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: Efektivitas Filter Portabel Berbasis Mikroba terhadap Kinerja Produksi Scylla serrata di Vertical Recirculating Aquaculture System
Abstrak: Kepiting bakau merupakan salah satu komoditas unggulan ekspor yang permintaannya selalu meningkat pada setiap tahunnya. Kondisi lahan budidaya yang terbatas menjadi salah satu hambatan dalam melakukan kegiatan budidaya. Penelitian ini bertujuan menguji efektivitas penggunaan filter portabel berbasis mikroba terhadap kinerja produksi kepiting bakau Scylla serrata pada vertikal recirculating aquaculture system. Penelitian ini menggunakan rancangan eksperimental semu dengan dua perlakuan berupa kepiting yang dipelihara menggunakan filter portabel dan filter non-portabel tanpa ulangan. Penelitian ini menggunakan kepiting dengan bobot rata-rata awal yaitu 112,48 ± 16,42 g. Kepiting bakau yang digunakan sebanyak 100 ekor pada setiap perlakuan. Kepiting bakau dipelihara selama 30 hari. Nilai pH dan amonia pada wadah filter portabel yaitu 7,10-8,50 dan 0,002 mg.L-1, dan pada wadah filter non-portabel yaitu 7,80-8,20 dan 0,003 mg.L-1. Nilai laju pertumbuhan spesifik dan total haemocyte count pada kepiting bakau yang dipelihara menggunakan filter portabel yaitu 0,09 %/hari dan 22,7 ± 1,84 x 104 sel.mL-1 , dan pada filter non-portabel yaitu 0,07 %/hari dan 17,6 ± 1,98 x 104 sel.mL-1. Nilai tingkat kelangsungan hidup pada kepiting bakau yang dipelihara menggunakan filter portabel yaitu 73% dan pada filter non-portabel yaitu 65%. Penggunaan filter portabel berbasis mikroba pada vertikal RAS memberikan unjuk kerja yang lebih baik dalam memanajemen kualitas air pada wadah pemeliharaan kepiting bakau sehingga kinerja produksi menjadi lebih optimal., Mud crab is one of the leading export commodities and the demand is always increasing every year. Limited condition of cultivated land is one of the obstacles in conducting cultivation activities. This study aims was to test the effectiveness of microbial based portable filters on production performance of mud crab Scylla serrata in a vertical recirculating aquaculture system. This study used a quasi-experimental design without repetition with two treatments which crabs were reared using a portable filter and a non-portable filter. This study used mud crabs with average initial weight of 112,48 ± 16,42 g. Mud crabs that used are 100 crabs for each treatment. Crabs were reared for 30 days. The values of pH and ammonia in the portable filter containers were 7.10-8.50 and 0.002 mg.L-1, and in the non-portable filter containers were 7.80-8.20 and 0.003 mg.L-1. The value of specific daily growth rate and total haemocyte count in mud crabs reared using a portable filter was 0,09 %/days and 22,7 ± 1,84 x 104 cell.mL-1, and at the non-portable filter was 0,07 %/days and 17,6 ± 1,98 x 104 cell.mL-1. The survival rate of mud crabs reared using a portable filter was 73% and at non-portable filter was 65%. The use of microbial-based portable filters in the vertical RAS provides better performance in managing the water quality in mud crab rearing containers so that production performance becomes more optimal.
Keyword: filters, growth, production performance, Scylla serrata, vertical aquaculture system

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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