Siombak lake (28 ha area) was a salty lake located in Medan coastal, Indonesia. Water fluctuation influenced by the sea tide. Therefore, it needed to do morphometry dynamical study as the first impression of lake physical characteristic. The purpose of this study was to understand the dynamical of Siombak lake morphometry. The research was done in September 2016. Lake mapping was done by making 100 line zig zag and draw with ArcMap. Bathymetry showed that the bottom of the lake was sloping at the center part of west and southeast of the lake, and steeping at north, south and east. Siombak Lake has shoreline length 2,535.78 m, with SDI value 2.70. Maximum length 756 m, with maximum width 246.15 m. Lake maximum depth was 17.7 m at MSL, 18.98 m at highest tide and 16.71 m at lowest tide, with average depth 5.33 m at MSL, 6.30 m at highest tide and 4.30 m at lowest tide. Lake volume was 783,607.16 m3 at MSL, 829,395.52 m3 at highest tide and 355,544.14 m3 at lowest tide, with water debit around 32.50 – 50.17 m3s-1. Water retention time was ± 4.33 – 6.75 hours

Tidal lakes are unique lakes because of the fluctuations of the water in the lake are influenced by the sea tides. Therefore, Tidal lakes are also called brackish lakes or salty lakes. Thus, the organisms that live in the lake must be able to adapt to the dynamics of brackish water changes. Therefore, the study of the biodiversity of flora and fauna is interesting to study related to organisms that are able to live and adapt to dynamic environments. This research was carried out in Siombak Lake, Medan City, North Sumatra Province from June to July 2018. The data collected were organisms in the form of flora (mangroves and aquatic plants) and fauna (ictiofauna or nekton which were fish, shrimp, crab, and mollusca). The results of research in the Siombak Lake ecosystem found 7 species of mangroves, 5 species of coastal plants, and 2 species of aquatic plant. Fauna found were 14 species of fish, 7 species of gastropods, and 1 species of bivalve, 1 species of shrimp and 1 species of crab.

<strong>Limnological Status of Lake Siombak, Medan, North Sumatra.</strong> Lake Siombak is located in the coastal area of Medan city, making its waters influenced by the tides. The lake serves as a water catchment, flood control, fishing area, and tourist destination. Various activities in the lake have led to changes in the environmental quality of the lake. To maintain the sustainability of the lake, efforts are needed for proper management. Lake management should begin with a good understanding of the nature and characteristics of the waters. This study aimed to determine the limnological status of Lake Siombak through morphometric analysis, aspects of physics, chemistry, and biology, as well as trophic status of the waters. Morphometry included dimensions of water surface and subsurface. Physics parameters included temperature, Total Suspended Solid (TSS), water clarity, electrical conductivity (EC), and salinity. Chemical parameters included pH, dissolved oxygen (DO), Biological Oxygen Demand (BOD5), Chemical Oxygen Demand (COD), nitrates, and phosphates. Biological parameters included community structure of nekton and benthos. Measurement of lake morphometry was performed in April 2014 at high and low tides. Measurements of water quality and biological sample collection were conducted in May-July 2014 at high and low tides. The results showed that Lake Siombak has an area of 41.44 ha with a maximum depth of 5 m at high tide and 4 m at low tide. Based on the aspects of physics, chemistry, and biology of the waters, Lake Siombak was categorized as an open waters influenced by the tides and was saline with high level of oxygen. The lake water retention time (Rt) was 15.65 hours and discharged (Q) 3.7 x 107 m3/h of water at high tide and 3.0 x 107 m3/h at low tide. High phosphate concentration indicated these waters have already been polluted. However, the water quality of Lake Siombak was still suitable for fishing activities. Benthos and nekton communities were relatively unstable. Benthic community was dominated by Blue Mussel (Mytilus edulis) at high tide (57%) and Red-rimmed Melania (Melanoides tuberculata) at low tide (41.34%). Nekton community was dominated by Blue Panchax (Aplocheilus panchax) at high tide (74.07%) and low tide (64.79%). In general, Lake Siombak was classified as eutrophic. <br /><br />

