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International Journal of Marine Science 2013, Vol.3, No.36, 285-294
http://ijms.sophiapublisher.com
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nearest to the Berau River mouth, at Rabu-rabu and
Panjang Islands. Locality 2 was an intermediate
distance from the river mouth, at Derawan Island,
Tababinga reefs, and Masimbung reefs. Locality 3 was
the farthest from the river mouth, at Semama and
Sangalaki Islands. Samples were generally collected
on the western and eastern sides of the islands at two
different depths, 3 m and 10 m.
Figure 1 Map of sampling points in Localities 1, 2 and 3 in the
Berau, Marine Conservation Area, East Kalimantan, Indonesia
Coral samples were collected in August 2006
(designated as the 1
st
dry season), November 2007
(the rainy season) and August 2008 (the 2
nd
dry
season). Average rainfall at those times were 83.7 mm,
235.8 mm and 141 mm, respectively.
In August 2006, a total of 70 coral samples were
collected
at 14 dive sites in the three localities, which
consisted of 34
Porites
samples, 17
Seriatopora
samples and 19
Stylophora
samples. In November
2007, a total of 62 coral samples were collected at
eight dive sites in the three localities, and these were
composed of 23
Porites
samples, 23
Seriatopora
samples and 16
Stylophora
samples. In August 2008, a
total of 30 coral samples were collected at five dive
sites in the three localities and these were composed
of 10
Porites
samples
,
12
Seriatopora
samples and 8
Stylophora
samples. Only genus names are referred to
in this paper.
The three branching coral genera,
Porites, Seriatopora
and
Stylophora
were relatively easy to find in clear
and turbid waters. All these corals are categorized as
small polyp stony (SPS) corals and possess short
tentacles. During three field seasons, most of these
three genera were present at the same dive sites in the
three localities. However,
Stylophora
was not found at
Locality 1 during the 2
nd
dry season and it may have
disappeared from this area.
Samples were collected using pliers to cut the apices
of individual branches from coral colonies. Coral
nubbins were placed in a clear plastic bag, and after
collection a field number was assigned to samples
before scientific identification. After identification, a
picture was taken of every sample before placing each
sample in a separate plastic bottle and adding ethanol
until the sample was totally immersed. Samples were
then transported to the laboratory for further analysis.
Zooxanthellae were separated from their host coral in
the laboratory using a standard ethanol and sonication
method (Piniak and Lipschultz, 2004). Coral samples
were treated with an ultrasonic generator for 10 min
and centrifuged at 3000 rpm for 10 min. After
sonication, the supernatant was separated from the
bulk coral samples and placed into a Falcon tube. The
supernatant was then centrifuged at 2500 rpm for 10
min to separate the zooxanthellae (pellet) from the
solution. The zooxanthellae pellet was decalcified
using 0.05 N HCl to remove any carbonates, before
rinsing twice with distilled and deionized water
(DDW). The pellet was kept in the deep freezer for c.
10 min until it was frozen, and it was then freeze-dried
overnight in an Eyela freeze-dryer (Tokyo-Rika, FDU
506). Sample aliquots of 0.8
±
0.05 mg were placed in
tin capsules (two capsules per sample) for isotopic
measurement, following the method of Chisholm et al
(1982) and Chisholm and Koike (1996).
Coral tissue was obtained using the decalcification
method. Each sample was ground to coarse fragments
using a ball mill and placed in a cellulose tube. The
tube was placed in a beaker containing 0.2 N HCl,
which was then put on a stirrer (Horai et al., 1989).
The HCl solution was changed every day for seven
days until the decalcification of the tissue samples was
complete. Decalcified tissues were then centrifuged
and freeze-dried overnight.
Twenty-six samples of particulate organic matter
(POM) were also collected using a 100
μ
m mesh
plankton net from coral reefs in the area of Locality 1
(eight samples), Locality 2 (eight samples) and
Locality 3 (10 samples). The samples were then
centrifuged at 3000 rpm for 10 min to remove the