Histological changes in the gill, kidney and liver of Lahontan cutthroat trout, Salmo clarki henshawi, living in lakes of different salinity‐alkalinity

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Abstract
Lahontan cutthroat trout thrive in saline‐alkaline lakes, where other trout species often cannot survive. We examined Lahontan cutthroat trout from nine lakes in which salinity and alkalinity ranged from about 90 to 12 000 mg1−1 and 60 to 3500mgl−1 as HCO3− respectively, for sublethal histological changes in gill, kidney, and liver tissues. Gill chloride cell hyperplasia, gill lamellar epithelial separation, kidney glomerular swelling, blood congestion in kidneys, and deposition of hyalin droplets in kidney glomeruli, tubules, and hemopoietic tissues were the histological alterations statistically associated with differences in lakewater chemistry.Deposition of hyalin in kidney tubules was the only histological change judged pathological and whose severity appeared sufficient to jeopardize normal organ function. Differences in lakewater chemistry explained nearly 90% of the variability observed in severity of tubular hyalin degeneration, and SO42− was the ion most positively correlated with increasing tubular hyalin. Our results suggest that Lahontan cutthroat trout will develop slight to moderate hyalin degeneration in kidney tubules if stocked into lakes where salinity and SO42− concentrations equal or exceed 5000 mgl−1 and 2000mgl−1, respectively.