Precision Light Attenuation to Reestablish Coral Spawning Synchrony

Abstract

This project investigates the effects of artificial light at night (ALAN) on synchronized spawning of reef-building corals in the Chaojing Bay Marine Protected Area, northeastern Taiwan. It also aims to establish a coastal restoration framework based on the recovery of natural coral spawning rhythms. Preliminary experiments indicate that even low-intensity artificial light can disrupt coral responses to natural darkness and lunar cycles, thereby reducing spawning synchrony. This disruption may subsequently reduce fertilization success and larval recruitment, with implications for coral population persistence and reef resilience.

We will integrate gamete development monitoring, spawning observations, and larval recruitment surveys to compare coral reproductive responses before and after improvements to the nighttime light environment. This comparison will determine whether reducing nighttime artificial light can restore synchronized spawning and increase larval recruitment. The results will provide a scientifically grounded, practical, and scalable framework for coastal light management and coral reef restoration.

Methodology and Implementation Steps

1. Establishment of Underwater Light Monitoring System
   A long-term underwater light monitoring framework is established in the Chaojing Bay Marine Protected Area. A self-developed underwater spectral monitoring system is deployed to quantify artificial light intensity, spectral composition, and natural lunar illumination. These measurements provide baseline information on nighttime light environments and their potential influence on coral reproductive processes.
2. Monitoring of Coral Reproductive Status
   During the coral spawning season, reef-building coral colonies are regularly monitored to evaluate gamete development and reproductive maturity. These observations provide essential information on coral reproductive cycles and the relationship between spawning patterns and environmental cues, including lunar cycles.
3. Observation of Spawning Synchrony and Data Collection
   Nighttime underwater observations are conducted in combination with a customized coral egg collection system to record spawning timing, gamete release, and colony-level spawning synchrony. These data are used to evaluate how artificial light exposure influences coral reproductive rhythms and spawning coordination.
4. Precision Light Attenuation and Habitat Restoration
   Based on underwater light assessments, targeted precision light attenuation strategies are implemented to reduce artificial light disturbance. Approaches include shading, reducing light intensity, and adjusting light direction while maintaining necessary coastal operational requirements. The effectiveness of these measures is evaluated through continuous environmental monitoring.
5. Assessment of Larval Settlement and Ecological Recovery
   Biomimetic molded settlement plates developed by the research team are deployed to quantify coral larval settlement and juvenile recruitment. These measurements are used to evaluate whether improved nighttime light conditions enhance coral population recovery and ecosystem restoration potential.
6. Data Integration and Restoration Framework Development
   Environmental light conditions, gamete development, spawning synchrony, and larval recruitment data are integrated to compare ecological responses before and after restoration. The results will support the development of a science-based and scalable framework for coastal light pollution management and coral reproductive rhythm restoration.

Innovation and Cross-Disciplinary Collaboration

This project develops a precision light attenuation strategy to restore coral spawning synchrony by incorporating nighttime light environment management into coral ecological restoration. By focusing on the recovery of natural reproductive rhythms and population renewal processes, this approach provides a new perspective for coral conservation.

Conducted in the Chaojing Bay Marine Protected Area, this project serves as an important demonstration of long-term ecological monitoring and conservation practice. Through collaboration with the National Museum of Marine Science and Technology, the project integrates marine ecological research, optical monitoring, conservation practices, and environmental education to establish a scalable framework for coastal light pollution management and coral reef conservation.

Expected Results and Contributions

This project aims to establish a science-based precision light environment management framework that reveals the relationship between human nighttime activities and coral reproductive rhythms. By quantifying underwater light conditions and coral responses, this study provides practical strategies to balance coastal development needs, human activities, and marine conservation.

Through scientifically guided adjustments of the nighttime light environment, the project demonstrates how natural ecological processes can be supported without eliminating human use of coastal areas. The outcomes will provide valuable scientific references for light pollution management, sustainable coastal development, and conservation planning within marine protected areas.

This research highlights a new approach in which ecological restoration and human activities can coexist through precise environmental management, offering a scalable model for future marine conservation and sustainable coastal governance.