Evaluating DNA metabarcoding to analyze diet composition of wild long-snouted seahorse Hippocampus guttulatus

Seahorses are small sedentary fish considered flagship species of the conservation efforts. During the last decades, worldwide decline of local populations led to the inclusion of all seahorse species on the IUCN Red List and Appendix II of CITES. Due to the threatening status, improving knowledge of their dietary composition, while using a noninvasive approach, might be of great importance as it could help to understand the way the environment is exploited. In the present study, we used an amplicon-based HTS (High Throughput Sequencing) approach to investigate the diet of wild long-snouted seahorse Hippocampus guttulatus. The results indicated that the applied approach is adequate for the characterization of diet in wild specimens. Indeed, the applied approach permitted identification of Amphipoda, Decapoda, Isopoda and Calanoida, present in most of the seahorse samples, while less common prey taxa were Gastropoda and Polyplacophora. As only a small amount of starting faecal material is needed and the sampling procedure is neither invasive nor lethal, DNA metabarcoding could be useful in the investigation of threatened seahorse diet in the wild and could help inform management and conservation actions.