Judul: EFFECT OF SEDIMENTATION RATES AND CARNIVOROUS FISHES ON FOOD & HABITAT PREFERENCES OF CORALLIVOROUS FISH (CHAETODON OCTOFASCIATUS) IN THE SERIBU ISLANDS
Abstrak: Sedimentation rates are a major stress factor for coral reefs. It also impacts the feeding behavior and habitat of corallivorous fishes. The presence of carnivorous fishes may also influence the feeding behavior of corallivorous fishes. This study aimed to assess the relationship between Chaetodon octofasciatus and hard coral (HC) cover. In addition, sedimentation rates and predator abundance were assessed as potential influence. Data were collected at 4 different sites in the Seribu Islands north of Jakarta/Indonesia, including the abundance of Chaetodontidae and carnivorous fishes, Chaetodon octofasciatus behavior, coral reef cover, and sedimentation rates. The abundance of fishes was assessed using 50-m length belt transects deployed at 3-m depth. Coral reef cover was assessed using the Point Intercept Transect (PIT) method with 100 points for each transect. Data on fish behavior was recorded using the Focal Animal method to assess feeding rates and prey selectivity. 10 sediment traps were mounted at each site and collected after 30 days of deployment to obtain sediment samples, which were analyzed for sediment dry weight, ash-free dry weight, and organic content in the laboratory. The study results showed that the condition of coral reefs at Panjang, Belanda, and Pelangi is currently fair in terms of hard coral cover (HC<50%), while Kelapa had poor reef conditions (HC<25%). The abundance of C. octofasciatus had a high relationship with HC cover and showed a weak relationship with predators. Sedimentation rates had the strongest relationship with the feeding rates of C. octofasciatus compared with predators and HC cover.
Keyword: Chaetodon octofasciatus, Terumbu karang, Sedimentasi, Kepulauan Seribu, Laju pemangsaan, Ikan terumbu, Ikan predator, Ikan Kupu-kupu, Butterflyfish, Coral reef, Sedimentation, Reef fishes, Predator fishes, Feeding rates

Judul: Respon Tingkat Pemangsaan Ikan Obligate Corallivore (Chaetodon octofasciatus, Bloch 1787) Terhadap Sedimentasi dan Pemutihan Karang di Perairan Taman Nasional Karimunjawa, Jawa Tengah.
Abstrak: Ikan pemakan polip karang atau koralivor dari Famili Chaetodontidae mempunyai hubungan yang sangat erat dengan terumbu karang. Namun sebagian besar terumbu karang saat ini sedang dalam tekanan akibat sedimentasi dan pemutihan karang, dimana tekanan tersebut mampu mempengaruhi kelimpahan dan kebiasaan makan dari ikan koralivor. Penelitian ini dilakukan untuk mengetahui kebiasaan makan Chaetodon octofasciatus sebagai spesies koralivor sejati selama terjadi sedimentasi dan pemutihan karang di Taman Nasional Karimunjawa, Jawa Tengah. Data lapangan diambil pada enam lokasi pengambilan data. Sebanyak lima sedimen trap dipasang pada setiap lokasi untuk mengetahui laju sedimentasi serta kandungan organik dan anorganik sedimen, Transek sabuk dan transek kuadran masing-masing digunakan untuk mengestimasi kepadatan karang dan kondisi pemutihan karang. Metode visual census digunakan untuk mengetahui kelimpahan dan kebiasaan makan Chaetodon octofasciatus. Hasil penelitian menunjukkan bahwa Chaetodon octofasciatus memakan berbagai genus karang dengan kecenderungan memilih atau menghindari genus tertentu. Dari 35 genus karang yang ditemukan, 22 diantaranya dikonsumsi oleh Chaetodon octofasciatus. Berdasarkan Indeks Pemilihan Makanan Strauss, Chetodon octofasciatus menunjukkan pemilihan makanan pada genus Acropora, Echinopora, Favites, Montipora, Pavona dan Porites. Hasil penelitian juga menunjukkan hubungan positif antara kelimpahan Chaetodon octofasciatus dengan kepadatan karang hidup. Kandungan sedimen organik secara signifikan mempengaruhi tingkat pemangsaan dengan menurunkan jumlah gigitan Chaetodon octofasciatus pada karang. Adapun laju sedimentasi, kandungan anorganik sedimen dan kejadian pemutihan karang tidak mempengaruhi pemangsaan Chaetodon octofasciatus. Penelitian ini mempertegas bahwa gangguan pada terumbu karang mampu mengubah kebiasaan makan pada ikan terumu karang.
Keyword: Chaetodontidae, Koralivor, Sedimentasi, Pemutihan, Karang, Chaetodon octofasciatus

Judul: The Exploration of Discrete Logarithm over Finite Field GF(3m)
Abstrak: The security of many public~key algorithms is based on the problem of finding discrete logarithms. The generalized discrete logarithm problem is the following: given a finite cyclic group G of order n, a generator a of G, and an element fl E G, find the integer x, 0 ~ x ~ n - 1, such that 0: = fl. Algorithm for discrete logarithm problem focused on Menezes et al. (1997) that consist of exhaustive search algorithm, the baby-step giant-step algorithm, Pollard's rho algorithm, Pohlig-Hellman algorithm, and index-calculus algorithm. These algorithms are explorated to be used in discrete logarithm problem over finite field GF(3m ). The exploration also produces some algorithms, i.e. naif negative algorithm, baby-step mother-step algorithm, baby-step mother free-step algorithm, and baby-step free-step algorithm. All algorithms implemented using Maple 11. The Pohlig-Hellman and baby-step giant-step algorithms are efficient enough to be used in discrete logarithm problem over finite field GF(3m ) for m < 20.
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