| Intermediate trophic components of pelagic ecosystem (from mesozooplakton to micronekton) funnel energy and organic matters from primary producers to many commercial species (anchovy, sardines…). Some of these organisms are supposed to be important contributors to the ubiquitous Sound Scattering Layers (SSLs) observed over a broad range of spatio-temporal scales and geographical areas. Yet, the SSLs taxonomic composition remains largely unknown. The aim of this PhD was to describe the composition and repartition of dense SSLs observed in the Bay of Biscay (France) in spring at several spatial scales, using broadband acoustics, nets and videos. In the first chapter, we showed that the echo sounder beam widths had few effect on the SSLs backscatter,... |
