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: Relationship between Seagrass Community Structure and Habitat Quality in Tidung Island, Seribu Islands
Abstrak: Ekosistem padang lamun merupakan ekosistem penting pesisir. Namun demikian, luas padang lamun di dunia terus menurun setiap tahunnya sekitar 7% per tahun. Salah satu wilayah yang memiliki ekosistem padang lamun adalah Pulau Tidung, Kepulauan Seribu. Penelitian ini bertujuan menganalisis keterkaitan struktur komunitas padang lamun dengan kualitas habitat di Pulau Tidung. Penelitian dilakukan pada bulan November 2023 dengan metode line transect untuk pengamatan lamun. Selain itu, juga dilakukan pengukuran kualitas air dan substrat (fraksi dan C-organik substrat). Analisis data yang digunakan antara lain penutupan jenis lamun, kerapatan jenis, frekuensi jenis, indeks nilai penting, indeks ekologi, serta Spearman rank correlation. Hasil penelitian ini menunjukkan kesehatan padang lamun di Pulau Tidung tergolong kategori miskin hingga kurang kaya/kurang sehat. Jenis lamun yang ditemukan sebanyak enam spesies. Thalassia hemprichii adalah jenis lamun dengan peran terbesar dalam komunitas padang lamun di Pulau Tidung. Kerapatan lamun berkaitan dengan suhu dan liat kasar secara kuat positif. Kandungan C-organik substrat memiliki kaitan yang kuat terhadap penutupan dan kerapatan lamun di Pulau Tidung., Seagrass ecosystems are important coastal ecosystems. However, the area of seagrass beds in the world continues to decline annually by about 7% per year. One of the areas that has seagrass ecosystem is Tidung Island, Seribu Islands. This study aims to analyze the relationship between seagrass community structure and habitat quality in Tidung Island. The research was conducted in November 2023 using line transect method for seagrass observation. Water quality and substrate (substrate fraction and C-organic) were also conducted. Data analysis used included seagrass species closure, species density, species frequency, importance index, ecological index, and Spearman rank correlation. The results of this study show that the health of seagrass beds on Tidung Island is classified as poor to less rich/unhealthy. Six species of seagrass were found with Thalassia hemprichii is a type of seagrass that has the largest role in the seagrass community in Tidung Island. Seagrass density was strongly positively related to temperature and coarse clay. Substrate C-organic content has a strong relationship with seagrass cover and density in Tidung Island.
Keyword: habitat, lamun, Pulau Tidung, struktur komunitas

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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