Fast and easy method for seagrass monitoring: Application of acoustic telemetry to precision mapping of Posidonia oceanica beds

► Acoustic telemetry is an efficient method for precision underwater mapping. ► Seagrass beds with various meadow/limit types were monitored by acoustic telemetry. ► Maps obtained on eight sites provide baseline documents for further monitoring. ► A four-year temporal survey shows a weak global progression of 4 m2.