Seagrass ecosystem is a coastal ecosystem where seagrass grows as the dominant vegetation and can live permanently below sea level. Of course, the existence of human activities that do not care about the coastal environment has an impact on changes in seagrass communities in supporting coastal ecosystems. This study aims to determine the structure of the seagrass community in Terkulai Island Waters, Tanjungpinang City, this research was conducted in May 2023. Determination of the sampling point was carried out using the purposive sampling method with 4 stations that have seagrass distribution. Observation of seagrass was carried out using the modified line transect method where the line transect was placed at the starting point where seagrass was found until the end point was not found, the transect placement was chosen based on the longest area of the seagrass stretch and as a benchmark the transect placement was squared 50 x 50 cm then each line transect length was divided by 10% to get the squared distance between transects. The results of the study found 3 types of seagrass in the waters of Terkulai Island namely Enhalus acoroides, Thalassia hemprichii, Halophila ovalis. Seagrass Thalassia hemprichiii has the highest density when compared to other seagrass species with density values ranging from 764 to 1928 shoots/m². If categorized, the value of seagrass cover at each station is included in the medium category. For seagrass biomass the Enhalus acoroides type is larger when compared to other seagrass species. The results of PCA (Principal Component Analysis) showed that seagrass cover was closely related to the environmental parameter characteristics of depth, brightness, salinity.

Gastropods are marine biota found in the waters of Pulau Terkulai, Tanjungpinang City and are one of the catch of fishermen. However, information on the structure of the gastropod community in these waters is not widely known. The purpose of this study was to determine the types of gastropods, gastropod community structure, and the relationship between gastropod community structure and environmental parameters in the waters of Terkulai Island. This research was conducted in April-August 2023. Determination of sampling points using random sampling method as many as 30 points with sampling plots measuring 1x1m². The results of this study obtained 650 individuals with 15 species of gastropods. The highest density was found in Batillaria attramentaria species with a total of 12.20 ind/m². Gastropod community structure diversity value (H') ranged from 1.512 which is classified as moderate. The uniformity value (E) ranges from 0.558 which is classified as moderate and the dominance value (D) ranges from 0.353 which is classified as moderate. The results of the measurement of the physicochemical parameters of the waters are still at a feasible threshold for gastropod life. The principal component analysis (PCA) shows that the density with water parameters has a positive correlation with temperature and organic matter.

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.

Macrozoobenthos are bottom animals that play an important role in the productivity of waters in seagrass beds. This study aims to determine the species composition, density of macrozoobenthos, community structure of macrozoobenthos and the relationship between seagrass density and density of macrozoobenthos. The research method used is purposive sampling method, this method is taken based on certain reasons and criteria. This research was conducted in June-July 2022 on Barrang Lompo Island. Sangkarrang District, Makassar City. There were 26 species found consisting of 4 classes namely Bivalvia, Gastropods, Chepalopods and Crustacea with a total of 283 ind and dominated by the Gastropod class, both from the number of species and individual density. Macrozoobenthos community structure on Barrang Lompo Island at station I and II with a moderate diversity index (H'), moderate uniformity index (E') and low dominance index (D). The types of seagrass found at stations I and II were Enhalus acoroides, Thalassia hemprichii, and Cymodocea rotundata. The regression results of the relationship between seagrass density and macrozoobenthos density on Barrang Lompo Island show a weak relationship, which means that seagrass density has no relationship with macrozoobenthos density but macrozoobenthos density is influenced by physical and chemical factors of the waters and the type of sandy substrate.