Judul: Kajian Degradasi Ekosistem Mangrove Terhadap Populasi Polymesoda erosa di Segara Anakan, Cilacap
Abstrak: Segara Anakan is an unique ecosystem with lagoons, mangrove and lowland. Segara Anakan located in the southerncoast of Java Island at 07°34'29 .42 "S - 07º47'32.39" S and 108º46'30.12"E-109°03'21.02"E. Mangroves is inhabited by typical mangrove ecosystem biotas, ones of which is clams. Clam is one of major components in the mangrove’s soft sediment community. One of biota living in mangrove ecosystem is Polymesoda erosa called “totok” or “kepah” in local name. The species is valuable both economically and ecologically. In the other side, degradation occurred in mangrove Segara Anakan. The economic demands of growing population at Segara Anakan are continuously increasing. Resulting in various human activities which strongly alter and deteriorate environmental conditions for the flora and fauna. These activities include mangrove cutting, reclamation of agricultural land and urbanisation. They are responsible for the destruction of almost half of the mangrove area. This study has four main objectives that include the following: (1) to determine degradation of mangrove in Segara Anakan; (2) to determine population condition of P. erosa in Segara Anakan; (3) to analyze its relationship with mangrove degradation in Segara Anakan; (4) to determine utilization of P. erosa in Segara Anakan. Purposive Sampling was used to collect the clams data and plots sampling techniques were applied to obtain vegetation data. Average of P. erosa abundance ranged from 9.83 + 4.68 ind/m2. Age distribution was presented as histograms and assumed be equal to length of shell. Dominant sizes were from 4.6 – 5.8 cm. The distribution pattern determined by variance index shows aggregate distribution. Very weak correlation was found between P. erosa and mangrove that indicates not connected directly. Tree category was dominated by Nypa fructicans. Sapling category was dominated by Rhizophora apiculata and Acanthus ebracteatus, Acanthus ilicifolius for seedlings, shrubs and herbs. Based on GIS analysis, mangrove area in Segara Anakan was 8036.9 ha. P. erosa strongly correlates to environmental components based PCA namely water content of soil, temperature and light intensity. People utilized P. erosa as source of food, income and land hoard.
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Judul: Distribusi Kelimpahan Gastropoda dan Kaitannya dengan Kawasan Mangrove di Segara Anakan, Cilacap.
Abstrak: Mangrove merupakan ekosistem pesisir yang berperan penting sebagai habitat bagi gastropoda. Beberapa tahun terakhir terjadi degradasi mangrove di kawasan Cilacap yang berdampak pada populasi gastropoda. Penelitian ini bertujuan untuk mengetahui keterkaitan struktur komunitas gastropoda dengan mangrove. Pengamatan mangrove menggunakan transek 10 x 10 m2 pada tiga stasiun sebanyak 9 kali pengulangan. Pengamatan gastropoda dilakukan pada tiga stasiun sebanyak di dalam transek mangrove dengan menggunakan transek 1 x 1 m2 yang ditempatkan pada 5 titik di dalamnya secara sistematis sebanyak 45 kali pengulangan. Analisis data gastropoda meliputi keanekaragaman, keseragaman, dominasi, kerapatan jenis mangrove, dan analisis koresponden (CA) terhadap kepadatan gastropoda dengan mangrove. Hasil penelitian ditemukan sebanyak 22 spesies dari 7 famili gastropoda yaitu Assimineidae, Ellobiidae, Littorinidae, Muriciidae, Neritiidae, Pachychilidae dan Potamididae. Spesies gastropoda yang mendominasi seluruh stasiun pengamatan adalah Cerithidea obtusa. Kepadatan jenis gastropoda tertinggi berada pada Stasiun 2 yaitu 0,86 ind/m2, sedangkan terendah berada pada Stasiun 3 yaitu 0,73 ind/m2. Spesies gastropoda yang ditemukan pada ekosistem mangrove memiliki nilai indeks keanekaragaman yang dikategorikan sedang dan tidak terdapat jenis gastropoda yang dominan. Kualitas lingkungan perairan Segara Anakan masih dalam kondisi baik dan layak untuk mangrove maupun gastropoda dengan dominasi substrat pada kawasan tersebut adalah pasir sangat halus. Nilai kepadatan gastropoda berkorelasi dengan kerapatan mangrove dan sebaran jenis gastropoda berasosiasi dengan jenis mangrove tertentu.
Keyword: ekosistem, gastropoda, indeks, kualitas perairan, mangrove

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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