Judul: Pemijahan ikan betutu, Oxyeleotris marmorata (Blkr.) pada kolam tanah dan kolam beton
Abstrak: Penelitian ini bertujuan untuk melihat pemijahan ikan betutu, Oxyeleotris marmorata (Blkr.), di kolam tanah yang rembes dan di kolam beton yang tidak rembes. Penelitian ini dilakukan di kolam Percobaan Babakan, Darmaga, Bogor, selama dua bulan yaitu satu bulan musim penghujan (1 Januari 1 Februari 1990) dan satu bulan musim kemarau (5 September 1990 - 28 September dan 9 Oktober 16 Oktober 1990). Ikan yang digunakan adalah induk ikan betutu yang diperoleh dari penangkapan di perairan umum dengan bobot antara 125 - 500 gram dan dengan kepadatan 16 pasang jantan dan betina untuk tiap kolam. Kolam yang digunakan adalah kolam dengan luas 200 m², dengan dasar tanah dan beton masing-masing. Penelitian ini menggunakan sarang yang terbuat dari asbes berukuran 30 x 30 cm sebanyak tiga buah dan dirangkai menjadi berbentuk segitiga dengan menggunakan tali plastik. Pakan yang diberikan berupa ikan teri segar sebanyak 7% dari bobot basah biomassa per hari dan diberikan sekali pada sore hari.
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Judul: Pengaruh padat penebaran terhadap kelangsungan hidup benih ikan betutu, Oxyeleotris marmorata (Blkr)
Abstrak: Penelitian ini dilaksanakan di Instalasi Kolam Percobaan BALITKANWAR Cibalagung, Bogor dari bulan Mei sampai dengan Juli 1989. Penelitian ini bertujuan untuk mengetahui pengaruh padat penebaran terhadap kelangsungan. hidup dan pertumbuhan benih ikan betutu, Oxyeleotris marmorata (Blkr.). Wadah penelitian yang digunakan adalah tangki fiberglass sebanyak 12 buah yang berbentuk bulat dengan diameter 50 cm dan tinggi 30 cm. Wadah diisi air sebanyak 20 liter dan air tidak mengalir serta diaerasi terus- menerus. Ikan yang digunakan adalah ikan betutu dengan bobot rata-rata 0,79 gram, panjang 35 cm. Pakan yang diberikan adalah cacing Tubifex dengan tingkat pemberian pakan 40% Pemberian pakan dilakukan 3 kali sehari sama banyak. Penyesuaian jumlah pakan dilakukan setiap 2 minggu sekali.
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Judul: Thermal Characteristics and Dynamics of Tropical Cyclone over Western North Pacific Ocean: A Case Study of Typhoon Songda (Chedeng) 2011
Abstrak: The frequent occasion of Tropical Cyclone (TC) over Western North Pacific (WNP) Ocean lies from 10˚N to 26˚N and 121˚E to 170˚E. Sources of TC development come from warm ocean temperature where latent heat is released during condensation processes and subsequently concentrated in the boundary layer. Relative humidity at 850-700 hPa is responsible to produce the most intense storm. Meanwhile, weak vertical wind shear between 850-200 hPa is one of the dynamical factors that lead to the development of TC. Pressure level of 850-200 hPa is chosen to minimize the thermodynamic effect in the lower troposphere. Typhoon Songda (Chedeng in the Philippines) or TSC lasted from May 18th to 30th, 2011 and strengthened into powerful Super Typhoon stage between May 24th and 27th. Long curving track and the exhibition of all sequences of TC life cycle, TSC is then considered as an ideal case of TC. The objective of the study with case of TSC is to investigate the role of thermal characteristics and dynamics on TC intensity. The research is carried out by using Advanced Research of Weather Research and Forecasting model (WRF ARW model) version 3.3. Two domains are employed in the model. The first domain situate from 02˚N to 40˚N and 118˚E to 149˚E and cover spatial resolution () of 33.1 km. The second domain situate from 09˚N to 27˚N and 119˚E to 132˚E with of 11 km. Timestep of the model () is 120 seconds. The model is supported by the following physical parameterization, i.e., Yonsei University Scheme (YSU) in the boundary layer, Kain-Fritsch scheme (KF) in the cumulus, and WRF Single-Moment 3-class scheme in the microphysics. Initial meteorological condition prior to the formation of the cyclone is generated using WRF ARW standard-release model. Sensitivity of the model output is obtained from a selected single-parameter change scenarios, namely, 10 % to 20 % decrease and increase of wind shear initial data at 850-200 hPa, and by 10 % to 20 % decrease of relative humidity initial data at 850-700 hPa. The result showed that the negative correlations between wind shear and intensity are found in wind shear scenarios. Wind shears of 10 ms-1 which lead to strengthening of the wind intensity in the early period of Typhoon development are found in wind shear scenarios. The effect of wind shear changes on wind intensity is statistically significant in the 20 % wind shear scenarios. During mature stage, weak wind intensity occurred when wind shear increase as given in the WRF standard-release and the 20 % decreasing scenario. Different situation is found in the 20 % increasing scenario where wind shear tend to weak and lead to strong wind intensity at this stage. Meanwhile, the reduction of moisture supply at 850-700 hPa resulting from 20 % decreasing relative humidity play a major role in the weakening of wind intensity and reduces mechanical energy of the cycle process as much as 300 J kg-1.
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