Achievements | Reef Pulse

SONOMAY 2022 - 2024

Departure at sea with a tripod for the seabed of Mayotte

In collaboration with the French Office for Biodiversity (OFB) through the Mayotte Marine Natural Park (PNMM), we implement Passive Acoustic Monitoring on Mayotte coral reefs over the period 2022 - 2024.

In Mayotte as elsewhere, coral reef monitoring is based until now on snapshot visual surveys carried out in situ by biologist divers. However, these visual assessments are biased by the subjectivity and degree of expertise of each observer, and by water turbidity variations. Variations in the time of day, lunar phase or season of the surveys are additional biases.

SONOMAY (Soundscapes of Mayotte) is an applied research project that aims to develop a new approach, Ecoacoustics, as a management tool for the coral reefs of the PNMM.

The project proposes the punctual acoustic monitoring (continuous recording over 24 hours) of 43 sites usually monitored by a snapshot visual method, and the comparison of the respective contributions of the two methods. It also proposes to implement the continuous monitoring of 4 sites of interest in order to develop this long term approach and initiate the response to certain management issues of the PNMM.

continuously monitored sites over 1 year

continuously monitored sites over 24 hours

SONOMAY has four objectives

Define a reference state of Mayotte outer reef slope soundscapes both in space (24 h recordings on 43 sites) and time (one year recordings on 4 sites)

Collected raw acoustic data are archived. These archives constitute a durable heritage of Mayotte reef soundscapes and can be analysed again in the future according to new developments of Ecoacoustics. The acoustic data collected are valued in scientific popularisation actions for the general public.
Develop ecoacoustic predictive models to evaluate the fish assemblage structure by trophic group

This ecoacoustic calibration is based on the soundscapes and videos recorded over 24 hours on the 43 sites. In the future, it will allow us to evaluate the fish assemblage structure on outer slope sites only relying on the soundscapes recorded there. Additional ecoacoustic indices are also computed to provide a holistic ecosystem assessment.
Study temporal variations at 4 pilot sites by continuously recording their soundscape over one year

We are particularly interested in quantifying noise pollution from passing motorboats and in identifying specific periods of biological activity. Among these specific periods, we are looking in priority for those that may be related to reproductive aggregations of commercial interest species such as groupers or snappers.
Evaluate the redundancies and complementarities between the visual and ecoacoustic monitoring methods

A committee of experts will discuss the results of this analysis as well as the results of the temporal monitoring. The aim is to establish recommendations on the most relevant ecoacoustic indices to be integrated into MPA managers' and other stakeholders' dashboards.

SONOMAY fall within several management orientations of the PNMM

Make Mayotte attractive for research and develop local skills
Know habitats and species to improve their conservation and their socio-economic valorisation
Know the activities and their proven or potential impacts
Adapt fishing pressure to the available reef resources
Protect the functional halieutic areas
Guarantee the good state of conservation of coral reefs

The mission in pictures

Others achievements

Departure at sea with a tripod for the seabed of Réunion

Reunion Island

Ecoacoustic reference state of coral reefs around Reunion Island in 2022.

Guadeloupe

Passive acoustic monitoring of coral reefs around Guadeloupe Island from 2023 to 2024 in collaboration with the Office de l'Eau de Guadeloupe.