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HYDRODYNAMICS MODELING IN KENDARI BAY, SOUTHEAST SULAWESI, INDONESIA Imalpen, Imalpen; Prartono, Tri; Rastina, Rastina; Koropitan, Alan Frendy; Yuliardi, Amir Yarkhasy
International Journal of Remote Sensing and Earth Sciences (IJReSES) Vol 21, No 1 (2024)
Publisher : Ikatan Geografi Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.30536/j.ijreses.2024.v21.a3906

Kendari Bay is coastal water in the center of the capital city of Southeast Sulawesi province. It is shaped like a pocket with a narrow mouth and there is an estuary of a large river, namely the Wanggu river, which makes the dynamics of its waters very interesting to study. The focus of the study is the hydrodynamic factors in the Kendari Bay and Wanggu River areas. This study aims to examine the hydrodynamic conditions of Kendari Bay, mainly due to the existence of reclamation and the influence of the Wanggu River which has not been studied previously. This research method uses a two-dimensional model based on bathymetric data, tides, and the flow of the Wanggu River with a simulation time of 15 days (1 March to 15 March 2020). The modeling results were then verified with PUSHIDROSAL tidal elevation data showing an RMSE value of 0.07 indicating that the model was well constructed. The mixed tidal type with a tendency to double daily is the tidal type of Kendari Bay waters based on the Formzahl number value of 0.51. The current pattern generally moves in and out from east to west and vice versa with a varying elevation range following spring conditions of 1.75 m. The maximum tidal speed is 0.1784 m/s and the minimum value is 0.0057 m/s which is shown in the sample results of the model when the hing to low tide, and low to high tide. The results of the hydrodynamic modeling show that the current velocity increases when passing through a narrow path, namely the bay estuary and river estuary. The existence of the reclamation area affects the changes in the velocity of the current which is significantly larger and the direction of the current that undergoes a deflection follows the shape of the reclamation area. The current direction is to the southeast and then turns towards the northeast when low to high tide and eastward then turns towards the northeast when the high to low tide spring conditions compared to research before the reclamation

RESPONSE OF SEA SURFACE TEMPERATURE (SST) AND CHLOROPHYLL-A ON MADDEN JULIAN OSCILLATION (MJO) IN INDONESIAN SEAS Nabil; Atmadipoera, Agus Saleh; Koropitan, Alan Frendy
Jurnal Ilmu dan Teknologi Kelautan Tropis Vol. 7 No. 2 (2015): Elektronik Jurnal Ilmu dan Teknologi Kelautan Tropis
Publisher : Department of Marine Science and Technology, Faculty of Fisheries and Marine Science, IPB University

Madden-Julian Oscillation (MJO) is a large-scale phenomenon that occurs in equatorial area, parti-cularly Indonesia. This research aimed to investigate the MJO propagation process and studied the correlation between MJO and sea surface temperature (SST) and chlorophyll-a. Sea variables (SST and chlorophyll-a) and atmosphere variables (outgoing longwave radiation/OLR, 1,5 km wind, and surface wind) were band-pass filtered for 20-100 days period. Spectral density from OLR and 1,5 km wind (2003-2012) shows that the MJO period was dominantly occurred for 40–50 days. Average pro-pagation of MJO velocity resulted from the atmospheric variable analysis by Hovmöller diagram was 4,7 m/s. Cross correlation between SST and OLR in South Java and Banda Sea results a strong corre-lation during MJO active phase, where MJO took place first and was then followed by the decreasing SST along the equatorial region. Increasing chlorophyll-a concentration occured at some areas du-ring MJO active phase with relatively short phase delay. During the MJO active phase, fluctuation of wind velocity generates variation over mixed layer depth and triggers upwelling /entrainment. Nutri-ent was upwelled to the water surface and hence increase phytoplankton production and chlorophyll-a concentration. Keywords: Madden Julian Oscillation, OLR, sea surface temperature, surface chlorophyll-a

