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Mandagi, Stephanus Vianny
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Environmental Science

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Macroalgae Community Structure in Tanjung Merah Waters, Bitung City Achmad, Febrio V.; Kepel, Rene Ch.; Mandagi, Stephanus Vianny; Tilaar, Ferdinand F.; Tombokan, John L.; Ngangi, Edwin L. A.
Jurnal Ilmiah Platax Vol. 9 No. 1 (2021): ISSUE JANUARY - JUNE 2021
Publisher : Sam Ratulangi University

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.35800/jip.9.1.2021.34427

Abstract

Seaweed is a component of coastal ecosystems that makes a major contribution to the Indonesian economy. This marine plant is a potential food source and industrial raw materials that can be used to improve people's welfare as these marine macroalgae are widely distributed in Indonesian waters. This study was carried out because of its important role for the ecosystems and the economy of the country. The purpose of this research is to determine the community structure of this macroalgae in the waters of Tanjung Merah Village of Matuari District of Bitung City. The data were collected from January 2021 to March 2021 using a transect of 1 x 1 m2 which was placed along a 100 m line transect with 5 m intervals. The macroalgae found were 6 species consisting of 2 types of Chlorophyta class and 4 species of Rhodophyta class. The macroalgae diversity index of around is 1.06 categorized as moderate diversity; the index of dominant is 0.44 moderate and the evenness index is 1.79 or low.Keywords: Macroalgae; Community; Diversity.AbstrakRumput laut merupakkan komponen ekosistem wilayah pesisir yang memberikkan kontribusi yang besar bagi ekonomi Indonesia. Potensi sumberdaya hayati laut Sulawesi Utara, khususnya Kota Bitung yang cukup potensial untuk dapat dimanfaatkan sebagai sumber pangan dan bahan baku industri guna peningkatan kesejahteran masyarakatkarena makroalga termasuk salah satu sumberdaya hayati laut yang banyak terdapat di perairan Indonesia. Makroalga memiliki potensi besar untuk dikembangkan, karena memiliki peranan penting baik dari aspek ekologi dan memiliki nilai ekonomi.  Tujuan penelitian ini adalah untuk mengetahui struktur komunitas makroalga yang ada di perairan Kelurahan Tanjung Merah Kecamatan Matuari Kota Bitung. Penelitian ini dilaksanakan pada bulan Januari 2021 sampai Maret 2021. Data dikumpulkan dengan cara di sampling menggunakan kuadrat berukuran 1x 1 m2 yang diletakkan pada garis transek sepanjang 100 m dengan interval 5 m. Makroalga yang ditemukan 6 spesies yang terdiri atas Kelas Chlorophyta berjumlah 2 jenis, dan kelas Rhodophyta 4 jenis. Indeks keanekaragaman makroalga sekitar 1.06 dikategorikan sedang, indeks dominasi 0.44 dikategorikan rendah dan untuk indeks kemerataan 1,79 dikategorikkan rendah.Kata kunci: Makroalga; Komunitas; Keanekaragaman
Community Structure of Hard Coral (Scleractinia) in the Walenekoko Reef Flat, Pasir Panjang, Bitung City Pratiwi, Utary; Kambey, Alex D.; Lalamentik, Laurentius Th. X.; Tilaar, Ferdinand Frans; Mandagi, Stephanus Vianny; Manembu, Indri S.
Jurnal Ilmiah Platax Vol. 10 No. 1 (2022): ISSUE JANUARY-JUNE 2022
Publisher : Sam Ratulangi University

