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Late Holocene Pollen Record of Environmental Changes in Karimata Strait, Sunda Shelf Region Yulianto, Eko; Sukapti, Woro Sri; Dewi, Kresna Tri
Indonesian Journal on Geoscience Vol 6, No 1 (2019)
Publisher : Geological Agency

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (2677.631 KB) | DOI: 10.17014/ijog.6.1.41-55

Abstract

DOI: 10.17014/ijog.6.1.41-55Pollen analysis has been conducted on a 90 cm gravity core taken from the Karimata Strait to reveal pollen facies in marine sediment and Late Holocene environmental changes in the central Sunda Shelf region. The core site is at 32 m water depth and located about 170 km northwest of Bangka Island, Indonesia. Ten samples were collected at 10 cm intervals through the core. The total number of pollen grains counted in the samples varies between very low (<50 grains) to abundant (>200 grains). High frequencies (50 - 70%) of mangrove pollen are found at 90 to 40 cm indicating that pollen facies in offshore marine sediment may be comparable with those in mangrove forest floor sediment. The core site has been in a neritic environment since its early deposition ca. 1,800 yr B.P. (~150 A.D.) when mangroves vastly grew on the tidal flats of the surrounding islands and they persisted to ca. 700 yr B.P. (~1,250 A.D.). In the middle of this period, a catastrophic event speculatively due to the 535 A.D. Krakatau eruption might have responsible for the decrease of mangroves and the disappearance of benthic foraminifers. The deposition of silicious materials (tephra) due to this eruption might have provided an opportunity for benthic foraminifers to increase their population subsequently. From ca. 700 yr B.P. (~1,250 A.D.) mangroves declined, as indicated by lower frequencies of pollen grain in samples from 30 cm deep upward. It occurred simultaneously with the deposition of coarser sediment and the increase of benthic foraminifer abundance. Interplay of anthropogenic activities, strengthening ENSO cycle, and lowering erosion base level might have been responsible for these environmental changes.
THE COMPOSITION AND DISTRIBUTION OF BENTHIC FORAMINIFERA AT CORAL REEF ECOSYSTEM IN THOUSANDS ISLAND Lumban Nauli Lumban Toruan; Dedi Soedharma; Kresna Tri Dewi
Jurnal Ilmu dan Teknologi Kelautan Tropis Vol. 5 No. 1 (2013): Elektronik Jurnal Ilmu dan Teknologi Kelautan Tropis
Publisher : Department of Marine Science and Technology, Faculty of Fisheries and Marine Science, IPB University

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (795.236 KB) | DOI: 10.29244/jitkt.v5i1.7741

Abstract

Composition and distribution of foraminifers are affected by human activities and have close association with coral reef ecosystem. The aims of this research were to investigate the benthic foraminifers’ composition and distribution in sediment of coral reef ecosystem. Eleven stations of Karang Bongkok, Pramuka, and Onrust Island were observed in this study. The sediments were taken from surface substrate up to 2 cm under the substrate. Samples were washed on sieve with mesh size 0,063 mm, and then dried in oven with 50°C of temperature  for two hours. After separating from the sediment, the foraminifers were laid on foraminiferal slide and indentified using binocular microscope. The highest composition of symbiont-bearing foraminiferal assemblages which associated with reef ecosystem was in East Pramuka (78.17%) and the lowest was in South Onrust (21,83%). The opportunistic type had the highest composition in South Onrust (38.67%) and the lowest was in South Karang Bongkok. In west Pramuka had the highest composition of heterotrophic type (57.17%) and the lowest was in North Onrust (11.33%). Onrust Island was dominated by opportunistic type, indicating high nutrient. The highest amount of foraminifers’ taxa was found in Karang Bongkok with good coral reef coverage, while the lowest in Onrust facing with Jakarta Bay. Keywords: composition, distribution, benthic foraminifers, coral reef.
THE CHARACTERISTIC OF DEEP SEA FORAMINIFERAL COMMUNITY IN TOMINI BAY, SULAWESI Kresna Tri Dewi; Mustafa Hanafi
Jurnal Ilmu dan Teknologi Kelautan Tropis Vol. 5 No. 1 (2013): Elektronik Jurnal Ilmu dan Teknologi Kelautan Tropis
Publisher : Department of Marine Science and Technology, Faculty of Fisheries and Marine Science, IPB University

