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: Production Performance of Spiny Lobster  Panulirus homarus Grow-out at in Submersible Net Cage with Different Depths
Abstrak: Suhu, intensitas cahaya, gelombang, kekeruhan, arus, dan tekanan dipengaruhi oleh kedalaman perairan. Kinerja produksi lobster pasir akan maksimal apabila diiringi dengan penyesuaian lingkungan budidaya dengan habitat alaminya. Tujuan penelitian ini adalah menentukan kedalaman optimal bagi kehidupan lobster untuk meningkatkan kinerja produksi dan keuntungan di Karamba Jaring Tenggelam. Penelitian ini menggunakan Rancangan Acak Lengkap dengan tiga kedalaman berbeda, yaitu 1 m, 2 m, dan 3 m di bawah permukaan air laut dengan tiga kali ulangan. Sebanyak 72 ekor lobster dipelihara di dalam karamba berukuran (1 x 1 x 1) m dengan kepadatan 8 ekor/m2 dan bobot rata-rata 80,14+0,33 g selama 40 hari. Pemberian pakan dilakukan sebanyak 2 kali sehari dengan bobot 5% dari biomassa lobster. Parameter uji pada penelitian ini meliputi kinerja produksi, kualitas air, dan analisis usaha. Data dianalisis menggunakan ANOVA pada selang kepercayaan 95%. Hasil penelitian menunjukkan tingkat kedalaman yang optimal pada penelitian ini untuk meningkatkan kinerja produksi pada pembesaran lobster pasir di karamba jaring tenggelam adalah kedalaman 2 m. Pada kedalaman tersebut, lobster memiliki hasil kinerja produksi terbaik, yang ditunjukkan dengan nilai produktivitas yang paling tinggi. Sedangkan kedalaman 3 m memiliki R/C rasio tertinggi dan PP yang lebih singkat dalam usaha budidaya lobster pasir pada sistem Karamba Jaring Tenggelam., Temperature, light intensity, waves, turbidity, currents, and pressure are affected by water depth. The performance of spiny lobster production will be maximized if it is accompanied by adjustment of the cultivation environment to its natural habitat. The purpose of this study was to determine the optimal depth for lobster life to increase production performance and profitability in the Submersible Net Cages. This study used a completely randomized design with three depths, namely 1 m, 2 m, and 3 m below sea level, with three replications. A total of 72 lobsters were kept in cages measuring 1 m x 1 m x 1 m with a density of 8 fish/m2 and an average weight of 80.14±0.33 g for 40 days. Feeding was carried out 2 times a day with a weight of 5% of the lobster biomass. The test parameters in this study include production performance, water quality, and business analysis. Data were analyzed using ANOVA at 95% confidence interval. The results showed that the optimal level of depth in this study to improve production performance on rearing spiny lobster in Submersible Net Cages was 2 m. At this depth, lobster has the best production performance, indicated by the highest production value. At the same time, the depth of 3 m has the highest R/C ratio and shorter PP in spiny lobster cultivation in the Submersible Net Cage system.
Keyword: cages, depth, production performance, spiny lobster

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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