Judul: Population Dynamics of Sea Urchin (Tripneustes gratilla Linnaeus 1758) in Semerang Beach, Eastern of Lombok
Abstrak: Sea urchins (T. gratilla) is one of marine biota which has high economic value. Gonads of sea urchins usually call with “Roe”. Sea urchins roe can be used as a highly nutritious food. The sea urchins roe are a popular food and has very decent trade value, especially for the export of Japan, Korea, USA, Russia, Canada, Chile, Mexico, France, China. Utilization of sea urchin roe as food for coastal communities has longstanding in Lombok island. During the time period of the exploitation of sea urchin population without any caught control to save it sustainability. Over exploitation is one of the causes of declining populations of sea urchins in the wild. Therefore, the over fishing could be threaten the sustainability of sea urchins resource in the coastal of Lombok island. This research has four main objectives that include the following: (1) study about the spatial distribution of sea urchin (T. gratilla) and environmental factors that influence; (2) study about the population dynamics of sea urchin (T. gratilla), such as growth rate, mortality, gonadal maturation and spawning season, (3) determine the length at sexual maturation (Lm) and length of sea urchin T. gratilla that caught by fishermen, and (4) to analyze the status and the resource utilization level of sea urchin (T. gratilla). This result showed that 6 species of seagrasses has been found in Semerang Beach includes Cymodocea rotundata, Cymodocea serullata, Syringodium isoetifolium, Halophila ovalis, Halodule uninervis, and Thalassodendron ciliatum. Seagrass vegetation types in Semerang Beach is mixed vegetation (mixed seagrass beds) were generally dominated by C. rotundata, S. isoetifolium and H. ovalis. Densities of sea urchin T. gratilla ranging from 1,07 to 6,32 individual/100m2 with uneven distribution and related to the depth of water and seagrass cover. The Result of analysis showed that sea urchins T. gratilla is alometric negative growth (b<3), rated slowly growth and has small infinity length (D∞ = 92,4, K =0,780 dan to = - 0,084). Result also showed the total mortality value of sea urchins is 3,78 year-1 with low natural mortality (1,13 year-1) and high fisheries mortality (2,65 year-1). Based on thes value, estimated of exploitation rate (E) is 0,70 that indicate the overfishing condition. Spawning peak and recruitment occur on June (25% spawning stage). Size at sexual maturation is fairly large (58,2 mm) and achieved in a long time (1,2 years). Numbers of fishermen ranging from 5 – 16 persons with catch amount ranging from 569 – 1598 urchins/period. Harvesting intensity reached 52 urchins/person/hour and diameter of harvest sea urchins by fishermen ranging from 48,5 mm – 89,1 mm with 67,3 mm mean size.
Keyword: exploitation, population dynamics, sea urchin, seagrass, Semerang beach

Judul: Performance of gonad development of sea urchin (Tripneustes gratilla) fed artificial diet with different protein level and energy-protein ratio, and estradiol 17-β hormone.
Abstrak: Sea urchin is one of the important marine biota which has economic value. Its gonads fetch high price in many countries. The research was conducted in four phases. The first phase was to study the biological reproduction aspect of sea urchin (Tripneustes gratilla) that catched from Kupang Bay. Ten to thirty individuals were catched every month from May until December 2008. Parameters observed consisted of gonad weight, gonad somatic index, oocyte diameter, gonad colour, test diameter, and body weigth. The second phase was to study gonad development of sea urchin that reared in captivity. Twenty five individuals were reared in tank (2.5 x 2.0 x 1.5 m) and fed macroalga every two days. Parameters such as testosterone and estradiol hormone in gonad and coelomic fluids, gonad weight, and oocyte diameter were measured every two weeks. The third phase was to know the requirement of protein and energy-protein ratio to maximize gonad production and quality. Adult sea urchins were collected from the wild and held in aquarium at laboratory. Nine formulated diet were prepared in order to examine two experimental factors: (1 protein levels (22, 27, and 32%) and (2) energy protein ratio (9, 11, 13 kcalGE/g protein). Gonad weight, protein, total carotenoid, β-carotene, colour, texture, and gonad taste were evaluated at the end of the experiment. The fourth phase was to study the effect of estradiol-17β at dose of 10 and 30 μg/g wet weight of diet for accelerating gonad maturation of sea urchin at different test diameter: 50 – 59, 60 – 69, and 70 – 79 mm. Parameter observed in this experiment were the same as that of the second phase. Result from the first phase showed gonad of sea urchin consisted of five stages of development, namely; developing/recovering, growing, pre mature, mature, and partial spawning. At the second phase, development stages of gonad were the same as observed at the first phase, gonad maturation achieved maximum at 9th week. At the third phase, the 32% protein level and 9 kcal GE/g energy-protein ratio gave higher production and gonad quality. At the fourth phase, estradiol-17β at dose 30 μg could accelerate gonad maturation of sea urchin at the 60 – 69 mm test diameter. Gonad maturation achieved maximum at 7th week. As conclusion, application of 32% protein and 9 ccal GE/g energy-protein ratio, as well as estradiol-17β could maximize gonad performance.
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Judul: Construction of Strongly Optimal Binary Linear Code with Minimum Distance 9 and 11
Abstrak: A binary linear code of length n over q F is a subspace of n q F . A code has three parameters that attached to it, namely length, dimension, and minimum distance. A code with length n, dimension k and minimum distance d is often called [n, k, d ]-code. Usually, when two parameters are given, then we want to find a code that has the best value for the last parameter. Based on Gilbert- Varshamov bound, if a [n, k, d ]-code exists and can not be expanded, we call it a strongly optimal code. In this paper, we construct strongly optimal code with minimum distance 9 and 11. In constructing the code, we created a theorem and algorithm based on Gilbert-Varshamov bound before we implement the algorithm to MAPLE programming language. Because of computational limitations, the program can only construct up to k = 10 for d = 9 and k = 12 for d = 11.
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