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Kasim F, Kadim MK, Nursinar S, Karim Z, Lamalango A. 2019. Comparison of true mangrove stands in Dudepo and Ponelo Islands, North Gorontalo District, Indonesia. Biodiversitas 20: 259-266. This study aimed to investigate and compare the current status of mangrove areas, as well as the composition and species diversity of mangrove stands in both regions of Dudepo and Ponelo Islands. The results showed that the mangrove areas calculated using the segmentation method in classifying image of Landsat-8 OLI (acquisition on September 2017) were 279.46 ha (Dudepo Island) and 113.35 ha (Ponelo Island) respectively. A total of 13 species of true mangrove were recorded from both islands, using survey method from 9 transect lines (TL), with a distance ranging from 40 to 210 meters (1-6 quadrats) per transect. The mean densities of trees were 2133 ± 329.78 ha-1 (Dudepo Island) and 2111 ± 234.28 ha-1 (Ponelo Island), while those of saplings and seedlings were 58 ± 13.48 ha-1 and 1425 ± 113.96 ha-1 (Dudepo Island), and 79 ± 14.51 ha-1 and 2963 ± 443.22 ha-1 (Ponelo Island). The mean diameter and basal area were 19.73 ± 10.65 cm and 84.22 ± 67.67 m2ha-1 (Dudepo Island), 17.04 ± 1.46 cm and 60.07 ± 15.12 m2ha-1 (Ponelo Island), respectively. The Importance Value Index (IVI) ranged between 3.97-114.87 (Dudepo Island) and 6.04-82.18 (Ponelo Island). The dominant and codominant species based on IVI in both islands were Rhizophora apiculata Blume and R. stylosa Griff. The indexes of diversity, richness, and evenness of mangrove species in both islands were 0.34-1.70, 0.48-1.18, 0.47-0.94 (trees), 0.00-1.10, 0.00-1.82, 0.00-1.00 (saplings), and 0.00.-1.48, 0.00-1.44, 0.72-1.00 (seedlings), respectively. The Bray-Curtis similarity index between Dudepo and Ponelo Islands, based on the overall values of community attributes, was 0.75.

The increasing of sea level due to climate change has been focused many research activities in order to know the coastal response to the change, and determine the important variables which have contribution to the coastal change. This paper presents a method for integrating Coastal Vulnerability Index (CVI), Multi Criteria Analysis (MCA) method and Geographic Information-System (GIS) technology to map the coastal vulnerability. The index is calculated based-on six variables: coastal erosion, geomorphology, slope, significant wave height, sea level change and tidal range. Emphasize has been made to the methodological aspect, essentially which is linked to: (i) the use of GIS technique for constructing, interpolation, filtering and resampling the data for shoreline grid, (ii) the standardization each rank of variables (0-1) and the use of several percentile (20%, 40%, 60%, and 80%) for each rank score, and (iii) the use of variable’s rank to map the relative (local) and standard (global) vulnerability of the coastline. The result show that for local, the index consist of four categories: very high (19.61%), high (68.63%), moderate (1,96%), and low (9.80%). Meanwhile, for global level, the index is constantly in low category.

This study aimed to investigate the community structure and distribution pattern of Gastropods in the mangrove ecosystem Bolihutuo village. The study was conducted in February and July 2021 in two different stations. Community structure analysis carried out includes species composition, density, diversity, evenness, dominance, and distribution patterns by Morisita dispersion index. The results showed that 13 species of gastropods were found from 8 families, namely Cassidula nucleus, Littoraria palescens, Chicoreus capucinus, Nasarius distortus and Phrontis polygonata, Nerita planospira, Faunus ater, Pirenella alata, Cerithidea obtuse, Telescopium Telescopium, Terebralia palustris, Terebralia sulcata and Monodonta labio. Gastropod diversity of each station in June was relatively higher than observations in February. The distribution of Gastropods has a clustered, random, and uniform pattern.Keywords: Bolihutuo, Community structure, distribution pattern, Gastropods, Mangrove

