Journal
AQUACULTURAL ENGINEERING
Volume 61, Issue -, Pages 35-42Publisher
ELSEVIER SCI LTD
DOI: 10.1016/j.aquaeng.2014.05.003
Keywords
Metals; Toxicity; Marine; RAS; Turbot
Categories
Funding
- Deutsche Bundesstiftung Umwelt (DBU)
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Intensification of recirculating aquaculture systems (RAS) production results in decreased water volume used per volume of fish produced. As a consequence metabolites, including the main dietary metals iron, zinc, copper, cobalt and manganese accumulate in the culture water, but effects of such sub-lethal concentrations on growth and health of marine fish species are still unknown. Therefore, five small-scale experimental RAS were filled with seawater and a mixture of iron, zinc, copper, cobalt and manganese, simulating the metal accumulation at water exchange rates of 1000, 330, 100, 33 and 101/kg feed applied. A total of 90 juvenile turbot (Psetta maxima) (16.8 +/- 0.1 g) were randomly distributed to the 5 RAS and fed ad libitum with a commercial diet for 63 days. Water concentrations of zinc, copper and cobalt were stable over time. Iron showed a quick precipitation in RAS water, t(1/2) was 1.4 +/- 0.7 days. Manganese showed a slower reduction in RAS water, t(1/2) was 6.3 +/- 0.4 days. Production performance, assessed as growth, feed intake and feed conversion was not significantly affected by treatment (p > 0.05). Health status, assessed as mortality, relative liver size, relative spleen size and total hemoglobin content was neither significantly affected by treatment (p > 0.05). Amounts of dissolved metals in RAS water were reflected in turbot body composition. Correlations between dissolved metal exposure and metals in whole body were found significant (p < 0.05) for zinc, manganese and cobalt but not for iron and copper. Dry matter content significantly decreased with increasing metal exposure (p < 0.05), in contrast crude ash content did not change. Since turbot grow-out time in RAS may take up to 3 years, toxic effects of metal bioaccumulation cannot be excluded. However, the absence of effects on health and production performance during the present study does not indicate that metal accumulation is a main factor limiting turbot grow-out in RAS. (C) 2014 Elsevier B.V. All rights reserved.
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