Diet composition of wild Loligo vulgaris paralarvae along the West Iberian Peninsula coast

Abstract

Trophic interactions in cephalopod paralarvae are difficult to evaluate due to the ingestion of liquified prey contents that are not recognizable by visual methods; however, molecular techniques such as next generation sequencing (NGS) can provide better resolution. In this study, we used NGS techniques to determine the diet of Loligo vulgaris paralarvae collected along the West Iberian Peninsula coast. Trophic analyses were conducted on 31 paralarvae ranging from 1.61-6.01 mm in dorsal mantle length, with an estimated age between 2 and 28 d. The digestive system of each paralarvae was dissected and a 300 bp section of the mitochondrial cytochrome c oxidase subunit I gene was sequenced with the MiSeq platform. After quality selection, 3201878 reads were obtained and 130 amplicon sequencing variants were identified as prey (158457 reads). Crustaceans accounted for 88.09% of the total reads, mainly represented by calanoids (73.22%), euphausiids (5.73%) and decapods (2.75%). Distance-based linear modelling showed that diet patterns depended mainly on spatial variables, accounting for 46.92% of the total variation, with calanoids and euphausiids comprising the dominant prey in the diet of paralarvae from SW Galicia, while siphonophores and myopsids constituted the most important prey on the Northern Galician coast.