Judul: Coconut Leaves as Subtitutes of Coral Reefs for Fish Pots Cover
Abstrak: Ekosistem terumbu karang pada Desa Selat Nasik, Kecamatan Selat Nasik, Kabupaten Belitung menghadapi permasalahan yang disebabkan oleh praktik perikanan bubu tidak ramah lingkungan. Penggunaan bahan lain sebagai penutup bubu dapat membantu mengurangi kerusakan terumbu karang. Salah satu bahan alternatif adalah daun kelapa. Tujuan penelitian ini adalah membandingkan komposisi hasil tangkapan, ukuran ikan target dan berat hasil tangkapan di antara dua jenis bubu yang berbeda tutupan, yaitu bongkahan karang dan daun kelapa. Perbandingan dilakukan dengan analisis deskriptif kuantitatif. Penelitian ini bersifat eksperimen menggunakan dua unit bubu dengan tutupan daun kelapa (bubu A) dan dua unit bubu tutupan karang (bubu B), masing-masing unit dioperasikan dalam 12 trip operasi. Total ikan yang tertangkap bubu A sebanyak 87 ekor (8.950 gram) dan bubu B sebanyak 103 ekor (16.250 gram). Ikan target paling dominan yang tertangkap bubu A adalah swangi batu dengan jumlah 17 ekor (1.320 gram) dan bubu B adalah kakatua biru dengan jumlah 19 ekor (5.290 gram). Komposisi jenis ikan yang tertangkap terdiri dari 14 famili dengan 20 spesies dengan ikan target berjumlah 12 spesies, ikan indikator tiga spesies dan ikan mayor sejumlah lima spesies. Bubu tutupan daun kelapa lebih efektif digunakan untuk menangkap ikan target (swangi batu) dibandingkan bubu tutupan karang., Coral reefs in Desa Selat Nasik, Kecamatan Selat Nasik, Belitung were threatened by destructive fishing practices with fish pots covered by coral boulders. Alternative cover materials could help mitigate further damage of the reefs. Coconut leaves could be used as alternative materials. The aims of this study were to compare species composition, length and weight compositions, dominant species captured between two pots, i.e., coconut leaves (trap A) and coral boulders (trap B). Quantitative descriptive analysis was applied to achieve the aims. Two units of trap A and two units of trap B were operated simultaneously within twelve one-day-fishing trips. Trap A captured 87 pieces that weighed 8.950 gram while the trap B had 103 pieces (16.250 gram). Redcoat was the most dominant species (17 pieces; 1.320 gram) captured in 5 out of 12 fishing trips in trap A. Blue-barred parrotfish was the most dominant species with 19 pieces; 5.290 gram captured in 7 out of 12 fishing trips with trap B. 14 families of fish were caught in Desa Selat Nasik (20 species), target group was 12 species, indicator and major group were 3 and 5 species respectively. Coconut leaves cover was more effective than coral cover for catching Redcoats.
Keyword: alternative materials, catch composition, coconut leaves cover, coral cover, target species

Judul: Produktivitas Hasil Tangkapan Bubu pada Terumbu Karang di Pulau Pramuka Kepulauan Seribu DKI Jakarta
Abstrak: Artificial reef made of coconut shell is an artificial habitat which is created to resemble the characteristics of natural reefs and become the alternative to improve the natural coral reefs that have been damaged. The opportunity of artificial reef utilization was researched by using experimental fishing and laboratory observe methods. The use of experimental fishing is to do the catching proses around the artificial reefs. The research was done in August 2013. Laboratory observe was done in September 2013 by observe the sample of fish intestines to get the data of abundance plankton from the inside of fish stomach. The results showed that 64 fishes was catches by bubu consist of 12 species. Red Breast Wrasse (Cheilinus fasciatus) from family Labridae is the dominant species. The plankton composition from the laboratory observe showed that Rhizosolenia and Leptocylindricus are the dominant plankton which indicate that the water is on good condition. Artificial diversity index ranged between 0,52-0,66; the uniformity index ranged between 0,17-0,21 and dominance index-0,45.
Keyword: plankton, artificial reef, coral reef, trap

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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