Variability of Marine Carbonate Systems in Seagrass and Coral Reef Ecosystems of Pari and Lombok Islands, Indonesia Afdal, Afdal; Bengen, Dietriech G.; Wahyudi, A’an Johan; Rastina, Rastina; Purwiyanto, Anna Ida Sunaryo; Prayitno, Hanif Budi; Hamzah, Faisal; Suteja, Yulianto; Adi, Novi Susetyo; Koropitan, Alan F.
ILMU KELAUTAN: Indonesian Journal of Marine Sciences Vol 30, No 2 (2025): Ilmu Kelautan
Publisher : Marine Science Department Diponegoro University

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.14710/ik.ijms.30.2.221-236

The increase in anthropogenic CO2 emissions has induced significant physical and biogeochemical alterations in oceans worldwide, including warming, acidification, and oxygen depletion. Coastal areas are particularly vulnerable due to intensified human activities and terrestrial influences, resulting in increased coastal ocean acidification driven by atmospheric CO2 absorption and regional biological and anthropogenic processes. However, research on the collective impact of land-sea interaction and air-sea CO2 exchange on coastal ocean acidification in severely disturbed areas, such as the small islands of Lombok and Pari in Indonesia, remains limited. This study aims to investigate the daily fluctuations in marine carbonate systems and aragonite saturation (Ωarag) levels in the vicinity of seagrass and coral reef habitats in Pari Island and Sire Bay, Lombok. Seawater samples were collected from Sire Bay, Lombok, and the coastal waters of Pari Island to analyze the carbonate systems, CO₂ flux, and metabolic processes. The findings indicate that Pari Island's coastal waters are more susceptible to ocean acidification than Sire Bay, Lombok, showing significantly lower pH values and Ωarag (P<0.05), ranging from 7.60 to 8.00 and 1.04 to 2.54, respectively. This disparity arises from the decreased temperature and salinity in Pari Island's coastal waters during the northwest monsoon, coupled with the deteriorated state of the seagrass and coral reef ecosystems, altering the equilibrium of ecosystem productivity and calcification. The study underscores the necessity of adopting specific coastal management tactics to lessen the effects on fragile ecosystems, highlighting the urgency for additional studies to evaluate adaptive and conservation strategies to preserve coastal biodiversity and ecosystem services.

Distribusi Bahan Organik dan Fraksi Sedimen di Perairan Teluk Lampung: Distribution of Sediment Fractions and Organic Matter in Lampung Bay Prartono, Tri; Koropitan, Alan Frendy; Khotib, Mohammad; Hartanto, Mochamad Tri; Kusumaningsih, Alvianita
Jurnal Ilmu dan Teknologi Kelautan Tropis Vol. 16 No. 1 (2024): 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 | DOI: 10.29244/jitkt.v16i1.48135

Deposisi sedimen di perairan sangat dipengaruhi oleh proses-proses pantai yang menyebabkan variasi karakteristik fisik dan kimiawinya. Penelitian ini mengungkap komposisi ukuran sedimen dan bahan organik di sedimen Teluk Lampung untuk menduga proses deposisi. Analisis fraksi sedimen dilakukan berdasarkan pada American Society for Testing and Materials (ASTM) standards D422-63, sedangkan bahan organik dilakukan dengan menggunakan metode loss on ignition (LOI). Fraksi pasir lanau (75,95-78,73%) dan fraksi lempung (18,27-20,28%) memiliki persentase yang lebih tinggi dibandingkan dengan fraksi pasir (3,00-3,81%). Kandungan organik di sedimen perairan Teluk Lampung berkisar antara 10,67-13,48%. Distribusi fraksi sedimen dan bahan organik di perairan Teluk Lampung tidak berbeda signifikan antar stasiun, yang artinya stasiun yang berada di dekat kepala teluk (TL 1 dan TL 2) memiliki persentase fraksi sedimen dan bahan organik yang tidak berbeda signifikan dengan stasiun yang berada di tengah atau ke arah mulut teluk (TL 3-TL5).

