Judul: Tingkat Kerentanan Sumber Daya Ikan Sidat (Anguilla bicolor bicolor Mcclelland, 1844) di Sungai Cimandiri, Palabuhanratu
Abstrak: Sungai Cimandiri merupakan salah satu habitat ikan sidat. Tingkat kerentanan ikan sidat di Sungai Cimandiri setiap tahun mengalami peningkatan. Hal ini disebabkan oleh pengaruh dari lingkungan fisik dan kualitas perairan yang mengalami degradasi akibat aktivitas manusia di sekitar Sungai Cimandiri. Tujuan dari penelitian ini adalah untuk menentukan tingkat resiko potensi kerentanan sumber daya ikan berbasis data kerentanan untuk mengkaji keberlanjutan spesies ikan sidat di Sungai Cimandiri, Palabuhanratu. Analisis dilakukan dengan kajian mengenai kerentanan menggunakan software PSA (Productivity and Susceptability Anayisis). Hasil penelitian menunjukkan bahwa nilai kerentanan sumber daya ikan sidat telah mendekati kondisi rentan. Tingkat kerentanan ikan sidat di Sungai Cimandiri yang tertinggi pada bulan Oktober dengan nilai produktivitas rendah dan resiko kerentanan tinggi. Nilai Produktivitas bulan Oktober yaitu 1.3, sedangkan nilai susceptabilitas adalah sebesar 2.5, dengan indeks kerentanan 2.3. Tingkat kerentanan di Sungai Cimandiri berdasarkan analisis yang dilakukan pada bulan Juli sampai Oktober menunjukkan tingkat kerentanan sedang hingga sangat rentan., Cimandiri River is one of eel habitat. The level of vulnerability eels in the Cimandiri River each year has been increasing. It caused by the influence of physical environment and degradation water quality due to human activities around Cimandiri River. The purpose of this study was to determine the risk potential vulnerability level of fish resources based vulnerability data to assess the sustainability of fish species in Cimandiri River, Palabuhanratu. The analysis was performed with software vulnerability assessment of the PSA (Productivity and Susceptibility Analysis). The results showed that the value of the vulnerability of eel resources has approached the vulnerable condition. The highest vulnerability level of eels in the Cimandiri River happen in October with low productivity and high risk vulnerabilities. Value Productivity in October was 1.3, while the value of susceptibility was 2.5, the vulnerability index of 1.8. The vulnerability level in Cimandiri River based on the analysis conducted in July and October showed the vulnerability of moderate to highly susceptible.
Keyword: Ikan sidat, tingkat kerentanan, Sungai Cimandiri

Judul: Kondisi perairan di beberapa sungai yang bermuara di Teluk Palabuhan Ratu, Jawa Barat sebagai habitat Ikan Sidat (Anguilla Spp.)
Abstrak: Ikan sidat (Anguilla spp.) merupakan salah satu sumber daya perikanan yang dapat pulih, namun rentan kepunahan. Penelitian ini bertujuan untuk mengetahui status kondisi perairan di beberapa sungai yang bermuara di Teluk Palabuhan Ratu sebagai habitat ikan sidat (Anguilla spp.). Kegiatan penelitian meliputi kegiatan lapang dan analisis laboratorium. Lokasi sampling terbagi menjadi dua bagian badan sungai yakni hulu dan hilir sungai, meliputi Sungai Cibareno, Sungai Citiis, Sungai Cimaja, Sungai Cisukawayana, Sungai Citepus, Sungai Cipalabuhan, dan Sungai Cimandiri. Hasil analisis menunjukkan bahwa Sungai Cimaja bagian hulu dan hilir memiliki status sangat baik, Sungai Citiis, Sungai Cibareno, dan Sungai Cisukawayana bagian hulu memiliki status baik dan hilir memiliki status sangat baik, Sungai Cimandiri bagian hulu dan hilir memiliki status baik, Sungai Citepus bagian hulu memiliki status baik dan hilir memiliki status sedang, dan Sungai Cipalabuhan bagian hulu dan hilir memiliki status sedang. Upaya pengelolaan meliputi membatasi limbah dari kegiatan antropogenik, membuat IPAL, pembuatan kawasan hijau di pinggiran sungai, dan membatasi penggunaan bahan berbahaya (mengandung logam berat)., Eels (Anguilla spp.) is one of the fisheries resources can be recovered but are susceptible to extinction. The purpose of the research was to determine the water quality status for eels in rivers that end in Palabuhan Ratu Bay, West Java as habitat for eels (Anguilla spp.). This research included field activity and laboratory analysis. Sampling location was divided into two parts on the body of the river that is upstream and downstream of the river which includes Cibareno, Citiis, Cimaja, Cisukawayana, Citepus, Cipalabuhan, and Cimandiri River. Result showed are Cimaja River upstream and downstream was a very good status, Citiis, Cibareno, and Cisukawayana River upstream was a good status and downstream was a very good status, Cimandiri River upstream and downstream was a good status, Citepus River upstream was a good status and downstream was a average status, and Cipalabuhan River upstream and downstream was a average status. Management efforts that are restricting waste input of anthropogenic activities, making WWTP, making green belt in beside the river, and restricting the use of hazardous materials (containing heavy metals).
Keyword: ikan sidat, pengelolaan, sungai

Judul: Bifurkasi Hopf pada Model Siklus Bisnis Kaldor Kalecki tanpa dan dengan Waktu Tunda
Abstrak: Business cycle model is one of dynamical system models in economic. One of the business cycles model is Kaldor-Kalecki model. Kaldor-Kalecki business cycle model that is written in delayed defferential equations, is a business cycle model that involves gross product and capital stock of a company. In this paper Kaldor-Kalecki business cycle model is analyzed using both nondelay and delay in time of capital stock. By Taylor expansion for the time delayed model, an analysis of stability around the fixed points has been done. Furthermore, by using Hopf bifurcation theorem, it can be shown that there exists periodic orbits and limit cycle. In the nondelayed model, changing the parameter of goods market could lead to the occurrence of Hopf bifurcation and the existence of limit cycle. Similarly, for the delayed model, it has been shown that changing the time delay parameter may result in the occurrence of Hopf bifurcation and limit cycle.
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