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Jurnal Kelautan Tropis
Published by Universitas Diponegoro
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Articles 451 Documents
Konektivitas Multi-Dimensi Sistem Sosial-Ekologi dalam Pengelolaan Ekosistem Mangrove (Studi Kasus: Pulau Tanakeke, Sulawesi Selatan) Puspita, Lorensia; Adrianto, Luky; Damar, Ario
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.v28i2.26814

Abstract

Characteristically, the mangrove ecosystem on Tanakeke Island, South Sulawesi, is a complex, adaptive system integrated between the ecological system and the social system within it (Social-Ecological System). This study aims to map SES connectivity in mangrove management in Minasa Baji Village using a Social-Ecological Network Analysis (SENA) approach. Data were collected through field observations and in-depth interviews with 55 respondents, including fishers, seaweed farmers, aquaculture farmers, charcoal producers, and other stakeholders. Network analysis identified 46 nodes (actors/components) and 89 edges (relationships), with four key variables: mangrove conditions, commodity prices, fishery yields, and rehabilitation efforts. Results highlight mangroves as the central node (highest degree centrality) in the SES network, strongly linked to economic factors like income and market prices. However, exploitation for livelihoods threatens ecosystem sustainability. The study also reveals governance fragmentation, where policies are poorly integrated with local practices. For sustainable management, a holistic approach integrating ecological, economic, social, and institutional aspects is critical, including community-based monitoring (POKMASWAS) and multi-stakeholder collaboration. Sesuai karakteristiknya, ekosistem mangrove di Pulau Tanakeke, Sulawesi Selatan, sistem yang kompleks, dan adaptif terintegrasi antara sistem ekologi dan sistem sosial di dalamnya (Social-Ecological System; SES). Penelitian ini bertujuan untuk memetakan konektivitas SES dalam pengelolaan mangrove di Desa Minasa Baji menggunakan pendekatan Social-Ecological Network Analysis (SENA). Data dikumpulkan melalui observasi lapangan dan wawancara mendalam dengan 55 responden, termasuk nelayan, pembudidaya rumput laut, petambak, pembuat arang, dan pemangku kepentingan lainnya. Analisis jaringan mengidentifikasi 46 node (aktor/komponen) dan 89 edge (relasi), dengan empat variabel kunci: kondisi mangrove, harga komoditas, hasil tangkapan, dan aktivitas rehabilitasi. Hasil menunjukkan bahwa mangrove berperan sebagai simpul utama (highest degree centrality) dalam jaringan SES, dengan keterkaitan kuat terhadap aspek ekonomi seperti pendapatan (income) dan harga (price). Namun, tekanan eksploitasi untuk kebutuhan ekonomi mengancam kelestarian ekosistem. Studi ini juga mengungkapkan fragmentasi dalam tata kelola (governance), di mana kebijakan pemerintah belum terintegrasi secara optimal dengan praktik lokal. Untuk mencapai pengelolaan berkelanjutan, diperlukan pendekatan holistik yang memadukan aspek ekologi, ekonomi, sosial, dan kelembagaan, termasuk penguatan peran pemantauan berbasis masyarakat (POKMASWAS) dan kolaborasi multi-stakeholder.
Profil Populasi Tuna Madidihang (Thunnus albacares Bonnaerre, 1880) yang Tertangkap pada Perikanan Handline di Perairan Nusa Tenggara Timur dan sekitarnya Anakotta, Anthoinette Rosaline Fransisca; Widjaya Saputra, Suradi; Fitri, Aristi Dian Purnama; Sabdaningsih, Aninditia; Baroqi, A. Riza; Timur, Putra Satria; M. Rehatta, Beatrix
Jurnal Kelautan Tropis Vol 28, No 3 (2025): JURNAL KELAUTAN TROPIS
Publisher : Universitas Diponegoro

