Coral Larvae Dispersal Following Observed Spawning Events at Tunda Island, Western Java, Indonesia

Abstrak

Graphical Abtsract Highlight Research 1. Integration of direct coral spawning observations with larval dispersal modeling at Tunda Island. 2. High local retention rates are predominantly driven by larval pre-competent periods. 3. Larval export patterns indicate significant connectivity toward existing Marine Protected Areas (MPAs) in Northern Java. 4. Emphasizes the critical need for integrated management of non-protected sites to sustain regional reef networks. Abstract Potential coral reef-associated encounter management cannot rely solely at a local-scale approaches, because reefs on small island may influence surrounding ecosystems through larva connectivity. This study quantifies larva dispersal following observed spawning events on Tunda Island, using a Lagrangian particle-tracking framework incorporating multiple spawning events. Coral spawning was observed through night scuba diving at several reef locations. For each spawning event, larval trajectories were simulated and the first stranding events were used as proxies for potential settlement. Stranding outcomes were classified according to pelagic larval duration phase, distinguishing precompetent and successive competent windows. Dispersal patterns exhibited temporal variation among the spawning event days. The 18 March event showed particle distribution that favored local retention, whereas other events in 13 and 14 March showed a more export-oriented. Most particles remained within 50 km of the source reef, but a fraction dispersed up to 230 km and remained active, indicating potential for regional connectivity. Overall, most stranded particles occurred during the pre-competent phase, suggesting a temporal mismatch between biological settlement and reef contact. Spatial aggregation data show Tunda Island may function as potential larval source under modeled conditions for multiple reef systems in Northern Java, such as Kepulauan Seribu, Biawak Island, Ujung Kulon, even Karimunjawa Islands. These findings emphasize the importance of integrating empirical spawning observation with biophysical modeling to capture event-scale variability in connectivity and underscore the ecological significance of reef outside formally designated marine protected area in sustaining regional reef networks.

Kata kunci

• Coral larval dispersal
• Coral spawning
• Langrangian particle tracking
• Larva connecticity
• Tunda island