Judul: THE INFLUENCE OF ENVIRONMENTAL FACTORS ON THE BEHAVIOR OF IRRAWADDY DOLPHIN (Orcaellabrevirostris) IN THE PELA RIVER AND LAKE SEMAYANG, EAST KALIMANTAN
Abstrak: Lumba-lumba Irrawaddy (Orcaella brevirostris) adalah spesies lumba- lumba kecil dengan populasi yang ditemukan di perairan pantai dangkal Indo- Pasifik tropis dan subtropis, tetapi juga di tiga sistem sungai besar: Mahakam di Indonesia, Ayeyarwady di Myanmar, dan Sungai Mekong yang melintasi Vietnam, Kamboja, dan Laos. Spesies ini secara morfologi mempunyai ciri kepala bulat dan leher fleksibel. Beberapa individu memiliki lipatan posterior di leher dan lekukan di punggung yang memanjang dari lipatan leher hingga sirip punggung. Spesies ini memiliki sirip punggung dengan berbagai bentuk berbeda seperti segitiga, melengkung, terbelah dan bengkok dan terletak sekitar 60% dari panjang tubuh hingga rahang atas. Siripnya memiliki ujung depan yang cembung dan berukuran relatif besar, menempati sekitar seperenam dari total panjang tubuh dan sekitar setengah lebar tubuh. Spesies lumba-lumba Sungai Mahakam terdaftar sebagai spesies yang terancam punah dalam daftar merah IUCN untuk sebagian besar populasi pesisir namun ada beberapa populasi yang terdaftar sebagai sangat terancam punah, yang melibatkan semua sub-populasi sungai (Sungai Mahakam, Mekong dan Ayeyarwady) serta sub-populasi pesisir termasuk penduduk Songkhla (Thailand), Iloilo-Guimaras dan Malampaya (Filipina). Sebaran populasi Lumba-lumba Sungai Mahakam di Sungai Mahakam, yang secara lokal disebut Pesut Mahakam, terbatas pada ruas sungai sepanjang 195 km dari sungai utama, dimulai dari hulu 180 km dari Muara sungai Sungai Mahakam. Diantaranya adalah anak-anak sungai Kedang Rantau, Kedang Kepala, Belayan, Kedang Pahu, dan Ratah, serta Sungai Pela dan Danau Semayang. Sebaran dan perilaku hewan cetacea dapat dipengaruhi oleh beberapa faktor, yaitu faktor biotik, aktivitas fisikokimia, klimatologi, dan faktor antropogenik. Misalnya perubahan suhu dan fluktuasi salinitas beberapa badan air mempunyai pengaruh besar terhadap sebaran (penampakan) dan perilaku Eubalaena glaciali, Delphinus delphis, Balaenoptera acutorostrata. Penelitian lain menemukan bahwa perilaku makan dan sosialisasi Orcaella brevirostris berkorelasi positif dengan suhu permukaan laut. Lumba-lumba diamati mencari makan ketika suhu air mencapai puncaknya pada siang hari (10-12 pagi). Penelitian lainnya dilakukan di Teluk Brunei, Malaysia. Perilaku mencari makan berkorelasi positif dengan peningkatan kedalaman dan tingkat kekeruhan air. Dalam penelitian yang dilakukan di Mahakam, padatnya lalu lintas kapal mempengaruhi kemunculan lumba-lumba sungai Mahakam. Saat ini informasi mengenai hubungan perilaku Lumba-lumba Sungai Mahakam dan korelasinya dengan faktor lingkungan di Sungai Pela dan Danau Semayang masih sangat terbatas. Oleh karena itu, penelitian ini bertujuan untuk membandingkan pengaruh faktor lingkungan di Sungai Pela dan Danau Semayang terhadap perilaku. Penelitian observasional dilakukan di Sungai Pela yang terletak di Kecamatan Kota Bangun Kabupaten Kutai Kartanegara dengan durasi penelitian selama dua bulan terhitung dari bulan Oktober 2021 sampai dengan November 2021, Pengamatan ini meliputi daerah Danau Semayang, Anak Sungai Pela, dan Muara sungai Sungai Pela. Analisis data dilakukan di Bagian Fungsi dan Perilaku Hewan Departemen Biologi. IPB pada bulan Januari 2023 sampai dengan April 2023. Pendugaan jumlah individu Lumba-lumba Sungai Mahakam dilakukan melalui identifikasi foto. Teknik ini melibatkan pengumpulan dan katalogisasi foto lumba-lumba dengan tanda khas pada sirip punggung yang memungkinkan identifikasi individu. Perhitungan jumlah individu yang teridentifikasi sebagai individu unik berdasarkan sirip punggungnya pada saat pengamatan di lokasi penelitian Danau Pela/Semayang adalah sebanyak 30 individu. Dari hasil perjumpaan terlihat bahwa Lumba-lumba Sungai Mahakam banyak ditemukan di kawasan Sungai Pela dan Danau Semayang, hal ini sesuai dengan penelitian sebelumnya yang mengindikasikan
