Autonomous cameras reveal larval reef fish responses to acoustic enrichment and lunar phase
摘要
Acoustic enrichment (AE)—the playback of ambient sound from healthy coral reefs—shows promise in attracting fish larvae to degraded or artificial reefs, but previous evaluations have used invasive diver-based sampling techniques, limiting most studies to short deployments in benign and accessible environments. This study used fully autonomous cameras to non-invasively evaluate AE efficacy in attracting settlement-stage fish larvae and mature fish over large fractions of a lunar cycle. We deployed an AE system in Kāne’ohe Bay (O‘ahu, Hawai‘i) over three spawning events (August 2023, June–July 2024). Treatment (active speaker) and control (inactive speaker) sites were built by placing artificial structures, autonomous cameras, and hydrophones on a sandy seabed at 5 m water depth, with sites separated by 42–65 m. Treatment and control designations were alternated between deployments to remove potential spatial bias. Manual and semi-automated image analysis found larval counts at both sites peaking around the new moon, but the treatment site attracted 4–14 times more larvae. Both sites encountered similar numbers of mature fish. These results demonstrate that autonomous camera systems can non-invasively study fish larval presence and provide further support that AE can enhance larval fish response.