Graded environmental hypercapnia in juvenile spotted wolffish (Anarhichas minor Olafsen): effects on growth, food conversion efficiency and nephrocalcinosis |
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| Authors: | A Foss B A Rsnes V
iestad |
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| Institution: | Norwegian College of Fishery Science, University of Tromsø, N-9037, Tromsø, Norway |
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| Abstract: | Growth performance and food conversion efficiency (FCE) were investigated in juvenile spotted wolffish (Anarhichas minor Olafsen), mean (S.D.) initial weight 15.7 (4.8) g, reared at four levels of carbon dioxide (CO2(aq)) for 10 weeks at 6 °C and 33‰. CO2 levels averaged 1.1 (control), 18.1 (low), 33.5 (medium) and 59.4 (high) mg l?1, with corresponding pH values of 8.10, 6.98, 6.71 and 6.45, respectively. In addition, kidneys from sampled fish were examined macroscopically for gross signs of calcareous deposits, i.e. nephrocalcinosis, at the start and end of the experiment. Growth was significantly reduced at the highest concentration (P<0.0001), as compared to all other groups, while no overall differences in growth rate or mean weight were seen in the range of 1.1–33.5 mg CO2 l?1 at the end of the experiment. Daily feeding rates and total food consumption were reduced at the highest concentration (P<0.001), whereas food conversion efficiency did not vary significantly between groups. Plasma chloride levels displayed a significant decrease with increasing CO2 levels, from 151.3 mmol l?1 (1.1 mg CO2 l?1) to 128.3 mmol l?1 (59.4 mg CO2 l?1) at the end of the experiment, whereas plasma osmolality in the high CO2 group was significantly higher compared to the control group at the end of the experiment (371.4 and 350.8 mOsmol kg?1, respectively). Nephrocalcinosis was observed in all groups at the end of the experiment, but was most pronounced in the medium and high CO2 group. |
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| Keywords: | Anarhichas minor Olafsen Environmental hypercapnia Nephrocalcinosis |
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