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Transmission of a Freshwater Isolate of Ichthyophonus (Clade C) to Two Marine Fish Species
Author(s) -
Kocan R. M.,
Kocan A. J.,
Reichley S. R.
Publication year - 2019
Publication title -
journal of aquatic animal health
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.507
H-Index - 52
eISSN - 1548-8667
pISSN - 0899-7659
DOI - 10.1002/aah.10087
Subject(s) - biology , predation , parasite hosting , zoology , freshwater fish , population , rainbow trout , fishery , ecology , fish <actinopterygii> , demography , sociology , world wide web , computer science
The ingestion of infected prey is the most recognizable mode of transmission for Ichthyophonus , but because this mode of transmission is unidirectional from small prey fish to larger predators, it cannot sustain the parasite within or among populations nor does it explain transmission to planktivores. Recently, waterborne transmission was demonstrated in cultured Rainbow Trout Oncorhynchus mykiss , which could explain how the parasite is transmitted without piscivory. However, it is possible that this is an adaptation to aquaculture conditions, and may not occur among wild fish. To address this question, experiments were conducted to determine if a freshwater isolate of Ichthyophonus is infectious and pathogenic to marine species, as well as if transmission is possible between different marine species. Pacific Staghorn Sculpins Leptocottus armatus were fed a freshwater isolate of Ichthyophonus (clade C) and then housed with susceptible sentinel Rock Soles Lepidopsetta bilineata . Ninety two percent of the orally exposed sculpins and 30% of the sentinel soles were Ichthyophonus ‐positive at the end of the study, with 0% infected controls. These results demonstrate that a freshwater isolate of Ichthyophonus is infectious and pathogenic to marine species and can be transmitted in seawater in the absence of piscivory. It also provides a plausible mechanism for transmission to small prey fish and planktivores, as well as within a population of piscivores when infected prey is not available.