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Jurnal Kelautan Tropis
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Articles 451 Documents
Distribusi Musiman Nitrat dan Fosfat serta Pemodelan Klorofil-a sebagai Indikator Ekologis Keberlanjutan Budidaya Kappaphycus alvarezii di Pulau Tarakan Cahyadi, Jimmy; Prayitno, Slamet Budi; Desrina, Desrina; Purwanti, Frida
Jurnal Kelautan Tropis Vol 28, No 2 (2025): JURNAL KELAUTAN TROPIS
Publisher : Universitas Diponegoro

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.14710/jkt.v28i2.24784

Abstract

Seaweed farming needs essential nutrients for growth. Nitrate and phosphate are essential nutrients for the growth of seaweed algae and phytoplankton produce chlorophyll-a. Chlorophyll-a content is needed in the photosynthesis process and triggers seaweed metabolism to absorb more nutrients. This study describes the relationship between nitrate, phosphate, chlorophyll-a for west and east monsoon waters with other water quality parameters in Tarakan Island. Insitu and exsitu measurements of water quality samples at 14 stations were determined by stratified random sampling in March 2024 for the west monsoon and June 2024 for the east monsoon. The distribution of chlorophyll-a was obtained from observations of the JAXA GCOM-C OCEAN CHLA V3 satellite image and the ocean contour model from BIG. There are significant differences in the distribution of chlorophyll-a, phosphate, and nitrate in the west and east monsoons. Chlorophyll-a distribution in the west monsoon of 0.60-1.10 mg/m3 tends to be higher than that in the east monsoon of 0.50-0.85 mg/m3 divergent pattern and correlates with nitrate, phosphate, water brightness, turbidity, sea surface temperature, current and pH. Water quality in the east and west monsoons supports seaweed farming.  Budidaya rumput laut membutuhkan nutrien penting untuk pertumbuhannya. Nitrat dan fosfat merupakan nutrien penting untuk pertumbuhan algae rumput laut dan fitoplankton penghasil klorofil-a perairan. Kandungan klorofil-a dibutuhkan pada proses fotosintesis dan memicu metabolisme rumput laut menyerap lebih banyak nutrien. Penelitian ini menjelaskan keterkaitan nitrat, fosfat, klorofila-a perairan musim angin barat dan timur bersama parameter kualitas perairan lainnya di Pulau Tarakan. Pengukuran insitu dan exsitu pada 14 stasiun ditetapkan secara stratified random sampling bulan Maret 2024 mewakili musim angin barat dan Juni 2024 musim timur. Distribusi klorofil-a diperoleh dari pemantauan citra satelit JAXA GCOM-C OCEAN CHLA V3 dan pemodelan kontur laut dari BIG. Terdapat perbedaan signifikan distribusi klorofil-a, fosfat dan nitrat musim angin barat dan timur. Distribusi klorofil-a perairan musim barat 0,60-1,10 mg/m3 cenderung tinggi dibandingkan musim timur 0,50-0,85 mg/m3 berpola divergen dan berkorelasi dengan kadar nitrat, fosfat, kecerahan perairan, kekeruhan, suhu permukaan laut, arus dan pH. Kualitas perairan musim angin timur dan barat mendukung budidaya rumput laut. 
Spatial Variability of Nutrients and Chlorophyll-A as Contributing Factors of Trophic Condition in Kendari Bay, Southeast Sulawesi Rahayu, Siti Mira; Azzahra, Mutiah; Irawan, Hendra; Salwiyah, Salwiyah; Sari, Iya Purnama; Alsita, Indah; Bramana, Aditya; Maulita, Mira
Jurnal Kelautan Tropis Vol 28, No 2 (2025): JURNAL KELAUTAN TROPIS
Publisher : Universitas Diponegoro

