Assessment of Hippocampus guttulatus diet using DNA metabarcoding of faeces

Seahorses are small sedentary fish considered flagship species of the conservation efforts. They are particularly vulnerable to human pressures because inhabiting threatened coastal ecosystems. Indeed, the worldwide decline of local populations in the last decades led to the inclusion of all seahorse species on the IUCN Red List, where most species, including Hippocampus guttulatus, were classified as 'Data Deficient' due to the lack of relative data on several biological and ecological traits of these fish. Because of such sensitive conservation status, improvement of the current knowledge on the diet composition of wild animals and its differences among habitats could be of great importance as it could help to understand the way the environment is exploited. In the present study, we used a non-invasive DNA metabarcoding technique to further elucidate long-snouted seahorse diet and expand our understanding of prey choice among different habitats. The diet was dominated by crustaceans, while less common were gastropods and polychaetes. We found significant differences in the diet composition among investigated habitats thus indicating a trophic flexibility of H. guttulatus among diverse habitats, a characteristic that may be essential for the resilience of this iconic yet threatened species.