The mangrove ecological services as carbon sinks and storage are very useful in the efforts to mitigate global warming and climate change. In this study, the above and below-ground biomass, carbon stock, as well as carbon sequestration by the mangroves in Demta Bay, Papua Province, Indonesia were estimated. Allometric equations were used to determine the mangrove biomass in 36 observation plots. The biomass value was used to determine carbon stock and estimate carbon sequestration. Nine mangrove species were found in Demta Bay, with the contribution of mangrove species to biomass (AGB and BGB) in the following order: Rhizophora apiculata > Rhizophora mucronata > Bruguiera gymnorhiza > Bruguiera cylindrica > Heritiera Littoralis > Xylocarpus molucensis > Rhizophora stylosa > Avicennia marina > Sonneratia caseolaris. The average mangrove biomass was estimated at 174.20 ± 68.14 t/ha (AGB = 117.62 ± 45.68 t/ha and BGB = 56.58 ± 22.49 t/ha). The carbon stocks in mangroves at the Ambora site were higher than the Tarfia and Yougapsa sites, averaging 123.57 ± 30.49 t C/ha, 81.64 ± 25.29 t C/ha, and 56.09 ± 39.03 t C/ha, respectively. The average carbon stock in the mangrove ecosystem of Demta Bay is estimated at 87.10 ± 34.07 t C/ha or equivalent to 319.37 ± 124.92 t CO 2 e/ha. The results of this study indicate that the mangrove ecosystem in Demta Bay stores quite high carbon stocks, so it is necessary to maintain it with sustainable management. Therefore, climate change mitigation is not only done by reducing the carbon emission levels but also needs to be balanced by maintaining the mangrove ecosystem services as carbon sinks and sequestration.

This research was conducted to test the mangrove crab of Sesarmidae family as bio-indicator to assess health status of mangrove ecosystem in Youtefa Bay of Jayapura. Conducted since March-August 2017. Conducted in 3 stations namely St. Enggros, St.Tobati, and St. Nafri. Using the quadratic transect method (1x 1 m) and the quadratic transect (10 x 10 m). Data were analyzed using index of diversity, dominance, evenness, abundance, density, simple linear regression and test criteria of indicator species. The result of the research found the level of mangrove diversity in Enggros Station with the value of index 1.9 then Tobati and Nafri Station of 1, 4 with abundant diversity level. The density of mangroves in the three stations is obtained by Enggors: 1455.6 trees / Ha, Naftri: 1477.8 trees / Ha, and Tobati 1033,5 trees / ha with moderate density categories and good ecosystem health conditions. The biological criteria indicator test shows that the Sesarmidae crab meets the six criteria of the indicator species, so that it can be designated as a species indicator of the health status of the ecosystem.Keywords: Indicator, Crab, Sesarmidae, Mangrove, Youtefa, Jayapura. AbstrakPenelitian ini dilakukan untuk menguji kepiting mangrove famili Sesarmidae sebagai bio-indikator untuk menilai status kesehatan ekosistem mangrove di Teluk Youtefa Jayapura. Dilakukan sejak bulan Maret sampai dengan Agustus 2017. Dilakukan di 3 stasiun yakni di St. Enggros, St.Tobati, dan St. Nafri dengan metode transek kuadrat (1x 1 m) dan transek kuadrat (10 x 10 m). Data dianalisis menggunakan indeks keanekaragaman, dominansi, kemerataan, kelimpahan, kerapatan, regresi linear sederhana dan uji kritaria spesies indikator. Hasil penelitian menemukan tingkat keanekaragaman mangrove di Stasiun Enggros dengan nilai indeks 1,9 serta Stasiun Tobati dan Nafri sebesar 1, 4 dengan tingkat keanekaragaman sedang melimpah. Kerapatan mangrove pada ketiga stasiun diperoleh Enggors: 1455.6 pohon/Ha, Naftri: 1477.8 pohon/Ha, dan Tobati 1033,5 pohon/ha dengan katagori kerapatan sedang dan kondisi kesehatan ekosistem baik. Uji kriteria biologi indikator menunjukan kepiting Sesarmidae memenuhi enam kriteria spesies indikator, sehingga dapat ditetapkan sebagai spesies indikator status kesehatan ekosistem .