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (881.044 KB) | DOI: 10.29244/jitkt.v5i1.7742

Abstract

A total of 14 sediment samples from Tomini Bay, Sulawesi were used for this study as a component of sediment. The samples were carried out by using a gravity corer at water depth range between 600 and 1400 m. This study was a part of mapping activity on marine geology and geophysics during the first cruise of R/V Geomarin III in 2010. The purpose of this study was to examine the subsurface geology related to the potency of energy and mineral resources. Top core sediment samples were washed through 0.063mm opening sieve and then dried in an oven.  About maximum 300 foraminiferal specimens were picked from every dried washed residue sample to separate them from other particles under a binocular microscope with brush and water. The result showed that most samples were dominated by planktonic foraminifera (>90%), such as Globorotalia menardii, Orbulina universa, Globigerinoides ruber and others as typical of deep sea sediments.  On the other hand, benthic foraminifera was found less than 10% that was represented by Cibicidoides wuellerstorfi, Ceratobulimina pacifica, Pyrgo sp., Bolivinita quadralatera, Uvigerina peregrina, etc. The characteristic of deep sea foraminiferal community of this area may be used for interpreting environmental deposition in the adjacent areas that is useful for petroleum exploration. Keywords: foraminifera, deep sea, Tomini Bay, Sulawesi.
Perubahan Lingkungan Holosen Akhir Berdasarkan Rekaman Polen dari Delta Berau-Kalimantan Timur Woro Sri Sukapti; Kresna Tri Dewi
Jurnal Geologi dan Sumberdaya Mineral Vol. 24 No. 1 (2023): JURNAL GEOLOGI DAN SUMBERDAYA MINERAL
Publisher : Pusat Survei Geologi

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.33332/jgsm.geologi.v24i1.713

Abstract

Biodiversitas atau keragaman hayati merupakan aspek penting dalam pengembangan geopark selain keragaman geologi dan keragaman budaya. Keragaman hayati modern dapat diketahui berdaasarkan survei flora dan fauna. Meskipun secara natural keragaman saat ini berasal dari keragaman di masa lalu, namun perbedaan keragaman hayati keduanya dapat berbeda karena terjadinya perubahan lingkungan. Keanekaraman hayati masa lalu dapat diketahui berdasarkan fosil yang terawetkan di dalam sedimen. Dalam konteks tumbuhan di masa lalu, keanekaragamannya dapat diketahui berdasarkan fosil serbuk sari yang terawetkan di dalam sedimen. Hasil identifikasi polen dari sebuah inti bor sepanjang 100 cm di Delta Berau, Kalimantan Timur menunjukkan 80 jenis polen dan 13 jenis spora. Jenis polen yang hadir didominasi oleh jenis-jenis polen tumbuhan hutan dataran rendah. Proporsi polen dari jenis dan kelompok tumbuhan tertentu memberi informasi tentang kelimpahan tumbuhannya di dalam hutan baik hutan dataran rendah, hutan mangrove, hutan pegunungan dan tumbuhan padang rumput. Data keanekaragaman dan kelimpahan tumbuhan berdasarkan fosil polen dan spora dalam sedimen ini dapat digunakan untuk menyokong tersedianya informasi saintifik tentang keanekaragaman hayati pada kala Holosen di Kawasan warisan geologi Sangkulirang-Mangkalihat.Katakunci: Biodiversitas, dinamika hutan, hutan dataran rendah, hutan padang rumput, hutan pegunungan, mangrove, polen, spora.
Sebaran ostracoda sebagai bioindikator kondisi perairan lepas pantai Balikpapan, Kalimantan Timur Wibowo, Ponco Agung; Kurniasih, Anis; Suprapto, Tjoek Aziz; Dewi, Kresna Tri
Majalah Geografi Indonesia Vol 38, No 1 (2024): Majalah Geografi Indonesia
Publisher : Fakultas Geografi, Universitas Gadjah Mada

