Judul: Fattening of Mud Crab Scylla serrata Fed with Artificial Feed and Trash Fish
Abstrak: Usaha penggemukan kepiting bakau biasanya menggunakan ikan rucah sebagai pakannya, karena pakan buatan komersial belum ada. Di sisi lain, salinitas air di tambak juga bervariasi. Di musim kemarau, salinitas air tambak sangat tinggi, bisa mencapai 50 ppt. Penelitian ini bertujuan mengetahui pertumbuhan kepiting bakau dengan dua jenis pakan berbeda ikan rucah dan pakan buatan yang dibudidaya di dalam bak dan tambak, masing-masing wadah berisi air salinitas 20-23 ppt dan 35-50 ppt. Setiap perlakuan diulang secara individu sebanyak 20 kali. Hasil penelitian menunjukkan bahwa pemberian pakan buatan mampu mempertahankan kelangsungan hidup, laju pertumbuhan relatif dan rasio konversi pakan yang lebih baik dari penggunaan ikan rucah, baik di dalam bak maupun tambak. Nilai-nilai ke tiga kinerja pertumbuhan tersebut lebih baik saat kepiting dibudidaya di dalam bak dari pada di tambak. Usaha penggemukan kepiting bakau di dalam bak (salinitas 20-23 ppt) menghasilkan pendapatan kotor dua kali lipat lebih tinggi dari usaha penggemukan di dalam tambak (salinitas 35-50 ppt)., Mud crab fattening usually use trash fish as feed, due to the unavailability commercial artificial feed. On the other hand, the salinity of the water in the ponds also varies. During dry season, the salinity of pond water is very high, reaching 50 ppt. This research aims to determine the growth of mud crabs feeding with trash fish and artificial feed which were cultivated in tanks and ponds, each containing water with a salinity of 20-23 ppt and 35-50 ppt. Each treatment was replicated with 20 individuals. The results showed that artificial feed was able to maintain survival, relative growth rate and feed conversion ratio better than using trash fish, both in tanks and ponds. These three growth performance values were better when crabs were cultivated in tanks compared to ponds. Mud crab fattening businesses in tanks (salinity 20-23 ppt) generate twice the gross income compared to fattening businesses in ponds (salinity 35-50 ppt).
Keyword: penggemukan, salinitas, Ikan rucah, kepiting bakau, pakan buatan

Judul: Assessment of Wastewater Quality from Mud Crab (Scylla  sp.) Rearing
Abstrak: Limbah kegiatan pemeliharaan kepiting dapat meningkatkan jumlah nutrien di perairan, sehingga menyebabkan terjadinya eutrofikasi. Penelitian ini bertujuan menganalisis limbah hasil pemeliharaan kepiting bakau (Scylla sp.) dengan sistem kolam terpal. Penelitian dilaksanakan pada bulan September hingga November 2023. Rancangan penelitian menggunakan rancangan acak lengkap (RAL) dengan dua perlakuan (rucah dan pelet) dan 20 ulangan. Parameter yang dikaji dan dianalisis meliputi kualitas air, limbah hasil pemeliharaan, dan kondisi biologis. Hasil penelitian menunjukkan, kondisi kualitas air pada kedua media pemeliharaan sesuai dengan baku mutu pemeliharaan kepiting. Persentase limbah sisa pakan perlakuan pelet lebih sedikit yaitu 12% dari jumlah makanan total yang diberikan. Kondisi kualitas perairan dan sisa pakan mempengaruhi kondisi biologis kepiting. Kondisi biologis kepiting dengan perlakuan pelet memiliki nilai yang lebih baik dibanding rucah dengan nilai survival rate 95.50±1.54%, specific growth rate 1.39±0.63%, molting rate 5.5±5.10%. Perlakuan makanan berupa pelet memiliki kualitas air yang baik, jumlah sisa pakan lebih sedikit, dan lebih mendukung pertumbuhan kepiting bakau, namun kandungan amonia dan nitrat pada media pemeliharaannya tinggi., Waste from crab rearing activities can increase the amount of nutrients in the water, causing eutrophication. This study aims to analyze the waste from rearing mud crabs (Scylla sp.) with a tarpaulin pond system. The research was conducted from September to November 2023. The research design used a complete randomized design (CRD) with two treatments (crabs and pellets) and 20 replicates. Parameters studied and analyzed included water quality, waste from rearing, and biological conditions The results showed that the water quality conditions in both rearing media were in accordance with the quality standards for crab rearing. The percentage of waste left over from the pellet treatment was less at 12% of the total amount of food given. Water quality conditions and residual feed affect the biological condition of the crabs. The biological condition of crabs with pellet treatment has a better value than rucah with a survival rate value of 95.50 ± 1.54%, specific growth rate 1.39 ± 0.63%, molting rate 5.5 ± 5.10%. The pellet food treatment had good water quality, less feed residue, and was more suitable of mud crab growth, but the amonia and nitrate content of the rearing medium was high.
Keyword: mud crab, water quality, waste, rearing, crab food

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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