Judul: Potensi Isolat Bakteri Simbion Spons Agelas conifera di Ekosistem Lamun Pulau Pramuka, Kepulauan Seribu, Jakarta
Abstrak: Pulau Pramuka merupakan pulau dengan banyak ekosistem, salah satunya adalah ekosistem lamun. Ekosistem lamun memiliki peranan sebagai habitat oleh banyak biota, salah satunya adalah spons. Spons Agelas conifera adalah jenis spons yang paling dominan ditemukan di Pulau Pramuka, Kepulauan Seribu. Kemampuan spons untuk memproduksi senyawa metabolit sekunder sangat dipengaruhi oleh kondisi habitat spons. Tingginya tingkat kesuburan ekosistem lamun dapat mempengaruhi produksi metabolit sekunder spons. Penelitian ini bertujuan mengisolasi dan menguji potensi bakteri simbion spons serta mengetahui jenis lamun yang berasosiasi dengan Agelas conifera. Isolasi bakteri simbion spons dilakukan mengunakan media Zobell 2216 ½ strength. Uji yang dilakukan adalah antibakteri, antifungi, selulase, kitinase, resistensi sinar UV, toleransi suhu, serta pengukuran kualitas perairan dan kualitas sedimen. Jenis lamun yang ditemukan pada lokasi pengamatan yaitu, Thalassia hemprichii, Cymodocea rotundata, Halophila ovalis, dan Enhalus acoroides. Thalassia hemprichii mendominasi di kedua Stasiun penelitian. Sebanyak 61 individu spons Agelas conifera ditemukan pada penelitian ini. Spons Agelas conifera lebih banyak ditemukan pada kerapatan dan tutupan lamun yang tinggi, yaitu jenis Thalassia hemprichii. Isolat bakteri ditemukan sebanyak 45 isolat yang bersimbiosis dengan spons. Jumlah spons yang ditemukan dikaitkan dengan persentase tutupan lamun perjenis dengan menggunakan analisis koresponden yang menunjukkan spons lebih banyak ditemukan pada tutupan lamun T.hemprichii. Potensi bakteri simbion yang ditemukan bervariasi seperti resisten terhadap sinar ultraviolet (UV) dan rentang toleransi suhu yang lebar. Hasil yang berbeda nyata antara potensi pada kedua stasiun ditunjukkan oleh uji ANOVA single factor dengan p<0.05. Dibutuhkan pengujian lebih lanjut untuk melihat potensi lebih dalam dari bakteri simbion spons Agelas conifera di ekosistem lamun Pulau Pramuka Kepulauan Seribu., Pramuka Island is an island with many ecosystems, one of which is a seagrass ecosystem. The seagrass ecosystem has a role as a habitat for many biota, one of which is a sponge. Agelas conifera sponge is the most dominant sponge found in Pramuka Island, Kepulauan Seribu. The ability of sponges to produce secondary metabolites is greatly influenced by the conditions of the sponge's habitat. The high fertility rate of the seagrass ecosystem can affect the production of secondary metabolites of the sponge. This study aims to isolate and test the potential of sponge symbiont bacteria and to determine the types of seagrass associated with Agelas conifera. Spongy symbiont bacteria was isolated using Zobell 2216 ½ strength media. The tests carried out were antibacterial, anti-fungal, cellulase, chitinase, UV resistance, temperature tolerance, and measurement of water quality and sediment quality. The types of seagrass found at the observation site were Thalassia hemprichii, Cymodocea rotundata, Halophila ovalis, and Enhalus acoroides. Thalassia hemprichii dominates at both research stations. A total of 61 individual Agelas conifera sponges were found in this study. Agelas conifera sponges are more commonly found in high density and cover of seagrass, namely Thalassia hemprichii. As many as 45 isolates were found in symbiosis with a sponge. The number of sponges found was associated with the percentage of seagrass cover per type using a correspondent analysis which showed that sponges were more common in T.hemprichii seagrass cover. The potential of symbiont bacteria found varied such as resistance to ultraviolet (UV) rays and a wide temperature tolerance
Keyword: Agelas conifera, Pramuka Island, Seagrass habitat, Symbiotic bacteria

Judul: Eksplorasi Bakteri Simbion Spons di Ekosistem Lamun
Abstrak: Sponge has been acknowledged for its ability to produce secondary metabolites compounds that have been explored for new source of marine natural product compounds. Unfortunately, information on sponge ecological interaction, especially concerning its secondary metabolite production and symbiotic organisms, are usually from observation and experimental researches in coral reefs ecosystem. Meanwhile, not many information has been gathered on sponge community and its ecological interaction in the seagrass ecosystem. Information on sponge community and its ecological interaction in seagrass ecosystem should be explored intensively, for seagrass vegetation could has different environmental