Aquat. Living Resour.
Volume 33, 2020
Special Issue - Ecological intensification: A new paragon for sustainable aquaculture
|Number of page(s)||13|
|Published online||04 December 2020|
Co-culture of Ulva sp. and Dicentrarchus labrax in Recirculating Aquaculture System: effects on growth, retention of nutrients and fatty acid profile
Laboratory of Applied Hydrobiology, Faculty of Animal Science and Aquaculture, Agricultural University of Athens, 75 Iera Odos, Athens
* Corresponding author: email@example.com
Handling Editor: Jacques Slembrouck
Accepted: 11 November 2020
European sea bass and Ulva sp. were co-cultured in different tanks of an indoor Recirculating Aquaculture System (Ulva-RAS) with bacterial biofilter, in an effort to optimize the efficiency of the system and to further decrease the waste effluent. A system with similar culture conditions, without Ulva, was used as a control-RAS to elucidate integration effects on growth performance and chemical composition of sea bass. The role of Ulva on N and P concentrations, gas (O2, CO2) and pH in water was also investigated. Fish were fed a diet of fish oil replacement (55%) with a mixture of rapeseed oil and palm oil (1:1). Our data showed that Ulva could uptake N and P nutrients, but could also enrich sea water with phosphates. Sea bass reared in Ulva-RAS exhibited isometric growth, while fish in control-RAS showed a positive allometric growth and an increased variance of body weight and length. In addition, sea bass in Ulva-RAS demonstrated significantly higher levels of condition factor (K), feed intake, protein, lipid, P, EPA and DHA content (% wet weight of total body) and lipid productive value, compared to fish in control-RAS. Ulva, after bi-weekly culture, showed increased protein content (60%) compared to wild seaweed collected nearshore. Cultivated Ulva obtained dark green color, doubled chlorophyll concentrations, and exhibited lower levels of saturated and higher levels of certain monounsaturated and n-3 polyunsaturated fatty acids, indicating increased photosynthetic activity. Present results revealed the beneficial effects of Ulva on sea bass growth and quality, which led to an improved response to the nutritional stress imposed by the fish oil replacement with vegetable oils, thus contributing to a sustainable aquaculture. Moreover, it was concluded that Ulva could improve water quality by increasing pH and O2, reducing CO2 and contribute to bioremediation of ammonia and nitrates from water in integrated aquaculture.
Key words: RAS / IMTA / Ulva / sea bass / fatty acid profile / proximate composition / nutrients
© EDP Sciences 2020
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