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: Interaksi landak laut dan lamun di Pulau Barrang Lompo,  Kepulauan Spermonde, Sulawesi Selatan
Abstrak: Sea urchin is an active grazer on seagrass. The grazing may have affected on the seagrass bed. The aim of this research was to study the interaction between the sea urchin and seagrass in the Barrang Lompo Island, South Sulawesi. The measurement of the seagrass and the sea urchin density were using a linier quadrant transect method. Correlation between the seagrass and the sea urchin were analyzed using Pearson‟s correlation. The results showed that the highest value of INP (Indeks Nilai Penting) were Thalassia hemprincii (129,39), Enhalus acoroides (88,92), Cyomodecea rotundata (36,10), Halodula uninervis (28,26), Halophila ovalis (9,23) and Syngirodium isoefolium (7,16), respectively. The community of sea urchin was dominated by Tripneustes gratilla (63.69 ind/m2), followed by Diadema setosum (23.10 ind/m2), Echinotrix calamaris (6.10 ind/m2), Echinotrix diadema (2.47 ind/m2), Echinometra matheai (1.33 ind/m2), and Mespilia globulus (1.33 ind/m2). No relationship beetwen seagrass and sea urchin was observed (r= -0.111, P= 0.485) since not all the sea urchin are grazer. Between seagrass on three age stages and sea urchin also showed no significant relationship since the stage pattern of seagrass and its tanin content may not preferred by the sea urchin. The present of T. gratilla and D. setosum as main grazer however showed no significant relationship with the seagrass. D. setosum is food adaptive and T. gratilla utilizes the seagrass leaf as food and protection from wave and predator.
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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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