Judul: Pemanfaatan Karang Hias Berkelanjutan di Perairan Teluk Lampung, Kabupaten Pesawaran, Provinsi Lampung.
Abstrak: Indonesia is the main supplier of ornamental coral reef in the world. The second biggest ornamental coral supplier in Indonesia is Lampung Bay, after South Sulawesi. According to the Convention on International in Endangered Species of Wild Fauna and Flora (CITES), ornamental corals are classified in Appendix 2, which means they are species that are not necessarily threatened with extinction, but may become so unless trade in specimens of such species is subject to strict regulation in order to avoid utilization incompatible with the survival of the species in the wild. Therefore, in order to ensure that management of the coral ornamental is sustainable, its abundance based on group size, its biological nature, environmental factors and its utilization should be considered. Data and information were collected and analyzed based on those above aspects. Approximately 90% of ornamental coral species usually characterized as slow growing corals. The commercial types have very high quota in the market. However, during three years of observation, the fishers were only able to deliver approximately 50% of exporter’s orders. The result of the survey taken from 16 stations showed that only 4 species of 24 species that had abundance of ≥2000 ind/ha, the rests had a very low abundance. The evidence of over-exploitation was also found. The ideal management should be based on the potential of ornamental coral in each location, in order to set the Total Allowable Collect (TAC). Based on the calculation of TAC, five species were not recommended for use because they had not only low abundance but also they did not have mature colony for reproduction. Hence the utilization of the other nineteen species should be limited in the range of 2-15% of the existing population in the area. According to value of TAC expected in the future, these species still have the opportunity to increase their population.
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Judul: Sustainable utilization strategy on ornamental reef fish resources in Weh Island, Aceh,
Abstrak: The ornamental reef fishery of Weh Island began in 1997, yet no assessment of reef fish resources, potential species for trade and their sustainable yields has been made. This study assesses the sustainable catch quota of potential ornamental reef fish species and provides optimum utilization strategies based on sustainable catch quotas, price, and effort capacity. Seventy-seven ornamental reef fish species were identified from underwater visual census at 20 sites in the marine waters of Weh Island. Catch and effort data were recorded for 12 months in 2010. Nineteen species of ornamental fish were landed by local fishers, and 83% of the total catch was comprised of the powder blue tang (Acanthurus leucosternon). The maximum sustainable yield (MSY) of ornamental fish species was assessed using a surplus production model, with an annual catch quota set at 80% of MSY. From catch data, we found that the harvest level of powder blue tang in 2010 exceeded its annual catch quota (103.5%), while the other 18 species were still under harvested. Optimization results using the Linear Programming suggested that increasing catch of three species, Acanthurus tenneti, Paracanthurus hepatus, and Pomacanthus imperator was required to achieve maximum economic yield. Based on sustainable catch quotas and financial analyses we conclude that the ornamental reef fishery of Weh Island can be managed sustainably and achieve positive ecological and economic outcomes.
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Judul: Metrik Einstein (Anti-) Self-Dual Berdimensi Empat dengan Metode Cartan
Abstrak: Gravitational field equation can be formulated in differential forms (differential geometry), which describes gravity as a manifestation of the curvature of space-time. Curvature of space-time is characterized by a metric that satisfies the gravitational field equation. With differential forms it can be formulated the (anti-) self-dual Einstein equation, which is a modification of the Cartan structure in (anti-) self-dual basis. Calculation of (anti-) self-dual metric with (anti-) self-dual Einstein equation is simpler than the calculation using Christoffel symbols.
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