Judul: Kinerja Produksi Pendederan II Lobster Pasir (Panulirus homarus) dalam Karamba Jaring Tenggelam dengan Kedalaman Berbeda
Abstrak: Kedalaman air laut berpengaruh terhadap faktor lingkungan seperti suhu, oksigen terlarut, kecepatan arus, gelombang, pH, salinitas, dan tekanan. Perubahan kondisi perairan laut dapat berdampak langsung terhadap kondisi fisiologi dan biokimia biota kultur, dan pada akhirnya akan berpengaruh kepada kinerja produksi. Tujuan penelitian ini adalah menentukan kedalaman yang memberikan kinerja produksi terbaik dan keuntungan yang maksimal pada pendederan II lobster pasir dalam karamba jaring tenggelam. Penelitian ini menggunakan rancangan acak lengkap dengan tiga perlakuan kedalaman dasar wadah 1, 3, dan 5 m dari permukaan air laut dengan tiga kali ulangan. Wadah yang digunakan berupa karamba jaring tenggelam (sub-mersible cage) berukuran 60 × 60 × 60 cm. Lobster pasir (Panulirus homarus) berbobot rata-rata 10,84±0,42 g dan panjang rata-rata 7,07±0,20 cm ditebar dengan padat tebar sebanyak 15 ekor/karamba dan dipelihara selama 40 hari. Lobster diberi ikan rucah segar sebanyak 10% dari biomassa per hari. Parameter uji pada penelitian ini meliputi kinerja produksi, kualitas air, dan analisis usaha. Data dianalisis menggunakan ANOVA dengan selang kepercayaan 95%. Hasil penelitian menunjukkan kedalaman 3 m memberikan kinerja produksi terbaik dan keuntungan yang maksimal pada pendederan II lobster pasir dalam karamba jaring tenggelam karena memiliki tingkat kelangsungan hidup, pertumbuhan, dan produktivitas yang tinggi, serta rasio konversi pakan yang rendah., The depth of sea water affects environmental factors such as temperature, dissolved oxygen, current speed, waves, pH, salinity, and pressure. Changes in marine water conditions can have a direct impact on the physiological and biochemical conditions of cultured biota, and will ultimately affect production performance. The purpose of this study was to determine the depth that gives the best production performance and maximum profit in nursery II spiny lobster in submersible cage. This study used a completely randomized design with three treatments for the bottom depth of the container 1, 3, and 5 m above sea level with three replications. The container used is a sub-mersible cage measuring 60 × 60 × 60 cm. Spiny lobster (Panulirus homarus) with an average weight of 10,84±0,42 g and an average length of 7.07±0.20 cm was stocked with a stocking density of 15 fish/karamba and reared for 40 days. Lobsters were given fresh trash fish as much as 10% of the total biomass per day. The test parameters in this study include production performance, water quality, and business analysis. Data were analyzedusing ANOVA with 95% confidence interval. The results showed a depth of 3 m gave the best production performance and maximum profit in nursery II spiny lobster in sinking net cages because it had a high survival rate, growth, and productivity, as well as a low feed conversion ratio.
Keyword: depth, production performance, spiny lobster

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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