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.14710/jkt.v28i3.27115

Abstract

Yellowfin tuna (Thunnus albacares) is the main target of capture fisheries in various tropical waters, including Indonesia, owing to its high economic value. Global market demand increases the rate of exploitation; therefore, the size of the catch is not considered. The increasing number of fishing units led to declines in tuna stocks, catches exceeding the limit, and a dominance of catch sizes smaller than the mature gonad size (Lc < Lm), resulting in a decrease in the biomass of spawning stocks. This study aimed to examine the profile of the yellowfin tuna population in the waters of East Nusa Tenggara (NTT) by analyzing its size structure, size-at-first-catch (Lc), mortality, recruitment patterns, production trends, and Catch Per Unit Effort (CPUE). Length and weight data were obtained from I-Fish (Indonesian Fisheries Information System) initiated by YMDPI. The analysis showed that the yellowfin tuna caught ranged in size from 78 to 173 cm and were dominated by the 94-125 cm size group (82.86%). The catch consisted of 99.99% adult fish and 0.01% juveniles. The Lc value ranged from 103.34–106.55 cm, fishing mortality (F=1.44) was higher than natural mortality (M = 0.71) and the exploitation rate (E) was 0.67, indicating overfishing. Recruitment occurred throughout the year, peaking in June. Production increases in April, June, and October. CPUE ranged from 0.45-0.80 tons/trip, most fish weighed 17-23 kg (38.32%) and fish weighed more than 45 kg <1%. Overall, this condition emphasizes the importance of sustainable management based on periodic data to maintain the sustainability of the tuna population and the fisheries industry. Tuna madidihang (Thunnus albacares) merupakan target utama perikanan tangkap di berbagai perairan tropis, termasuk Indonesia, karena bernilai ekonomi tinggi. Pemintaan pasar global meningkatkan laju eksploitasi, sehingga ukuran layak tangkap tidak diperhatikan. Penurunan stok tuna disebabkan oleh, meningkatnya jumlah unit penangkapan, volume tangkapan yang melebihi batas serta dominasi ukuran tangkapan lebih kecil dari ukuran matang gonad (Lc < Lm), menyebabkan biomassa stok memijah berkurang. Penelitian ini bertujuan untuk mengkaji profil populasi tuna madidihang di perairan Nusa Tenggara Timur (NTT) melalui analisis struktur ukuran, ukuran pertama kali tertangkap (Lc), mortalitas, pola rekrutmen, tren produksi dan Catch Per Unit Effort (CPUE). Data panjang dan berat diperoleh dari I-Fish (Indonesian Fisheries Information System) yang diinisiasi oleh YMDPI. Hasil analisis menunjukan, tuna madidihang yang tertangkap berukuran 78-173 cm, didominasi oleh kelompok ukuran 94-125 cm (82,86 %). Komposisi tangkapan terdiri dari 99,99% ikan dewasa dan 0,01% juvenil. Nilai Lc berisar dari 103,34–106,55 cm, mortalitas penangkapan (F=1,44) lebih tinggi dari mortalitas alami (M = 0,71) dan laju eksploitasi (E) sebesar 0,67, mengindikasikan terjadinya overfishing. Rekrutmen terjadi hampir sepanjang tahun, puncaknya pada bulan Juni. Produksi meningkat pada bulan April, Juni dan Oktober. CPUE berkisar antara 0,45-0,80 ton/trip, sebagian besar ikan berbobot 17-23 kg (38,32%) dan ikan berukuran lebih dari 45 kg < 1%. Secara keseluruhan kondisi ini menegaskan pentingnya pengelolaan berkelanjutan berbasis data periodik untuk menjaga kelestarian populasi dan industri perikanan tuna.
Kontaminasi Kadmium (Cd) serta Analisis Risiko Kesehatan Manusia melalui Konsumsi Kerang Tahu (Meretrix spp.) di Pesisir Bangkalan Nurrizal, Muhammad Naufal; Asih, Eka Nurrahema Ning; Kartika, Ary Giri Dwi
Jurnal Kelautan Tropis Vol 28, No 3 (2025): JURNAL KELAUTAN TROPIS
Publisher : Universitas Diponegoro

