Judul: Evaluation of Seagrass Habitat Conditions Through Analysis of Seagrass Community Structure on Pramuka Island, Seribu Islands
Abstrak: Lamun memiliki peran penting bagi kehidupan biota laut sebagai produsen primer dan penyusun habitat perairan. Kualitas air dan kandungan substrat berpengaruh terhadap kelimpahan lamun di suatu perairan. Penelitian ini bertujuan untuk menganalisis hubungan antara kualitas habitat yaitu kualitas air dan kandungan substrat dengan struktur komunitas padang lamun. Penelitian ini dilakukan pada bulan November 2023 di Pulau Pramuka, Kepulauan Seribu, DKI Jakarta. Pengambilan data dilakukan di tiga stasiun meliputi pengambilan data lamun dengan tiga line transect di setiap stasiun, pengambilan data kualitas air, dan pengambilan contoh sedimen. Hasil penelitian menunjukkan terdapat 5 jenis lamun yang ditemukan yaitu T. hemprichii, E. acoroides, C. rotundata, H. ovalis, dan S. isoetifolium. Kerapatan dan penutupan tertinggi didapatkan oleh jenis T. hemprichii di tiga stasiun. Hasil analisis menunjukkan, kerapatan lamun memiliki hubungan positif dengan suhu, salinitas, oksigen terlarut, dan C-organik namun memiliki hubungan negatif dengan pH dan substrat pasir kasar. Kandungan karbon organik pada substrat dipengaruhi oleh komposisi sedimen dan kandungan karbon pada lamun dipengaruhi oleh kerapatan. Hal ini menunjukkan kondisi lingkungan perairan berpengaruh terhadap struktur komunitas lamun., Seagrasses have an important role for marine life as primary producers and aquatic habitat builders. Water quality and substrate content affect the abundance of seagrass in a body of water. This study aims to analyze the relationship between habitat quality, namely water quality and substrate content with seagrass community structure. This research was conducted in November 2023 on Pramuka Island, Thousand Islands, DKI Jakarta. Data collection was carried out at three stations including seagrass data collection with three line transects at each station, water quality data collection, and sediment sampling. The results showed that there were 5 seagrass species found, namely T. hemprichii, E. acoroides, C. rotundata, H. ovalis, and S. isoetifolium. The highest density and closure were obtained by T. hemprichii species in three stations. The analysis showed that seagrass density had a positive relationship with temperature, salinity, dissolved oxygen, and C-organic but had a negative relationship with pH and coarse sand substrate. Organic carbon content in the substrate was influenced by sediment composition and carbon content in seagrass was influenced by density. This shows that the condition of the aquatic environment affects the structure of the seagrass community.
Keyword: C-organik, Kualitas air, lamun, sedimen

Judul: Macrozoobenthos Community Structure in the  Seagrass Ecosystem as an Indicator of Habitat Quality for Pramuka Island, Seribu  Islands
Abstrak: Aktivitas antropogenik di ekosistem lamun dapat menyebabkan pencemaran dan mempengaruhi biota di dalamnya, seperti makrozoobenthos dan lamun. Penelitian ini bertujuan untuk menganalisis struktur komunitas makrozoobenthos yang dikaitkan dengan kesehatan lamun, kualitas air dan substrat pada ekosistem lamun di Pulau Pramuka, Kepulauan Seribu. Metode yang digunakan yaitu analisis parameter kualitas air, kepadatan makrozoobenthos, indeks keanekaragaman, indeks keseragaman, indeks dominansi, tipe substrat, analisis komponen utama, dan analisis Spearman Rank. Makrozoobenthos yang diperoleh terdiri atas 6 kelas, yaitu Gastropoda, Bivalvia, Asteroidea, Malacostraca, Polychaeta, dan Echinoidea. Tipe substrat di Pulau Pramuka yaitu berpasir. Indeks keanekaragaman dan indeks keseragaman tergolong tinggi dan indeks dominansi tergolong rendah. Kualitas air tergolong masih baik dan masih di batas baku mutu air laut. Kepadatan lamun di Pulau Pramuka tergolong rendah atau rusak., Anthropogenic activities in seagrass ecosystems can cause pollution and affect the biota within them, such as macrozoobenthos and seagrass. This research aims to analyze the macrozoobenthos community structure which is associated with seagrass health, water and substrate quality in the seagrass ecosystem on Pramuka Island, Seribu Islands. The methods used are analysis of water quality parameters, macrozoobenthos density, diversity index, uniformity index, dominance index, substrate type, principal component analysis, and Spearman Rank analysis. The macrozoobenthos obtained consists of 6 classes, namely Gastropoda, Bivalvia, Asteroidea, Malacostraca, Polychaeta, and Echinoidea. The substrate type on Pramuka Island is sandy. The diversity index and uniformity index are relatively high and the dominance index is low. The water quality is still classified as good and still within the sea water quality standards. Seagrass density on Pramuka Island is classified as low or damaged.
Keyword: makrozoobentos, lamun, struktur komunitas, kepadatan, community structure, density, macrozoobenthos, seagrass

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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