Diet and trophic ecology of the lanternfish Electrona risso (Cocco 1829) in the Strait of Messina (central Mediterranean Sea) and potential resource utilization from the Deep Scattering Layer (DSL)

The feeding habits of the mesopelagic lanternfish Electrona risso from the Strait of Messina (central Mediterranean Sea) were analyzed for the first time. A total of 326 individuals were collected stranded along the Sicilian coast of the Strait of Messina from October 2012 to May 2013. Specimens ranged from 12.0 to 53.8 mm LS (mean LS = 38.6 ± 8.4 mm). Their stomach content was examined and prey composition and feeding strategy were investigated. The results indicate that E. risso is a specialist predator, which feeds mainly on the small mesopelagic fish Cyclothone braueri (%IRI = 74.06) and in minor proportion on zooplankton, with a prevalence of copepods. The specialized feeding strategy of E. risso is confirmed by the low value of Levins standardized index (Bj =0.141), which indicated a restricted niche breadth. The value of the index of trophic level (TROPH) for E. risso resulted 4.20. The prey composition suggests that E. risso can be considered a weakly vertical migrating species, that feeds on the DSL crustacean and fish communities below 300 m of depth.