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.14710/jkt.v28i3.29550

Abstract

Venus clams are a fishery commodity on the coast of Bangkalan and a source of animal protein for the local people. However, the accumulation of cadmium in these clams could pose a health risk to humans through consumption. Therefore, this study aims to assess the level of cadmium contamination in the environment and analyze the health risks of consuming venus clams on the coast of Bangkalan. Seawater, sediment, and venus clamps samples were taken at two stations (Bancaran and Sambilangan) in the coastal area of Bangkalan, then analyzed for cadmium (Cd) content using Atomic Absorption Spectrophotometry (AAS). The analysis results showed that cadmium in seawater at Bancaran Station (0.003 mg/L) and Sambilangan Station (0.008 mg/L) had exceeded the quality standard threshold. Conversely, the cadmium content in sediment and venus clams at both stations was still below the threshold. Based on Target Hazard Quotients (THQ) and Estimated Weekly Intakes (EWI), consumption of tofu clams from both stations did not pose a health risk. Kerang tahu banyak dimanfaatkan sebagai komoditas perikanan di pesisir Bangkalan dan menjadi salah satu sumber protein hewani bagi masyarakat setempat. Namun, akumulasi kadmium dalam kerang tersebut dapat menimbulkan risiko kesehatan bagi manusia melalui konsumsi. Oleh karena itu penelitian ini bertujuan untuk menilai tingkat cemaran kadmium pada lingkungan serta menganalisis risiko kesehatan dari konsumsi kerang tahu di Pesisir Bangkalan. Pengambilan sampel air laut, sedimen dan kerang laut dilakukan di dua stasiun (Bancaran dan Sambilangan) di lingkup pesisir Bangkalan, kemudian dilakukan analisis kandungan cadmium (Cd) dengan menggunakan alat Atomic Absorption Spectrophotometry (AAS).  Hasil analisis menunjukkan kadmium pada air laut di Stasiun Bancaran (0,003 mg/L) dan Sambilangan (0,008 mg/L) telah melebihi ambang batas baku mutu. Sebaliknya kandungan kadmium di sedimen dan kerang tahu pada kedua stasiun masih dibawah ambang batas. Berdasarkan Target Hazard Quotients (THQ)dan Estiamted Weekly Intakes (EWI), konsumsi kerang tahu di kedua stasiun tidak berisiko terhadap kesehatan. 
Struktur Komunitas Ikan Karang di Perairan Kota Sorong, Papua Barat Daya, Indonesia Ghofir, Abdul; Haryanti, Dwi; Hartati, Retno; Orisu, Anthon Apolos
Jurnal Kelautan Tropis Vol 28, No 3 (2025): JURNAL KELAUTAN TROPIS
Publisher : Universitas Diponegoro

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.14710/jkt.v28i3.28886

Abstract

Reef fish are one of the biota that are sensitive to environmental changes. Their abundance and diversity are supported by good coral reef conditions. This makes them a bioindicator of coral reef conditions. This study aims to examine the diversity of reef fish, ecological indices, and conditions of coral reef benthic substrates in Sorong City waters from September to November 2024 at ten research stations using the Underwater Visual Census (UVC) and Underwater Photo Transect (UPT) methods. The study found 174 species of reef fish from 26 families (107 major, 55 target, and 12 indicator). The diversity (H') and evenness (E) indices were moderate to high at 1.59-3.41 and 0.41-0.89, respectively, and dominance (C) was low at 0.04-0.48. PCA analysis showed that hard coral cover (HC) as the main determinant of reef fish community structure correlated with the families Pomacentridae, Chaetodontidae, Scaridae, Pempheridae, and Blennidae. This finding is important for marine resource management and conservation in the waters of Sorong City.   Ikan karang merupakan salah satu biota yang peka dengan perubahan lingkungan. Kelimpahan dan keanekaragamannya didukung oleh kondisi terumbu karang yang baik. Hal ini menjadikannya sebagai bioindikator kondisi terumbu karang. Penelitian ini bertujuan mengkaji keanekaragaman ikan karang, indeks ekologi, dan kondisi substrat bentik terumbu karang di perairan Kota Sorong pada September-November 2024 di sepuluh stasiun penelitian menggunakan metode Underwater Visual Census (UVC) dan Underwater Photo Transect (UPT). Hasil penelitian ditemukan ikan karang 174 spesies dari 26 famili (107 mayor, 55 target, dan 12 indikator). Indeks keanekaragaman (H’) dan keseragaman (E) sedang hingga tinggi 1,59-3,41 dan 0,41-0,89, serta dominasi (C) rendah 0,04-0,48. Analisis PCA menunjukkan tutupan karang keras (HC) sebagai penentu utama struktur komunitas ikan karang berkorelasi dengan Pomacentridae, Chaetodontidae, Scaridae, Pempheridae dan Blennidae. Temuan ini penting untuk pengelolaan sumber daya laut dan konservasi di perairan Kota Sorong. 
Mengungkap Aspek Biologi dan Emergence Point Hiu Berjalan Halmahera (Hemiscyllium halmahera) di Laut Pulau Maitara Maluku Utara Indonesia Akbar, Nebuchadnezzar; Ismail, Firdaut; Siolimbona, Abdul Ajiz; Tahir, Irmalita; Paembonan, Rustam E; Subhan, Beginer; Arafat, Dondy; Baksir, Abdurrachman; Subur, Riyadi; N, Furqan; Yidoatimojo, Sudibyo; Nurjaya, I Wayan; Restu, Yunan Gilang; N Natih, Nyoman Metta; Hari, Restu Fajar; Bengen, Dietriech G.
Jurnal Kelautan Tropis Vol 28, No 3 (2025): JURNAL KELAUTAN TROPIS
Publisher : Universitas Diponegoro