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.22146/mgi.89541

Abstract

Abstrak Perairan lepas pantai Balikpapan memiliki kerentanan tinggi terhadap perubahan kualitas air yang diakibatkan sedimentasi di sekitar kawasan tersebut. Oleh sebab itu, penelitian mengenai kondisi lingkungan perairan di daerah ini penting dilakukan.  Salah satu bioindikator yang dapat digunakan untuk menentukan kualitas perairan adalah ostracoda, yang merupakan mikroorganisme dari jenis Crustacea. Penelitian ini dilakukan di selatan Teluk Balikpapan menggunakan data kemelimpahan ostracoda dalam sedimen Resen pada 25 sampel permukaan dasar laut. Tujuan penelitian ini adalah untuk mengetahui kondisi lingkungan perairan di area penelitian berdasarkan distribusi ostracoda. Hasil penelitian menunjukkan kemelimpahan ostracoda semakin rendah ke arah perairan laut terbuka, dan dari tingkat keanekaragamannya diketahui kondisi perairan tergolong stabil. Hasil analisis cluster membagi area penelitian menjadi dua biotop yakni Biotop1, merupakan lingkungan laut dangkal dengan spesies penciri Cytherella semitalis, Cytherelloidea sp., Phlyctenophora orientalis dan Neomonoceratina indonesiana; Biotop2, berasosiasi dengan lingkungan terumbu karang ditandai dari kehadiran spesies Bairdopillata paraalcyonicola, Paranesidea sp., dan Loxoconcha sp.  Abstract The offshore waters of Balikpapan considered as vulnerable in term of changes in water quality due to high sedimentation. Therefore, research on the condition of the aquatic environment in this area is necessary. One bioindicator that can be used to determine water quality is ostracods, the Crustacean microorganisms that commonly found in the seabed sediments. This research was conducted in southern Balikpapan Bay using ostracod abundance in Recent sediments on 25 seabed surface samples. The aim of this research is to determine the condition of the aquatic environment based on the distribution of ostracods. The results show that the abundance of ostracods is lower towards open sea waters, and from the level of diversity it is known that water conditions are relatively stable. The results of the cluster analysis divided the research area into two biotopes, Biotope1, a shallow marine environment with the diagnostic species Cytherella semitalis, Cytherelloidea sp., Phlyctenophora orientalis and Neomonoceratina indonesiana; Biotope2, associated with coral reef environments, is characterized by the presence of Bairdopillata paraalcyonicola, Paranesidea sp., and Loxoconcha sp.
MIKROFAUNA (OSTRAKODA) DARI TELUK BALIKPAPAN: IMPLIKASINYA UNTUK INTERPRETASI LINGKUNGAN PENGENDAPAN Dewi, Kresna Tri; Priohandono, Yusuf Adam
JURNAL GEOLOGI KELAUTAN Vol 21, No 1 (2023)
Publisher : Pusat Penelitian dan Pengembangan Geologi Kelautan

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.32693/jgk.21.1.2023.779

Abstract

Studi mikrofauna (ostrakoda) dilakukan terhadap 25 sampel sedimen dari Teluk Balikpapan, Kalimantan Timur yang diambil pada kedalaman 1,5- 27 m. Tujuan dari studi ini adalah untuk mengetahui keragaman dan kelimpahan ostrakoda sebagai acuan dalam menginterpretasi lingkungan pengendapan mewakili perairan marginal. Hasil identifikasi menunjukkan 62 spesies ostrakoda yang didominasi oleh ostrakoda laut dangkal: Hemicytheridea reticulata, Cytherella semitalis, dan Alocopocythere kendengensis. Kehadiran Argilloecia, Leptocythere, Miocyprideis, dan Pontocythere dalam jumlah sedikit menunjukkan perairan transisi/marginal.  Kelimpahan ostrakoda rendah terkonsentrasi di bagian tengah teluk yang berkaitan dengan hidrodinamika dan jenis sedimen. Kelimpahan tertinggi terjadi di perbatasan antara teluk bagian tengah dan bagian luar sebagai pusat akumulasi spesimen dari berbagai sumber. Variasi keragaman dan kelimpahan ostrakoda Resen di Teluk Balikpapan ini dapat dipertimbangkan dalam upaya menginterpretasi lingkungan pengendapan di Indonesia. Data dan informasi ostrakoda ini juga sebagai data rona awal dalam memantau perubahan lingkungan beberapa dekade ke depan.