Abstract
Periods of high or fluctuating seawater temperatures result in several physiological challenges for farmed salmonids, including an increased prevalence and severity of cataracts. The aim of the present study was to compare cataractogenesis in Atlantic salmon (Salmo salar L.) and rainbow trout (Oncorhynchus mykiss) reared at two temperatures, and investigate whether temperature influences lens metabolism and cataract development. Atlantic salmon (101±2 g) and rainbow trout (125±3 g) were reared in seawater at either 13°C (optimum for growth) or 19°C during the 35 days experiment (n = 4 tanks for each treatment). At the end of the experiment, the prevalence of cataracts was nearly 100% for Atlantic salmon compared to ~50% for rainbow trout, irrespective of temperature. The severity of the cataracts, as evaluated by slit-lamp inspection of the lens, was almost three fold higher in Atlantic salmon compared to rainbow trout. The global metabolic profile revealed differences in lens composition and metabolism between the two species, which may explain the observed differences in cataract susceptibility between the species. The largest differences were seen in the metabolism of amino acids, especially the histidine metabolism, and this was confirmed by a separate quantitative analysis. The global metabolic profile showed temperature dependent differences in the lens carbohydrate metabolism, osmoregulation and redox homeostasis. The results from the present study give new insight in cataractogenesis in Atlantic salmon and rainbow trout reared at high temperature, in addition to identifying metabolic markers for cataract development.
Highlights
Cataract is characterized as the presence of opacities in the eye lens, which can be caused by changes in the epithelial tissues surrounding the lens fibres, or the composition and structure of the lens fibres, resulting in reduced vision [1]
The rainbow trout had a higher feed intake and growth rate compared to the Atlantic salmon, no differences were found within the species as a result of different temperatures
Atlantic salmon and rainbow trout were characterized to investigate differences in lens metabolism between the species and study metabolic changes in the lenses caused by water temperature
Summary
Cataract is characterized as the presence of opacities in the eye lens, which can be caused by changes in the epithelial tissues surrounding the lens fibres, or the composition and structure of the lens fibres, resulting in reduced vision [1]. The specific roles of these authors are articulated in the ‘author contributions’ section
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