Kajian Pertumbuhan Terumbu Karang Jenis Porites Berdasarkan Anthropogenic Causes dan Natural Causes di Kabupaten Tapanuli Tengah

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KAJIAN PERTUMBUHAN TERUMBU KARANG JENIS PORITES
BERDASARKAN ANTHROPOGENIC CAUSES DAN NATURAL CAUSES
DI KABUPATEN TAPANULI TENGAH
ABSTRAK

Penelitian pertumbuhan terumbu karang jenis porites di pulau Ungge kabupaten
Tapanuli Tengah telah dilakukan berdasarkan rekaman lingkaran tahunan 19972012, dengan tujuan untuk mengetahui kandungan logam berat, struktur dan
morfologi terumbu karang, pengaruh aktivitas manusia (Anthropogenic Causes)
dan aktivitas alam (Natural Causes). Metode yang digunakan berupa pengujian
dissolved oxygen (DO), Biochemical oxygen demand (BOD), kandungan logam
berat pada air sungai dan air laut di lima stasiun dengan Titrimetri dan Inductively
coupled plasma (ICP). Struktur dan morfologi terumbu karang dengan Rongent
sinar-x, Thin slice, Atomic absorption spectrometer (AAS), difraksi (XRD),
scanning electron mikroscope (SEM), dispersive X-Ray (EDX), Transmission
electron microscopy (TEM), Thin slice, spektofotometer UV-Vis. Hasil analisa
air sungai dan air laut diatas baku mutu sehingga telah tercemar logam berat Cu
dan Fe. Hasil analisis mineralogi pada terumbu karang jenis porites menunjukkan
CaCo3 aragonit 99,67 %, sistem kristal orthorhombik, didominasi O, C, Ca,
terdapat logam berat Cu, Fe. Pertumbuhan terumbu karang pada musim kemarau

menunjukkan low density (LD) ditemukan mikrit 2% dan kalsit 8% dengan
porositas 55% - 60%, tipe cavity, nilai absorbansi sebesar 0,441. Sebaliknya
pertumbuhan pada musim hujan high density (HD) mikrit 8% dan kalsit 12%
dengan porositas ± 35-43% , nilai absorbansi sebesar 0,549. Faktor aktivitas
antropogenic causes tahun 2012 jumlah kenaikan penduduk tertinggi sebesar 7,7
% dari tahun sebelumnya, terjadi degradasi penurunan pertumbuhan terumbu
karang sebesar 62,5 %. Tahun 2007 peningkatan jumlah industri tertinggi
mencapai 81,5% menunjukkan pertumbuhan terumbu karang sebesar 7,5 mm
dibawah pertumbuhan rata-rata 9,1 mm. Faktor aktivitas natural causes tahun
1998 saat iklim ekstrim menunjukkan suhu udara naik 0,5 0C dan suhu air laut
29,89 0C naik mencapai 0,90 C dari tahun sebelumnya, pertumbuhan terumbu
karang mengalami penurunan 1 mm sebesar 10,5 % dari tahun sebelumnya.
Tahun 2010 curah hujan tertinggi mencapai 455,4 mm naik 19,3 % teramati
pertumbuhan terumbu karang 8,5 mm dibawah nilai rata-rata 9,1 mm. Tahun
1997, 1998, 2001 gempa bumi dengan magnitude < 3 skala Richter
pertumbuhan terumbu karang diatas nilai rata-rata 9,1 mm. Tahun 2005 terjadi
gempa bumi dengan frekuensi perulangan 33 dalam setahun magnitude tertinggi
6,8 skala Richer, teramati terjadi penurunan pertumbuhan terumbu karang 6,5
mm turun 23,1 % dari tahun sebelumnya. Hal ini menunjukkan telah terjadi
degradasi pertumbuhan terumbu karang jenis porites di kabupaten Tapanuli

Tengah disebabkan faktor anthropogenic causes dan natural causes .
Kata kunci ; Anthropogenic causes, Natural causes, Terumbu karang jenis
porites

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RESEACH OF THE PORITES CORAL REEF GROWTH BASED ON
NATURAL CAUSES AND ANTHROPOGENIC CAUSES IN CENTRAL
TAPANULI SUB REGION

ABSTRACT

A research about the growth of coral reef, Porites type in Ungge Island, North
Tapanuli regency based on the record of annual ring. The research purpose is to
investigate the composition of hard metal, structure and morphology of coral
reef, anthropogenic causes, and natural causes.The research method used the
testing of dissolved oxygen (DO) and biochemical oxygen demand (BOD) to know
composition of hard metals on the river and sea water at 5 stations by titrimetri
and inductively coupled plasma (ICP). Structure and morphology of coral reef is
observed by using X-Ray Rontgen, Thin Slice, atomic absorption spectrometer

(AAS), X-Diffraction (XRD), scanning electron microscope (SEM), X-Ray
dispersion (EDX), transmission electron microscopy (TEM), and UV-Vis. Analysis
result of DO and BOD testing more than national standard showed that river and
sea water had been contaminated by hard metals Cu and Fe. Analysis result of
mineralogy on the coral reef pirotes type showed that there are hard metal Cu
and Fe founded in CaCo 3 aragonit 99,67% which its orthorhombic crystal system
is dominated by O, C, and Ca element. The growth of coral reef at dry season
showed low density, its micrit is 2% and calsit is 8% with its porosity 55% - 60%
belong to cavity type, and absorbance value 0.411. Meanwhile, the growth at
rainy season at high density, its micrit is 8% and calsit is 12% with its porosity
35% - 43% and absrobance value 0.549. Factor of antropogenic causes in 2012
with the highest population increase about 7.7% from the previous year caused
degradation in growth of coral reef about 62.5%. in 2007, development of the
number of industrial business about 81.5 % caused the growth of coral reef being
7.5 mm, it is below of average growth of 9.1 mm. Factor of natural causes, in
1988 when extreame climate occured in which air temperature rose 0.5 and
temperature of sea water was 29.89 , it rose 0.9 from previous year, the
growth of coral reef decreased 1 mm, about 10.5% from previous year. In 2010
with the highest rainfall intensity reached 455.4 mm, increase 19.3%, the growth
of coral reef was 8.5 mm, it is below of standard value 9.1 mm. Years 1997, 1998,

2001, earthquake occured with magnitude < 3 SR caused the growth of coral reef
was above average value 9.1 mm. In 2005, an earthquake with repetition
frequency of 33 times/year and highest magnitude 6.8 SR caused decline in
growth of coral reef 6.5 mm, decreased 23.1% from previous year. Concludedthat
degradation of coral reef porites type central Tapanuli caused by anthropogenic
causes, natural causes.

Keyword: Anthropogenic causes, Natural causes, Coral reef Porites type