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.14710/jkt.v28i3.28334

Abstract

The Halmahera Walking Shark (Hemiscyllium halmahera) is an endemic marine biota in the Halmahera Sea. This species has a local migration pattern and is territorial. The distribution of this species is in the intertidal area to a depth of 10-15 meters. Previous studies have shown that this species is spread across several islands in the North Maluku Islands. Maitara Island is a small island located between the North Maluku archipelago. The Halmahera Walking Shark species is also found on this island. Information on the Halmahera Walking Shark species is not fully documented. The purpose of the study is related to biological information and emergence points (emergence points) in the Maitara Island Sea. Data collection was carried out on coral reefs, seagrass and mangroves. Samples were captured and morphometric measurements, weight and sex observations were taken. The sea area where the species was found was used to obtain coordinates for the emergence point. An analysis of length-weight relationship data was carried out to see growth patterns. The study found that morphometric measurements varied among individuals, although there were general similarities. Sexes were found in pairs (Male and Female), indicating that proportions and mating were still normal in nature. The habitat of this species is found in the mangrove area, coral reefs, and seagrass, thus describing that there is an association in nature. The emergence point shows that the Halmahera Walking Shark is found along the coast of Maitara Island although the frequency of the number is different. The length-weight relationship found a negative allometric growth pattern. Information on biological aspects and emergence points is important, to be used as a reference for migration areas and habitats for the interests of species, waters, and ecosystem conservation.  Hiu Berjalan Halmahera (Hemiscyllium halmahera) merupakan biota laut endemik di laut Halmahera. Spesies ini memiliki pola migrasi lokal dan bersifat teritorial. Penyebaran spesies ini di wilayah intertidal hingga kedalaman 10-15 meter. Penelitian terdahulu menunjukan bahwa spesies ini tersebar di beberapa pulau di Kepulauan Maluku Utara. Pulau Maitara merupakan pulau kecil yang terletak diantara gugusan kepulauan Maluku Utara. Pulau ini juga ditemukan speises Hiu Berjalan Halmahera. Informasi belum terekam lengkap terkait spesies Hiu Berjalan Halmahera. Tujuan penelitian terkait informasi biologi dan emegence point (titik kemunculan) di Laut Pulau Maitara. Pengambilan data dilakukan di terumbu karang, lamun dan mangrove. Sampel ditangkap dan diambil ukuran morfometrik, berat dan pengamatan kelamin. Area laut ditemukannya spesies diambil koordinat untuk di jadikan sebagai titik kemunculan.  Analisis data hubungan panjang-berat dilakukan untuk melihat pola pertumbuhan. Hasil penelitian ditemukan ukuran morfometrik bervariasi pada setiap individu, meskipun terdapat kemiripan secara umum. Kelamin ditemukan sepasang (Jantan dan Betina), dengan demikian menunjukan proporsi dan perkawinan masih normal di alam. Habitat tertangkap spesies ini di area mangrove, terumbu karang dan lamun, sehingga mendeskripsikan terdapat asosiasi di alam. Titik kemunculan menunjukan bahwa, Hiu Berjalan Halmahera ditemukan di sepanjang pesisir laut Pulau Maitara meskipun frekuensi jumlah berbeda. Hubungan panjang berat menemukan pola pertumbuhan allometrik negatif. Informasi aspek biologi dan emergence point penting, untuk dapat dijadikan rujukan wilayah migrasi dan habitat untuk kepentingan konservasi spesies, perairan dan ekosistem.    
Skrining Fitokimia dan Evaluasi Antioksidan serta Antibakteri Ekstrak Mangrove Asal Pantai Lampu Satu Nuskiya, Amila; Pringgenies, Delianis; Trianto, Agus
Jurnal Kelautan Tropis Vol 28, No 3 (2025): JURNAL KELAUTAN TROPIS
Publisher : Universitas Diponegoro

