total shade of vegetation coverage at the beach area. Sand subsurface under vegetation at beach area still experienced peak during daylight while sand
subsurface at hatchery B asbestos roof did not
.
Figure 17 Ambient temperature of subsurface sand ± 10 cm depth at hatchery and beach area in Pangumbahan November 1
st
-4
th
2011. Pooled data of hatchery A and B: at unshaded area r = 6, shaded area r = 8
and total shade coverage by roof r =10 at hatchery A open cage and hatchery B asbestos roof, and beach area: at unshaded area r =
4, shaded area r = 4 and total shade coverage by vegetation r = 4, see
Appendix 7b for mean of datasets. Measurement was taken at deeper sand, approximately 10 cm from surface
Figure 17. Fluctuation pattern of subsurface sand temperature was similar to surface sand. It fluctuated during 10.00 am until 14.00 pm and more or less stable
at 6.00 am – 8 am and 18.00 pm – 04.00 am but in less range. The warmest temperature was at the unshaded area of hatchery. In general, subsurface sand was
more stable than surface sand. This indicated that deeper sand was not influenced greatly by the changing of surface temperature. But intense heat at the surface
could induce temperature increase. This shown by sand at unshaded area of hatchery A. Surface temperature was highly influenced by air temperature.
Extreme condition at surface sand may also influence temperature at deeper sand.
20 25
30 35
40 45
50
6.00 8.00 10.00 12.00 14.00 16.00 18.00 20.00 22.00 24.00 02.00 04.00
Time
Te m
p e
r atu
r e
° C
unshaded hatchery shaded hatchery
roof hatchery B unshaded beach
shaded beach under veg beach
Table 12 Sand characteristic at hatchery
Sample Sand humidity
Dominant sand grain size
Surface Subsurface
Hatchery A open cage n = 11 0.0 - 3.6
0.8 ± 1.1 0.4 - 5.7
2.6 ± 1.3 very fine - fine sand
Hatchery B asbestos roof n = 11
0.0 - 6.1 1.1 ± 1.8
0.3 - 27.0 4.0 ± 7.7
very fine - fine sand
∗ Sand humidity was sampled at day; Medium sand :0.50 - 0.25 mm; fine sand: 0.25 - 0.10 mm; very fine sand: 0.10 - 0.05 mm; sub surface : ± 10 cm depth
There was a trend of drier sand at warmer temperature at the surface and more humid sand at cooler temperature at subsurface Table 12. The sand was
sampled during daylight. Intense rain fall during sampling made the humidity was slightly higher than at prevoius sampling at nest. High humidity at subsurface of
hatchery B was due too watering effort by the wardens. Nest temperature will increase during incubation period Miller, 1997. The
crucial part is during middle third of incubation period when the embryo sex is developed Miller, 1997; Broderick et al., 2001. Although nest temperature range
may differ by species and region, in general, higher temperature will result in shorter egg incubation period Marquez-M, 1990 and the production of more
female individuals Limpus et al., 1985; Miller, 1997. By the increasing of global temperature, it is likely to have sex ratio skewed toward female sex. However, to
assure that estimation, there is important information which is still missing, particularly, in Pangumbahan, i.e. green turtle C. mydas pivotal temperature.
Pivotal temperature is certain temperature when the ratio of female:male is 50:50 Marquez-M, 1990.
4.1.2.3. Green turtle morphometric adult female and hatchling
There were a total of 27 adult green turtle sampled during the field work which 21 individuals were nesting and six individuals were not nesting wandered
only. Body size of adult green turtles measured during field sampling and previous sampling of UPTD Konservasi Penyu Pangumbahan 2010 and 2011
were in the range of CCL = 87-127 cm 102.4 ± 5.8 cm, n = 165; CCW = 62-108 cm 93.2 ± 6.7, n = 165; SCL = 86.5-113 cm 98.7 ± 7.4, n = 21 and SCW = 57-
103 cm 75.3 ± 9.7, n = 21 see Figure 18. It appears that the measured curved 36
carapace length and width of green turtle in Pangumbahan was more or less in the same range of size in consecutive years and during the period of investigation.