The aim of this study was to find out the condition of coral reef coverage and the presence of Chaetodontidae fish in coastal waters of Jayapura City, Indonesia. The observation of coral reef coverage was performed using point intercept transect (PIT) method; meanwhile the observation of the presence of Chaetodontidae fish used visual census method. The result of this study described that coral reef condition in the study site was in severely damage (live coral 0%) in the DOK II site at 6 m depth, moderately damage (live coral 32.00% ± 2.13% to 42.00% ± 13.18%) in Kayu Pulo Island and the DOK II at 3 m depth, and good condition (live coral 56.00% ± 7.48% to 60.00% ± 5.55%) in the Tanjung Kayu Batu. There were 9 Chaetodontidae fish species from Chaetodon genus, Forcipiger genus, and Heniochus genus. The number of Chaetodontidae fish was 95, of which Heniochus acuminatus was the most dominant, as many as 46 individuals.

AbstrakPerairan Yapen Timur di Kepulauan Yapen, Papua merupakan perairan semi terbuka dengan potensi sumber daya alam hayati yang sangat tinggi. Penelitian terkini mengenai parameter kimia dan biologi lebih khusus konsentrasi sat hara serta kelimpahan fitoplankton masih sangat terbatas. Penelitian bertujuan untuk mengkaji tentang konsentrasi zat hara (nitrat dan fosfat), dan keterkaitannya dengan kelimpahan fitoplankton di Perairan Yapen Timur, dilakukan pada 5 Januari -5 Februari 2016. Menggunakan metode eksploratif dan purposive sampling method, menggunakan 15 titik pengambilan sampel. Analisis data menggunakan Spektrofotometer pada panjang gelombang 545 nm untuk nitrat dan 885 nm, sedangkan untuk kelimpahan fitoplankton mengunakan persamaan APHA, distribusi spasial nitrat, fosfat dan kelimpahan fitoplankton menggunakan persamaan kriging-metode dan bantuan Sofware Ermaper 7.0. Konsentrasi nitrat ditemukan berkisar antara 0,2 mg -0,7 mg/l, fosfat berkisar antara 0,2 -0,6 mg/l dan kelimpahan fitoplankton berkisar 49.682 -139.490 ind/l. Analisis koefisien korelasi mengindikasikan hubungan antara nitrat dan fitoplankton sebesar 0,3947, fosfat dan fitoplankton sebesar. 0,0068. Konsentrasi nitrat dan fosfat pada lokasi pengamatan mengindikasikan kualitas perairan tergolong dalam perairan oligotrofik, kelimpahan fitoplankton tergolong tinggi dan tidak terdapat blooming pada spesies tertentu, serta hubungan antara konsentrasi nitrat dan fosfat berkorelasi positip terhadap kelimpahan fitoplankton pada lokasi pengamatan.Kata Kunci: Fitoplankton, Fosfat, Nitrat, Yapen-Timur AbstractThe waters of Yapen Timur in Yapen Islands, Papua are semi-open waters with high potential natural resources. Recent research on chemical and biological parameters more specifically of nutrient concentration and phytoplankton abundance is still very limited. The study aimed to observe the concentration of nutrients (nitrates and phosphates), and their relation with the abundance of phytoplankton in Yapen Timur waters, was conducted on January 5Th to February 5 th , 2016. Using explorative method and purposive sampling method, with 15 sampling points. Data analysis using Spectrophotometer at wavelength 545 nm for nitrate and 885 nm, whereas for phytoplankton abundance use APHA equation. Spatial distribution of nitrate, phosphate and phytoplankton abundance using kriging-method equation and Software Ermaper 7.0. Nitrate concentrations were found to be between 0.2 mg -0.7 mg / l, phosphates ranging from 0.2 to 0.6 mg / l and the abundance of phytoplankton ranged from 49,682 to 139,490 ind / l. The correlation coefficient analysis indicates the relationship between nitrite and phytoplankton of 0,6738, phosphate and phytoplankton of. 0,7356. The concentration of nitrate and phosphate at the observation site indicated that the water quality belongs to the oligotrophic waters, the abundance of phytoplankton is high and there is no blooming in certain species, and the relationship between the nitrate and phosphate concentration is positively correlate...

Species checklists are a fundamental component of biodiversity research. They foster understanding of species distributions and habitat preferences, thus reducing gaps of knowledge in geographical occurrences of species. Especially in light of the limited availability of data on species distributions for Tanah Papua, an increasing scientific focus on the region is crucial to foster and refine the knowledge of species occurrences and to inform potential conservation planning. Despite a strong focus on conservation of Raja Ampat´s marine areas, surprisingly few studies have focused on the terrestrial biodiversity of the archipelago. As a consequence, detailed species checklists are largely missing. Here, we provide a preliminary bird species checklist for the island of Gam and its surrounding islands, located in the central Raja Ampat archipelago. During nine sampling periods between 2013 and 2019, we recorded 132 bird species in six distinct habitat types. Of the detected species, six are considered threatened by IUCN Red List criteria. We further recorded three new species for Gam Island, thereby expanding their known extent of occurrence.