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.14710/jkt.v28i3.29937

Abstract

The mangrove ecosystem is characterized by high biodiversity and the production of various secondary metabolites with potential bioactive properties, making it a promising source of natural cosmetic ingredients. Phytochemical screening was carried out to detect the present of tannins, saponins, steroids, alkaloids, and flavonoids. Antibacterial activity was evaluated using disc diffusion method, while antioxidant activity was assessed through the DPPH assay. Seven species were identified in this study, namely Exoecaria agallocha, Laguncularia racemosa, Nypa fructicans, Bruguiera cylindrical, Amyema anisomeres, Ipomoea pes-caprae, and Acrostichum aureum. Phytochemical analysis revealed that saponins and tannins were present in most species, whereas alkaloids and flavonoids were specific to certain taxa. None of the tested extracts exhibited antibacterial activity against Eschericia coli. Antioxidant evaluation showed that Acrostichum aureum exhibited very strong activity (IC50 = 38,3 ppm), while Ipomoea pes-caprae and Laguncularia racemosa demonstrated strong antioxidant potential, and the remaining species ranged from weak to very weak activity. These findings indicate considerable variation in secondary metabolite composition and antioxidant capacity among mangrove species from Merauke, and suggest that Acrostichum aureum could serve as a promising natural source of antioxidants for the development of plant-based cosmetic formulations. Ekosistem mangrove memiliki keanekaragaman hayati tinggi dan menghasilkan berbagai metabolit sekunder dengan potensi bioaktif, menjadikannya sumber yang menjanjikan untuk bahan kosmetik alami. Uji fitokimia yang dilakukan adalah uji tanin, saponin, steroid, alkaloid dan flavonoid. Uji antibakteri dilakukan dengan metode difusi cakram serta uji antioksidan dengan metode DPPH. Hasil penelitian menunjukkan bahwa 7 spesies yang teridentifikasi meliputi Excoecaria agallocha, Laguncularia racemosa, Nypa fruticans, Bruguiera cylindrica, Amyema anisomeres, Ipomoea pes-caprae, dan Acrostichum aureum. Analisis fitokimia memperlihatkan bahwa saponin dan tanin banyak ditemukan pada sebagian besar spesies, sedangkan alkaloid dan flavonoid bersifat spesifik pada jenis tertentu. Seluruh spesies yang diuji tidak menunjukkan aktivitas antibakteri terhadap E. coli. Evaluasi antioksidan menunjukkan bahwa Acrostichum aureum memiliki aktivitas sangat kuat (IC₅₀ = 38,3 ppm), sementara Ipomoea pes-caprae dan Laguncularia racemosa menunjukkan aktivitas antioksidan kuat, dan spesies lainnya berkisar dari lemah hingga sangat lemah. Hasil ini menunjukkan adanya variasi kandungan metabolit sekunder dan kapasitas antioksidan antarspesies mangrove asal Merauke, serta mengindikasikan bahwa Acrostichum aureum berpotensi menjadi sumber antioksidan alami untuk pengembangan kosmetik berbasis bahan alam.
Mapping of Submarine Geomorphological Structures Using Satellite-Derived Bathymetry and Depth Data in the Waters of Lambasina Island, Kolaka Regency Prasetya, Muhammad Iqra; Siregar, Vincentius Paulus; Agus, Syamsul Bahri
Jurnal Kelautan Tropis Vol 28, No 3 (2025): JURNAL KELAUTAN TROPIS
Publisher : Universitas Diponegoro

