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Acoustic Distribution Maps of Phonating Species in Coral Reefs34Marine Research of the National Academy of Marine ResearchDOI: 10.29677/MR.202406_4(1).0003 The silent moving platform effectively captured fish and crustaceans sounds in the noisy coastal waters, successfully helping the authors visualize the ocean's underwater soundscape. For safety measures, kayaks should be operated in calm weather conditions, which also reduces the ambient noise contamination caused by waves and wind. This method is suitable for use within coral reefs and in small bays that are semi-enclosed. As long as the sound characteristics of the source species/family are identified, acoustic maps of corresponding animals can be extracted from the same sound files. The rule-based filter that focuses on sound characteristics is not perfect. In the present study, speciesidentification of damselfish was impossible since their sound characteristics are generally overlapping, and marginal zones of the rules exist. In addition to PAM, underwater visual and acoustical observation are required to identify the source species. However, precise matching of visual and acoustical observations containing aggressive behavior and sound recordings were rare and required time-consuming efforts. These are some of the future challenges to achieve a species-specific sound database. The intense pulse sounds were labeled as ''snapping shrimp sounds,'' but could also include other crustacean sounds. Increasing our knowledge of the sound characteristics of marine phonating organisms in reefs willsignificantly improve the resolution and potential of marine bioacoustics monitoring in this rich and threatened ecosystem. A potential further application of towed passive acoustic monitoring of marine species is the impact assessment of ocean engineering works on local areas. Towed recording conducted through a silent moving platform can provide an acoustic distribution map of phonating animals with faint source levels, which can be used to identify the location-dependent effect of ocean engineering works. In addition, fixed long-termmonitoring of underwater soundscape is recommended to observe the time-dependent effect of anthropogenic impacts. Employing both towed and fixed acoustic monitoring systems can enable spatio-temporal observation dynamics in coastal underwater ecosystems.4 CONCLUSIONS This work was supported by the Japan Society for the Promotion of Science KAKENHI, Japan (GrantNumbers 17H00799) and Japan Science and Technology Agency CREST (Grant number JPMJCR11A1). We thank Professors Hajime Kayanne, Tamaki Ura, and Isao Koike for their effort to organize and conduct the inter-project survey of the CREST program.ACKNOWLEDGEMENTS