Trophic ecology of "Diaphus mollis" (Taning, 1928) in the Canary Islands (Centra-east Atlantic)

Abstract

Diaphus mollis was one of the most abundant species in the captures in the Deep Scattering Layer (DSL) made by La Bocaina R/V during the oceanographic surveys carried out between 1997 and 2002, in the surroundings of the Canary Islands. D. mollis presented a wide vertical distribution in the water column, reaching the surface waters (up to 34 m) at night hours, while during the day it was captured at depths of 772.5 m. These circadian changes in its vertical distribution are associated with vertical migrations for trophic reasons. Thus, the specimens captured in surface waters during the night presented higher values of the Stomach fullness index than captured in deep waters during the day. On the other hand, the morphological analysis and diet allowed to establish an ontogenetic and behavioral change around 37.1 mm of total length. However, the analysis of the diet did not show changes in the composition of the stomach contents, showing that the main prey were the copepods (> 99% of the diet), followed by misyds, ostracods, gastropods, chaetognaths, polychaetes and cephalopods. However, if it was observed that larger D. mollis specimens consumed prey of larger sizes