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.35800/jip.v10i1.37277

Abstract

Coral reefs are one of the potential good water resources in Indonesian marine waters. Ecologically, coral reefs can only develop in tropical climates. Hard coral is one of the important components as a constituent of coral reef ecosystems and plays an important role for marine biota. The research was conducted at the reef flat of Walenekoko Village, Pasir Panjang Village, South Lembeh District, Bitung City. The research covers the species, family and life form composition, and ecological indices (diversity, species equitability, and dominance indices). The research was carried out with an Underwater Photo Transect (UPT) method. The results obtained 18 types of hard corals belonging to 5 families. Montipora samarensis was the most abundant coral in the area with 43% of the community composition. The Faviidae family and Acroporidae (33%) had the largest percentage in all transects. The form of coral growth consisted of Acropora Submassive (ACS) 53%, Coral Massive (CM) 30%, and for Acropora Branching (ACB) 16%. The highest diversity value is at point 3 of 1.64, and point 1 of 1.60, while the lowest is at point 2 of 0.56. The evenness index obtained at point 1 is 0.70, and at point 2 is 0.30. The dominance values obtained ranged from 0.25 to 0.52.Keywords: Community Structure; Hard Coral; Reef FlatAbstrakTerumbu karang merupakan salah satu potensi sumberdaya perairan yang baik di perairan laut Indonesia. Secara ekologis terumbu karang hanya dapat berkembang di wilayah beriklim tropis. Karang keras merupakan salah satu komponen penting sebagai penyusun ekosistem terumbu karang dan berperan penting bagi biota laut. Penelitian ini dilakukan di rataan terumbu Desa Walenekoko, Desa Pasir Panjang, Kecamatan Lembeh Selatan, Kota Bitung. Penelitian meliputi komposisi spesies, famili, dan bentuk kehidupan, serta indeks ekologi (keanekaragaman, keseragaman spesies, dan indeks dominasi). Penelitian dilakukan dengan metode Underwater Photo Transect (UPT). Hasil penelitian diperoleh 18 jenis karang keras yang termasuk dalam 5 famili. Montipora samarensis adalah spesies yang paling banyak ditemukan di daerah tersebut dengan persentase 43%. Famili Faviidae dan Acroporidae (33%) memiliki persentase terbesar di semua transek. Bentuk pertumbuhan karang terdiri dari: Acropora Submassive (ACS) 53%, Coral Massive (CM) 30%, dan untuk Acropora Branching (ACB) 16%. Nilai keanekaragaman tertinggi yaitu pada titik 3 sebesar 1,64, dan titik 1 sebesar 1.60, sedangkan yang termasuk rendah yaitu pada titik 2 sebesar 0,56. Indeks kemerataan diperoleh pada titik 1 sebesar 0,70, dan pada titik 2 sebesar 0.30. Nilai dominasi diperoleh berkisar antara 0.25 hingga 0.52.Kata kunci: Struktur Komunitas; Karang Keras; Rataan Terumbu.
Community Structure of Macroalgae in the Coastal Waters of Tiwoho Village, Wori District, North Minahasa Regency Iyanleba, Jonathan Yohanes; Kepel, Rene Ch.; Tombokan, John Leonard; Kondoy, Khristin F. I.; Mandagi, Stephanus Vianny; Kambey, Alex D.
Jurnal Ilmiah Platax Vol. 13 No. 1 (2025): ISSUE JANUARY-JUNE 2025
Publisher : Sam Ratulangi University

