. huxleyi
, the differences in [PIC] :[Cell] ratios and in
the size and weight of coccoliths observed between
the treatments is direct evidence that calcification
itself was affected by the changes of the carbonate
chemistry. Reduced calcification rates and direct
effects of low pH on cell physiology nevertheless
might have affected cell division rates. It has been
previously demonstrated that many coastal marine
phytoplankton species are directly sensitive to the pH
of seawater and that the growth rate of some
phytoplankton species has an optimum pH, below and
above which the rate of cell division decreases (Hinga,
2002).
4 Conclusions
Increasing CO
2
concentration affected significantly to
alkalinity, DIC, POC, PIC, physiological aspect of
phytoplankton. Alkalinity and DIC were varied
between location of mesocosm experiment and the
treatments of CO
2
concentration and length period of
incubation. In general, alkalinity decreased with
increasing CO
2
concentration. However, length of
incubation was showed no significant affected to DIC
for all CO
2
concentration at Barru and Barrang Lompo
mesocosm experiment.
PIC and POC showed a varied response between all
locations of mesocosms experiment. POC at Barru
showed a higher at 48 hours than 96 hours of
incubation period. For Takalar and Barrang Lompo
mesoscosm experiment was an apposite trend, which
was higher of POC at 96 hours than 48 hours of
incubation period. There was a trend where increasing