Acoustic observation model: linking ecological models to acoustic signals

The mesopelagic (200 – 1000 m) micronekton (2 to 20 cm) community, formed mainly of small fish, cephalopods, crustacean and gelatinous zooplankton, hide in near darkness during the daytime to reduce the risk of being preyed on by visual predators. A proportion of this community migrates daily to the surface at night to feed (diel vertical migration, DVM). DVM provides a biological pathway for carbon to be transported to the surface from the deep ocean. The impact of this active component (as opposed to passively sinking matter) of the so called ‘biological carbon pump’ (BCP) on our climate, will be related to total migrant biomass, its metabolic activity at various depths, predator-prey interactions, and DVM dynamics. Recently, studies have shown that global biomass of mesopelagic fish could be more than 10 times an historic estimate of c. 1 gigaton: should these new estimates be proven correct, our view of the importance of the mesopelagic community in the carbon-cycle, will shift to a new paradigm.