translate English to French: Of this total, roughly four-fifths was consumed, and the rest was deposited on the bottom, providing a rich substrate for bacteria and other benthic organisms.
Sur ce total, les quatre cinquiÃ¨mes environ ont Ã©tÃ© consommÃ©s et le reste s'est dÃ©posÃ© sur le fond, fournissant un riche substrat aux bactÃ©ries et aux autres organismes benthiques.