Judul: Diversity and Association of Epifauna Gastropods in Mangrove and Seagrass of Tidung Kecil Island, Seribu Island
Abstrak: Pulau Tidung Kecil memiliki berbagai ekosistem pesisir, seperti ekosistem mangrove dan lamun. Kedua ekosistem tersebut menjadi tempat berlindung, mencari makan, dan memijah bagi gastropoda. Penelitian ini bertujuan menganalisis keanekaragaman dan asosiasi gastropoda epifauna pada mangrove dan lamun Pulau Tidung Kecil, Kepulauan Seribu. Pengamatan data mangrove, lamun, dan gastropoda dilakukan pada 4 (empat) stasiun dengan metode transek garis dan transek kuadrat, setiap stasiun dilakukan pengukuran kualitas perairan. Gastropoda epifauna yang ditemukan pada lokasi penelitian terdiri dari 25 spesies dan 11 famili yaitu famili Cerithiidae, Ellobiidae, Littorinidae, Muricidae, Nassariidae, Naticidae, Neritidae, Potamididae, Strombidae, Trochidae, dan Turbinidae dengan nilai keanekaragaman keseluruhan stasiun tergolong sedang. Spesies gastropoda epifauna yang mendominasi yaitu Terebralia palustris dari famili Potamididae. Spesies mangrove yang ditemukan pada lokasi penelitian yaitu Rhizophora stylosa, sedangkan spesies lamun yaitu Thalassia hemprichii, Enhalus acoroides, Cymodocea rotundata, dan Halophila ovalis. Kualitas perairan pesisir Pulau Tidung Kecil tergolong baik untuk mangrove, lamun, dan gastropoda dengan tipe substrat lempung berdebu. Hasil analisis CA menunjukkan bahwa famili gastropoda Cerithiidae, Ellobiidae, Muricidae, Naticidae, Neritidae, Strombidae, dan Turbinidae berasosiasi dengan lamun, sedangkan famili gastropoda Littorinidae dan Trochidae berasosiasi dengan mangrove., Tidung Kecil Island has various coastal ecosystems, such as mangrove and seagrass ecosystems. Both ecosystems provide shelter, foraging, and spawning for gastropods. This study aims to analyze the diversity and association of epifauna gastropods in the mangrove and seagrass of Tidung Kecil Island, Seribu Island. Observation of mangrove, seagrass, and gastropod data was carried out at 4 (four) stations using line transect and quadratic transect methods, each station measuring water quality. The epifauna gastropods found at the study site consisted of 25 species and 11 families, namely Cerithiidae, Ellobiidae, Littorinidae, Muricidae, Nassariidae, Naticidae, Neritidae, Potamididae, Strombidae, Trochidae, and Turbinidae with the overall diversity value of the stations classified as moderate. The dominant epifauna gastropod species was Terebralia palustris from family Potamididae. The mangrove species found at the research site was Rhizophora stylosa, while the seagrass species were Thalassia hemprichii, Enhalus acoroides, Cymodocea rotundata, and Halophila ovalis. The coastal water quality of Tidung Kecil Island was classified as good for mangroves, seagrasses, and gastropods with a silt loam type of substrate. The results of CA analysis showed that the gastropod families Cerithiidae, Ellobiidae, Muricidae, Naticidae, Neritidae, Strombidae, and Turbinidae were associated with seagrass, while the gastropod families Littorinidae and Trochidae were associated with mangrove.
Keyword: lamun, association, diversity, gastropod, mangrove, seagrass, asosiasi, gastropod, keanekaragaman

Judul: Community Structure of Bivalve and Its Relationship with the Seagrass Ecosystem on Tidung Kecil Island, Seribu Islands.
Abstrak: Pulau Tidung Kecil merupakan pulau yang memiliki padang lamun yang dapat menunjang keberlangsungan hidup organisme laut salah satunya bivalvia. Penelitian bertujuan menganalisis struktur komunitas bivalvia dan keterkaitannya dengan ekosistem lamun di Pulau Tidung Kecil, Kepulauan Seribu. Penelitian dilakukan pada empat stasiun dengan tiap stasiun diukur kualitas lingkungan perairan dan sedimen. Pengambilan data lamun dan bivalvia menggunakan transek garis dengan panjang 50 m dan transek kuadrat ukuran 0,5 x 0,5 m². Hasil penelitian ditemukan empat spesies lamun dengan kerapatan tertinggi yaitu Thalassia hemprichii. Bivalvia yang ditemukan terdiri dari tujuh famili dan 15 spesies, dengan kepadatan spesies tertinggi yaitu Tellina timorensis sebesar 6,67 ind/m2. Kualitas lingkungan perairan Pulau Tidung Kecil tergolong baik dengan substrat dominan pasir. Analisis Koresponden menunjukkan terdapat tiga kelompok keterkaitan bivalvia dan lamun. Famili Tellinidae dan Cardiidae dengan lamun Thalassia hemprichii, Famili Lucinidae, Arcidae dan Veneridae dengan lamun Halophila ovalis dan Enhalus acoroides dan famili Mactridae dan Donacidae dengan lamun Cymodocea rotundata., Tidung Kecil Island is an island that has seagrass beds can support the survival of marine organisms, including bivalves. The study aims to analyze the bivalve community structure and its relationship with the seagrass ecosystem on Tidung Kecil Island, Seribu Islands. The study was conducted at four stations with measures quality of the aquatic and sedimentary. The collection of seagrass data used line transect 50 m and quadrat transect 0,5 x 0,5 m2. The results of the study found four seagrass species with the highest density is Thalassia hemprichii. Bivalves were found consisting of seven families and 15 species, with the highest density is Tellina timorensis at 6,67 ind/m2. The quality of Tidung Kecil Island aquatic environment is good with a dominant sandy substrate. Correspondence analysis showed that there are three groups related of bivalve and seagrass on Tidung Kecil Island. The families Tellinidae and Cardiidae with seagrass Thalassia hemprichii, families Lucinidae, Arcidae and Veneridae with seagrasses Halophila ovalis and Enhalus acoroides and famili Mactridae and Donacidae with seagrass Cymodocea rotundata.
Keyword: bivalve, correspondence analisys, seagrass, Tidung Kecil Island

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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