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.35800/jip.v13i1.60693

Abstract

The purpose of this study is to describe the morphology and anatomy of each macroalgae species and to analyze the community structure of macroalgae from the study location. Data collection was carried out using the Line Transect method with quadrat sampling techniques conducted at the lowest tide. Temperature measurement was done using a thermometer and salinity using a refractometer, while substrate determination was visually assessed based on the type of substrate. The results of this study found 7 species, consisting of 1 species of red algae, 4 species of brown algae, and 2 species of green algae. The morphology of these algae types varies with different anatomies based on cross and longitudinal sections of each part of the algal thallus. The highest species density was Turbinaria ornata (transect 1), while the lowest density was Halimeda opuntia and Sargassum polycystum (transect 1), Turbinaria ornata (transect 2 and transect 3). The macroalgae diversity index values on the three transects were in the medium category. The species evenness index values on the three transects were stable. The species richness index values on the three transects were in the low category. The dominance index values on the three transects were in the low category. Keywords: Macroalgae, Community, Transect, Quadrat, Tiwoho. Abstrak Tujuan penelitian ini adalah mendeskripsikan morfologi dan anatomi masing-masing spesies makroalga, dan menganalisis stuktur komunitas makroalga dari lokasi penelitian. Pengambilan data menggunakan metode Line Transect dengan teknik sampling kuadrat yang dilakukan pada saat surut terendah. Pengukuran suhu menggunakan Termometer dan salinitas menggunakan Refraktometer, dan untuk penentuan substrat dilihat secara visual jenis dari substrat tersebut. Hasil penelitian ini ditemukan 7 spesies yang terdiri dari 1 spesies alga merah, 4 spesies alga coklat dan 2 spesies alga hijau. Morfologi jenis-jenis alga tersebut beragam dengan anatomi yang berbeda berdasarkan potongan melintang dan memanjang dari masing-masing bagian thallus alga. Kepadatan spesies tertinggi yaitu Turbinaria ornata (transek 1) sedangkan kepadatan terendah yaitu Halimeda opuntia dan Sargassum polycystum (transek 1), Turbinaria ornata (transek 2 dan transek 3). Nilai indeks keanekaragaman makroalga pada ketiga transek termasuk dalam kategori sedang. Nilai indeks kemerataan jenis pada ketiga transek termasuk dalam keadaan stabil. Nilai indeks kekayaan jenis pada ketiga transek termasuk dalam kategori rendah. Nilai indeks dominasi pada ketiga transek termasuk dalam kategori rendah. Kata kunci: Makroalga, Komunitas, Transek, Kuadrat, Tiwoho.
Analysis Of Tsunami Hazard Potential On The Coast Of Bitung City, North Sulawesi Ulus, Frangky Octavian; Mandagi, Stephanus Vianny; Sumilat, Deiske Adeliene
Jurnal Ilmiah Platax Vol. 13 No. 1 (2025): ISSUE JANUARY-JUNE 2025
Publisher : Sam Ratulangi University

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.35800/jip.v13i1.60969

Abstract

This thesis aims to study the tsunami hazards in the Maluku Sea region, particularly in the coastal area of Bitung, Indonesia. The research focuses on modeling and analyzing the potential tsunamis triggered by earthquake events in that region. The data used includes bathymetry, topography, coastline, and river data obtained from the Geospatial Information Agency (Badan Informasi Geospatial-BIG). The tsunami modeling process utilizes the software COMCOT (Cornell Multi-grid Coupled Tsunami).  The earthquake source parameters (PusGen) used in the modeling, such as magnitude, focal depth, length of the fault plane, the width of the fault plane, dislocation of the fault plane, strike, dip, slip/rake, and modeling area, were obtained from worst-case scenarios based on PusGen's research results. The research consists of two main stages: the pre-verification stage, where data processing and tsunami modeling are conducted, and the verification stage, where field surveys are carried out to determine the coordinates for Temporary Evacuation Sites (TEP) and Final Evacuation Sites (FEP).  Various equipment, such as GPS, altimeters, stopwatches, cameras, and drones, are used during the field verification. The research procedures include a literature review, data collection of topography, bathymetry, earthquake parameters, and fault mechanism. Subsequently, tsunami modeling is conducted, and hazard analysis is performed based on the model results. Tsunami hazard maps are generated to highlight high-risk areas in the coastal region of Bitung, and evacuation routes are identified to prepare the coastal community of Bitung to face potential tsunami threats.  The research offers important information to assist in the development of warning systems and efficient evacuation strategies to protect the coastal community of Bitung from tsunamis' devastating impacts. Keywords: Tsunami; Bitung; coastal area; earthquake; PusGen
Co-Authors Achmad, Febrio V. Alex D. Kambey Deiske Adeliene Sumilat, Deiske Adeliene Edwin D Ngangi Ferdinand Frans Tilaar Indri Manembu Iyanleba, Jonathan Yohanes John L. Tombokan Kepel, Rene Ch. Kondoy, Khristin F. I. Lalamentik, Laurentius Th. X. Pratiwi, Utary Tilaar, Ferdinand F. Tombokan, John Leonard Ulus, Frangky Octavian