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.14710/jkt.v28i2.26579

Abstract

Estuaries and coastal waters are heavily influenced by anthropogenic activities and environmental factors, which can lead to ecosystem degradation, increased nutrients, and the risk of eutrophication. Kendari Bay, with its complex hydrodynamic conditions and various human activities in the vicinity, requires an analysis of the distribution of nutrients and chlorophyll-a (chl-a) to estimate the potential for eutrophication and its impact on aquatic ecosystems. This research was conducted in March-May 2023 at six stations in Kendari Bay. The distribution of nutrients in Kendari Bay revealed a varied pattern, with DIN concentrations higher in the “neck area” or narrow parts of the bay, phosphates more concentrated in the inner part due to slow water flow, and silica more abundant in estuaries because it comes from weathering rocks carried by river flows. Chl-a concentration tended to correspond DIN pattern, suggesting that phytoplankton growth was more influenced by nitrogen nutrients than phosphorus nutrients, as supported by an N:P ratio of less than 16. Overall, Kendari Bay was classified as mesotrophic with a relatively uniform trophic level due to morphological and hydrodynamic characteristics that narrow towards the sea and a low flushing rate. A comprehensive approach to managing human activities from upstream to downstream must be performed effectively to protect the bay area from eutrophication and environmental decline due to excessive nutrient runoff from land-based activities.
Analisis Kondisi Terumbu karang dan Biodiversitas ikan di Pulau Tidung Kepulauan Seribu Abdullah, Muhammad Hendy; Yulianda, Fredinan; Kurnia, Rahmat
Jurnal Kelautan Tropis Vol 28, No 2 (2025): JURNAL KELAUTAN TROPIS
Publisher : Universitas Diponegoro

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.14710/jkt.v28i2.26485

Abstract

Coral reefs are complex ecosystems with high productivity. Various species of fish grow and develop in coral reef areas, making reef conditions influential on fish biodiversity. This study aims to identify and analyze the condition of coral reefs and fish biodiversity around Tidung Island, Thousand Islands. Data collection was conducted by dividing the study area into five zones, using the Point Intercept Transect (PIT) method for coral data collection and the Underwater Fish Visual Census (UVC) method for fish data collection. In-depth interviews were also conducted to gather data on preferences related to the aesthetic value of corals found in Tidung Island. The results showed that the average coral reef cover in Tidung Island was 45.78%, which is categorized as moderate. Area 3 had the highest coral cover at 89%. Corals with a thin plate lifeform and those from the Acropora genus were considered the most aesthetically pleasing. Reef fish in Tidung Island belonged to 12 families, with the highest biodiversity index found in Area 2 and the lowest in Area 5. The Pomacentridae family exhibited the highest abundance and a widespread distribution across Tidung Island. However, fish biodiversity in Tidung Island was found to be relatively unstable.  Terumbu karang merupakan ekosistem yang kompleks dan memiliki produktifitas tinggi. Berbagai jenis ikan tumbuh dan berkembang di area terumbu karang sehingga kondisi terumbu karang akan mempengaruhi biodiversitas ikan. Penelitian ini bertujuan untuk mengidentifikasi serta menganalisis kondisi terumbu karang serta biodiversitas ikan di Pulau Tidung, Kepulauan Seribu. Pengambilan data dilakukan dengan membagi area penelitian menjadi 5 area dan menggunakan metode Point Intercept Transect (PIT) untuk pengambilan data karang dan metode Underwater fish Visual Census (UVC) untuk pengambilan data ikan. Metode wawancara mendalam digunakan untuk mengambil data preferensi terkait keindahan karang yang ada di Pulau Tidung. Hasil yang diperoleh adalah tutupan rata-rata terumbu karang di Pulau Tidung sebesar 45,78% dengan kondisi yang termasuk sedang. Area 3 memiliki tutupan paling tinggi sebesar 89%. Karang dengan lifeform thin plate dan genus acropora merupakan karang yang diniliai paling indah. Ikan karang di Pulau Tidung berasal dari 12 famili dengan indeks keanekaragaman tertinggi di area 2 dan yang terendah di area 5. Famili Pomacentridae memiliki nilai kelimpahan tertinggi dan distribusi yang menyebar di Pulau Tidung. Kondisi biodiversitas ikan di Pulau Tidung cenderung tidak stabil. 
Perbandingan Kondisi Terumbu Karang dan Hubungannya dengan Ikan Karang di Perairan Karimunjawa dan Bali Ayu, Trifajriah Lutea; Munasik, Munasik; Trianto, Agus; Munru, Maestro
Jurnal Kelautan Tropis Vol 28, No 2 (2025): JURNAL KELAUTAN TROPIS
Publisher : Universitas Diponegoro

