Judul: Study Spatial and Temporal of Coral Reef State and Reef Fish Community after Tsunami In Weh and Aceh Islands Waters
Abstrak: The Tsunami in Aceh had caused to the damage of the Aceh nese reefs ecosystem. However, the ability to recover is naturally found in the coral reef. The purpose of the research are to determine percentages of hard coral cover and coral recruitment in Weh and Aceh Islands. The research was conducted in 2006, 2008, 2009, and 2011. The research was done in Aceh islands, utilization areas, marine natural tourist park (TWAL) and regional marine conservation areas (KKLD). Point Intercept Transect (PIT) and square transect Methods were applied in the research. The research showed that the percentages of hard coral cover in 2011 in Aceh island and utilization areas are 49,38% and 34,16 %, respectively. On the other hand, in marine natural tourist park (TWAL) and regional marine conservation areas (KKLD) are 32,66% and 41,27 % respectively. The percentages of coral cover had increased from 2006, 2008 to 2009. Meanwhile in the percentages of coral cover marine natural tourist park (TWAL) and regional marine conservation areas (KKLD) decreased in 2011. The highest recruitment occurred in 2008 in all survey areas and decreased in 2009. Thus, this study concluded that there existed a recovery of coral reef ecosystem with an increase in the percentage of hard coral cover and coral recruitment from 2006 to 2011. The highest abundances of reef fish in 2011 were found in marine natural tourist park (TWAL) with total amount and biomasses of 15.559 individual/ha and 1.574,43 kg/ha, respectively.
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Judul: Coral Reef Health Condition based on Herbivorous Fish Density in Pulau Tiga Subdistrict, Natuna District
Abstrak: The research was conducted in Pulau Tiga Subdistrict, Natuna District, Riau islands Province from April to August 2009. Pulau Tiga is an area dominated by a sea area with marine resource potential, particularly coral reefs. Around the area of coral reefs, fishing activities have been carried out intensively by fishermen using explosives (bombs) and toxic (potassium). Consequently, aquatic ecosystems have been exploited, take time to make a natural recovery in order to maintain and restore the quality and quantity of available resources. Especially for coral reef ecosystem, one of the factors that influence the resilience rate is the availability of hard substrate in a bottom waters as a settlement for coral larvae. Herbivorous animal has a major influence in determining the rate of coral reef animal larval settlement on a substrate because it can prevent the occurrence of a macro-algae excessive closure of hard substrate. This study was aimed to know the relationship between the conditions of the abundance of herbivorous fish with coral reef recovery rate. The methods used were the square transect for determining the condition of coral reefs, growth of juvenile corals and algae cover (DCA), whereas for the determination of herbivorous fish community structure using modification of Line Intercept Transect (LIT), Quadrat Method (QM) and Underwater Fish Visual Census (UVC). The analysis used was standard ecological analysis, correlation test, linier regression and multivariate analysis to find the relationship between the abundance of herbivorous fish, algae (DCA) and coral reefs. The results showed that coral reefs ecosystem in the area are still in good condition with live coral cover average of 63.17%, and shown an indication of an increase in the percentage of coral cover which previously <25%. The result of multivariate analysis can be stated that the higher the abundance of herbivorous fish, then live coral cover and growth of juvenile corals increasing, and decreasing algae cover on coral reef ecosystems. The results of correlation test, multivariate analysis and linear regression (t-Student test), show that from 24 species of herbivorous fish recorded then obtained three species of herbivorous fish that play a role in herbivory in stabilizing coral reefs ecosystem in Pulau Tiga Subdistrict, they are Chlorurus microrhinos, Scarus rivulatus and Siganus doliatus.
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Judul: Analysis of M/G/1 Queue Model with Two Phases of Service and Bernoulli Feedback System
Abstrak: Model antrean M/G/1 dengan sistem feedback Bernoulli adalah model antrean dengan proses kedatangan mengikuti proses Poisson. Pada karya ilmiah ini dibahas sistem antrean M/G/1 dengan dua fase layanan. Setelah layanan pertama selesai, pelanggan dapat memilih untuk meninggalkan sistem dengan peluang ... dst, The M/G/1 queueing model with the Bernoulli feedback system is a queueing model with the arrival process following the Poisson process. In this manuscript M/G/1 queueing system with two phases of service is discussed. After the first service is completed, the customer can choose to leave the system with probability ... dst
Keyword: queue, Bernoulli, probability generating function, expected value