Judul: Crustacean and Seagrass Association on Coastal Waters Pramuka Island, Thousand Islands, DKI Jakarta
Abstrak: Lamun merupakan tumbuhan berbunga (Angiospermae) yang mampu hidup dan beradaptasi di perairan dengan salinitas yang tinggi. Ekosistem lamun berperan penting bagi kehidupan biota-biota di laut dangkal. Krustasea termasuk salah satu kelompok biota yang memanfaatkan padang lamun sebagai tempat berlindung, mencari makan serta memijah. Penelitian ini bertujuan menganalisis hubungan antara krustasea dan lamun di perairan pesisir Pulau Pramuka, Kepulauan Seribu, DKI Jakarta. Pengambilan data dilakukan dari tanggal 3-7 Februari 2020 pada 2 stasiun. Lamun yang ditemukan sebanyak 4 jenis, yaitu Enhalus acoroides, Cymodocea serrulata, Thalassia hemprichii, dan Halophila ovalis dengan kerapatan tertinggi dijumpai pada jenis Cymodocea serrulata di kedua stasiun. Dari hasil CA sebaran lamun dan krustasea berdasarkan stasiun, terdapat 2 kelompok asosiasi krustasea dan lamun. Kelompok I mengasosiasikan krustasea jenis Calappa depressa, Scylla serrata, Pagurus granosimanus, Ocypode occidentalis, dan Palaemon serenus dengan lamun jenis Enhalus acoroides dan Cymodocea serrulata. Pada kelompok II, Clibanarius cruentatus, Clibanarius vittatus, dan Pagurixus handrecki berasosiasi dengan Thalassia hemprichii., Seagrass is a flowering plant (Angiosperms) that can live and adapt in high saline waters, thus forming coastal ecosystem with vital roles for diverse marine biota. Crustaceans are a group of biota that use seagrass beds as nursery, feeding, and spawning ground. This study aimed to analyze the relationship between crustaceans and seagrass in coastal waters of Pramuka Island, Kepulauan Seribu, DKI Jakarta. Data collection was carried out from 3-7 February 2020 at two stations. There were four types of seagrass observed: Enhalus acoroides, Cymodocea, Thalassia hemprichii, and Halophila ovalis. Cymodocea serrulata had the highest density at both stations. From CA results, seagrass and crustacean distribution formed two groups of association. In group I, crustaceans of Calappa depressa and Scylla serrata, Pagurus granosimanus, Ocypode occidentalis, and Palaemon serenus were associated with seagrass Enhalus acoroides and Cymodocea serrulata. In group II, Clibanarius cruentatus, Clibanarius vittatus, and Pagurixus handrecki were associated with Thalassia hemprichii.
Keyword: seagrass, crustaceans, habitat, association, Pramuka Island

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: Dynamical System of Hepatitis B in Three Groups with Vaccination
Abstrak: The aim of this study is to modify the hepatitis B transmission model in three age groups involving vaccination from the model conducted by Zhoe and Zhang.The method used is to analyze the stability of the fixed point and its basic reproduction number (R_0). Performed stability analysis and numerical simulation to see population dynamics. Next, a sensitivity analysis of the parameters was carried out to see its effect on R_0. From the analysis obtained two fixed points, namely non-endemic and endemic fixed points. Non-endemic fixed points are locally asymptotically stable if R_0 <1 Meanwhile, the endemic fixed point is locally asymptotically stable if R_0 > 1. Hepatitis vaccination affects the number of susceptible population, because the more successful the vaccination, the smaller the number of susceptible populations so that the smaller the population will be infected.
Keyword: Dynamic, Hepatitis B, Vaccine, Mathematical model