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

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.

Abstrak Pelibatan masyarakat dalam pengelolaan ekowisata mangrove dapat dilakukan dalam bentuk kelembagaan yang dibangun berbasis masyarakat. Kelembagaan dapat berupa organisasi atau wadah (players of the game) dan aturan main (rules of the game) yang mengatur kelangsungan organisasi maupun kerjasama antara anggotanya untuk mencapai tujuan bersama. kajian ini diperlukan untuk membuat suatu model atau pola pengelolaan ekowisata mangrove berbasis masyarakat. Kajian ini dilakukan di ekowisata mangrove di Pantai Bali, Kecamatan Talawi Kabupaten Batubara. Data yang dikumpulkan adalah kondisi sosial-ekonomi dan kelembagaan masayarakat sekitar serta karakteristik pengunjung. Analisis data dilakukan dengan analisis deskriptif terrhadap kondisi sosial-ekonomi masyarakat. Analisis kelembagan mengacu pada konsep kelembagaan dari Taryono (2009) dan Ruddle (1998). Hasil yang diperoleh adalah karakteristik usia masyarakat yang banyak memanfaatkan Pantai Bali tertinggi pada usia 20-29 tahun yaitu sebanyak 54%. Keterlibatan masyarakat dalam kegiatan ekowisata mangrove, diperoleh 80%. Berdasarkan wawancara yang dilakukan dilapangan diperoleh hasil karakteristik usia pengunjung yang paling banyak pada kisaran 20-29 tahun dengan latar belakangg pendidikan SLTA sebesar 65%. Saat ini terjadi dualisme pengelolaan mangrove antara masyarakat sekitar dengan PT. Obor. Perbaikan dalam struktur organisasi pengelolaan minawana menjadi langkah pertama dalam perbaikan pengelolaan. Oleh karena itu, pemerintah tentunya perlu memberikan kewewenangan terhadap Kelompok Tani Hutan sebagai organisasi resmi yang mengatur pengelolaan dilapangan. Langkah selanjutnya adalah perbaikan pengelolaan minawana adalah perbaikan dalam aturan main dalam pengelolaan. Aturan main ini terkait dengan apa yang boleh dan tidak boleh dilakukan terhadap pengelolaan minawana. Selain itu, tentunya sanksi atau imbalan apa yang diperoleh jika melanggar aturan yang ditetapkan. Abstract Community involvement in the management of mangrove ecotourism can be done in the form of community-based institutions are built. Institutions may be in an organization or container (players of the game) and rules (rules of the game), which regulates the survival of the organization as well as the cooperation between members to achieve a common goal. This study is required to make a model or pattern of mangrove community-based ecotourism management. The study was conducted in the mangrove eco-tourism in Bali Beach, District Talawi Coal County. The data collected is the socioeconomic and institutional surrounding communities as well as the characteristics of the visitors. Data was analyzed using descriptive analysis terrhadap socioeconomic conditions of society. Institutional analysis refers to the institutional concept of Taryono (2009) and Ruddle (1998). The results obtained are characteristic of the age of the people who are making use of the highest Bali Beach at the age of 20-29 years is 54%. Community involvement in ecotourism activities mangrove, gained 80%. Based on interviews conducted...

This study aimed to determine the community structure of echinoderms and how it related to seagrass cover and water chemical and physical parameters in Pandaratan Beach, Tapanuli Tengah Regency. The research was conducted from Maret to April 2018. Data analysis included community structure analysis and Principal Component Analysis (PCA). The result showed that there were seven species of echinoderms from four classes in Pandaratan Beach. The station I had the highest composition of echinoderms, while the lowest noted at station II. The highest abundance of 77 ind/m2 was found at the station I and the lowest of 44 ind/m2 was at station III. The highest diversity index was recorded at the station I, while the highest evenness and dominance index was at station II. Water quality of the waters was still in capacity to support the life of echinoderms. Based on PCA analysis, it was obtained that the abundance of echinoderms was positively correlated with seagrass cover, DO, depth, and phosphate.

Coral reef ecosystems in Unggeh Island waters have recently declined in quality due to natural factors and human activities. The declining quality can affect the biota of the coral reef ecosystem, such as coral reef fish. Coral reef fish belong to the groups of fish whose lives are associated with the coral reef ecosystem environment. This study aims to determine the abundance and diversity of coral reef fish and the relationship between abundance of coral reef fish and the percentage of coral cover in Unggeh Island Waters, Badiri District, Central Tapanuli Regency, North Sumatra. This research was conducted in December 2017 and April 2018. The method used to observe the coral was Underwater Photo Transect (UPT) method. And the method used to observe the coral reef fish was Underwater Visual Census (UVC) method. To determine the relationship between coral cover and coral reef fish was by using a simple linear regression equation. The results showed that the relationship of coral cover with coral reef fish was in the correlation value (R) of 0.418.

This study aims to determine the carbon stock in seagrass communities in Central Tapanuli, North Sumatera, Indonesia. The research was conducted from July to August 2020 in the coastal areas of Hajoran and Jago Jago. The parameters measured in this study were density, coverage, biomass, carbon content, and carbon stock in seagrass. Biomass analysis and carbon measurement are divided into the top (above-ground biomass) and the bottom substrate (below-ground biomass). Carbon measurements are conducted using the loss on ignition (LOI) approach. The results showed that the seagrass ecosystem on the coast of Central Tapanuli Regency, which was covered by monospecies Enhalus acoroides, was in a less healthy condition with a cover percentage of 30.3-33.3% and a density of 59-67 shoots/m2. Above-ground and below-ground seagrass biomass reached 140.19-188.72 g/m2 and 368.13-423.69 g/m2 respectively, while carbon stock reached 70.57-94.86 g Corg/m2 and 18731-19603 g Corg/m2 and total standing stock range 257.87-290.90 g Corg/m2. The data obtained from this research can be used as a database to see the potential of seagrass beds as storage of CO2 and as an effort to mitigate and adapt to climate change.

Highlight Calculated and assested the percentage of live coral coverIdentified reef fishes and calculated fish abundanceMeasured physical and chemical oceanography parameter Analyzed carrying capacity and suitability of Unggeh Island for tourism utilization especially marine diving and snorkeling.AbstractUnggeh Island located in the administration of the Village Sitardas Badiri District, Central Tapanuli Regency into a marine tourism area. The development of marine ecotourism Unggeh Island is an alternative to the economic improvement of so- ciety. This study aims to assess the potential of coral reef ecosystem in the form of percentage of life form coral, coral species and species and abundance of reef fish found in Unggeh Island waters of Central Tapanuli Regency and to analyze the suitability of coral reef ecosystem in Unggeh Island for tourism utilization es- pecially marine diving and snorkeling. Coral reef community data collection was done by using SCUBA divers equipment, in identifying The coral community used underwater photo transect (UPT) method, while coral fish diversity was observed by underwater visual census (UVC) method. Physical and chemical oceanography parameter data such as temperature, salinity, pH, current, transparency and DO are performed at each observation station. The survey results of coral reef observation at four stations showed different results. Percentage of live coral cover of station 1 to 4 were 25.40 %, 12.33%, 28.53%, and 25.53 respectively. Therefore, reef fishes found 36 species that consist of ten families and 423 individual fishes. The results showed that Unggeh Island was suitable (S2) for diving and snorkeling activities, with the carrying capacity was 3.054 persons/day.

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