Siombak Lake is a brackish or coastal lake in Medan, Indonesia. Water fluctuation in the lake was affected by sea tide, so it was more appropriately called tidal lake. Thus the influence of tides could affect the quality of water in the lake, especially temperature, salinity, dissolved oxygen, and pH. The purposed of this study was to describe the profile of temperature, salinity, dissolved oxygen, and pH in the waters of Siombak. Lake. This study was conducted in June to July 2018. The data measured and were analyzed in the waters spatially (horizontally) and vertically. The results showed no significant difference of temperature distribution in surface between high tide and low tide. However, it was more influenced by daily time differences. While salinity was quite different between high tide and low tide. In the dry season (April to June) salinity values were higher during high tide compared to low tide. Conversely, during the rainy season (June to August) the salinity values in low tide were higher than when they were in high tide. The vertically distribution of temperature, oxygen, and pH decreases with respect to increasing depth. But the salinity value increases with depth increased.

Siombak Lake is a tidal lake whose waters are affected by Belawan tidal in the Malacca Strait. The characteristics of the waters are dynamic, especially its salinity. The existence of salinity causes the lake and the surrounding area growth by mangrove. This study aims to map the distribution and condition of mangrove forests in Siombak Lake. This research was carried out in Siombak Lake, Medan City, North Sumatra Province in August 2019. The data were collected of mangrove vegetation and density at the study site. The results of research on Siombak Lake found 14 species of mangrove. There are 2 species of mangrove that is rarely found before, that is found at the research location, namely the powder-puff tree and looking glass tree. Nipa palm and mangrove apple are mangrove species that have the highest distribution and density in the Siombak Lake ecosystem. The condition of mangroves at the Siombak Lakeside is in damage to good condition, while in the Siombak Lake ecosystem can be said in good condition.

Abstract. The study was conducted to determine the condition of the habitat and the diversity of fish in the watershed tambra. The higher diversity index (H ') was recorded in the Bahorok River with a value of 4.5 followed by Berkail River (3.45) and Landak River with a value of 2.46. Keywords : Biodiversity, nekton, Tor fish, fresh water crustaceaAbstrak. Penelitian ini dilakukan untuk mengetahui kondisi habitat dan keragaman ikan di DAS Wampu. Pengukuran kondisi habitat dengan mengukur parameter suhu, kecerahan, kecepatan arus, kedalaman, DO, pH, jenis substrat, lebar dan lebar badan sungai. Jenis nekton ditangkap dengan alat backpack electrofishing units dimana arus listrik yang dihasilkan bersumber dari batere 15 volt dan 9 ampere. Kondisi habitat pada bagian hulu DAS Wampu yaitu bertipe substrat batu besar, kerikil, dan pasir dengan arus yang sedang -besar serta perairan yang jernih. Parameter fisika-kimia perairan di hulu DAS Wampu masih layak dan cocok untuk habitat ikan, kepiting dan udang. Selama penelitian nekton yang terkoleksi sebanyak 15 jenis ikan dan 1 jenis kepiting air tawar serta 1 jenis udang air tawar. Pada survei ini ditemukan dua jenis ikan Tor yakni T. soro, dan T. Tambra. Keanekaragaman (H') tertinggi terdapat pada Sungai Bahorok dengan nilai 4,5 diikuti Sungai Berkail dengan nilai 3,45, dan Sungai Landak dengan nilai 2,46. Kata kunci: Biodiversitas, nekton, ikan Tor, krustacea air PendahuluanSungai adalah perairan yang sangat dinamis, karena ada dimensi waktu yang berhubungan dengan arus dan berfluktuasi setiap saat (Gordon et al., 2004; Mihov dan Hristov, 2011). Lebih lanjut Muhtadi et al. (2014) menyebutkan sungai sebagai perairan yang terbuka, memiliki arus, terdapat perbedaan gradien lingkungan, serta masih dipengaruhi oleh daratan. Sungai merupakan habitat berbagai jenis organisme perairan termasuk, plankton, benthos maupun nekton (Odum, 1996;Gordon et al., 2004). Nekton merupakan organisme yang dapat berenang dan bergerak aktif, misalnya ikan dan udang, termasuk amfibi dan serangga air besar (Welch, 1954;Odum, 1996). Walaupun udang dan kepiting hidupnya umumya di dasar perairan, akan tetapi karena memiliki kemampuan melawan arus dan berenang bebas sehingga dapat dikategorikan sebagai nekton.Kondisi dan karakteristik habitat perairan termasuk kualitas air sangat berpengaruhi terhadap pola persebaran, keanekaragaman, kelimpahan ikan, udang dan kepiting (Simanjuntak, 2012a;

