Tujuan dari penelitian yaitu untuk mengetahui struktur komunitas mangrove di Desa Lamanggo dan Desa Tope, untuk mengetahui kelimpahan kepiting bakau di hutan mangrove, dan untuk mengetahui hubungan antara kerapatan mangrove dengan kepadatan kepiting.Penelitian dilakukan dengan menggunakan metode line transek kuadran dengan menentukan lima lokasi titik pengamatan pengambilan sampel, dan untuk mengetahui kondisi mangrove maka dilakukan perhitungan kerapatan jenis, frekuensi jenis, penutupan jenis, dominasi, indeks nilai penting dan keanekaragaman serta analisis kelimpahan kepiting bakau yang berhubungan dengan kerapatan mangrove dengan rumus Y = a + b X.. Dari hasil penelitian yang dilakukan, diketahui bahwa jenis mangrove yang memiliki nilai kerapatan tertinggi yaitu Rhizophora apiculata, dan untuk nilai frekuensi tertinggi juga yaitu jenis Rhizophora apiculata, sedangkan untuk nilai dominasi tertinggi dimiliki oleh jenis Sonneratia alba.Berdasarkan uji korelasi antara kerapatan pohon mangrove (X) terhadap kepadatan kepiting (Y) sebagaimana terlihat diperoleh r sebesar = 0,814 dengan Fhitung sebesar 1.94 < Ftabel 10.12. Hal ini berarti tidak terdapat hubungan yang signifikan antara kerapatan mangrove dengan kepadatan kepiting bakau. Selanjutnya untuk melihat besarnya kontribusi kerapatan mangrove terhadap kepadatan kepiting dicari melalui koefisien determinasi R² = 0.66 yang berarti variabel kerapatan pohon mangrove tidak memberikan kontribusi terhadap kepadatan kepiting. Karena jika setiap penambahan variabel X, maka variabel Y akan berkurang sebesar 67.54937 - 0.110 X.
During rainy season, a various type of litter can enter the ocean through rivers. This is a significant contributor to the amount of marine litter in the waters. In order to access the type, composition, and density of the litter during rainy season, this study was conducted in Manado Bay, North Sulawesi. The observation was done on the litter stranded on the beach, and they were classified into two different size groups, macro (>2,5 cm)- and meso (0,5-2,5 cm)-sizes. Malalayang Beach and Bailang Beach were chosen for the location of the study. Litter type, composition, and density was evaluated according to National Marine Litter Monitoring Guide. The result showed that there were 7 types of macro-size and 6 types of meso-size marine litter in Malalayang Beach and it was dominated by glass and ceramic for both sizes. In Bailang Beach, 9 types of macro-size and 7 of meso-size were found, and it was dominated by plastics. It can be concluded that various type of marine litter present in Manado Bay, both macro- and meso- sizes, during the rainy season. The highest composition was the glass and ceramics type. However, the highest density was the plastic type.---Pada musim hujan, berbagai jenis sampah dari daratan masuk ke perairan pantai melalui sungai. Hal ini merupakan penyumbang signifikan bagi jumlah sampah laut di perairan. Untuk menilai jenis bahan, komposisi, dan kepadatan sampah laut pada musim hujan, penelitian ini dilakukan di Teluk Manado, Sulawesi Bagian Utara. Pengamatan dilakukan terhadap sampah laut yang terdampar di pantai (beach litter), berukuran makro (> 2,5 cm) dan meso (0,5-2,5 cm), di dua lokasi, yaitu Pantai Malalayang dan Pantai Bailang. Sampah laut dievaluasi menggunakan Pedoman Nasional tentang Pemantauan Sampah Pantai. Hasil penelitian menunjukkan, sampah laut jenis plastik, kaca & keramik, busa plastik, kertas & kardus, logam, karet, kayu, kain, dan bahan lainnya, baik berukuran makro maupun meso ditemukan di perairan. Di Pantai Bailang, komposisi sampah laut berukuran makro dan meso didominasi oleh jenis bahan plastik; tetapi, di Pantai Malalayang didominasi oleh jenis kaca & keramik. Demikian juga untuk kepadatan sampah laut di Pantai Bailang, jenis bahan plastik mendominasi, baik sampah berukuran makro maupun meso. Sedangkan di Pantai Malalayang, jenis kaca & keramik mendominasi kepadatan sampah laut pada semua ukuran. Selanjutnya, dapat disimpulkan, pada musim hujan, berbagai jenis bahan sampah laut berada di Teluk Manado, baik berukuran makro maupun meso. Komposisi terbesar untuk ukuran makro dan meso ialah jenis bahan kaca & keramik. Namun, kepadatan tertinggi untuk ukuran makro dan meso ialah sampah jenis bahan plastik.
Abstract. Wullur S, Napitupulu H, Wantania LL, Ginting EL, Warouw V, Tallei TE, Rumengan IFM. 2020. Molecular identification of bacteria isolated from culture medium of rotifer fed on fishery waste diet. Biodiversitas 21: 2735-2740. The aim of this study was 16S-rRNA sequences based molecular identification of bacteria isolated from culture medium of rotifer fed with fishery waste diet (FWD). We cultured rotifer Brachionus rotundiformis in sterilized seawater (salinity 25 ppt) using FWD, following the procedure in Patent No. P00201609066. Bacteria from the culture were collected, homogenized, diluted 10 to 1000 fold, spread on agar plates and incubated at 370C for 24 to 48 hours. Representative colonies of the bacteria according to their morphologies were isolated for further characterization. Genomic DNA of the isolates were extracted, and the 16S rRNA gene of the isolates were amplified. Polymerase Chain Reaction (PCR) product of each isolate was sequenced and queried against the NCBI GenBank database. Six different isolates based on size, color, elevation, margin, and colony were observed during 24-48 hours incubation at 370C. The 16S rRNA genes of the six isolates were successfully amplified and produced DNA band at 1300-1500 bp, with quality value equal to or greater than 20 (QV20+) of each entire sequence around 941-1253 bases. Basic Local Alignment Search Tool (BLAST) queries in the NCBI GenBank and EzBioCloud database using the 16S-rRNA gene sequences showed that the six isolates belong to four different genera, i.e: Bacillus, Staphylococcus, Vibrio, and Alteromonas.
Marine debris has become a global concern due to its impact on marine ecosystems. These materials generally come from land and are deposited to marine environment through different agent of carrier. Many efforts are being made to monitor the dynamics of the debris including their presence and their variability in relation to seasons. The latter are assumed from the facts that the presence of the debris is mainly affected by the waves, speed, and direction of ocean currents in the area of interest. In this study, variation of debris in dry and wet season at Manado Bay was assessed by using a shoreline technique. Two locations are selected, Bailang and Malalayang beach. The samplings were conducted in August 2019 (represent dry season) and January 2020 (represent wet season). Several parameters are examined during the sampling; they are: amount of material, type of debris, composition, and spatial density of each type for macro-size (>2.5 cm) and meso-size (0.5–2.5 cm). The results showed that there was variation on composition and density, but the types of debris remain unchanged. Our present study concluded that variation in the season do not affect the variability of marine debris in Manado Bay.
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