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.14710/jkt.v28i2.22473

Abstract

 This study aims to compare the ecological conditions of coral reefs and reef fish communities between the shallow waters of Karimunjawa, Jepara (Java Sea) and North Bali waters (Buleleng Regency). The research was conducted at 6 stations (2 stations in Karimunjawa and 4 stations in Bali) with different depths. The coral reef observation method used Underwater Photo Transect (UPT), while reef fish observation was conducted using the Underwater Visual Census (UVC) method. Results showed that coral reef conditions in general were not significantly different between locations. However, the abundance, biomass and biodiversity of reef fishes were significantly different between Karimunjawa and Bali. Further analysis showed that coral growth form (lifeform) was a strong predictor of reef fish community structure, and related to reef fish trophic groups (corallivores, herbivores and carnivores). The abundance and diversity of reef fish species were not only influenced by live coral cover, but also by the complexity of habitat structure. These findings highlight the importance of local oceanographic and topographic factors in supporting reef fish abundance and diversity. Penelitian ini bertujuan untuk membandingkan kondisi ekologi terumbu karang dan komunitas ikan karang antara perairan dangkal Karimunjawa, Jepara (Laut Jawa) dan perairan Bali Utara (Kabupaten Buleleng). Penelitian dilakukan pada 6 stasiun (2 stasiun di Karimunjawa dan 4 stasiun di Bali) dengan kedalaman yang berbeda. Metode pengamatan terumbu karang menggunakan Underwater Photo Transect (UPT), sementara pengamatan ikan karang dilakukan dengan metode Underwater Visual Census (UVC). Hasil menunjukkan bahwa kondisi terumbu karang secara umum tidak berbeda nyata antar lokasi. Namun, kelimpahan, biomassa dan biodiversitas ikan karang berbeda nyata antara Karimunjawa dan Bali. Analisis lebih lanjut menunjukkan bahwa bentuk pertumbuhan karang (lifeform) adalah prediktor kuat struktur komunitas ikan karang, dan berhubungan dengan kelompok trofik ikan karang (koralivora, herbivora dan karnivora) Kelimpahan dan keragaman jenis ikan karang tidak hanya dipengaruhi oleh tutupan karang hidup, tetapi juga oleh kompleksitas struktur habitat. Temuan ini menyoroti pentingnya faktor oseanografi lokal dan topografi dalam mendukung kelimpahan dan keanekaragaman jenis ikan karang.
Bioekologi Bulu Babi (Echinoidea) pada Ekosistem Padang Lamun Di Kecamatan Kupang Barat Klau, Fransiska Reni; Subagiyo, Subagiyo; Riniatsih, Ita
Jurnal Kelautan Tropis Vol 28, No 2 (2025): JURNAL KELAUTAN TROPIS
Publisher : Universitas Diponegoro