Lake Kelapa Gading is an artificial lake located in Asahan district of North Sumatra province. Thepurpose of this study was to determine: 1) description of conditions of temperature, dissolved oxygenand pH vertically in the water for 24 hours, 2) production and consumption of oxygen in the waters ofLake Kelapa Gading. The study was conducted in March-April 2016 with preliminary and mainresearch activities. There are three observation stations are stations 1 (near KJA), station 2 (the areanear the settlement) and station 3 (outlet). The measured temperature ranges from 30-35 ºC.dissolved oxygen highest in the surface waters of 5.12 mg / l during the afternoon and the lowestoccurred at a depth of compensation of 0.64 mg / l when the weather is rainy. The measured pHvalue ranging between 6-9. In general there is a decrease in temperature, dissolved oxygen, and pHwith increasing depth. The highest percent saturation of 71.30 % in the surface waters. Comparisonbetween photosynthesis to respiration indicates that there has been a deficit in respiration is greaterthan the value of photosynthesis. dissolved oxygen concentration has reached a deficit at a depth of36.5 cm to reach at night.  Keywords: dissolved oxygen, lake, pH, saturation, temperature.

Tanaman mangga (Mangifera indica L.) adalah tanaman berbuah musiman yang banyak terdapat di Indonesia. Secara umum, daun tanaman ini mengandung saponin, alkaloid, fenol, tannin, flavonoid, steroid, diterpene dan glikosida. Senyawa metabolit sekunder yang umum ditemukan dalam tanaman ini adalah mangiferin (2-C-β-D-glucopyranosyl-1,3,6,7-tetrahydroxyxanthone), yang termasuk dalam golongan polifenol. Mangiferin memiliki beberapa aktivitas seperti antikanker, antiinflamasi, antidiabetes, dan antihiperlipidemia. Artikel ini membahas teknik isolasi mangiferin dan elusidasi strukturnya yang dilakukan dengan kombinasi spektrofotometri infra merah, Kromatografi Cair-Spektroskopi Massa (Liquid Chromatography-Mass Spectrometry/LC-MS), dan spektroskopi Resonansi Magnetik Inti (Nuclear Magnetic Resonance/NMR) baik berupa 1H-NMR ataupun 13C-NMR. Metode yang digunakan adalah review pustaka dengan pustaka yang digunakan sebanyak 34 artikel yang berasal dari jurnal internasional. Hasil yang didapatkan yaitu isolasi mangiferin dari tanaman mangga dapat dilakukan dengan metode refluks, soxhletasi, partisi tiga fase atau dengan bantuan microwave. Dari hasil tersebut, ditemukan bahwa ekstraksi dengan bantuan microwave memberikan persentase mangiferin lebih tinggi dari metode lain. Tetapi, penggunaan skala besar masih jarang dilakukan karena kemampuan penetrasi microwave yang rendah sehingga ada kemungkinan pemanasan kurang merata.