SIMULASI PERTUMBUHAN TERUMBU KARANG (Porites lutea) DENGAN METODE LOGIKA FUZZY DI PULAU TUNDA PROVINSI BANTEN Koropitan, Alan Frendy; Zamani, Neviaty P; Idris, Muhamad Kemal
Jurnal Ilmu dan Teknologi Kelautan Tropis Vol. 17 No. 2 (2025): 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 | DOI: 10.29244/jitkt.v17i2.63475

Corals grow annually at varying rates, influenced by environmental conditions. As key indicators of marine ecosystem health, studying coral growth is essential for predicting the impacts of environmental change. While previous research has explored coral growth extensively, most studies focus on existing conditions and the descriptive influence of environmental parameters. In fact, coral growth time-series data offer potential for deeper analysis, particularly in identifying dominant periodicities and enabling long-term projections. This study aims to develop an annual coral growth model using fuzzy logic approach. The Indian Ocean Dipole (IOD) is identified as a significant factor influencing the growth of Porites lutea in Tunda Island. Variations in sea surface temperature during IOD events notably affect coral growth, with positive IOD phases (IOD+) generally enhancing it. Analysis shows that the annual growth rings of Porites lutea in the northern station of Tunda Island, which borders open waters respond more slowly to SST fluctuations compared to the southern station, which is more sheltered. Fuzzy simulation results suggest that corals may be able to adapt to climate change. By the year 2085, coral growth is projected to recover from -0.75 cm to 0.1 cm by 2100. Based on SST projections from 1900 to 2100, SST anomalies are expected to continue increasing, reaching +0.45 °C.

LAJU AKUMULASI SEDIMEN MANGROVE DI TANJUNG BATU, KEPULAUAN DERAWAN KALIMANTAN TIMUR Dewi, Intan Sari; Prartono, Tri; Arman, Ali; Koropitan, Alan Frendy
Jurnal Ilmu dan Teknologi Kelautan Tropis Vol. 12 No. 2 (2020): 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 | DOI: 10.29244/jitkt.v12i2.28427

Keberlangsungan ekosistem mangrove merupakan aspek penting karena berkaitan dengan pengurangan atau penambahan akumulasi sedimen seperti proses abrasi dan akresi. Mangrove di pesisir Tanjung Batu telah mengalami penurunan sejak 2001-2010 yang disebabkan oleh aktivitas masyarakat seperti penebangan pohon, pembukaan lahan untuk tambak dan perkebunan kelapa sawit. Penelitian ini bertujuan mengestimasi laju akumulasi sedimen mangrove di Tanjung Batu. Penelitian dilakukan pada bulan Februari-Juli 2018. Pengambilan sampel dilakukan pada 3 stasiun meliputi identifikasi jenis mangrove, pengukuran Diameter at Breast Height (DBH) mangrove dan pengambilan sedimen corring menggunakan pipa stainless. Sampel sedimen dipotong berdasarkan interval 5 cm (kedalaman 0-15 cm), dan interval 2 cm (kedalaman 48-50 cm) yang digunakan sebagai Pb-210 supported (Stasiun 1 dan 3). Stasiun 5 dipotong dengan interval 4, 6 dan 8 cm (kedalaman 1-50 cm). Analisis sampel menggunakan alpha spektrometer dengan radioisotop Pb-210. Penentuan umur sedimen dan laju akumulasi sedimen menggunakan model Constant Rates of Supply (CRS). Hasil menunjukkan bahwa laju akumulasi sedimen selama 20 tahun terakhir (1998-2018) berkisar 0,09-0,20 g cm-2 tahun-1. Laju akumulasi tertinggi adalah Stasiun 1 yang merupakan lokasi dengan umur sedimen paling tua dan didominasi mangrove dengan DBH > 5 cm, sedangkan laju akumulasi terendah adalah Stasiun 5 yang memiliki umur sedimen paling muda dan didominasi mangrove dengan DBH < 5 cm.

Primary Productivity of Jakarta Bay in A Changing Environment: Climate Change and Anthropogenic Impacts Siregar, Vincentius; Koropitan, Alan F.
BIOTROPIA Vol. 20 No. 2 (2013): BIOTROPIA Vol. 20 No. 2 December 2013
Publisher : SEAMEO BIOTROP

