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All Journal ILMU KELAUTAN: Indonesian Journal of Marine Sciences Indonesian Journal of Oceanography
Widiaratih, Rikha
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Agriculture, Biological Sciences & Forestry Decision Sciences, Operations Research & Management Earth & Planetary Sciences Environmental Science

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Kajian Pergerakan Mikroplastik dengan Parcels di Perairan Pulau Sintok, Kepulauan Karimunjawa Marganita, Dia; Marwoto, Jarot; Widiaratih, Rikha
Indonesian Journal of Oceanography Vol 4, No 2 (2022): Indonesian Journal of Oceanography
Publisher : University of Diponegoro

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.14710/ijoce.v4i2.14177

Abstract

Mikroplastik adalah partikel kecil dari sampah plastik yang mengalami fragmentasi selama berada di alam. Ukurannya yang kecil dan ketahanannya yang lama menyebabkan mikroplastik berbahaya jika terakumulasi di dalam tubuh makhluk hidup. Sehingga kajian mengenai pergerakan mikroplastik perlu dilakukan untuk mengetahui persebaran mikroplastik yang sudah berada di lingkungan, terutama lingkungan laut. Penelitian ini dilakukan dengan tujuan mengetahui pergerakan (tujuan dan sumber) mikroplastik di Perairan Pulau Sintok. Pulau Sintok merupakan salah satu pulau di Kepulauan Karimunjawa yang menjadi destinasi singgah dan bertelur penyu. Pulau Sintok, sebagai pulau yang tidak berpenghuni, memiliki potensi untuk terkontaminasi partikel mikroplastik yang terbawa oleh pergerakan arus. Pergerakan mikroplastik dilakukan dengan pemodelan particle tracking dengan Parcels dan model GOFS 3.1 yang telah divalidasi dengan data pengukuran arus ADCP. Pemodelan particle tracking menggunakan dua skenario, yaitu forward time dan backward time dengan masing-masing runtime 7 hari, 30 hari, dan 60 hari pada Musim Peralihan I tahun 2020. Dari pemodelan particle tracking, partikel mikroplastik bergerak menuju arah timur laut Laut Jawa dan diduga berasal dari Pulau Kemujan dan utara Pulau Jawa, tepatnya yaitu Sungai Cisanggarung, Kota Cirebon, dan Sungai Citarum. Kata kunci: Mikroplastik, Particle Tracking, Parcels, Karimunjawa Abstract Study of Microplastic Movement with Parcels in Sintok Island Waters, Karimunjawa Archipelago Microplastics are small particles of plastic waste that undergo fragmentation while in nature. Their small size and long durability make microplastics dangerous if they accumulate inside living things. A study of microplastic movement needs to be carried out to determine the distribution of microplastics that are already in the environment, especially the marine environment. This research was conducted to understand the movement (destination and source) of microplastics in Sintok Island Waters. Sintok Island is one of the islands in the Karimunjawa Archipelago that is also a stopping-by and spawning destination for sea turtles. Sintok Island, as an uninhabited island, has the potential to be contaminated with microplastic particles carried by sea currents. The movement of microplastics is carried out using particle tracking modeling with Parcels and the GOFS 3.1 model which has been validated with ADCP current data. The particle tracking modeling uses two scenarios, namely forward time and backward time with runtime of 7 days, 30 days, and 60 days in the Transition season I 2020 for each scenario. From the particle tracking modeling, microplastic particles move towards the northeast of the Java Sea and are estimated to have come from Kemujan Island and northern Java Island, namely Cisanggarung River, Cirebon City, and Citarum River.Keywords: Microplastic, Particle Tracking, Parcels, Karimunjawa
Variabilitas Bulanan Klorofil-A Dan Suhu Permukaan Laut Pada Perairan Teluk Rembang Dengan Menggunakan Citra Sentinel-3 Ningrum, Devita; Zainuri, Muhammad; Widiaratih, Rikha
Indonesian Journal of Oceanography Vol 4, No 2 (2022): Indonesian Journal of Oceanography
Publisher : University of Diponegoro