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.14710/jkt.v28i2.25627

Abstract

Sea urchins (Echinoidea) are one of the marine biota found in seagrass ecosystems in West Kupang District, East Nusa Tenggara. Sea urchins have an important role in the food chain cycle in seagrass ecosystems and are known as healthy food due to their high nutritional content. Sea urchin gonads contain protein, fat, vitamins and essential fatty acids, which are beneficial for human health. In addition to economic value, sea urchins also have ecological value in balancing and controlling macroalgae in coral reef and seagrass ecosystems. The aim of this research is to determine the bioecology of sea urchins in four research locations, namely Bolok, Lalendo, Baliana, and Tablolong beaches. The research method used was direct observation with Megabenthos and Benthos Belt Transect (BBT) techniques. The results showed that there were five types of sea urchins in the study site, namely Diadema setosum, Tripneustes gratilla, Echinometra calamaris, Echinothrix diadema, and Echinometra mathaei.   The results showed that the abundance of Diadema setosum individuals on Tablolong beach (0.46 ind/m²) while Tripneustes gratilla was dominant on Baliana beach (0.22 ind/m²). The highest species diversity index (D) was found in Lalendo (0,7) and the lowest in Tablolong (0,5), indicating moderate diversity. The uniformity index (E) was highest in Baliana (0.8) indicating a more even distribution of species than Tablolong (0.6), the dominance index (C) was highest in Lalendo (1.0), indicating a strong dominance of species at the site.   The highest Index of Gonadal Maturity (IKG) value for Diadema setosum was found in Tablolong (26.9), while Echinometra mathaei in Lalendo (68.6). The food consumption pattern of sea urchins showed that Tripneustes gratilla consumed more seagrass, especially at Baliana beach (82,08%), while Echinothrix diadema predominantly consumed seagrass at Lalendo and Baliana beaches.  Bulu babi (Echinoidea) merupakan salah satu biota laut yang banyak ditemukan pada ekosistem padang lamun di Kecamatan Kupang Barat, Nusa Tenggara Timur. Bulu babi memiliki peran penting dalam siklus rantai makanan di ekosistem lamun dan dikenal sebagai makanan yang menyehatkan karena kandungan nutrisinya yang tinggi. Gonad bulu babi mengandung protein, lemak, vitamin, dan asam lemak esensial, yang bermanfaat bagi kesehatan manusia. Selain nilai ekonomi, bulu babi juga memiliki nilai ekologi dalam menyeimbangkan dan mengendalikan makroalga di ekosistem terumbu karang dan lamun. Tujuan dari penelitian ini adalah untuk mengetahui bioekologi bulu babi di empat lokasi penelitian, yaitu pantai Bolok, Lalendo, Baliana, dan Tablolong. Metode penelitian yang digunakan adalah pengamatan langsung dengan teknik Megabentos dan Benthos Belt Transect (BBT). Hasil penelitian menunjukkan bahwa terdapat lima jenis bulu babi di lokasi penelitian yaitu Diadema setosum, Tripneustes gratilla, Echinometra calamaris, Echinothrix diadema, dan Echinometra mathaei. Hasil menunjukkan bahwa  kelimpahan individu Diadema setosum terrtinggi di pantai Tablolong (0,46 ind/m²) sedangkan Tripneustes gratilla dominan di pantai Baliana (0,22 ind/m²). Indeks keanekaragaman jenis (D) tertinggi ditemukan di Lalendo (0,7) dan terendah di Tablolong (0,2), menunjukkan keanekaragaman sedang. Indeks keseragaman (E) tertinggi di Baliana (0,8) menandakan distribusi spesies lebih merata dibandingkan Tablolong (0,6), Indeks dominansi (C) tertinggi di Lalendo (1,0), menunjukkan dominasi spesies yang kuat di lokasi tersebut.   Nilai Indeks Kematangan Gonad (IKG) tertinggi untuk Diadema setosum ditemukan di Tablolong (26,9), sedangkan jenis Echinometra mathaei tertinggi di Lalendo (68,6). Pola konsumsi jenis makanan bulu babi menunjukkan bahwa Tripneustes gratilla lebih banyak mengonsumsi lamun, terutama di pantai Baliana (82,08%), sementara Echinothrix diadema lebih dominan mengonsumsi lamun di pantai Lalendo dan Baliana. 
Identifikasi Dan Kelimpahan Famili Acartiidae (Copepoda) Di Perairan Banggai, Sulawesi Tengah Fitriyan, Jodhi Kusumayudha; Widianingsih, Widianingsih; Widowati, Ita; Hartati, Retno; Riniatsih, Ita
Jurnal Kelautan Tropis Vol 28, No 2 (2025): JURNAL KELAUTAN TROPIS
Publisher : Universitas Diponegoro