Jakarta Bay receives direct impact from the rapid development of infrastructure and landbased industries which contributed to the increase in pollution and nutrient, and at the same time facing climate change. This condition influenced growth of chlorophyll- and primary production. To investigate changes of primary production in Jakarta Bay due to anthropogenic and climate change impacts, a field measurement, laboratory experiment and collection of several data sets have been conducted. The study showed that impact of anthropogenic, particularly sediment load from the land to primary production is important. The intensification of primary production occurs in the middle region of Jakarta Bay, while the chlorophyllconcentration is high in the river mouth area. The anthropogenic impact is indicated by the land use change that has increased to 73% during the last ten years. The laboratory experiments by injecting CO in the waters, as a global warming simulation, have shown a decrease in chlorophyll- and primary production. Therefore, the combination of anthropogenic and climate changemay have a double impact on the Jakarta Bay ecosystem.Key words: Primary production, Jakarta Bay, anthropogenic, climate change, impact

HYDRODYNAMICS MODELING IN KENDARI BAY, SOUTHEAST SULAWESI, INDONESIA Imalpen Imalpen; Tri Prartono; Rastina; Alan Frendy Koropitan; Amir Yarkhasy Yuliardi
International Journal of Remote Sensing and Earth Sciences Vol. 21 No. 1 (2024)
Publisher : BRIN

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.30536/j.ijreses.2024.v21.a3906

Kendari Bay is coastal water in the center of the capital city of Southeast Sulawesi province. It is shaped like a pocket with a narrow mouth and there is an estuary of a large river, namely the Wanggu river, which makes the dynamics of its waters very interesting to study. The focus of the study is the hydrodynamic factors in the Kendari Bay and Wanggu River areas. This study aims to examine the hydrodynamic conditions of Kendari Bay, mainly due to the existence of reclamation and the influence of the Wanggu River which has not been studied previously. This research method uses a two-dimensional model based on bathymetric data, tides, and the flow of the Wanggu River with a simulation time of 15 days (1 March to 15 March 2020). The modeling results were then verified with PUSHIDROSAL tidal elevation data showing an RMSE value of 0.07 indicating that the model was well constructed. The mixed tidal type with a tendency to double daily is the tidal type of Kendari Bay waters based on the Formzahl number value of 0.51. The current pattern generally moves in and out from east to west and vice versa with a varying elevation range following spring conditions of 1.75 m. The maximum tidal speed is 0.1784 m/s and the minimum value is 0.0057 m/s which is shown in the sample results of the model when the hing to low tide, and low to high tide. The results of the hydrodynamic modeling show that the current velocity increases when passing through a narrow path, namely the bay estuary and river estuary. The existence of the reclamation area affects the changes in the velocity of the current which is significantly larger and the direction of the current that undergoes a deflection follows the shape of the reclamation area. The current direction is to the southeast and then turns towards the northeast when low to high tide and eastward then turns towards the northeast when the high to low tide spring conditions compared to research before the reclamation

THREE-DIMENSIONAL SIMULATION OF TIDAL CURRENT IN LAMPUNG BAY: DIAGNOSTIC NUMERICAL EXPERIMENTS Alan Frendy Koropitan; Safwan Hadi; Ivonne M.Radjawane
International Journal of Remote Sensing and Earth Sciences Vol. 3 (2006)
Publisher : BRIN

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.30536/j.ijreses.2006.v3.a1205

Princeton Ocean Model (POM) was used to calculate the tidal current in Lampung Bay using diagnostic mode. The model was forced by tidal elevation, which was given along the open boundary using a global ocean tide model-ORITIDE. The computed tidal elevation at St. 1 and St 2 are in a good agreement with the observed data, but the computed tidal current at St 1 at depth 2 m is not good and moderate approximation is showed at depth 10 m. Probably, it was influenced by non-linier effect of coastal geometry and bottom friction because of the position of current meter, mooring closed to the coastline. Generally, the calculated tidal currents in all layers show that the water flows into the bay during flood tide and goes out from the bay during ebb tide. The tidal current becomes strong when passing through the narrow passage of Pahawang Strait. The simulation of residual tidal current with particular emphasis on predominant contituent of M2 shows a strong inflow from the western part of the bay mouth, up to the central part of the bay, then the strong residual current deflects to the southeast and flows out from the eastern part of the bay mouth. This flow pattern is apparent in the upper and lower layer. The other part flows to the bay head and froms an antic lockwise circulation in the small basin region of the bay head. The anticlockwise circulations are showed in the upper layer and disappear in the layer near the bottom.

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