Keyword: Faktor lingkungan, Lumba-lumba irrawaddy, perilaku, Behavior, environmental factors, mahakam river dolphin

Judul: Re-Design of mahakam irrawaddy dolphin (Orcaella Brevirostris Gray, 1866) conservation based on distributional changes in Mahakam River, East Kalimantan
Abstrak: The intensive bio-ecological research on the Mahakam dolphins (Orcaella brevirostris Gray,1866) from 1997 to 2004 revealed that there were two core habitats/core areas with high dolphin densities in the Mahakam River i.e. the MuaraPahu-Penyinggahan area and Pela-Muara Kaman area. Since 2007, there have been unusual occurrences within the distribution of the Mahakam dolphins. The core habitat of Muara Pahu-Penyinggahan, which was previously known to support a large population of Mahakam dolphins has apparently been left. The changes in distribution were also detected in 2010 when the population monitoring was conducted and no individuals were found in the Muara Pahu-Penyinggahan core habitat . The Mahakam dolphins are now more concentrated in the area of Muara Muntai and in their other core habitat, Pela-Muara Kaman. This research aimed to reveal whether the changes in distribution were persistent and to respond to this phenomenon by improving the conservation design. To predict the persistency of these changes population dynamics, habitat and socio-political environmentv(policies) were studied and formed the research goal.. Thus, the research objectives of this dissertation are as follows: 1) predicting the survival of the Mahakam dolphin population for a period of100 years, 2) analyzing the characteristics of the Mahakam dolphin habitats; 3) evaluating the effectiveness of coordination and consistency of the Mahakam dolphin conservation policies; and 4) perfecting the design of dolphin conservation to accommodate the current situation of the population, the Mahakam dolphin habitat and socio-political environment that support the conservation efforts. The research on the population of Mahakam dolphins in 2012 revealed that the individual number of Mahakam dolphins, the number of births, and the number deaths were as many as 92 individuals, 5 individuals, and6 individuals, respectively. This research also demonstrated that changes in the distribution of dolphins had occurred inMahakam River. The Mahakam dolphins do no longer live in their core habitat of PenyinggahanMuaraPahu. Currently, the dolphin habitat is concentrated in the core habitat of Pela-Muara Kaman. The changes in the distribution indicate that further shrinkage in the habitat of Mahakam dolphins has occurred Mahakam River. As a result of this, an analysis on the survival of the Mahakam dolphin population was conducted. The results of the analysis predict that the life chances of the Mahakam dolphin population in the next one hundred years are less encouraging as the number of individuals will continue to diminish. The only scenario that predicts a stable dolphin population in one hundred years is when the mortality rate of dolphins is reduced to two individuals per year with the conditions that there is no further shrinkage of habitat, which will result in the reduction of its carrying capacity, and the birth rate is maintained at five individuals per year. vii Networks for coordination for dolphin conservation, which includes 16 organizations have not been effective. There has been a lack of coordination in most networks especially related to organizations/actors included in groups (factions) that work in WestKutai Regency. The lack of coordination started from the time when the dolphins moved away from their conservation area and habitat in Muara Pahu. There has been no coordination
Keyword: Mahakam dolphins, probality of survival, probality of survival, strengthening of coordination, redesign of conservation

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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