Judul: Makanan ikan oskar (Amphilophus citrinellus) di Waduk Jatiluhur
Abstrak: Ikan introduksi diduga menimbulkan dampak negatif terhadap ikan asli di perairan Waduk Jatiluhur. Ikan introduksi yang perlu diwaspadai bukan hanya ikan yang berperan sebagai pemangsa, tetapi juga potensial menjadi pesaing ikan asli dalam mendapatkan makanan dan ruang untuk kelangsungan hidupnya. Ikan oskar (Amphilophus citrinellus) merupakan ikan introduksi yang terbawa dengan benih ikan dalam keramba jaring apung (KJA). Penelitian makanan ikan oskar (Amphilophus citrinellus) di Waduk Jatiluhur bertujuan untuk mengkaji makanan ikan oskar berdasarkan waktu dan perubahan ukuran tubuh. Penelitian ini dilakukan pada bulan Maret-Juni 2010. Ikan contoh ditangkap pada dua stasiun yaitu Stasiun Ubrug dan Pasir Jangkung. Analisis data yang digunakan adalah metode indeks bagian terbesar (Ii). Ikan oskar di perairan Waduk Jatiluhur bersifat omnivor dan cenderung karnivor. Makanan ikan oskar bervariasi namun ikan ini cenderung memilih ikan sebagai makanan utamanya. Ikan oskar di perairan Ubrug dan Pasir Jangkung memiliki kesamaan dalam hal ragam makanan dan makanan utama, namun komposisi setiap jenis makanannya berfluktuasi selama waktu pengamatan. Fenomena perubahan makanan seiring dengan perubahan ukuran tubuh juga terjadi pada ikan oskar di Waduk Jatiluhur. Ikan oskar memanfaatkan sumber daya makanan yang hampir sama dengan ikan asli dan ikan ekonomis di Jatiluhur, seperti ikan benteur, kebogerang, kongo, dan nila. Hal ini dapat menimbulkan kompetisi antar ikan tersebut. Kemampuan ikan oskar dalam memanfaatkan makanan yang beragam menunjukkan ketahanan hidup ikan oskar yang tinggi. Hal tersebut ditengarai menjadi ancaman bagi ikan asli dan ekonomis, sehingga diperlukan suatu pengelolaan untuk mengendalikan populasi ikan oskar di Jatiluhur.
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Judul: Karakter Ekobiologi Ikan Oskar (Amphilophus citrinellus Günther, 1864) sebagai Dasar Pengendalian Ikan Asing di Waduk Ir. H. Djuanda, Jawa Barat
Abstrak: Midas cichlid is an alien fish species found in Ir. H Djuanda Reservoir and known to be disrupting the stability of the native fish population. This research was conducted in order to analyze the ecobiological characteristic of the fish such as food composition, distribution, growth, reproduction, food utilization and food similarity with other fish species in the area. The samples were taken from six stations from October 2011 to January 2012 in Ir. H. Djuanda Reservoir, in the Province of West Java. Gill nets were used with mesh-size of 1, 1,5, 2, 2,5, 3, 3,5 and 4 inches. The total number of fish being caught during those times were 657 individuals, with six of 12 species caught being native species, while the rest were alien species. Midas cichlid dominated the amount of fish caught (460 individuals). This fish has a total body length and weight ranges between 62–210 mm and 4.81–187.18 gram, respectively. The growth pattern showed that this fish is positive allometric. The condition factor of this fish tended to be similar throughout the stations. Midas cichlid was in good condition at the time sampling occurred The sex ratio of midas cichlid was even at 1:1. The size of mature males and females individuals were 125 mm and 121 mm, respectively. Total fecundity ranged between 729–3,299 of eggs. This fish is a partial-spawning type. Midas cichlid is an omnivore species and usually consumed all sorts of food within the feeding ground. The diet of this fish include phytoplankton, zooplankton, mollusks, earthworms and small fish in general. According to the index of preponderance, this kind of fish prefers to eat zooplankton. There were occurence of food ontogenetic variance found from this fish. Other fish species thought to be utilizing in the same way the small-sized, medium-sized, and the large-sized midas cichlid does is Barbonymus balleroides. Midas cichlid is being considered as an invasive spesies in Ir. H. Djuanda Reservoir and its existence should be controlled. The controlling could be done preventively and curatively. Preventive controlling could be conducted by sorting the fry population that would be stocked into the reservoir and by ensuring the fish hatchery used was free from midas cichlid fry. Curative controlling could be done by using a well-planned and scheduled catching method using a 1.5 inches gill nets in the litoral area body of water.
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Judul: Penentuan Nilai Eigen dan Vektor Eigen dari Matriks Tridiagonal 2-Toeplitz dengan Pendekatan Polinomial Chebyshev
Abstrak: The eigenvalues and eigenvectors of a matrix can be determined by finding its characteristic polynomials. The characteristic polynomials of a tridiagonal 2-Toeplitz matrix is shown to be closely connected to polynomials which satisfy the Chebyshev recurrence relationship. If the order of the matrix is odd, then the eigenvalues are found explicitly in terms of the Chebyshev zeros and the eigenvectors are found in terms of the polynomials satisfying the recurrence relationship. For even ordered matrices, the situation is more complicated. The problem in these cases is that although the Chebyshev recurrence formula is still applied, its initial values are not generating Chebyshev polynomials
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