<pre><strong><em>Abstract. </em></strong><em>Lake Sentani is located in Jayapura Regency, Papua Province with an area 9,360 ha and 70-90 meters above sea level. The lake directly adjacent to Cycloops Mountains Nature Reserve, obtaining supplies of about 34 springs.  The aim of the research was to describes the lake bathymetry as a basic information for the utilization. The function are as habitat place for many species, water resources, fisheries, transport and tourism. M</em><em>orphometry and bathymetry of the lake is very important for the sustainable management of the lake functions as a topography and relief lakes that have different extreme depths. Making the bathymetry of the lake is done with the acoustic method. Recording data using Garmin GPSmap 76CSx and Garmin Echo 100 Fishfinder. The result of the research showed that the depth of Lake Sentani with 9 variation at the different location, in generally range 15-23 m. Meanwhile, the waters of the deepest lake located in the eastern part of the lake is more than 70 m and the lowest depths of 0-7 m are in the middle of the Sentani area.</em></pre><p><strong><em>Keywords:</em></strong><em> bathymetry; morphometry; acoustic method; Garmin Echo 100 Fishfinder; Lake Sentani</em></p><p><strong>Abstrak. </strong>Danau Sentani terletak di Kabupaten Jayapura, Provinsi Papua dengan luas 9.360 ha dan ketinggian   70–90 m dpl. Danau ini berbatasan langsung dengan Cagar Alam Pegunungan Cycloops dan memperoleh suplai dari sekitar 34 sumber mata air. Tujuan penelitian ini adalah menggambarkan batimetri danau sebagai informasi dasar pemanfaatan danau. Fungsi danau adalah sebagai habitat makhluk hidup, sumber air masyarakat sekitar, perikanan, transportasi dan pariwisata. Mengetahui morfometri dan batimetri danau sangat penting untuk pengelolaan fungsi danau yang berkelanjutan karena kondisi topografi dan relief danau yang memiliki perbedaan kedalaman ekstrim. Pembuatan batimetri danau dilakukan dengan metode akustik. Perekaman data menggunakan <em>Garmin GPSmap 76CSx</em> dan <em>Garmin Echo 100 Fishfinder</em>. Hasil penelitian menunjukkan bahwa kedalaman perairan Danau Sentani terdiri dari 9 variasi yang umumnya berkisar 15–23 m. Perairan danau terdalam berada di wilayah timur danau yaitu lebih dari 70 m dan kedalaman terendah antara 0–7 m berada di wilayah Sentani tengah.</p><p><strong>Kata kunci:</strong><em> batimetri; morfometri; metode akustik; Garmin Echo 100 Fishfinder; Danau Sentani</em><em></em></p>

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.

AbstrakKajian mengenai analisis kandungan nitrogen (N), fosfor (P) dan karbon organik (KO) telah dilakukan di Danau Sentani, Papua. Penelitian ini bertujuan untuk mempelajari kandungan ketiga unsur tersebut di perairan. Metode penelitian yang digunakan adalah metode survei berstrata (stratified sampling method) sesuai dengan tujuan (purposive). Abstract Study on the analysis of nitrogen (N), phosphorus (P) and organic carbon (OC) content has been conducted at

MAS diseases (Motile Aeromonas Septicaemia) is caused by the bacterium Aeromonas hydrophila. One of the natural ingredients that can be used as an alternative to inhibit bacterial activity is the extract of red galangal rhizome (Alpinia purpurata). Active substances possessed of this material have potential as antibacterial. The purpose of this study is to determine the effectiveness of red galangal rhizome extract in the control of MAS disease in tilapia. The type of this research is experimental research in Completely Random Design (RAL) with 6 treatments, which are positive control, negative control, 250, 500, 750, and 1000 ppm. The result of the research on the activity of the galangal extract bacteria on A. hydrophila obtained the widest clear zone at 1000 ppm constipation, which is 9.7625 mm. The treatment has been conducted by immersion of Tilapia fish into the extracted red galangan rgizomes for 5 minutes, then it was put into aquarium for maintenance for 7 days. 0.1 ml A. hydrophila (108 cfu/ml) was injected to Tilapia. The result of the research on antibacterial shoes the wides clear zone at 1000 ppm with constipation, which is 9.7625 mm and the effectiveness test of red galangal extract on tilapia infected by A. hydrophila bacteria experience (ulcer) healing after 7 days with the concentration of rhizome extract of galangal 1000 ppm. Key words: red galangal rhizome extract, A. hydrophila, A. purpurata.

Sea cucumbers are organisms which have very important role in aquatic ecosystems as benthic biotas. The purpose of this study is to understand the public's knowledge about the diversity of sea cucumbers and its utilization in Tablasupa village. This study was conducted in May 2016, using a survey method by means of sampling and interviews. The results showed that based on the knowledge of local people, there are six species of sea cucumber. On the other hand, based on morphological identification, there were found eight species, which are Genus Actinopyga (2 types), Bohadschia (2 types), and Holothuria (6 types). Many people take advantage of the type of sea cucumbers for sale, and only a small portion is consumed. As a consequence of community activities is that increase the potential of reducing the species biodiversity of sea cucumber in the region. However, the existence of local knowledge management in this region is expected to reduce the loss of diversity and may improve the local environment ecosystem.Key words: benthic, ecosystems, Jayapura, Tablasupa, sea cucumbers