condition due to seagrass species characterization that composing the ecosystem. Thus, vegetation characterization of seagrass will influence sponge community and its secondary metabolite, and also its interaction with symbiotic microbial (bacterial). This research wants to figure out several issues concerning sponge community in seagrass ecosystem. These issues are: will sponge species composition and association be different due to condition of seagrass vegetation in the ecosystem; is sponge species in seagrass ecosystem have the same potential concerning its antibacterial activity as in reefs area; how diverse the sponge bacterial symbiont and the potential of its secondary metabolite; and also how the ecological interaction between sponge and its symbiotic bacterial. This research was conducted in several stages. The first stage is field observation at seagrass ecosystem. The next stage was conducted as laboratory activities. Laboratory activities were conducted in several phases. The phase was an assay to test the antibacterial activity of sponges tissues on generally tested bacteria (Escherichia coli and Staphylococcus aureus) and marine bacteria isolates from surrounding water (Al1, Al2, Al3, Al4 and Al5). The aims of this activity were to screen potential sponge that having antibacterial activity, and isolating its symbiotic bacterial. Afterwards, the next phase was an assay to test the antagonistic activity of sponge symbiotic bacterial against marine-biofilm forming bacteria. Symbiotic bacterial with high antagonistic activity then analyzed for its species diversity, using molecular analysis of symbiotic bacterial DNA fingerprinting and identification. Field observation was done in two different seagrass meadow/bed in Pramuka Island, Seribu Islands, near Jakarta Bay, Indonesia, since September 2013 to Mei 2014. Laboratory assays activities were done in Marine Microbiology Laboratory and Marine Biosystematics and Biodiversity, Departement of Marine Science and Technology, Bogor Agricultural University (IPB). Antibacterial assay on sponge tissue was conducted since September 2013 to March 2014, whilst isolation on symbiotic bacterial and secondary metabolites assay were done from December 2013 to November 2015. Molecular analysis on bacterial symbionts diversity and identification were just done ons January to May 2016. Results of this research showed that sponge community in seagrass ecosystem was influenced by the density, morphological form and vegetation architectural of seagrass beds. Sponge will have more species number (higher diversity), with lower abundance in patchy seagrass bed. On the contrary, diversity of sponge will be lower, with higher individual number (abundance) in continuous seagrass bed, regarding higher protection mechanism from predatory activities in continuous bed. Overall, sponge community at both seagrass beds (Site 1 and 2) were dominated by Spirastrella sp. (Sp) and Agelas conifera sponges. Antibacterial assay showed that only
Keyword: asosiasi spons, anti biofilm, bakteri simbion, interaksi ekologis, lamun

Judul: Pemodelan Nilai Tukar Rupiah terhadap Dollar Amerika Menggunakan Deret Waktu Hidden Markov Empat Waktu Sebelumnya
Abstrak: The exchange rate of Rupiah to US Dollar fluctuates according to time in a long period. An existing exchange rate might happen again in the future. Assume that the causes of the fluctuation are not observed directly and form a Markov chain, then the exchange rate of Rupiah to US Dollar can be modeled by the hidden Markov time series. In this research, the model used to describe the exchange rate of Rupiah to US Dollar is the four previous time in hidden Markov time series. This model assumes that the exchange rate of Rupiah to US Dollar depends on Markov chain explained by the cause of occurence and the four previous exchange rates of Rupiah to US Dollar. The model parameter is estimated by using the maximum likelihood method, while the estimation itself is calculated using the expectation maximization algorithm, which is implemented using Mathematica. After estimating the parameter, the exchange rate of Rupiah to US Dollar are calculated. The results are as follows. The symmetric mean absolute percentage error (SMAPE) is 2,1%, the maximum absolute error is 19,16%, the minimum absolute error is 0,0036%, and only 1,95% of the whole absolute percentage error that is bigger than 10%. These results show that the four previous time in hidden Markov time series can describe the exchange rate of Rupiah to US Dollar very well.
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