Judul: Effects of Temperature Change on Activity and Survival of Selected Tropical Ophiuroidea (Ophiomastix annulosa, Ophiarachna incrassata, Ophiocoma cf. dentata) and Asteroidea (Fromia milleporella)
Abstrak: It is widely accepted that global warming and climate change are have occured over the past 30 years and it changed the temperature in the air and in marine waters. Organisms in all areas, in this case in marine, are quite sensitive to temperature changes. They have a certain capacity to cope with the changing environment. If these organisms cannot adapt to environmental changes, they could die. The main stress factor that was being used in this research is temperature, and salinity as another stressor for comparison. Using selected tropical Echinoderms, the thermal and salinity capacity of these organisms was tested through simulation of environmental changes in lab. The objectives of this study are to identify the temperature limit (in comparison to lower salinity limit), activity, and assess the impact of temperature and salinity stress for selected tropical Ophiuroidea (Ophiomastix annulosa, Ophiarachna incrassata, Ophiocoma cf. dentata) and Asteroidea (Fromia milleporella). The velocity of changes (increase or decrease) in temperature might also affect the survival of the organisms. Different velocities (hourly and daily)of temperature change were investigated to see if there was any difference in temperature limit (the organisms’ capacity and adaptation) and the effects to these organisms (Ophiuroidea and Asteroidea). This experiment was conducted in Marine Habitat Lab, Faculty of Fisheries and Marine Sciences, Bogor Agricultural University (IPB); from December 2010-November 2011. The upper thermal limit (hourly increase) for Ophiomastix annulosa, Ophiarachna incrassata, Ophiocoma cf. dentata, and Fromia milleporella was 36.5 0C and 37 0C, 37.2 0C, 40.5 0C, and 35.8 0C and 35.0 0C (respectively). The upper thermal limit (daily increase) for Ophiomastix annulosa, Ophiarachna incrassata, and Fromia milleporella was 35.0 0C, 34.0 0C, and 33.0 0C (respectively). The lower thermal limit (hourly decrease) for Ophiomastix annulosa was 12.8 0C. Lower salinity limit (hourly decrease) for Ophiomastix annulosa and Ophiocoma cf. dentata was 20.5 and 13 (respectively). The thermal window for Ophiomastix annulosa (hourly experiment) was between 12.8-37.0 0C. From the result, it can be assumed that these ophiuroids and asteroids species can acclimatize and survive to more rapid changing environment than slow changing environment; as long as the oxygen is available in sufficient amount.
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Judul: Perbedaan Toleransi Antara Dua Spesies (Perna Viridis Dan Vasticardium Cf. Flavum) Di Bawah Paparan Stres Termal Dan Hipoksia
Abstrak: The environmental shifting is one major stress to sessile organisms such Bivalves. Two of most vital environmental parameters are temperature and oxygen availability. High water temperature and low oxygen concentration leading to hypoxia conditions will affecting the performance of Perna viridis and Vasticardium cf. flavum. Hypoxia (DO 0,5 mg/l) significantly causing stress to both species (pperna < 0,01; pvasticardium < 0,01), and P. viridis has higher tolerance to hypoxia compare to V. cf. flavum (p < 0,05). Heat stress (34°C) also significantly causing stress to both (pperna < 0,01; pvasticardium < 0,05), though the values of their survivorship was not differ significantly when they were compared (p > 0,05). Based on the result, can be concluded that even both factors are stressors for each species, P. viridis has better tolerance to hypoxia than V. cf. flavum; as in heat stress, both species undergo the same impact in attempt to survive.
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Judul: Closed Knight’s Tour pada Papan Catur Berbentuk Persegi Panjang dengan Ukuran Maksimal 8 × 8
Abstrak: Closed Knight’s Tour merupakan langkah kuda yang mengunjungi setiap kotak pada papan catur tepat satu kali dengan langkah kuda berawal dan berakhir pada kotak yang sama. Graf yang terbentuk dari closed knight’s tour dinotasikan sebagai graf G(m,n), dengan m adalah banyaknya baris dan n adalah banyaknya kolom. Graf tersebut memuat Hamiltonian cycle. Sebuah graf terhubung G adalah graf bipartite jika dan hanya jika graf tersebut tidak memiliki cycle dengan panjang ganjil. Papan catur yang memenuhi syarat cukup untuk memiliki closed knight’s tour adalah papan catur berukuran 5 × 6, 5 × 8, 6 × 6, 6 × 7, 6 × 8, 7 × 8, dan 8 × 8.
Keyword: bipartite, closed knight’s tour, hamiltonian cycle, knight’s tour, teori graf