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
Figure 20 Sea bottom substrate classification map at Pangumbahan coast and adjacent Landsat image 40
Based on information above, we might imply that green turtle C. mydas food were available at near Pangumbahan coast and Cikarang estuary. However,
specific seagrass and seaweed species identification and green turtle C. mydas stomach content investigation should be done for further validation, in future
study. According to substrate type information, we may also imply the
accessibility for green turtle to migrate toward nesting beach which indirectly leads to nesting beach selection. Dead coral was identified at the bottom of
Pangumbahan near shore and closer reef edge. Continental slope is around 10 km away from Pangumbahan shore line and a crest in another ± 2 km Segara, 2007
see Figure 21. Pangumbahan beach is directly connected to Indian Ocean. This
type of bathymetry generates the wave to break close to shore line. Green turtle will not have to spare much effort to enter beach area with support of wave
driven. Even though the food is available around Cikarang estuary, the green turtle can not nest there simply because Cikarang estuary is inaccessible. The area
is confined by steep rocky substrate.
Figure 21 Bathymetry of Pangumbahan waters Segara, 2007
4.2.2. Sea surface temperature regime
Monthly mean sea surface temperature distribution map for April 2011 day and night and October 2011 day and night was produced from AquaModis
satellite imagery. The map was visualized by Ocean data view program. The map processing was supported by Aldino Rahadiyan Wicaksono. In order to
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