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Monitoring | CHORUS

Mediterranean sound surveillance network

CALME logo

What is CALME?

CALME is a monitoring program and network of underwater soundscapes along the Western Mediterranean coastline. Born in 2015 thanks to a partnership between CHORUS and the Water Agency RMC, CALME is operated by CHORUS and co-funded by the Water Agency RMC and CHORUS.


The objectives of CALME are to measure, analyze and broadcast marine soundscapes of the Western Mediterranean coastline in terms of biological and anthropogenic underwater noise levels. The outputs of CALME are available to the public and to the scientific community, Governmental Agencies, NGO and private firms involved in environmental marine activities.

One specific aim of CALME is to acquire data on underwater noise levels of the of the Mediterranean Sea for two EU directives: the Water Framework Directive and the Marine Strategy Framework Directive.

CALME architecture

Data acquisition

CALME screening


The coastline screening aims to capture the spatial variability of key habitat soundscapes (e.g., sea grass, coralligenous reefs) and relate it to ecosystem health. Over 90 recording positions cover the Western Mediterranean coastline. Each year, a third of the recording sites (30 positions) is sampled using temporarily bottom-moored recording devices (EA-SDA14 recorders of RTSYS).

The recording positions coincide with those of three other monitoring networks promoted by Water Agency: TEMPO, RECOR and  CALOR (see www.medtrix.fr). This concomitant multidisciplinary data acquisition enables to acquire ground truth to help evaluate soundscapes analysis results.

CALME long-term moorings


The long-term measurements capture soundscape temporal variability and trends. Overall 6 continuous recording stations will be set up. Each one is characterized by a key focus.  Four long-term moorings are operational today:

1) The Marine Protected Area (MPA) of Caro (Parc Marin de la Côte Bleue, France), focusing on the spawning functionality of the MPA for seabass and breams and the impact of shipping noise associated with the busy harbor of Fos sur Mer.

2) The bay of the Revellata (Corsica, France) focusing on Posidonia oceanica long-term recordings that serve as a reference for seagrass soundscapes.

3) Cala Gonone (Sardinia, Italy) focusing on rocky reef long-term recordings that serve as a reference for rocky habitats.

4) Cap d’Agde (Golfe du Lyon, France), focusing on vessel traffic, including fisheries.

CALME glider


The glider transects aim to sample offshore soundscapes at the scale of the Northwestern Mediterranean sea. After successful feasibility test run in 2015 & 2016 (cf www.medtrix.fr, MAGMA project), CALME implements 3 glider transects (Toulon-Calvi 2017, Golfe du Lion 2018, Pelagos Sanctuary 2019) every six years to measure offshore ambient noise levels and to evaluate the contribution of shipping noise. Each transect (range~600 kms, 1 month) is chosen to sample both the busiest and nosiest and the quietest areas with lowest traffic levels. Two transects (Golfe du Lion, Toulon-Calvi) are co-funded by CHORUS and Water Agency. We are looking for fundings for the 2019 transect in the Pelagos sanctuary. The noise levels (ambient, oceanic) along the transects are used to calibrate in space and time a numerical mapping of the shipping noise managed by CALME.

Data processing

800AM detection

The data collected by CALME is processed offline by CHORUS with its BIOSOUND software that implements several peer reviewed algorithms dedicated to a multi-purpose analysis of underwater biotic and anthropogenic sounds (ambient noise estimation, detection, classification, census of acoustic signatures, etc.).

The processing of the raw data acquired by CALME produces 32 descriptors:

  • 8 related to the Oceanic and Ambient Noise Levels,
  • 14 related to the biophony ( 3 for the benthic biophony, 9 for the fish biophony and 2 for the cetacean biophony),
  • 6 related to the anthropophony,
  • 4 related to the degradation of the acoustic habitat by the anthrophony.

In terms of antrhopophony and its impacts on marine fauna and habitats, shipping noise is modeled and mapped at the basin level based on in situ recordings, shipping traffic data available from AIS data and a set of measured geo-oceano-acoustic properties. We use our own peer-reviewed novel simulation scheme to obtain accuracy and numerical efficiency. To calibrate the model, its degrees of freedom are adjusted until the modeled noise levels fit the measured noise along the transects of the glider. Monthly maps of the statistical distribution of ship noise for each third octave band from 30 Hz to 30 000 Hz in the area of simulation (AS) are produced.


WEB Calme

Then the processed descriptors are broadcasted by two complementary web platforms. The first is the platform «WEB-CALME », it is dedicated to underwater acoustic monitoring only and offers access to a large amount of descriptors and specification on how they were computed. The second one is the platform « MEDTRIX » operated by Andromède Oceanologie. Only a selected set of acoustics descriptors are broadcasted by MEDTRIX. MEDTRIX facilitates their ecological interpretation by allowing a comparison with the outputs of other monitoring programs dedicated to assess ecosystem health and anthropogenic pressures along the Western French Mediterranean littoral.