Due to rapid urban development in the coastal area of the East Aceh Regency, water quality degradation and marine pollution issues become the primary concern in this region. Moreover, seasonal observation of water quality and phytoplankton has yet to be assessed. This study aimed to determine the...

Coral reef is an important underwater ecosystem supporting people’s lives in coastal areas. One of the communities depending on the coral reef ecosystem for its food, livelihood, shoreline protection, and recreation needs is a community in Tunda Island. This research aims to analyze and determine the health status of coral reef in the island using a survey method. It was conducted in July 2018 and July 2019. Underwater photography transects were established at two depth areas of ± 3-4 m (shallow water) and ± 10-11 m (reef slope). Analysis of the results of live coral cover was divided into eight categories of groups based on CPCe output series 4.1. The values of coral reef cover at first depth (± 3-4 m) were 64.86% (east side of the island), 55.76% (north toward east side), and 32.22% (west side). The values of coral reef cover at second depth (± 10-11 m) were 36.36%, 25.00%, and 23.63% on the north toward east, east, and central north sides of the island, respectively. In shallow waters of Tunda Island, the coral reef health is classified as moderate to good, mostly those located on the east and the north toward the east sides. At reef slope, the coral reef health is classified as damaged to poor, particularly those located on the south and the south toward the west sides. The difference in the health values implies that most corals occur in shallow waters while deep corals differ from those near the surface and are not safe from impacts of the activities in the coastal area of Tunda Island.

Reef composition and diversity of coral reef fishes play an essential role in the ecosystem. The reef fish diversity is a crucial indicator of the health level of coral reef ecosystems. The benefit of fish diversity in coral reef ecosystems is to describe ecological services. This research intended to determine reef fish diversity among stations at different depths, consisting of shallow water and reef slope. Research sampling was done in July 2018 and July 2019 in Tunda Island waters at eight stations billowing the coral distribution pattern. Collected data of reef fishes were by using Underwater Visual Census (UVC) on Belt Transects Method at 250 m2 transect area (50 meters of length and 2.5 m on either side). The result showed 69 reef fishes in shallow water and 67 species on the reef slope. The total of fish species ware from 13 families consisting of Acanthuridae, Apogonidae, Blenniidae, Chaetodontidae, Ephippidae, Haemulidae, Labridae, Lutjanidae, Nemipteridae, Pomacentridae, Pseudochromidae, Scaridae and Serranidae. The community services structure of coral reef fishes is included in the moderate community stability category with an H’ value ranging from 1.19-1.60 in shallow water and 1.23-1.44 at reef slope, respectively. Diversity in coral reef fish communities might be associated with species' spatial distribution over the reef habitat's physical structure, but these patterns could be highly scale-dependent. In general, it could be said that the higher the coral reef diversity, the higher the reef fish diversity.

Seaweed is one of the vital export aquaculture commodities in West Java of Indonesia. Since 2013, seaweed production in Muara Gembong Sub-District, especially Pantai Mekar Beach and Pantai Sederhana Villages, can be produced 7.000 tons from total 10.000 seaweed culture fisheries of Bekasi District (80%) that was developed with a polyculture system. To ensure the long-term success of providing seaweed production, evaluation of suitable location is an essential step in any aquaculture operation. This study was conducted to analyze suitable sites for seaweed aquaculture in the coastal area of Muara Gembong based on the condition of water quality. Water quality data were collected from 11 stations during field surveys in March, July, and October 2018. Water quality parameters were observed with physical parameters (Secchi disk transparency, temperature, and depth) and chemical parameters (salinity, pH, DO, phosphate, and nitrate). Evaluation of water quality data included compile of matrix suitability design through some works of literature. The suitability coastal areas were analyzed to get suitable location used GIS software from coordinate data and water quality parameters, which were compared. The class “suitable” has a score of 4, the “suitable enough” class has a score of 3, the “suitable with conditionals” class has a score of 2, and the class “not suitable” has a score of 1. Based on the measurement result, the “suitable” areas were Station 7 (Front of Muara Mati), Station 8 (Outermost Muara Mati), Station 11 (Muara Kuntul), and Station 12 (Front of Muara Kuntul). The coverage area that was in a suitable area category is 962.72 Ha (9.63 km²). The location also linear with the result based on salinity, DO, and transparency (Secchi dish transparency). There are selected locations compared with other stations in Muara Gembong coastal waters because those locations face waste problems from Citarum Watershed and Jakarta Bay. Also, the sites serve as a source of livelihood for the community.

Fisheries and Aquatic Sciences

Indonesia is home to significant populations of globally vulnerable reef manta rays (Mobula alfredi) in at least four key regions: Berau, Nusa Penida, Komodo, and Raja Ampat. Despite detailed population studies in each of these regions, little is known about their horizontal movement patterns. Our study used satellite telemetry to investigate reef manta rays’ habitat use and home ranges. A total of 33 manta rays were tagged with SPLASH10F-321A satellite tags across the four regions: Berau (n = 5), Nusa Penida (n = 8), Komodo (n = 6), and Raja Ampat (n = 14), yielding usable data from 25 tags. The rays were tracked for 7 to 118 days (mean ± SD = 50 ± 30) from July 2014 to July 2022. The results showed localized movements, strong residency near tagging sites, and high site fidelity as evidenced by area-restricted search (ARS) behaviors and frequent revisitations. Most manta rays showed restricted home ranges in each region, with no connectivity between regions. Across 25 individuals, the home range (95% utilization distributions) varied significantly, ranging from 19 to 48,294 km² (mean ± SD = 4667 ± 10,354). These findings offer important insights into the spatial movement patterns of reef manta rays in Indonesia, allowing the formulation of more effective management strategies.