Environmental effects of plastic pollution from lost, discarded, and abandoned fishing gear on underwater pinnacles in the Gulf of Thailand

Underwater pinnacles in the Gulf of Thailand are ecologically significant habitats supporting diverse coral communities and associated marine life. However, these areas are increasingly threatened by abandoned, lost, or otherwise discarded fishing gear (ALDFG), which causes several damages to coral colonies and disrupts benthic ecosystems. This study investigates the occurrence, types, sources, distribution, and ecological impacts of ALDFG at 13 underwater pinnacles across six coastal provinces. Using SCUBA-based belt transects and roving diving surveys. We assessed coral cover, identified ALDFG materials, and evaluated damage indicators such as tissue necrosis, coral fragmentation, algal overgrowth, and sediment accumulation. A total of 138 ALDFG items were recorded, predominantly composed of polyethylene nets, monofilament lines, and squid jigs. Identified gear types included otter board trawl nets, handlines, gillnets, crab traps, and squid hooks. The most common damage was tissue necrosis, with massive corals such as Porites lutea showing the highest vulnerability. Statistical analysis revealed significant spatial differences in gear types and coral impacts are influenced by distance from mainland and the level of utilization. Our findings call attention to the urgent need for targeted management strategies, including gear marking, community-based retrieval programs, and integration of ALDFG monitoring into national marine conservation frameworks. This research supports sustainable fisheries and coral reef protection through evidence-based policy and stakeholder engagement.