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.14710/jkt.v28i2.26774

Abstract

Perairan Banggai merupakan salah satu laut yang memiliki upwelling atau fenomena kenaikan massa air pada periode tertentu. Peristiwa ini menyebabkan meningkatnya kandungan nutrien pada perairan disebabkan adanya proses pengadukkan massa air menuju kolom atas perairan yang mempengaruhi kelimpahan produsen primer dan produsen sekunder, salah satunya zooplankton dari Famili Acartiidae. Penelitian mengenai keberadaan dan kelimpahan spesies zooplankton belum banyak dilakukan di perairan bagian timur, terutama studi mengenai spesies-spesies dari Famili Acartiidae. Berdasarkan keterangan di atas, perlu adanya pengkajian keberadaan dan kelimpahan Acartiidae. Sampel zooplankton diperoleh dari proses pengambilan  di 35 stasiun secara aktif vertikal menggunakan plankton net. Pengamatan dan pengambilan foto spesies plankon dilakukan di bawah Mikroskop Stereo Olympus SZ61 yang disesuaikan dengan ukuran zooplankton dengan perbesaran 30x sampai 45x. Hasil pencacahan diolah menggunakan Ms. Office Excel 2016 (Excel 16) untuk mengetahui jumlah keberadaan dan kelimpahan Famili Acartiidae. Terdapat 7 spesies famili Acartiidae dari genus Acartia dan Acartiella yang didapatkan di Perairan Banggai, Sulawesi Tengah, yaitu Acartia clausi, Acartia longiremis, Acartiella faoensis, Acartiella gravelyi, Acartiella minor, Acartiella natalensis, dan Acartiella tortaniformis. Spesies dengan sebaran distribusi terbesar atau memiliki kemunculan terbanyak adalah dari genus Acartia dengan Acartia clausi muncul di 14 stasiun. Total keberadaan famili Acartiidae di Perairan Banggai sebanyak 41 individu, meliputi 35 betina dan 6 jantan dengan rata-rata di semua stasiun penelitian sebanyak 2 individu.
Klasifikasi Gelembung Gas Menggunakan Multibeam Echosounder dan Machine Learning Rabbani, Mochamad Rafif; Manik, Henry Munandar; Hestirianoto, Totok
Jurnal Kelautan Tropis Vol 28, No 2 (2025): JURNAL KELAUTAN TROPIS
Publisher : Universitas Diponegoro

