Judul: Juvenile Fish Assemblages in Seagrass Beds of Pari Island,  Seribu Islands, Jakarta
Abstrak: Padang lamun sebagai salah satu ekosistem pesisir memiliki peranan penting dalam menunjang kelangsungan hidup ikan. Tujuan dari penelitian ini adalah untuk menganalisis kumpulan yuwana ikan meliputi kelimpahan, kekayaan spesies, keanekaragaman, keseragaman, dan dominansi spesies baik secara spasial maupun temporal di ekosistem padang lamun Pulau Pari, Kepulauan Seribu, Jakarta. Pengambilan contoh ikan menggunakan alat tangkap pukat tarik di perairan padang lamun Pulau Pari, Kepulauan Seribu, Jakarta yang dilaksanakan pada bulan November 2023 – April 2024. Contoh ikan dianalisis dengan melakukan identifikasi, serta pengukuran panjang dan bobot di laboratorium. Kumpulan ikan yang tertangkap selama penelitian terdiri dari 9.298 individu, 68 spesies, 29 famili, dan 16 ordo. Sebagian besar komposisi ikan yang terkumpul merupakan yuwana sebanyak 78% dengan status penghuni sementara. Penelitian ini membuktikan bahwa ekosistem padang lamun Pulau Pari memiliki peranan penting sebagai daerah asuhan bagi beragam spesies ikan. Oleh sebab itu, maka konservasi sumberdaya ikan melalui rehabilitasi habitat lamun yang telah rusak dan melindungi ekosistem lamun yang ada di Pulau Pari menjadi sebuah keharusan., Seagrass beds, as a vital coastal ecosystem, play a crucial role in supporting the survival of fish. This study aimed to analyze juvenile fish assemblages, including abundance, species richness, diversity, evenness, and dominance of species both spatially and temporally in the seagrass ecosystem of Pari Island, Seribu Islands, Jakarta. Fish samples were collected using a seine net in the seagrass meadows of Pari Island, Seribu Islands. The fish collection was conducted from November 2023 to April 2024. Fish samples were analyzed in the laboratory by identifying them and measuring their length and weight. The fish samples consisted of 9,298 individuals, representing 68 species, 29 families, and 16 orders. The majority of the fish samples were juveniles, with as much as 78% having temporary resident status. This study demonstrates the importance of seagrass meadows as nursery grounds for juvenile fish. Therefore, it is essential to conserve fish resources by rehabilitating damaged seagrass habitats and protecting the seagrass ecosystem in the Pari Island
Keyword: daerah asuhan, Pulau Pari, padang lamun, yuwana ikan

Judul: Diel Variation of Fish Community  Associated with Seagrass Beds in Panggang Island, Kepulauan Seribu National  Park
Abstrak: Lamun merupakan salah satu ekosistem utama yang memiliki peran penting di wilayah pesisir yang berfungsi sebagai habitat dan daerah asuhan ikan. Penelitian ini bertujuan untuk mengungkap variasi komunitas ikan yang berasosiasi dengan padang lamun di Pulau Panggang bagian timur pada waktu siang dan malam hari. Pengambilan ikan dilakukan selama bulan Februari hingga Agustus 2018 menggunakan pukat tarik (seine net). Sampel ikan diidentifikasi dan diukur panjang serta bobotnya di laboratorium. Ikan yang terkumpul selama penelitian sebanyak 9.026 ekor yang terdiri atas 82 spesies, 63 genera, 35 famili, dan 15 ordo. Atherinomorus duodecimalis, Cheilodipterus quinquelineatus, dan Gerres oyena ditemukan dengan kelimpahan besar selama penelitian pada waktu siang dan malam. A. duodecimalis dan G. oyena banyak ditemukan dalam stadia yuwana. Terdapat perbedaan struktur komunitas ikan pada siang dan malam hari. Biomassa ikan pada siang hari didominasi oleh famili Labridae (24%), sedangkan biomassa ikan malam hari didominasi oleh famili Apogonidae (31%). Perubahan biomassa ikan menunjukkan adanya migrasi harian ikan untuk mencari makan. Komposisi ikan pada waktu siang dan malam didominasi oleh yuwana sebesar 73% dan 65%. Temuan ini menunjukkan bahwa padang lamun di Pulau Panggang berperan sebagai daerah asuhan yuwana ikan dan tempat mencari makan bagi ikan-ikan dewasa., Seagrass is one of the main ecosystems which has an important role in the coastal area as a habitat and nursery area for fishes. This study aimed to compare the fish communities associated with seagrass beds in the eastern part of Panggang Island during the day and night time. The fish collection was carried out from February to August 2018 using a seine net. Fish samples were identified and their body length and body weight were measured in the laboratory. A total of 9,026 individuals were collected, consisting of 82 species, 63 genera, 35 families, and 15 orders. Atherinomorus duodecimalis, Cheilodipterus quinquelineatus, and Gerres oyena were found in great abundance during the day and night time. A. duodecimalis and G. oyena mostly found in the juveniles stage. There was a significant difference in the structure of the fish community between day and night. Labridae was the most abundant in biomass in the day (24%), while Apogonidae was the most abundant at night (31%). Changes in fish biomass indicate that daily fish migration for feeding is occurring. During the day and night time, the composition of fish was dominated by juveniles with 73% and 65% of total catches, respectively. These findings indicate that seagrass beds in Panggang Island play an important role as nursery ground for fish juveniles and feeding ground for adult fishes.
Keyword: daerah asuhan, daerah mencari makan, komunitas ikan, lamun, variasi harian

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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