Molecular ontogeny of the immune system and characterization of bacterial community structure in feeding European eel (Anguilla anguilla) Larvae.

Abstract

European eel (Anguilla anguilla) is a commercially important species for aquaculture in Europe. Commercial aquaculture of this species still depends on the wild-caught juvenile glass eels entering coastal waters, which are farmed until marketable sizes. However, due to historically low levels of recruitment, a supply of hatchery produced glass eels is required to ensure the sustainability of aquaculture and to assist the conservation of this critically endangered species (Pike et al., 2020). Negative host-microbial interactions (Sørensen et al., 2014) and an immune system under development during the early larval stages (Miest et al., 2019), among other factors, have been reported to challenge the European eel larval performance under captive conditions. Feeds are one of the major sources of organic matter supply during first feeding of fish larvae (Vadstein et al., 2018). Food added to the system favours bacterial growth, in response to which fish larvae might develop an immune response. During this experiment, we studied the molecular ontogeny of the immune system of the feeding European eel larvae and characterized the microbial community structure of larvae and the corresponding rearing water throughout feeding culture.