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.14710/jkt.v28i2.26778

Abstract

The urgency of detecting gas bubbles in the water column is crucial in various fields, ranging from environmental monitoring to detecting underwater gas leaks. One method that can be used to detect gas bubbles is the Multibeam Echosounder. However, processing Multibeam Echosounder data is prone to human error and inefficient in terms of time, necessitating a more practical approach, such as utilizing Artificial Intelligence, specifically Machine Learning. This study aims to classify gas bubbles using Multibeam Echosounder and Machine Learning and determine the best algorithm. The acquired acoustic data were first processed using FMMidwater Fledermaus software for feature extraction and depth analysis in the water column, followed by target tagging on the echogram as a visual labeling process for Machine Learning model input. Three algorithms were tested: Random Forest, K-Nearest Neighbor, and Support Vector Machine. Model evaluation was conducted using a confusion matrix to generate accuracy, F1-score, and kappa coefficient values. The evaluation results showed that the Random Forest algorithm achieved the highest accuracy of 89.02%, followed by Support Vector Machine with 86.76% and K-Nearest Neighbor with 85.41%. These findings demonstrate that the Machine Learning approach effectively classifies gas bubbles in the water column and distinguishes them from other objects in the water column.   Kepentingan pendeteksian gelembung gas di kolom air menjadi urgensi dalam berbagai bidang, misalnya dalam pemantauan lingkungan hingga deteksi kebocoran gas bawah laut. Salah satu metode yang dapat digunakan dalam mendeteksi gelembung gas adalah dengan menggunakan Multibeam Echosounder. Namun, pengolahan data Multibeam Echosounder rawan terjadi human error dan tidak cukup efisien dalam skala waktu, sehingga diperlukan metode praktis dalam pengolahan data Multibeam, salah satunya adalah dengan menggunakan bantuan Artificial Intelligence, yaitu Machine Learning. Penelitian ini bertujuan untuk mengklasifikasikan gelembung gas dengan menggunakan Multibeam Echosounder dan Machine Learning, serta menentukan algoritma terbaik. Data akustik yang telah diakusisi diolah terlebih dahulu dengan bantuan perangkat lunak FMMidwater Fledermaus untuk ekstraksi fitur dan kedalaman objek di kolom air, serta proses tagging target pada echogram sebagai proses pelabelan secara visual untuk input pada model Machine Learning. Terdapat tiga algoritma yang diuji, yaitu Random Forest, K-Nearest Neighbor dan Support Vector Machine. Evaluasi model menggunakan confusion matrix untuk menghasilkan nilai akurasi, F1-Score dan koefisien kappa. Evaluasi performa model menunjukkan algoritma Random Forest memiliki nilai akurasi tertinggi yaitu 89.02 % diikuti oleh Support Vector Machine dengan akurasi 86.76% dan K-Nearest Neighbor dengan akurasi 85.41%. Hasil ini membuktikan bahwa pendekatan Machine Learning mampu mengklasifikasikan gelembung gas di kolom air serta dapat membedakannya terhadap objek lain di kolom air
Pemetaan Tata Kelola Interaktif Jasa Provisioning Ekosistem Skala Kecil: Pendekatan Sistem Sosial-Ekologi Di Teluk Jor, Lombok Timur Wahid, Mathori Abdul; Adrianto, Luky; Zairion, Zairion; Adhuri, Dedi Supriadi
Jurnal Kelautan Tropis Vol 28, No 2 (2025): JURNAL KELAUTAN TROPIS
Publisher : Universitas Diponegoro

