Ichthyodinium identified in the eggs of European eel (Anguilla anguilla) spawned in captivity

A presumed parasitic protozoan was found in the eggs of European eel obtained from an experiment on captive breeding of eel, Anguilla anguilla, based on silver eels from a freshwater lake in the northern part of Denmark. Gross morphology of the organism was comparable to that of early stages of Ichthyodinium, a syndinian dinoflagellate parasite found in pelagic eggs of various marine fish species. Sequences of genes coding for small subunit ribosomal RNA confirmed that the organism was an Ichthyodinium species, and molecular phylogenetic analysis demonstrated the presence of two Ichthyodinium genotypes: one occurring in the Atlantic Ocean and adjacent coastal waters and one in the Pacific Ocean area. The inclusion of several GenBank-derived environmental gene sequences, from the Caribbean Sea, revealed to represent Ichthyodinium, suggesting that this parasite genus is ubiquitous in the World's oceans.