Judul: Profile of water Quality at Different Depths in  the Thousand Island on the Productivity of Growing Lobsters with Submersible Net Cage System
Abstrak: Budidaya perikanan laut di Indonesia terus mengalami perkembangan seiring tingginya permintaan pasar dalam negeri maupun luar negeri. Salah satu komoditas utama hasil perikanan laut yang memiliki eksistensi tinggi terhadap permintaan pasar luar negeri adalah lobster pasir. Penelitian ini bertujuan untuk menganalisis parameter kualitas air, kelimpahan plankton, dan bakteri terhadap pertumbuhan pada budidaya lobster sistem karamba jaring tenggelam. Pengukuran parameter lingkungan dilakukan sebanyak empat kali, dan bobot sebanyak dua kali pada dua kedalaman berbeda (3 m dan 5 m). Hasil penelitian didapatkan bahwa kondisi lingkungan perairan di dua kedalaman bernilai optimum untuk pemeliharaan lobster. Keberadaan mikroorganisme berupa fitoplankton banyak ditemukan pada kedalaman 3 m sebesar 402.957 sel/m3 , sedangkan zooplankton banyak ditemukan pada kedalaman 5 m sebesar 15.030 ind/m3 . Keberadaan bakteri di perairan banyak ditemukan pada kedalaman 5 m sebesar 312 × 107 CFU mL-1 . Kinerja pertumbuhan bobot lobster terbaik terdapat pada perlakuan 80 g di kedalaman 5 m sebesar 39,64±9,01 g. Oleh karena itu, disimpulkan bahwa profil perairan di kepulauan seribu bernilai optimum, dan kedalaman 5 m menghasilkan pertumbuhan terbaik pada pembesaran lobster di karamba jaring tenggelam., Marine aquaculture in Indonesia continues to develop in line with the high demand for domestic and foreign markets. One of the main commodities of marine fishery products that has a high existence against foreign market demand is sand lobster. This study aims to analyze the parameters of water quality, an abundance of plankton, and bacteria on the growth of lobster culture in the Sinking Net Cage system. Measurement of environmental parameters was carried out four times, and weights twice at two different depths (3 and 5 m). Data were analyzed using ANOVA test and continued with Tukey's test. The results showed that the environmental conditions of the waters at two depths were of optimum value for lobster rearing. The presence of microorganisms for lobster in the form of phytoplankton was found at a depth of 3 m at 402.957 cells/m3 , while zooplankton was found at a depth of 5 m at 15.030 ind/m3 . The presence of bacteria in the waters was found at a depth of 5 m at 312 × 107 CFU mL-1 . The best lobster weight growth performance was found in the treatment of 80 g at a depth of 5 m of 39.64±9.01 g. Therefore, it was concluded that the water profile in the Thousand Islands was of optimum value, and a depth of 5 m resulted in the best growth of lobster rearing in the submersible cage.
Keyword: cages, depth, growth, lobsters

Judul: Production Performance of Spiny Lobster Panulirus  homarus Grow-out I in Submersible Net Cage by Different Depth
Abstrak: Aplikasi keramba jaring tenggelam (KJTe) merupakan salah satu alternatif untuk meningkatkan kinerja produksi pada budidaya lobster. Penelitian ini bertujuan untuk menganalisis kinerja produksi pembesaran I lobster pasir dalam KJTe pada berbagai kedalaman. Penelitian dilakukan di Balai Sea Farming Pusat Kajian Sumberdaya Pesisir dan Laut, Institut Pertanian Bogor (PKSPL-IPB), Pulau Semak Daun, Kabupaten Administratif Kepulauan Seribu, DKI Jakarta. Penelitian menggunakan rancangan acak lengkap dengan dua perlakuan yaitu kedalaman dasar KJTe 3,6 m dan 5,6 m dari permukaan air, dengan tiga kali ulangan. Lobster pasir dari hasil tangkapan nelayan di Ujung Genteng, Sukabumi berukuran 124,45±0,17 g/ekor dan panjang 13,93±0,13 cm dipelihara dalam KJTe 1 m × 0,6 m × 0,6 m dengan kepadatan 22 ekor per m2 atau 8 ekor per keramba selama 40 hari. Lobster diberi ikan rucah sebanyak 10% dari biomassa atau sekitar 51 – 99 g per hari, dua kali sehari dengan mengangkat KJTe sampai permukaan air, kemudian pakan disebar. Bobot, panjang lobster dan fisika-kimia perairan diukur setiap 10 hari. Pengukuran dan pengamatan meliputi tingkat kelangsungan hidup, laju pertumbuhan spesifik (panjang dan bobot), laju pertumbuhan mutlak (panjang dan bobot), rasio konversi pakan, produktivitas, dan tingkah laku lobster. Hasil penelitian menunjukkan tingkat kelangsungan hidup dan produktivitas lobster pada KJTe di kedalaman 5,6 m lebih baik sebesar 66,67% dan 0,104 kg m-2 dibandingkan dengan yang lebih dangkal (P < 0,05). Pembesaran I lobster pasir pada keramba jaring tenggelam disarankan pada kedalaman 5,6 m., The application of sinking net cages (KJTe) is one alternative to improve production performance in lobster aquaculture. This study aims to analyze the production performance of sand lobster rearing I in KJTe at various depths. The research was conducted at the Sea Farming Center for the Study of Coastal and Marine Resources, Bogor Agricultural University (PKSPL-IPB), Semak Daun Island, Thousand Islands Administrative District, DKI Jakarta. The study used a completely randomized design with two treatments, namely the bottom depth of KJTe 3,6 m and 5,6 m from the water surface, with three replications. Sand lobster caught by fishermen in Ujung Genteng, Sukabumi measuring 124,45±0,17 g/head and 13,93±0,13 cm long, was reared in 1 m × 0,6 m × 0,6 m KJTe with a density of 22 fish/m2 or 8 fish per cage for 40 days. Lobsters were fed with trash fish as much as 10% of the biomass or about 51 – 99 g per day, twice a day by lifting the KJTe to the surface of the water, then the feed was distributed. Lobster weight, length, and physical-chemistry of the waters were measured every 10 days. Measurements and observations included survival rate, specific growth rate (length and weight), absolute growth rate (length and weight), feed conversion ratio, productivity, and lobster behavior. The results showed that the survival rate and productivity of lobsters at KJTe at a depth of 5,6 m were better than 66,67% and 0,104 kg m-2 those at shallower ones (P < 0,05). Grow-out of I sand lobster in submersible cages is recommended at a depth of 5,6 m.
Keyword: kelangsungan hidup, pertumbuhan, produktivitas, growth, productivity, survival rate

Judul: Metrik Einstein (Anti-) Self-Dual Berdimensi Empat dengan Metode Cartan
Abstrak: Gravitational field equation can be formulated in differential forms (differential geometry), which describes gravity as a manifestation of the curvature of space-time. Curvature of space-time is characterized by a metric that satisfies the gravitational field equation. With differential forms it can be formulated the (anti-) self-dual Einstein equation, which is a modification of the Cartan structure in (anti-) self-dual basis. Calculation of (anti-) self-dual metric with (anti-) self-dual Einstein equation is simpler than the calculation using Christoffel symbols.
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