Title: Rapid response of benthic deep-sea microbes (viruses and prokaryotes) to an intense dense shelf water cascading event in a submarine canyon of the NW Mediterranean Sea
Abstract: A major dense shelf water cascading (DSWC) event occurred in 2005 downward the Cap de Creus 3 Canyon (Gulf of Lion, NW Mediterranean Sea), which caused a significant change in 4 environmental parameters and biological components.Here we describe the effects of this DSWC 5 event on benthic microbes and on virus-prokaryote interactions, and we explore their implications 6 on the functioning of the canyon's ecosystem.We collected sediment samples at increasing depths 7 inside the canyon and in the adjacent deep continental margin over a period of five years, i.e. during 8 and after the DSWC event, which led to the deposition of high amounts of fresh and labile organic 9 matter that stimulated C production by benthic prokaryotes and increased their abundance and 10 biomass.The enhanced prokaryotic metabolism, still evident 6 months after the DSWC event, was 11 associated with high viral replication rates and prokaryotic mortality, which released 3.4-6.3gC m -2 12 over such a 6 months period.Such values are up to 3-times higher than the yearly C-flux to the 13 seafloor reported in this area in years without DSWC.We conclude that DSWC can significantly 14 enhance benthic prokaryotic metabolism and C cycling through viral-induced prokaryotic mortality.