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.14710/ijoce.v4i2.14258

Abstract

Perairan Teluk Rembang merupakan salah satu sumber penghidupan bagi penduduk bermata pencaharian nelayan. Penelitian ini menggunakan citra Sentinel-3 OLCI dan SLSTR memiliki resolusi sebesar 300 m x 300m, dengan resolusi spasial tersebut citra yang dihasilkan oleh Sentinel-3 OLCI dan SLSTR dapat dikatakan cukup baik untuk diteliti lebih lanjut. Penelitian ini menggunakan data citra Sentinel-3 OLCI dan SLSTR serta data angin reanalysis ERA-5 dari (Climate Copernicus) yang diolah menggunakan bantuan program SNAP dengan metode C2RCC. Berdasarkan hasil penelitian didapatkan bahwa nilai variabilitas bulanan klorofil-a memiliki nilai yang bervariasi setiap bulannya. Nilai konsentrasi klorofil-a tertinggi terjadi pada bulan Juli sebesar 6,72 mg/l dan terendah pada bulan November sebesar 0,87 mg/l. Nilai konsentrasi Klorofil-a memiliki keterkaitan dengan suhu permukaan laut dan angin. Nilai konsentrasi klorofil-a berbanding lurus dengan kecepatan angin yang nilai korelasinya sebesar -0,54, sedangkan nilai konsentrasi klorofil-a berbanding terbalik dengan suhu permukaan laut yang nilai korelasinya sebesar 0,42. Tingginya nilai konsentrasi klorofil-a terjadi pada saat kecepatan angin meningkat, dan suhu permukaan laut rendah terjadi ketika kecepatan angin tinggi. Begitupun sebaliknya, konsentrasi klorofil-a menurun dan suhu permukaan laut meningkat terjadi pada saat kecepatan angin menurun. Kata kunci: Klorofil-a, Suhu Permukaan Laut, Sentinel-3, Perairan Teluk Rembang Abstract Rembang Bay has been one of the sources of livelihood for residents who work as fishermen. This study uses Sentinel-3 OLCI and SLSTR images with a resolution of 300 m x 300m, with this spatial resolution the images produced by Sentinel-3 OLCI and SLSTR can be said to be good enough to be investigated further. This research uses Sentinel-3 OLCI and SLSTR image data as well as ERA-5 wind reanalysis data from (Climate Copernicus) which was processed using the SNAP program with the C2RCC method. Based on the results of the study, it was found that the monthly variable value of chlorophyll-a has a value that varies every month. The highest value of chlorophyll-a concentration occurred in July of 6.72 mg/l and the lowest was in November of 0.87 mg/l. Chlorophyll-a concentration value have a relationship with sea surface temperature and wind. The value of chlorophyll-a concentration is directly proportional to wind speed with a correlation value of -0.54, while the value of chlorophyll-a concentration is inversely proportional to sea surface temperature with a correlation value of 0.42. High concentration values of chlorophyll-a occur when wind speed increases, and low sea surface temperatures occur when wind speeds are high. Conversely, chlorophyll-a concentration decreases and sea surface temperature increases when wind speed decreases. Keywords: Chlorophyll-a, Sea Surface Temperature, Sentinel-3, Rembang Bay
Modelling Migratory Pinch Points and Connectivity of Pygmy Blue Whale Using Circuit Theory: A Case Study of Savu Sea, Indonesia Jihadi, Muhammad Shulhan; Zainuri, Muhammad; Goff, Virginia Andrews-; Widiaratih, Rikha; Kunarso, Kunarso; Indrayanti, Elis
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.30.2.174-182

Abstract

Blue whale and their subspecies is an endangered whale species that needs to be conserved by protecting their important habitat and migration corridor. Research about designing and modelling blue whale habitat for marine protected area has been done many times. However, incorporation of connectivity in marine protected areas design and management has been limited due to the complexity of methods used to model connectivity, therefore the implementation among practitioners is inconsistent. An alternative method to model connectivity of pygmy blue whale habitat is discussed through a combination of maximum entropy model and circuit theory. The habitat suitability models were made using satellite-tagged pygmy blue whale data (2012-2016) and oceanographic variables, such as sea surface temperature, chlorophyll, salinity, bathymetry, and seafloor geomorphology for four season that is March-April-May (MAM), June-July-August (JJA), September-October-November (SON), and December-January-February (DJF). The habitat suitability model shows different importance of environmental variables in their preference of habitat in each season, with distance from slope as the most influential parameter during the migration season (54.4% for MAM, 37.8% for SON), mean climatological chlorophyll during winter (31%), and mean climatological sea surface temperature during summer (54.7%). Habitat suitability result were then used to model connectivity, assuming that the whales migrate during MAM and SON. The migration model from Omniscape showed some pinch point, such as Sumba-Sape strait, Alor strait, Rote strait, Ombai strait. These pinch points can be seen as corridors with high potential of pygmy blue whale migration or high connectivity, therefore this area could become priority for conservation.
Modeling Seasonal Variability of Trophic Index (TRIX) in Indonesian Waters Using PISCES Biogeochemical Data Krisna, Heru Nur; Maslukah, Lilik; Wirasatriya, Anindya; Indrayanti, Elis; Widiaratih, Rikha
ILMU KELAUTAN: Indonesian Journal of Marine Sciences Vol 30, No 3 (2025): Ilmu Kelautan
Publisher : Marine Science Department Diponegoro University

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.14710/ik.ijms.30.3.373-381

Abstract

Eutrophication poses a significant challenge in Indonesian waters, largely due to a lack of data for effective mitigation. This complex issue, characterized by a time lag and multi-phase progression, is triggered by an influx of nutrients like nitrate and phosphate, leading to harmful algal blooms (HABs) that degrade water quality. This study proposes a more comprehensive approach using the Trophic Index (TRIX), which integrates multiple parameters from the PISCES global biogeochemical model data. The PISCES model accurately captures seasonal TRIX trends, with high values in the southern islands during the southeast monsoon and in northern areas during the northwest monsoon. The model's reliability is confirmed by RMSE and Bias data to be quite low, respectively, for Chl-a (0.065, -0.005), Nitrate (0.144, -0.080), Phosphate (0.084, -0.059), and DO (3.109, 0.919), from the World Ocean Database. The highest TRIX values (8-10) were found in Jakarta Bay, while the Lombok Strait had values (5-7), a difference attributed to varying oceanographic conditions. However, it is crucial to consider physical oceanography and boundary conditions when using the TRIX model. So then, model TRIX data is more valuable for informing policy and mitigation plans for the various Indonesian waters, taking into account their unique characteristics. These findings underscore the importance of considering both monsoon cycles and local conditions when assessing eutrophication risk. The TRIX data is therefore a valuable tool for developing informed policies and mitigation plans for Indonesia's diverse coastal areas.
Co-Authors Anindya Wirasatriya Elis Indrayanti Goff, Virginia Andrews- Jarot Marwoto Jihadi, Muhammad Shulhan Krisna, Heru Nur Kunarso Kunarso Lilik Maslukah Marganita, Dia Muhammad Zainuri Ningrum, Devita