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.14710/jkt.v28i3.29091

Abstract

This research examines the geomorphological characteristics of the seabed around Lambasina Besar and Lambasina Kecil Islands, Kolaka Regency, by integrating Satellite-Derived Bathymetry (SDB) and the Benthic Terrain Modeler (BTM). Depth estimates were derived from Sentinel-2 imagery using the Support Vector Machine (SVM) algorithm and compared with in-situ depth measurements. The validation results indicated a high level of agreement, with R² values ranging from 0.81 to 0.82. The bathymetric data were then processed using Bathymetric Position Index (BPI), slope, and rugosity parameters, which allowed the classification of the seafloor into 13 geomorphological structure classes. The analysis identified various seabed forms, including flat plains, steep slopes, broad slopes, ridges, narrow depressions, and localized basins. These morphological patterns correspond well with coral reef zonation observed in the field. The findings highlight the important role of geomorphological variability in shaping benthic habitats and influencing biodiversity distribution. This approach demonstrates strong potential for supporting marine spatial analysis, conservation planning, and the identification of areas suitable for marine protection. Moreover, the study provides a basis for further research on the relationships between habitat complexity, biomass, coral diversity, and reef-associated fish abundance, which are essential for advancing ecosystem-based coastal management strategies.
Analisis Kesesuaian Lahan Rehabilitasi Mangrove di Desa Pasar Banggi, Desa Tireman, dan Desa Kabongan Lor, Kecamatan Rembang Ain, Rahmayani Kurnia; Pribadi, Rudhi; Suryono, Suryono
Jurnal Kelautan Tropis Vol 28, No 3 (2025): JURNAL KELAUTAN TROPIS
Publisher : Universitas Diponegoro

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.14710/jkt.v28i3.28379

Abstract

Environmental degradation, coastal abrasion, and pollution are strategic issues in Rembang District. Rembang subdistrict, which includes extensive mangrove areas along its coastline particularly in the villages of Pasar Banggi, Tireman, and Kabongan Lor has become increasingly vulnerable to these environmental challenges. This study aims to evaluate land sustainability in these three villages to support future mangrove rehabilitation planning. Fieldwork was conducted in September 2024 across 14 sampling stations. Data collection included assessments of mangrove vegetation by counting individual trees, identifying species, and measuring relevant environmental parameters. Land suitability analysis was carried out by constructing a mangrove land suitability matrix, assigning weights, and calculating scores based on the degree of suitability. Based on land suitability analysis, Pasar Banggi Village was identified as highly suitable for mangrove survival, Tireman Village as suitable, and Kabongan Lor Village as conditionally suitable.   Permasalahan degradasi lingkungan, abrasi dan pencemaran menjadi isu strategis yang ada di Kabupaten Rembang. Kecamatan Rembang yang memiliki kawasan mangrove di sepanjang pesisirnya terutama Desa Pasar Banggi, Tireman, dan Kabongan Lor menjadi kawasan yang rentan. Penelitian ini bertujuan untuk mengetahui kesesuaian lahan yang ada di 3 Desa tersebut sehingga dapat digunakan untuk rencana rehabilitasi selanjutnya. Penelitian dilakukan pada Bulan September 2024 dengan total 14 stasiun. Pengambilan data lapangan dilakukan untuk mengetahui kondisi vegetasi mangrove dengan menghitung jumlah individu, jenis, dan pengukuran parameter lingkungan. Analisis kesesuaian lahan dilakukan dengan pembuatan matriks kesesuaian lahan mangrove, penentuan bobot dan perhitungan skor berdasarkan tingkat kesesuaiannya. Berdasarkan kesesuaian lahan mangrove Desa Pasar Banggi menjadi lokasi yang sangat sesuai untuk kelangsungan hidup mangrove, dengan Desa Tireman masuk dalam kategori sesuai dan Desa Kabongan Lor masuk dalam kategori sesuai bersyarat. 
Effect of Sea Surface Temperature and Chlorophyll-a On the Catch of Yellowfin Tuna (Thunnus albacares) in The Waters of North Maluku, Indonesia Muksin, Darmiyati; Rumagia, Faizal; Syukur, Kartina; Abubakar, Salim; Kadir, Irwan Abdul; Taeran, Imran; Darmawaty, Darmawaty; Kaidati, Bahar
Jurnal Kelautan Tropis Vol 28, No 3 (2025): JURNAL KELAUTAN TROPIS
Publisher : Universitas Diponegoro

