Judul: Temporal Pattern of Coral Reef Fish Comunity in Tidung Kecil Island Using eDNA Metabarcoding and Underwater Visual Census
Abstrak: Coral reef fish is one of the indicator for assessing the level of biodiversity of a coral reef ecosystem. The existence of coral reef fish can be affected by anthropogenic and natural factors, one of which is a seasonal variability. Various studies have reported that the structure of fish communities can be influenced by seasonal variations. Seasonal monitoring is important to detect temporal variation in fish communities. This study aims to assess the structure of coral reef fish communities based on seasons in Tidung Kecil Island using environmental DNA metabarcoding and Underwater visual census. Underwater visual census was conducted on 250 m2 and 1 L water sample was collected from sediment. The sample extraction was carried out using a Zymo Research Extraction Kit and follwed by PCR process using MiFish primers targeting 12S rRNA, then sequencing using Next Generation Sequencing from Illumina Nextseq 500. Sequencing product was analyzed using MiFish Pipeline and followed by abundance and ecological index analysis. The UVC identified 32 species belonging to 10 families in the rainy season and 29 species belonging to 7 families in the dry seasons. The eDNA metabarcoding identified 209 species belonging to 56 families and 27 species belonging to 17 families in the western and eastern seasons, respectively. Based on eDNA metabarcoding data, coral reef fish abundance and community composition differed significantly between seasons (Mann Whitney, p<0.01), while the UVC method did not detect these seasonal differences (Mann Whitney, p>0.05). Based on group category, fish abundance was dominated by major and target fish in west and eastern seasons both using UVC and eDNA. Diveristy indice did not differ significantly between seasons for either method. The Similarity Percentages (SIMPER) analysis was discovered Pomacentrus alexanderae (10.24%) and Abudefduf vaigiensis (44.40%) as highest contribution in western and eastern season using UVC, while Planiliza macrolepis (66.54%) and Plectropomus aerolatus (8.80%) in western and eastern season using eDNA., Ikan terumbu karang merupakan salah satu indikator dalam menilai keanekaragaman hayati di ekosistem tersebut. Keberadaan ikan terumbu karang dapat dipengaruhi oleh faktor antropogenik maupun faktor alam, salah satunya adalah faktor perubahan musim. Beberapa penelitian telah melaporkan bahwa struktur komunitas ikan dapat dipengaruhi oleh variasi musim. Kegiatan monitoring secara musiman sangat penting untuk mendeteksi variasi temporal pada komunitas ikan. Penelitian ini bertujuan untuk mengkaji struktur komunitas ikan terumbu karang berdasarkan musim di Pulau Tidung Kecil dengan menggunakan metabarkoding DNA Lingkungan dan Sensus Visual. Pengamatan secara sensus visual dilakukan dengan luas area 250 m2 , dan sampel air laut diperoleh dari bagian sedimen sebanyak 1 L. Proses ekstraksi sampel dilakukan dengan menggunakan protokol dari Kit Zymo Research, USA dan dilanjutkan dengan proses PCR menggunakan primer MiFish U dengan target lokus 12S rRNA. Sekuensing sampel dilakukan dengan menggunakan Next Generation Sequencing dari Illumina Nextseq 500. Produk sekuensing dianalisis menggunakan perangkat lunak MiFish Pipeline dan dilakukan analisis lebih lanjut mengenai kelimpahan dan indeks ekologi. Penelitian ini berhasil mengidentifikasi 32 spesies pada musim barat dari 10 famili dan 29 spesies dari 7 famili pada musim timur menggunakan UVC, sedangkan eDNA berhasil mendeteksi 209 spesies dari 56 famili pada musim barat dan 27 spesies dari 17
Keyword: Next generation monitoring, Underwater Visual Census, Seasonal Abundance, Reef Fish

Judul: Community Structure of Reef Fish in Coral Reef Ecosystem on Tidung Island, DKI Jakarta
