Judul: Spatial Distribution of Benthic Communities in The Kepulauan Seribu Marine National Park, DKI Jakarta
Abstrak: Dalam beberapa dekade terakhir, diketahui bahwa tutupan terumbu karang di Kepulauan Seribu mengalami degradasi akibat dari pengaruh non-antropogenik (perubahan ekologis, faktor alam) dan pengaruh antropogenik (kegiatan manusia) seperti pariwisata dan perikanan tangkap. Taman Nasional Kepulauan Seribu memiliki sistem zona pengelolaan perairan yang berfungsi melindungi ekosistem bahari yang ada di dalamnya seperti ekosistem terumbu karang. Terdapat empat zona perairan yaitu ada zona inti, zona perlindungan, zona pemanfaatan wisata, dan zona pemukiman. Penelitian ini bertujuan mengetahui sebaran komunitas bentik, sebaran lifeform karang keras, dan sebaran genus karang lunak serta persentase tutupannya berdasarkan zonasi di Perairan Taman Nasional Kepulauan Seribu, DKI Jakarta. Metode yang digunakan adalah Underwater Photo Transect dengan ukuran 58 cm x 44 cm. Berdasarkan pengamatan di empat zona perairan tersebut, diketahui bahwa kategori abiotic merupakan yang tertinggi dibandingkan dengan enam kategori lainnya dengan total nilai tutupan berada pada rentang 40 - 50%. Kondisi tutupan karang keras hidup di perairan zona inti, zona pemanfaatan, dan zona pemukiman masuk ke dalam kategori cukup (25 - 49,9%). Adapun tutupan karang keras hidup di perairan zona perlindungan masuk ke dalam kategori buruk (0 - 24,9%). Sebaran genus karang lunak pada zona inti didominasi oleh genus Sarcophyton (0,28%), zona pemanfaatan oleh genus Gorgonian (0,13%), zona pemukiman oleh genus Gorgonian (1,04%), dan zona perlindungan oleh genus Nephthea (0,15%)., In the last few decades, it has been known that coral reef cover in the Kepulauan Seribu has been degraded as a result of non-anthropogenic influences (ecological changes, natural factors) and anthropogenic influences (human activities) such as tourism and capture fisheries. The Kepulauan Seribu Marine National Park has a water management zone system that functions to protect the marine ecosystems in it such as coral reef ecosystems. There are four water zones, namely the core zone, protection zone, tourism utilization zone, and residential zone. This study aims to determine the distribution of benthic communities, distribution of hard coral lifeforms, and distribution of soft coral genera and their percentage of cover based on zoning in the waters of the Kepulauan Seribu Marine National Park, DKI Jakarta. The method used is Underwater Photo Transect with a size of 58 cm x 44 cm. Based on observations in the four water zones, it is known that the abiotic category is the highest compared to the other six categories with a total cover value in the range of 40 - 50%. The condition of living hard coral cover in the waters of the core zone, utilization zone, and settlement zone was in the sufficient category (25 – 49,9%). As for the live hard coral cover in the waters of the protection zone, it is in the bad category (0 – 24,9%). The distribution of soft coral genera in the core zone is dominated by Sarcophyton (0,28%), the utilization zone by Gorgonian (0,13%), the settlement zone by Gorgonian (1,04%), and the protection zone by Nephthea (0,15%) .
Keyword: category, coral, cover, Kepulauan Seribu Marine National Park, zone

Judul: Spatial Variability of Coral Coverage in the Waters of North Seribu Islands District, DKI Jakarta
Abstrak: Terumbu karang membutuhkan waktu yang lama untuk pulih dan rentan terhadap kerusakan. Penelitian ini bertujuan untuk menganalisis variabilitas spasial tutupan terumbu karang berdasarkan kategori pemanfaatan yang berbeda di Perairan Kepulauan Seribu Utara. Penelitian ini dilaksanakan pada bulan Agustus 2022 di enam stasiun pengambilan sampel di Perairan Kepulauan Seribu Utara. Pengambilan data tutupan karang diestimasi menggunakan metode Line Intercept Transect, sampel kualitas air yang diambil meliputi parameter kecerahan, nitrat, oksigen terlarut, pH, dan salinitas. Kategori pemanfaatan yang berbeda antar- stasiun pengambilan sampel tidak berpengaruh nyata terhadap besar persen tutupan karang hidup, kecuali pada stasiun yang berkategori dilindungi. Penyebab utama yang mempengaruhi nilai persen tutupan terumbu karang antar-stasiun pengambilan sampel diduga karena kerusakan fisik akibat benturan secara langsung dari aktivitas manusia, seperti kegiatan penangkapan, pariwisata, dan transportasi. Tutupan karang tertinggi dengan kategori baik terdapat pada Area Perlindungan Laut, sementara tutupan karang terendah dengan kategori rusak terdapat di Barat Pulau Pramuka sebagai stasiun yang paling terpengaruh oleh aktivitas manusia., Coral reefs take a long time to recover and prone to damage. This study aims to analyze the spatial variability of coral reef coverage based on different utilization categories in the Waters of the North Seribu Islands District. This study was conducted in North Seribu Islands District that divided into six sampling points in August 2022. The coral coverage data collection was estimated using the Line Intercept Transect method, the water quality samples taken were brightness, nitrate, dissolved oxygen, pH, and salinity. Different utilization categories between sampling stations have no significant effect on coral cover percentage, except for protected categorized station. The main cause affecting the coral coverage is suspected to be due to physical damage caused by direct impacts from human activities, such as fishing, tourism, and transportation activities. The highest coral coverage in the good category was in the Marine Protected Area, while the lowest coral coverage in the damaged category was in West Pramuka Island as the location most affected by human activities.
Keyword: Kepulauan Seribu, kualitas perairan, terumbu karang, coral reef, Seribu Islands, water quality

Judul: Penentuan Nilai Eigen dan Vektor Eigen dari Matriks Tridiagonal 2-Toeplitz dengan Pendekatan Polinomial Chebyshev
Abstrak: The eigenvalues and eigenvectors of a matrix can be determined by finding its characteristic polynomials. The characteristic polynomials of a tridiagonal 2-Toeplitz matrix is shown to be closely connected to polynomials which satisfy the Chebyshev recurrence relationship. If the order of the matrix is odd, then the eigenvalues are found explicitly in terms of the Chebyshev zeros and the eigenvectors are found in terms of the polynomials satisfying the recurrence relationship. For even ordered matrices, the situation is more complicated. The problem in these cases is that although the Chebyshev recurrence formula is still applied, its initial values are not generating Chebyshev polynomials
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