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.14710/jkt.v28i2.26947

Abstract

The utilization of coastal and marine resources in Teluk Jor, East Lombok, faces significant pressures that threaten the sustainability of small-scale ecosystem provisioning services, such as mangroves, seagrass beds, and coral reefs. This study aims to map the social-ecological system (SES) network using the Social-Ecological Network Analysis (SENA) approach based on the Russian Doll Framework. Primary data were obtained through field observations and in-depth interviews with 68 respondents, including fishers, community leaders, fisheries extension officers, and relevant institutions. Secondary data were collected from previous literature reviews. The analysis results indicate that the Local Rule (customary regulations) holds the highest degree centrality (10), followed by ResThreat (ecosystem threats) such as mangrove conversion and destructive fishing practices (9), and HumConFac (human-made infrastructures) including floating net cages, salt ponds, and shrimp ponds (8). Regarding betweenness centrality, the Local Rule occupies the most central position (59.67), followed by HumConFac (49.83), ResThreat (32.67), and EcoQual (ecosystem quality) (24.50). These findings demonstrate that customary institutions play a crucial role in connecting governance actors, while economic activities and ecological threats significantly shape SES network dynamics. This study underscores the need for adaptive governance strategies that integrate collaboration among communities, government, and stakeholders to ensure ecosystem sustainability while supporting the well-being of coastal communities. Pemanfaatan sumber daya pesisir dan laut di Teluk Jor, Lombok Timur, menghadapi tekanan signifikan yang mengancam keberlanjutan jasa provisioning ekosistem skala kecil, seperti mangrove, lamun, dan terumbu karang. Penelitian ini bertujuan untuk memetakan jejaring social-ecological system (SES) menggunakan pendekatan social-ecological network analysis (SENA) berbasis Russian Doll Framework. Data primer diperoleh melalui observasi lapangan dan wawancara mendalam dengan 68 responden, mencakup nelayan, tokoh masyarakat, penyuluh perikanan, serta instansi terkait. Data sekunder dikumpulkan dari kajian literatur sebelumnya. Hasil analisis menunjukkan bahwa Local Rule (aturan lokal) memiliki nilai degree centrality tertinggi (10), diikuti oleh ResThreat (ancaman ekosistem) seperti konversi mangrove dan praktik perikanan destruktif (9), serta HumConFac (infrastruktur buatan) seperti KJA, tambak garam, dan tambak udang (8). Pada indikator betweenness centrality, Local Rule menempati posisi sentral (59,67), diikuti HumConFac (49,83), ResThreat (32,67), dan EcoQual (kualitas ekosistem) (24,50). Temuan ini menunjukkan bahwa kelembagaan adat memainkan peran penting dalam menghubungkan aktor-aktor tata kelola, sementara aktivitas ekonomi dan ancaman ekologis berperan besar dalam membentuk dinamika jaringan SES. Penelitian ini menegaskan perlunya strategi tata kelola adaptif yang mengintegrasikan kolaborasi antara masyarakat, pemerintah, dan pemangku kepentingan, guna menjaga keberlanjutan ekosistem sekaligus mendukung kesejahteraan masyarakat pesisir. 
Genetic Analysis on Horseshoe Crab for Phylogenetic Tree Study from Jambi, Bangka Belitung, Central Java, and East Java Province, Indonesia Kholilah, Nenik; Kurniatami, Gabriella Tarida; Kurniasih, Eka Maya; Nursalim, Nining; Janarkho, Galank Fad’qul; Ambariyanto, Ambariyanto; Wijayanti, Diah Permata; Putro, Sapto Purnomo; Cahyani, Ni Kadek Dita
Jurnal Kelautan Tropis Vol 28, No 2 (2025): JURNAL KELAUTAN TROPIS
Publisher : Universitas Diponegoro

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.14710/jkt.v28i2.25923

Abstract

Order Xiphosura, or horseshoe crabs, are rarely found and classified as macrofossils. In Indonesian waters, there are three species: Tachypleus tridentatus, Tachypleus gigas, and Carcinoscorpius rotundicauda. The genetic analysis of their kinship, however, has been extensively unexplored. This study aims to utilize DNA barcoding, focusing on the cytochrome c oxidase subunit I (COI) locus from mitochondrial DNA and investigating the phylogenetic relationships of horseshoe crabs from the four sites (Tanjung Jabung Timur Regency in Jambi, Bangka Regency in Bangka Belitung, Demak Regency in Central Java, and Tuban Regency in East Java). Additionally, the study provides insights into the biodiversity and ecological roles of horseshoe crabs within their ecosystems and surrounding habitats. Through molecular methods, this research focuses on biodiversity analysis through Sanger sequencing and MEGA 11 software for constructing phylogenetic trees and calculating genetic distances. With a total of 22 horseshoe crabs, the DNA samples from four different sites were amplified via Sanger sequencing, targeting the COI locus and analyzing with MEGA 11. The phylogenetic tree analysis revealed two distinct species, Tachypleus gigas, and Carcinoscorpius rotundicauda, exhibiting significant genetic variation between them. A clear genetic separation between the two species was observed. Otherwise, within the C. rotundicauda species, a minor genetic variation was detected between sampling sites. Notably, the genetic composition displayed greater differences between samples from Java and Sumatra compared to differences within each island. The future research should expand the sampling size and include additional genetic markers to provide a more comprehensive understanding of the genetic diversity and evolutionary history of horseshoe crabs in Indonesian waters. Integrating ecological and environmental data could further elucidate the factors driving genetic differentiation and inform conservation strategies.
Pemodelan Spektrum Gelombang di Pantai Barat hingga Selatan Indonesia Bangguna, David S. V. L .; Zalukhu, Aisyah Christine; Laia, Debora; Harianja, Jhonson Andar
Jurnal Kelautan Tropis Vol 28, No 2 (2025): JURNAL KELAUTAN TROPIS
Publisher : Universitas Diponegoro

