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International Journal of Marine Science 2014, Vol.4, No.1, 1-15
http://ijms.sophiapublisher.com
5
not observed. As groundwater inflow is apparent,
∆C
inflow
must be accounted for to derive the effect of
benthic activity on carbon and inorganic nitrogen flux.
Figure 3 Correlations between total alkalinity (A), nitrite +
nitrate (NO
x
) (B), and ammonium (NH
4
+
) (C) with salinity.
3.2 Organic carbon production (photosynthesis-
respiration process)
Figure 4 shows organic carbon production rate vs
photon flux fitted to the function of y=a(1-e
-x/b
)+c
which is a typical equation for photosynthesis-
respiration vs irradiance curves (P-I curve). In the
sand habitat (SD) and acorn worm habitat (AC),
organic carbon production (OP) ranged from –4.49 to
5.53 and –5.18 to 4.47 mmol m
–2
h
–1
respectively
indicating photosynthesis and respiration were low in
comparison to the other habitats (Figure 4). The
seagrass habitat (SG), coral-seagrass habitat (CS) and
coral habitat (CR) showed higher organic production
rates than the SD and AC habitats, and ranged from
–12.11 to 27.26, –12.46 to 21.70 and –10.36 to 17.53
mmol m
–2
h
–1
along with the P-I curve, respectively.
The results of the metabolic parameters of
photosynthesis and respiration which shows gross
production (P
gross
), 24h respiration (R
24h
), and
P
gross
/R
24h
ratio are summarized in Table 2. P
gross
and
R
24h
in SG were both significantly different from the
other habitats (Tukey-Kramer HSD; p<0.05) except
for the coral-seagrass habitat. P
gross
/R
24h
ratios were
approximately 1 in all habitats except for the AC
habitat where the P
gross
/R
24h
= 0.64 and was
significantly lower than the CS, SG and CR habitats
(Tukey-Kramer HSD; p<0.05). This indicates the AC
habitat has a higher respiration rate relative to the
photosynthesis.
3.3 Inorganic carbon production (calcification-
dissolution process)
The inorganic carbon production (IP) rate was linearly
correlated with photon flux in the CS and CR habitat
while the other habitats were not (Figure 5). IP in the
coral habitat was about 2-fold higher than that in the
CS habitat, ranging from 0.23 to 14.42 and –0.39 to
7.14 mmol
CaCO
3
m
–2
h
–1
, respectively. On the other
hand IP rates in the SD, SG and AC habitat which did
not include the coral component showed lower values;
from –0.85 to 1.26, –2.14 to 1.17 and –1.68 to 0.89
mmol
CaCO
3
m
–2
h
–1
, respectively. The negative
values of IP indicate CaCO
3
dissolution. Most of the
IP rates in the AC habitat indicated dissolution and
were independent of photon flux. Dissolution was also
notably high in the SG habitat at night. Metabolic
parameters of calcification during the light and dark
periods and net rate during the day are also
summarized in Table 1. Most of the calcification in the
dark (G
dark
) showed negative values except for the CR
habitat. The value in the SG habitat showed a
significantly higher dissolution rate than that in the SD
and CS habitats (Tukey-Kramer HSD; p<0.05). At
night time, a slight dissolution of CaCO
3
was found in
the CS habitat. Both calcification rate during the light
(G
light
) and net calcification rate (G
net
) in the CR
habitat were the highest followed by those in the CS
habitat and were significantly different from the other
habitats (Tukey-Kramer HSD; p<0.05). From these
results, it appears that inorganic carbon production in
Bise moat is primarily controlled by coral calcification.