Judul: Perbandingan Hasil Tangkapan Bubu pada Terumbu Buatan Bambu dan Ban di Sekitar Pulau Pramuka Kepulauan Seribu
Abstrak: The objectives of the research were to compare fish composition and abundance between tire and bamboo reefs and to compare yields traps. The study was conducted in 4 steps i.e ; survey location, make the design tire and bamboo artificial reefs, construction and maintenance of artificial reefs, determination of physics parameters, collection of perifiton sample, observation fish abundance among artificial reefs, operation by fish traps, fish identification, determination of fishing catch and analyze data using t-test. The result showed that no difference fish composition collected in around artificial reefs. The fish collected consists of 15 family, 19 genus and 27 species with 789 and 402 fishes in tire and bamboo artificial reefs respectively. Dominant species were collected in artificial reefs are Caesio cuning, Scolopsis sp, Siganus sutor and Sargocentron cornutum. Catch of traps between tire and bamboo artificial reefs is significant (thit 3,6 dan ttab 1,7, α 0,05) which artificial reef made of tire more bigger than bamboo.
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Judul: Efektivitas Terumbu Buatan Berbahan Dasar Tempurung Kelapa sebagai Fish Aggregating Device di Pulau Pramuka Kepulauan Seribu
Abstrak: Artificial reefs is an artificial habitat which is created to resemble the characteristics of natural reefs to improve the community of coral reefs that have been damaged in natural waters ecosystem. The effectiveness of artificial reefs made of coconut shell is observed during the period of March 2012 - May 2012 in the waters of Pramuka island, Kepulauan Seribu, Jakarta. The method used experimental method, where bubu tambun is used to capture the specimen that will be analyze for it’s level of gonad maturity. The observations is done with the visual census method with 2 areas i.e. 1 meter and 2 meter that would later be analyzed for it’s index of diversity (H’), index homogeneity (E) and the dominance index (C) at the artificial reefs site. The results showed that 10 family with 13 species are dominant to stay while in the natural coral reef consists of 8 family with 25 described species. The result of fishing capture, it consist of 10 family (Pomacentridae, Balistidae, Chaetodontidae, Holocent, Labridae, Scaridae, Siganidae, Xanthidae, Muraenidae). Gonado Stomato Index (GSI) of fishing capture are GSI I (46%); GSI II (28%); GSI III (22%) and GSI IV (4%). Artificial reefs with 1 meter areas has a range of diversity index between 1.68 -2.5; and the uniformity index ranged between 0,68-1.07 and dominance index 0.11-0.16. Artificial reefs with 2 meters areas has a range of diversity index between 1,79 – 2,15; range of uniformity index 0.59-0.90 and the index of the dominance of 0.09- 0.16.
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Judul: Hamiltonian formulation for linear waves motion in two layers fluid
Abstrak: The surface wave could be considered as a wave that separates two fluids, namely water and air. Based on this assumption, it is introduced the interfacial wave, a wave between two layers of fluid with different density. The formulation of interfacial waves motion begins with deriving the base equation of irrotational ideal fluid. Furthermore, according to irrotational fluid assumption, the base equation can be stated in velocity potential. In this derivation, the fluids domain is assumed to be restricted by rigid lid boundary conditions, both at the upper and lower limit. Therefore, the interfacial waves motion can be explained in a hamiltonian formulation. In the hamiltonian formulation, total energy is defined as the sum of kinetic and potential energy. The hamiltonian system is obtained from reduction of kinetic energy by using the Dirichlet Neumann Operator. The resulted kinetic energy equation is nonlinear. Therefore, this form is linearized by first part of the Taylor expansion. This linearization gives a dispersion relation of linear wave. Based on this dispersion relation, the phase speed of the linear wave depends on the density ratio of the two layers fluid.
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