This study aims to determine the type and density of gastropods, the density of seagrass, seagrass closure. It also knows the association gastropods in seagrass ecosystem in the waters of the Senggarang Besar. The research was conducted by random sampling method using a point 31 transect squares measuring 1x1 meters for observation gastropods and seagrass. Results of the study were found 12 species of gastropods. Gastropod density values range between 0.35-2.94 individual/m². Results of research on the type of seagrass found 4 species of seagrass that is, Enhalus acoroides, Thalassia hemprichii, Halodule uninervis and Syringodium isoetifolium. A density value of seagrass species Enhalus acoides 14.32 individual/m², Thalassia hemprichii 86.39 individual/m², Halodule uninervis 21.58 individual/m² and Syringodium isoetifolium 3.87 individual/m². Total density of all seagrass 126.16 individual/m². The closure of the Seagrass Enhalus acoides 12,63%, Thalassia hemprichii 50,96%, Halodule unnerves 13,40%  and Syringodium isotifolium 0.29%. Total closure of all seagrass is 77,29%. The level of association between species of gastropods as many as 11 species have negative associations of which is Leavistrombus turturela, Strombus urceus, Planaxis sulcatus, Cerithium nesioticum, Cerithium Aluco, Cerithium zonatum, Pugilina cocholidium, Cronia margariticola, Muricodrupa fiscela, Pyrene epamella, Otopleura auriscati. While 1 species has a positive association level is kind of Rhinoclavis aspera.

Global warming is becoming increasingly apprehensive day by day, marked by the continued increase in levels of carbon dioxide (CO₂) in nature. One of the efforts made to reduce the effects of global warming is biosequestration by empowering photosynthetic organisms, one of which is seagrass beds. This study aims to measure the density and percentage of seagrass cover, biomass value, and estimate carbon storage in seagrass biomass in the form of tissue at the top (leaves and upright stems) and tissue at the bottom (roots and rhizomes), as well as estimate carbon storage in sediments. Sampling was carried out using line transect and quadrant plot methods at each station. Calculation seagrass carbon storage using the Loss of Ignition (LOI) method at the Soil Chemistry Laboratory of the Pangkep State Agricultural Polytechnic, a total of 5 species of seagrass were found, namely Enhalus accoroides, Thalassia hemprichii, Halodule uninervis, Halopila ovalis, and Cymodocea rotundata. The average seagrass carbon storage on Badi Island is 18.92 gC/m², or 0.189 MgC/ha. The species that act as the largest contributor to carbon storage are Cymodocea rotundata, namely 35.44 gC/m², and Halopila ovalis, which acts as the lowest contributor to carbon storage, namely 1.92 gC/m². The average seagrass carbon storage at the bottom of the substrate was three times greater than that at the top of the substrate, namely 14.10 gC/m² at the bottom and 4.82 gC/m² at the top. The average carbon storage in sediments is 10.98 gC/m², or 0.109 MgC/ha.

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.

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.