Median 25-75
Non-Outlier Range Outliers
Extremes C
C L
p ri
m a
ry d
a ta
C C
W p
ri m
a ry
d a
ta
C C
L u
p td
2 1
C C
W u
p td
2 1
C C
L u
p td
2 1
1
C C
W u
p td
2 1
1 50
60 70
80 90
100 110
120 130
L e
n g
th c
m n=32
n=37 n=111
n=111 n=43
n=43
Figure 18 Female adult green turtle carapace sizes in cm curved carapace length and width obtained during field work primary data and secondary
data UPTD 2010 and UPTD 2011. CCL: Curved carapace length, CCW: Curved carapace width
Total of 39 living and 19 dead hatchling specimens were measured and listed in Table 13 below. Carapace sizes of living and dead hatchlings were in the
same range. However, there was a big contrast in body weight. The dead hatchlings were lighter than the living ones Figure 19. There was a study at
Ascension Island Equatorial Atlantic which showed result of smaller hatchlings produced at higher incubation temperature Glen, 2003. There might be similar
indication happened in Pangumbahan hatchery. But we can not verify the speculation in this study because there was no direct measurement applied.
Table 13 Green turtle hatchling straight carapace size and body weight
Living Dead
Length cm 4.1 - 5.1
4.6 ± 0.2 n=39 4.1 - 4.7
4.4 ± 0.2 n = 19
Width cm
2.7 - 3.9 3.5 ± 0.2 n=39
2.7 - 3.9 3.4 ± 0.2 n = 19
Weight g 15.32 - 25.96
20.52 ± 2.67 n=37 14.75 - 16.99
15.80 ± 0.73 n=19
Median 25-75
Non-Outlier Range Living
Dead 14
16 18
20 22
24 26
28
W e
ig h
t g
n=37
n=18
Figure 19 Live and dead specimens of green turtle hatchlings body weight in gram
4.2. Near shore habitat
Seaturtle have two kinds of habitat, which are pelagic habitat at sea and terrestrial habitat at beach. They spend almost their life at sea and only less at
beach Miller, 1997; Bjorndal, 1999. Tagged turtle in Banyak Island, Aceh was migrated from nesting beach toward open sea and moved along the coast
http:wildlifetracking.org. This implied that nesting habitat connected with near shore habitat. Hence, we extended habitat characteristic study for Pangumbahan
green turtle C. mydas nesting population toward near shore habitat around
Pangumbahan beach. Nearshore bottom substrate type and sea surface temperature is studied to explain about nesting movement of Pangumbahan green
turtle nesting population.
4.2.1. Sea bottom substrate
Near shore habitat type around Pangumbahan beach is presented by sea bottom substrate map produced from Landsat satellite image Figure 20. The map
processing was supported by Anugrah Adityayuda. The sea bottom substrate was classified into five substrate type utilizing the most commonly used algorithm,
Lyzenga equation. The substrate type are live corals, dead corals, seagrasses and
or seaweeds, seawater and sand substrate.
Pangumbahan coast’s bottom substrate was predominantly dead corals Figure 20. Much seaweed found grow attach to dead corals substrate here. Large
seagrass andor seaweed meadow extended eastward off Pangumbahan coast. Seaweed and seagrass were sampled to know possible food availability referred
literature. There was an extensive Sargassum Divison: Phaeophyta meadow grew at eastern part of Pangumbahan beach. It was at the outermost part of Pos 1
extended eastward. Patches of other seaweed genus found here were Amphiroa, Galaxaura
, Gracilaria, Gelidium, Jania Division: Rhodophyta; Enteromorpha, Ulva
, Codium Division: Chlorophyta see Appendix 8a. Small patches of seagrass Halodule pinifolia Division: Cymodoceae. Green turtle C. mydas
were grazed upon Halodule, Gelidium, Gracilaria, Amphiroa, Codium and Ulva Marquez-M, 1990 and Lopez-Mendilaharsu et al., 2006.
Cikarang estuary is a steep rocky shore which bottom substrate was dead corals Figure 20. Extensive seagrass andor seaweed meadow grow in front of
dead corals area. However, there were also many seaweed grow attached to the rock near shore. Seaweed was sampled to confirm the possible food availability
for green turtle C. mydas referred to literature. Seaweed genus found there includes Amphiroa, Galaxaura, and Gracilaria Division: Rhodophyta,
Chaetomorpha , Ulva Division: Chlorophyta, Padina Divison: Phaeophyta see
Appendix 8b. Green turtle Chelonia mydas were grazed upon Gracilaria, Amphiroa
, and Ulva Marquez-M, 1990 and Lopez-MFendilaharsu et al., 2006. 39
