Bintan Island has a high potential for bauxite mining. Many ex-mining areas have not been reclaimed properly, resulting in erosion and accumulation of heavy metals Pb and Cr which are high in the sediment (red-mud) and deposited in the roots of mangrove forests on the coast of Bintan. Rhizophora mucronata is one of the species that dominates the Bintan mangrove forest. The purpose of this study was to determine the phytoaccumulation of Pb and Cr metals in R. mucronata in the former bauxite mining area ofBintan Island. This research was conducted by survey, digested and analysed using Atomic Absorption Spectrophotometer (AAS). The concentrationof Pb and Cr in the sediment, as well as the roots, stems and leaves of R. mucronata were used for the analysis of phytoaccumulation types. The results of the Pb concentration test were higher than Cr. Based on the sampling location, the concentration of Pb metal accumulation in the sediment is Tembeling <Sei Carang <Wacopek <Senggarang, while Cr metal is Tembeling <Wacopek <Sei Carang <Senggarang. The highest metals accumulation in R. mucronata was found in the roots (Pb = 3,3482 ppm, Cr = 0,7664 ppm), while the leaves (Pb = 1,1076 ppm, Cr = 0,0413 ppm) had the lowest concentration. Based on the type of accumulation, R. mucronata absorbs Pb metal with a rhizofiltration mechanism (TF <1), which means that the roots of R. mucronata effectively translocate Pb as a pollutant to its body from the soil. In addition, the bio-concentration factor (BCF) concentration of R. mucronata <1 indicates the role of R. mucronata as a plant that accumulates very little Pb (low accumulator/non-hyperaccumulator). This adaptation mechanism is important information in the rehabilitation of mangrove areas using R. mucronata, because it can still live and grow in an environment contaminated with Pb metal by absorbing a little Pb from the soil and translocating it effectively in its organs.

Research has been conducted in Kepenghuluan Melayu Besar Subdistrict Tanah Putih Tanjung Melawan in January to February 2018. The aim of this research was to analyze the indicator of the presence of Aedes aegypti mosquito larvae on 3M Plus movement in Kepenghuluan Melayu Besar Subdistrict Tanah Putih Tanjung Melawan and analyze the effect of 3M Plus movements and impacts socio-economic on the existence of Aedes aegypti mosquito larvae in Kepenghuluan Melayu Besar Subdistrict Tanah Putih Tanjung Melawan. The results showed that 3M Plus movement affected to decrease larva population in an area. The impact of the 3M Plus movement was viewed from an economic aspect, namely the costs incurred was cheaper than before the 3M Plus movement. The social impact gained from 3M's movement Plus the empathy and feeling of mutual cooperation in the community, the use of recycled goods increases the aesthetic value because the use of used goods to be used as crafts, feeling safe and comfortable and not panicking when there is an attack of DHF and the emergence of clean living behavior and healthy in the community.

Abstract. Fatonah, Hamidy R, Mulyadi A, Efriyeldi. 2021. Floristic composition and stand structure of mangrove forests with varying vegetation conditions in Sungai Apit, Siak, Riau, Indonesia. Biodiversitas 22: 3972-3983. Mangrove forest in Sungai Apit Sub-district, Siak District, Riau is one of mangrove ecosystems that is still partly natural with some parts being damaged or rehabilitated. Degraded mangrove forest is a mangrove forest that has been disturbed by human activities and natural factors. This study aimed to investigate the floristic composition and stand structure of trees and seedlings in mangrove forests in Sungai Apit, Siak District, Riau Province, Indonesia in three vegetation conditions, i.e., natural, degraded, and rehabilitated forests. Line Transect Plot Method was used to collect data in three stations (i.e., Rawa Mekar Jaya, Sungai Rawa and Mengkapan villages) where each station consisted of three transects with a size of 10 x 100 m. A total of 20 species belonging 11 families were recorded in the studied sites with Rhizophora apiculata was the most dominant species in all forest conditions. The natural forest had the highest number of species followed by rehabilitated forest and the degraded forest. Stand structure in terms of tree density, mean diameter of mangrove trunks, and basal area differed significantly across the three vegetation conditions with the natural forest had the highest values followed by the rehabilitated forest, while the degraded forest was the lowest. For the seedling, the lowest number of species was observed in the degraded forest while the highest was in the rehabilitated forest, indicating the result of rehabilitation activities. Yet, seedling density in natural forests was lower than that in rehabilitated and degraded forests. This study provides information that differences in structure, species composition and recruitment of seedlings in mangrove forests in the three conditions and locations can be related to differences in recovery time and degradation levels which may be important for developing mangrove forest management and conservation strategies.

Hutan mangrove menyediakan berbagai pelayanan ekologi, namun saat ini sedang mengalami tekanan dari aktivitas manusia seperti industrialisasi di wilayah pesisir. Kajian regenerasi alami semai populasi Rhizophora apiculata telah dilakukan diantara kawasan industri perminyakan dan kawasan non industri Provinsi Riau. Hasil penelitian menunjukan bahwa kerapatan regenerasi semai alami R. apiculata tertingginya berada di kawasan non industri (Stasiun 4) dan kerapatan semai alami terendahnya berada di kawasan industri perminyakan (Stasiun 1, 2 dan 3). Selain itu, faktor kualitas perairan masih dalam batasan toleransi bagi kehidupan regenerasi semai alami R. apiculata dengan suhu perairan tertingginya berada di Stasiun 3, salinitas (Stasiun 4), pH (Stasiun 1), DO (Stasiun 4) dan potensial redoks (Stasiun 1). Selain itu, berdasarkan analisis keterkaitan kualitas perairan terhadap regenerasi semai alami R. apiculata mengunakan PCA, pada Stasiun 2, 3 dan 4 dicirikan oleh parameter suhu dan DO. Sementara Stasiun 1 dicirikan oleh parameter potensial redoks dan pH.

Natural disasters that occur in the city of Dumai such as degradation of mangrove forests, coastal abrasion and tidal flooding can be mitigated by maintaining the existence of mangrove forests. Mangrove forests have important benefits on the coast of the city of Dumai, so they need to be protected together. One of the efforts to maintain the existence of mangroves can be through the use of mitigation-based mangrove ecotourism, especially in the Bandar Bakau area of Dumai City. The data collection technique in this study used a quadratic transect and added secondary data from the relevant agencies. Based on the results of the study found 9 types of mangroves that have a role as mitigation in ecotourism locations and there are biota supporting tourism, namely 13 species of birds, 7 species of reptiles and 16 species of molluscs. To maintain the sustainability of the ecotourism area of Bandar Bakau, several disaster mitigations have been carried out for retaining cliffs (revetment), reforestation of mangroves, construction of facilities that adapt to the environment, coastal education, and outreach to the community. In addition, it is very potential to develop several other forms of mitigation such as: beach nourishment, breakwater or construction of embankments to minimize abrasion, as well as construction of diversion canals and tidal flood control gates, strengthening regulations. legislation, making land use policies, policies on flood and wave resistant building standards, policies on exploration and community economic activities, promoting local cultural wisdom of maritime communities.