Acoustique passive et peuplements benthiques avec applications aux études d'impact EMR

Abstract : Understanding the spatial and temporal dynamics of benthic populations, both natural and induced by anthropogenic pressures, requires new observation methods with high temporal resolution and long periods of measurement. The recording and analysis of sounds produced in the marine environment give access to the soundscape, and in particular to one of its biological components, the benthic biophony. Observing the spatiotemporal variability of this benthic biophony, in order to contribute to the evaluation of the structure, functioning, state and evolution of the benthic compartment, is the main objective of the thesis. To do this we have developed two tools to evaluate the spatial variability of these emissions with one sensor or more. The first is a descriptor of the shape of the spectra of the benthic snaps allowing to better characterize the diversity of benthic biophony. The second is a method of three-dimensional localization of the benthic sound sources and mapping of this biophony for spatial scales ranging from 500 meters to 5 meters. Using these two tools, we have demonstrated the feasibility of benthos monitoring through its biophony at specific sites. In an applicative part, we were interested in sites of production of marine renewable energies and the understanding and observation of their impacts on the marine fauna. On a workshop site of geometry similar to that of an offshore wind farm, we defined, realized and analyzed a proof of concept for the observability of a binary impact: presence or absence of fixed benthic fauna in a sentinel area of a few square meters. The thesis work was concluded by a study measuring the sound level radiated by a tidal current turbine in the energy production phase (Paimpol-Bréhat) and then evaluating the acoustic impacts on three biological compartments: marine mammals, fish and invertebrates.
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Julie Lossent. Acoustique passive et peuplements benthiques avec applications aux études d'impact EMR. Traitement du signal et de l'image [eess.SP]. Université de Bretagne occidentale - Brest, 2017. Français. ⟨NNT : 2017BRES0013⟩. ⟨tel-01691648⟩

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