Effect of Ichthyophonus on blood plasma chemistry of spawning Chinook salmon and their resulting offspring in a Yukon River tributary

Abstract

Ichthyophonus is a protozoan parasite of Alaska Chinook salmon Oncorhynchus tshawytscha. In this study, we determined whether spawning Chinook salmon in the Yukon River drainage exhibited a measurable stress response (i.e. elevated plasma cortisol concentrations) and detectable changes in selected blood plasma chemistry parameters when infected with Ichthyophonus. The resulting alevin were also analyzed for any differences in blood plasma chemistry caused by parental infection with Ichthyophonus. In 2010, spawning adult Chinook salmon were collected from the Salcha River, Alaska, USA, and the prevalence of Ichthyophonus in these fish was 7.8, 6.3, and 8.3%, respectively. Fish with no clinical signs of Ichthyophonus and Ichthyophonus-positive parents were cross-fertilized to investigate potential second-generation effects as a result of Ichthyophonus infection. We found no significant difference in cortisol concentrations in blood plasma between Ichthyophonus-positive and -negative adults or between alevin from Ichthyophonus-positive and -negative parents. There were no significant differences in blood plasma parameters (e.g. alanine aminotransferase, creatine kinase, glucose) of Ichthyophonus-negative and -positive adults, with the exception of aspartate aminotransferase, which was significantly higher in plasma of Ichthyophonus-negative adults. All clinical chemistry parameters for alevin resulting from both Ichthyophonus-negative and -positive parents were not significantly different. Based on this study, which has a limited sample size and low prevalence of Ichthyophonus, offspring of Chinook salmon appear to suffer no disadvantage as a result of Ichthyophonus infection in their parents on the Salcha River.KEY WORDS: Oncorhynchus tshawytscha · Protozoan · Parasite · Yukon River · Salcha River · Cortisol concentration · Clinical blood chemistry Resale or republication not permitted without written consent of the publisherDis Aquat Org 122: [223][224][225][226][227][228][229][230][231][232][233][234][235][236] 2017 by up to 50% (JTC 2011(JTC , 2013(JTC , 2014. In 2014, all Chinook salmon harvest, including subsistence, was closed on the Yukon River. In 2015, the run was still below the historical average, but escapement into Canada was met and some subsistence fishing was allowed (ADF&G 2015). While the ultimate cause(s) for the continued run failures of Chinook salmon remain unknown, infectious diseases play a role in some other salmon population declines (Kocan et al. 2004. Disease may be a contributing factor, either due to pathogen-induced mortality, reduced fecundity, or the inability of Chinook salmon to successfully migrate and spawn.Ichthyophonus is a marine-derived protozoan parasite infecting a variety of marine and anadromous fish species, including salmonids (McVicar 1999, Kocan et al. 2004, Tierney & Farrell 2004, Gavryuseva 2007. This parasite was identified in the mid1980s after fishers reported white papules on the heart, liver, and musculature of Chinook salmon returning to spawn...

Evaluation of the Effects of Carbon 60 Nanoparticle Exposure to Adult Zebrafish: A Behavioral and Biochemical Approach to Elucidate the Mechanism of Toxicity

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