Memanfaatkan lahan dan sumber daya alam untuk tujuan ekowisata membutuhkan desain yang terkait dengan kesesuaian atraksi dan daya dukung wilayahnya. Penelitian ini bertujuan untuk menilai kesesuaian alokasi lahan kawasan dan daya dukungnya untuk kegiatan pariwisata di wilayah Pantai Tilalohe. Metode penelitian terdiri dari metode survei untuk kondisi bio-fisik dan penelitian literatur untuk karakteristik area pantai Tilalohe, serta kesesuaian dan daya dukung wilayah sebagai tujuan wisata. Hasilnya menunjukkan bahwa pantai Tilalohe secara geomorfologis memiliki karakteristik pantai saku. Jenis atraksi yang paling cocok adalah duduk dengan santai di semua stasiun pada lahan utama dengan luas 1315,45 m2 dengan garis pantai di sepanjang 114,84 m. Perairan di depan tanah utama, dengan luas 5965,20 m2 dan garis pantai 182,79 m, sangat mendukung pengunjung untuk kegiatan mandi dan berenang di wilayah timur. Studi ini menunjukkan peran penting analisis kesesuaian dan daya dukung untuk arahan peruntukan lahan untuk kegiatan ekowisata berdasarkan prinsip-prinsip perlindungan lingkungan dan keberlanjutan manfaat. Utilizing land and natural resources for ecotourism purposes requires a design related to the suitability of the attractions and its region's carrying capacity. This study aims to assess the suitability of the region's land allocation and its carrying capacity for tourism activities in the Tilalohe Beach area. The research method consists of survey methods for bio-physical conditions and literature research for the characteristics of the Tilalohe Beach area, as well as the suitability and carrying capacity of the region as a tourist destination. The results show that geomorphologically Tilalohe beach has characteristics of a pocket beach. The most suitable attraction is sitting casually at all stations on the main land with an area of 1315.45 m2 with coastlines along 114.84 m. This study shows an essential role of analysis of the suitability and carrying capacity of the area in the direction of land allotment for ecotourism activities based on the principles of environmental protection and the sustainability of benefits.

Highlight ResearchThe fishing area of S. leptolepis in this study was confirmed to be located in Tomini BayThe fish samples were gathered randomly from fishers’ catch using purse seinesThe growth curve for the male and female fish data were both plotted following the trend of the Von Bertalanffy equationThis study estimates the growth parameters, mortality, and exploitation rates of the male and female fish separately.AbstractComprehensive data is required for implementing sustainable fisheries management. Population dynamic and stock assessment aspects of Selaroides leptolepis species in Tomini Bay have not been entirely reported. This study aimed to determine the fishing mortality rate and exploitation status of S. leptolepis in Tomini Bay by calculating Von Bertalanffy growth model parameters (L∞, K, t0) then plotting them into Pauly's empirical equation. The sampling was conducted monthly from April to September 2020 at Gorontalo City Fishing Port. Samples were collected randomly from five commercial fishing vessels shortly after the fishermen landed their catch at the fishing port. All fish samples were confirmed to be obtained by the fishermen from Tomini waters. The growth parameters of the samples were analyzed using FiSAT II based on Von Bertalanffy mathematical model. While the mortality and exploitation values were calculated manually using Pauly's equation. The study showed that the growth parameter values of S. leptolepis in Tomini Bay were 245.47 mm, 0.49/year, and -3.04/year for males, while 227.80 mm, 0.63/year, and -2.72/year for females separately for L∞, K, and t0. The total, natural, and fishing mortality rates were 3.06/year, 0.61/year, and 2.45/year for males and 0.99/year, 0.74/year, and 0.25/year for females. The analysis results showed that the female's natural mortality (M) was higher than the male. In contrast, the fishing mortality (F) and total mortality (Z) of male fish exceed the female. The exploitation value of males (E=0.80) was greater than that of females (E=0.26).

The concentration of three heavy metals Pb, Cd and Hg ware measured in Bone River, Gorontalo sediment. The heavy metal pollution on sediment in Bone River have not been explored longitudinally. The samples were taken in July 2021 at 8 stations.  The trend of metals ware observed in sediment as PbCdHg. The level of studied metals Cd and Hg did not exceed the safe limit by ANZECC, OSQG LEL and CCME TEL meanwhile Pb was met the limit by by ANZECC. However, the investigated showed that fluctuations due to differences in the characteristics of each location. Contamination factor (CF) and geoaccumulation index (Igeo) demonstrated that the sediment samples were low contamination and lightly polluted. Contamination by heavy metals in the Bone River implies that the conditions are much frightening for the biota and residents around the river.

Research on the rare mangrove Avicennia lanata (Ridley) is based on the habitat affinity of this species on the coast of North Gorontalo observed during 2017-2019. The current search was carried out in geographically isolated areas (land and islands) using a combination of tracking and Point Centered Quarter (PCQ) techniques to observe the substrate condition and elevation of the mangrove patch habitat, as well as to observe the morpho-anatomical character of the stand. The results showed that the habitat affinity of A. lanata species in North Gorontalo covers a wide range of substrate types, including mud, sandy mud, sand, muddy sand, and sandy and muddy soil on land with an elevation of 5.11–6.57 MDPL. The morpho-anatomical character as a distinguishing feature of A. lanata species from other Avicennia species found in leaves, stems, and fruit, could only be observed clearly in individual stands and trees. This study recommends restoration/monitoring of mangrove species A. lanata (Ridley) with a mixed-species restoration approach and community-based co-planting in a long-term mangrove restoration program in the coastal area of North Gorontalo.