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.14710/jkt.v28i2.26108

Abstract

Wave spectrum modeling can describe the distribution of wave energy based on frequency and direction over a specific time period in the observed water area. Understanding the energy distribution from the wave spectrum is highly beneficial for designing structures that are stronger, more stable, and resistant to extreme ocean conditions. The aim of this research is to model the wave spectrum characteristics of the waters from the western to southern regions of Indonesia. The western coast of Sumatra Island to the southern coast of Papua Island was selected as the study area because these coastal regions are more exposed to wave propagation from the Indian Ocean, making them more vulnerable to wave impacts. The specific locations include Meulaboh Beach (West Aceh), Sorake (South Nias), Lais (North Bengkulu), Bunton (Cilacap), Jerman Beach (Bali), Walakiri (East Sumba), and Wendu (Merauke). The wave height analysis at the seven locations along the western to southern coasts of Indonesia shows that Walakiri Beach experiences higher wave heights compared to other locations, with wave heights of 4.8 m (West monsoon), 4.9 m (Transitional Season I), 5.7 m (East monsoon), and 4.3 m. During the Transitional Season II, the highest wave energy also occurs at Walakiri Beach. The wave energy values for the four consecutive seasons are: West monsoon (34.461 m²/Hz), Transitional Season I (35.911 m²/Hz), East monsoon (46.180 m²/Hz), and Transitional Season II (23.987 m²/Hz). The wave energy values are directly proportional to the wave heights—the higher the wave, the greater the energy it carries. This occurs because ocean waves are the result of accumulated wind energy that blows across the sea surface.   Pemodelan spektrum gelombang dapat menggambarkan distribusi energi gelombang berdasarkan frekuensi dan arah dalam jangka waktu tertentu pada daerah perairan yang diamati. Pemahaman penyebaran energi dari spektrum gelombang akan sangat membantu perancangan struktur yang lebih kuat, stabil, dan tahan terhadap kondisi laut ekstrem. Tujuan penelitian yaitu untuk memodelkan karakteristik spektrum gelombang dari perairan Barat hingga Selatan Indonesia. Pantai Barat pulau Sumatera hingga pantai Selatan pulau Papua dipilih untuk lokasi penelitian ini karena lokasi pantai ini lebih terbuka terhadap penjalaran gelombang dari Samudra Hindia, sehingga pantai lebih rentan terhadap gempuran gelombang. Lokasi tersebut yaitu pantai Meulaboh (Aceh Barat), Sorake (Nias Selatan), Lais (Bengkulu Utara), Bunton (Cilacap), Jerman (Bali), Walakiri (Sumba Timur), dan Wendu (Merauke). Hasil analisis tinggi gelombang pada tujuh lokasi di pantai Barat hingga Selatan Indonesia, menunjukkan bahwa tinggi gelombang di pantai Walakiri lebih tinggi dibandingkan dengan lokasi pantai yang lainnya yaitu 4,8 m (musim Barat), 4,9 m (musim Peralihan I), 5,7 m (musim Timur) dan 4,3 m. Saat musim Peralihan 2, energi gelombang terbesar terjadi juga di pantai Walakiri. untuk empat musim berturut-turut dari musim Barat (34,461 m2/hz), musim Peralihan 1 (35,911 m2/Hz), musim Timur (46,180 m2/Hz), musim Peralihan 2 (23,987 m2/Hz). Nilai energi gelombang yang terjadi berbanding lurus dengan tinggi gelombangnya, semakin tinggi gelombang maka energi gelombangnya juga semakin besar, hal ini terjadi karena gelombang di laut merupakan hasil dari akumulasi energi angin yang berhembus di atas permukaan air laut.