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.14710/jkt.v28i3.29397

Abstract

The waters of North Maluku, abundant in nutrients and ocean currents, provide an ideal habitat for yellowfin tuna (Thunnus albacares), indicating a healthy marine ecosystem. Tuna, an oceanic pelagic species that migrates with ocean currents, is affected by sea surface temperature (SST) and chlorophyll-a plays an important role in determining yellowfin tuna fishing grounds. This study aims to analyze the spatial and temporal distribution of SST and chlorophyll-a concentration in North Maluku waters and analyze the relationship between SST, chlorophyll-a, and tuna catches. The present study employed both descriptive and quantitative analysis methods to examine the relationship between sea surface temperature, chlorophyll-a, and yellowfin tuna catch. The result shows that the temporal fluctuations in the highest recorded SST were seen in the 2021 transitional season, and the lowest in the 2019 East season. Chlorophyll-a concentrations also showed fluctuations, with the highest value recorded in the 2019 East season and the lowest in the 2020 second transitional season. There is an inverse correlation between SST and chlorophyll-a, with low SST tending to be accompanied by high chlorophyll-a concentrations. The decline in chlorophyll-a concentration can be attributed to various factors, including nutrient availability, sunlight intensity, and water temperature. About 17.48% of the catch of yellowfin tuna (Thunnus albacares) in North Maluku waters is influenced by SST and chlorophyll-a while the rest is influenced by other factors. This indicates that other factors play an important role in determining the catch of yellowfin tuna in North Maluku waters.
Growth Mechanism and Carbon Sequestration of Gracilaria verrucosa Wahdaningsih, Sri Muliani; Mulyani, Sri; Salam, Suryawati
Jurnal Kelautan Tropis Vol 28, No 3 (2025): JURNAL KELAUTAN TROPIS
Publisher : Universitas Diponegoro

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.14710/jkt.v28i3.28590

Abstract

Gracilaria verrucosa, a commercially valuable red macroalga, plays a pivotal role in coastal aquaculture and carbon sequestration. This study investigates the effects of varying initial seedling weights (50 gram, 75 gram, 100 gram, and 125 gram/tie) on biomass yield, specific growth rate (SGR), and carbon sequestration over a 49-day cultivation period. Conducted in a floating raft system under controlled coastal conditions in South Sulawesi, Indonesia, the experiment followed a completely randomized design (CRD) with three replications per treatment. Biomass was harvested at seven-day intervals and assessed for dry weight, growth rate, and carbon composition using standardized methods and elemental analysis protocols. The results indicate that the 125 grams/tie treatment yielded the highest biomass, suggesting that larger initial weights enhance growth through enhanced nutrient uptake. However, the highest SGR and carbon sequestration were recorded in the 50 grams/tie treatment, highlighting the impact of planting density on physiological performance and carbon sequestration. The 100 grams/tie treatment presented the most balanced profile, maintaining high biomass while avoiding significant declines in SGR or carbon sequestration. These findings reveal a critical trade-off between economic and ecological outcomes, with implications for seaweed-based climate mitigation strategies and sustainable aquaculture design. Optimizing planting density can improve both yield and ecosystem services, aligning cultivation strategies with environmental sustainability objectives.