Abstrak: Ekosistem terumbu karang merupakan ekosistem produktif untuk perikanan dan organisme akuatik lainnya. Ekosistem terumbu karang menjadi habitat vital bagi komunitas ikan khususnya ikan terumbu. Ikan terumbu adalah komponen penting di lingkungan perairan, keberadaan komunitas ikan terumbu pada ekosistem terumbu karang penting untuk diketahui, karena peran dan fungsi secara ekologi ikan dalam menjaga kestabilan komunitas terumbu karang dan keseimbangan komponen penyusun ekosistem terumbu karang lainnya. Penelitian ini bertujuan mengetahui struktur komunitas ikan terumbu di Pulau Tidung. Penelitian ini dilakukan di Pulau Tidung pada tanggal 9 - 12 Juni 2022. Metode pengambilan data ikan terumbu menggunakan Underwater Visual Census (UVC) dengan transek 50 meter, dan diletakkan tiga transek di setiap stasiunnya. Data ikan terumbu dianalisis dengan tiga indeks komunitas, yaitu indeks keanekaragaman, indeks keseragaman, dan indeks dominansi. Hasil penelitian ditemukan 3982 individu ikan terumbu, 24 famili dan 91 spesies. Komposisi ikan indikator sebesar 2,44%, target 17,20%, dan ikan mayor sebesar 80,36% dari total individu yang ditemukan. Nilai rata-rata indeks keanekaragaman 2,77, keseragaman sebesar 0,88, dan dominansi 0,08. Nilai ini menunjukkan bahwa kondisi komunitas ikan terumbu di Pulau Tidung tergolong baik, stabil, dan tidak ada dominansi antar spesies., Coral reef ecosystems are productive ecosystems for fisheries and other aquatic organisms. Coral reef ecosystems are vital habitats for fish communities, especially reef fish. Reef fish are important components in the aquatic environment, the existence of coral fish communities in coral reef ecosystems is important to know, because of the ecological role and function of fish in maintaining the stability of coral reef communities and the balance of other components of coral reef ecosystems. This study aims to determine the structure of the reef fish community on Tidung Island. This research was conducted on Tidung Island from 9 June to 12 June 2022. The reef fish data collection method uses Underwater Visual Census (UVC) with a 50 meter transect, and placed three transects at each station. Reef fish data were analyzed with three community indices, namely diversity index, uniformity index, and dominance index. The results of the study found 3982 individuals of reef fish, 24 families and 91 species. The composition of indicator fish is 2,44%, target is 17,20%, and major fish is 80,36% of the total individuals found. The average value of diversity index is 2,77, uniformity is 0,88, and dominance is 0,08. This value indicates that the condition of the reef fish community on Tidung Island is good, stable, and there is no dominance between species.
Keyword: Community structure, reef fish, Tidung Island, Underwater Visual Census

Judul: Natrium lignosulfonat sebagai agen pendispersi pada mortar
Abstrak: Lignosulphonate, a modification product of lignin waste from pulp and paper industry can be used as water reducer in mortar mixture. This substance can influence the mechanical characteristic of mortar such as diameter of flow, flexural strength, compressive strength, and setting time of cement paste. Lignosulphonate shows it function as dispersant on cement hydration at 3 days that analyzed with x-ray difractometer. Research result show that flow of fresh mortar rise with increase concentration (from weight of cement) of synthetic sodium lignosulphonate (NaLS). It show that mortar homogenity also increasing. The result of flexural strength and compressive strength test use synthetic NaLS 0.1-0.3% from weight of cement show that addition synthetic NaLS 0.2% is the best result because it has the biggest of flexural strenght and compressive strength value. Initial setting time of cement paste increase, about 50% with addition of synthetic NaLS 0.2%. Whereas the final setting time decrease, about 8%. Cement hydration test show increase hydration product peak, Ca(OH)2 dan calcium silicate hydrate (C-S-H).
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