2172 Proposal of a trophic relationship between chaetognatha and cnidaria based on coi mitochondrial sequences

Resumo

This is the first study in Brazil to propose a trophic relationship between Chaetognatha and Cnidaria
based on molecular data (COI gene - DNA barcode). Cnidaria COI sequences were detected in tissue samples
from two specimens of Flaccisagitta enflata collected in the surroundings of Fernando de Noronha archipelago,
Tropical Western Atlantic. The methodology used followed all the requirements for a safe molecular manipulation,
making the possibility of contamination unlikely. A search carried in BLAST showed that both sequences provided
here presented a combination of highest query coverage and match identity with Nemopilema nomurai (Cnidaria:
Scyphozoa), supporting the hypothesis that they belong to a species of jellyfish. Since gelatinous taxa are known to
integrate the broad diet of Chaetognatha, it is possible that F. enflata has ingested this type of item, which was not
fully digested until the moment of sampling and was not visualized by the transparency method. Thus, the record
of Scyphozoa by the COI marker suggests a trophic relationship between the respective taxon and F. enflata. Future
studies using the association of markers as well as specific methodologies may constitute a new perspective on how
to evaluate the trophic ecology of key zooplankton species, including the abundant F. enflata in the Atlantic ocean.