DNA metabarcoding suggests dietary niche partitioning in the Adriatic European hake

Giulia Riccioni,Corrado Piccinetti,Chiara Manfredi,Fausto Tinti,Marco Stagioni,Simone Libralato

doi:10.1038/s41598-022-05346-0

Abstract

The Northern Adriatic Sea (FAO Geographical Sub-Area 17) is one of the most productive fishing areas of the Mediterranean Sea and it includes a broad diversity of habitats. In the Northern Adriatic basin, the Pomo Pit (200–273 m of depth) is one of the most important areas of aggregation for some demersal stocks shared in the Adriatic Sea and it is an important spawning/nursery area of the European hake (Merluccius merluccius). Through a metabarcoding approach we investigated the feeding habits of European hake, both inside and outside the Pomo Pit, and their temporal variability comparing samples collected in 2016 and 2014. Our analyses proved the presence of an ontogenetic shift from a diet based mainly on crustaceans in juveniles to a more piscivorous feeding behaviour in adult hakes and suggested the presence of a specific niche partitioning and food preferences between hakes living inside and outside the Pomo Pit. The main differences among adult hakes refer to the presence of molluscs in the stomachs of hakes collected within the Pomo Pit and the presence of high depth prey species (i.e., Micromesistius poutassou). Metabarcoding revealed the relevant ecological role played by the Pomo Pit in M. merluccius feeding behaviour and ontogenetic development, promoting a careful ecosystem-based management of fisheries in this area through focused conservation measures.

Highlights

The Northern Adriatic Sea (FAO Geographical Sub-Area 17) is one of the most productive fishing areas of the Mediterranean Sea and it includes a broad diversity of habitats
MiSeq sequencing produced about 18 million of reads from the stomach content DNA of 100 M. merluccius specimens collected both inside the Pomo Pit and outside on the shelf area (Fig. 1, see “Methods” for sampling description)
Our metabarcoding analyses provided crucial insights into M. merluccius feeding behaviour in very heterogeneous habitats and unprecedented fine scale descriptions of trophic relationships within a nursery area currently managed as Fisheries Restricted Area since 2018

Summary

Introduction

The Northern Adriatic Sea (FAO Geographical Sub-Area 17) is one of the most productive fishing areas of the Mediterranean Sea and it includes a broad diversity of habitats. We set up and tested a molecular genetic method to provide an in-depth description of M. merluccius food preferences in the Adriatic Sea improving the taxonomic identification of prey compared to the classical morphological identification in stomach c ontent[35] This metabarcoding method allowed us the identification of a broad range of prey for M. merluccius highlighting different food preferences by size classes. Considering the pressure currently exerted to permanently close Pomo Pit area, the knowledge on the ontogenetic diet shifts associated with the nursery area could further stress the ecological importance of the Pomo Pit and could support the temporal extension of the spatial management measures temporarily in place

Methods

Results

Conclusion