Reciprocal modelling between the underwater ambient noise and the coastal maritime traffic density in the Calvi bay

Maritime traffic is the main contributor to anthropogenic underwater noise; its increase changes the acoustic landscape. To follow these evolutions, maps of ambient noise are created by modelling radiated noise of boats equipped with the AIS system. Because of the absence of AIS data in coastal environments, the modelling of the acoustic coastal landscape is barely treated, while coastal environments provide 42% of the ecosystem services given by the oceans. To overcome this issue, a specific acoustic and photographic protocol is established in the Calvi bay (Corsica, France). Specific images processing algorithms are devoted to the location and the counting of boats. A relation is established between the Ambient Noise Level ANL (during 1 hour / 100 Hz-30 kHz band) and the number of boats present in a specified radius. Such link allows to create two simple empirical parametric models characterizing these variables. These models explain 74 to 80% of the observations for the model ANL as a function of the number of boats, and 72 to 76% for the model the number of boats as a function of ANL.