Levels of density, production and decomposition of litter in Dompak Estuary Waters. The aim of this research is to determine the level of density, production and decomposition of Mangrove litter in the Dompak Estuary Waters of Tanjungpinang City. This research was carried out in February - March 2024. In determining the sampling points the researchers used the Purposive Sampling method. Sampling in this research used the line transect method. The results of the research show that the level of mangrove density at station 1 is 1,299 ind/ha in the medium category, station 2 is 599 ind/ha in the rare category and station 3 is 1,666 ind/ha in the dense category. Mangrove cover at station 1. Amounted to 73.83% with medium criteria in the medium category. Station 2. Amounting to 65.60% with medium criteria in the medium category and station 3 amounting to 79.93 with solid criteria in the good category and the production of mangrove litter in Dompak Estuary Waters is 3.09 gbk/m2. With a leaf composition of 7.10 gbk/m2, twigs of 0.48 gbk/m2 and flowers/leaves of 1.69 gbk/m2. Mangrove decomposition at station 1 was 21.74%, station 2 was 29.88% and station 3 was 21.14%.

The morphometric characteristics of the red crab (Thalamita spinimana) have not been widely studied. This research was conducted from March to May 2021 in the waters of Dompak Tanjungpinang, Riau Islands. Each sample obtained directly measured the morphometric part using a caliper or calipers with an accuracy of 0.05 mm and the crab body weight was also weighed using a digital scale with an accuracy of 0.1 g. The samples obtained during the study were 119 crabs, of which 84 female red crabs and 35 male red crabs. The carapace width range for female crabs is 55.40 – 88.32 mm, while in male crabs the carapace width range is 16.35 and 34 individuals 68.96 – 90.94 mm. The weight of female red crabs is in the range of 50.0 – 103.6 g, while the weight of male crabs is in the range of 49.0 – 142.8 g.

The waters of the Beladeng River Muara is one of the areas in the Dompak Tanjungpinang Sub-District which has quite large potential for mangrove ecosystems. To maintain the condition of the mangrove ecosystem, it is necessary to know the structure of the mangrove community itself. The purpose of this study was to determine the types of mangroves and the structure of the mangrove community which includes the level of species density, species frequency, species closure, importance value index and mangrove canopy cover in the waters of the Beladeng River estuary, Dompak Tanjungpinang Village. This research was conducted in April-December 2022 using the Purposive Sampling method with 3 stations. In observing the mangrove ecosystem using the Transect Line Plot method measuring 10x10 m². Based on the results of the study, there were 3 types of mangroves found, namely Rhizophora apiculata, Xylocarpus granatum, and Brugueira gymnorhiza. Meanwhile, the mangrove community structure obtained the highest density at station 3 with a value of 4733.34 ind/ha. At station 1, the types of Rhizophora apiculata and Xylocarpus granatum received the same frequency values, and the highest IVI was achieved by Xylocarpus granatum. At station 2 the highest species frequency values were found in 2 species, namely Xylocarpus granatum and Rhizophora apiculata, and the highest IVI was Rhizhopora apiculata. For station 3, the 3 types of mangroves got the same type frequency value, and the highest IVI was achieved by Rhizophora apiculata. Meanwhile, the highest percentage of mangrove canopy cover was found at station 1 with good and very dense categories.