The dual objective of sustainable aquaculture, i.e., to produce food while sustaining natural resources is achieved only when production systems with a minimum ecological impact are used. Recirculating aquaculture systems (RASs) provide opportunities to reduce water usage and to improve waste management and nutrient recycling. RAS makes intensive fish production compatible with environmental sustainability. This review aims to summarize the most recent developments within RAS that have contributed to the environmental sustainability of the European aquaculture sector. The review first shows the ongoing expansion of RAS production by species and country in Europe. Life cycle analysis showed that feed, fish production and waste and energy are the principal components explaining the ecological impact of RAS. Ongoing developments in RAS show two trends focusing on: (1) technical improvements within the recirculation loop and (2) recycling of nutrients through integrated farming. Both trends contributed to improvements in the environmental sustainability of RAS. Developments within the recirculation loop that are reviewed are the introduction of denitrification reactors, sludge thickening technologies and the use of ozone. New approached towards integrated systems include the incorporation of wetlands and algal controlled systems in RAS. Finally, the review identifies the key research priorities that will contribute to the future reduction of the ecological impact of RAS. Possible future breakthroughs in the fields of waste production and removal might further enhance the sustainabilty of fish production in RAS.

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ÔØ Å ÒÙ× Ö ÔØPlease cite this article as: Abbink, Wout, Blanco Garcia, Ainhoa, Roques, Jonathan A.C., Partridge, Gavin J., Kloet, Kees, Schneider, Oliver, The effect of temperature and pH on the growth and physiological response of juvenile yellowtail kingfish Seriola lalandi in recirculating aquaculture systems, Aquaculture (2011), doi: 10.1016/j.aquaculture.2011.11.043 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. A C C E P T E D M A N U S C R I P T ACCEPTED MANUSCRIPT A C C E P T E D M A N U S C R I P T ACCEPTED MANUSCRIPT2 AbstractA search for a viable new fish species for culture in recirculating aquaculture systems (RAS) in the Netherlands identified yellowtail kingfish Seriola lalandi as having excellent potential.To assist in determining the most appropriate water quality conditions for this species in RAS, the effect of water temperature (21, 23.5, 25, 26.5 and 29 ˚C) and pH (6.58, 7.16 and 7.85) were tested in two separate experiments. Growth performance, feed conversion, stressphysiological and metabolic parameters were assessed in juvenile yellowtail kingfish grown in pilot-scale RAS. Growth was optimised at a water temperature of 26.5 °C, in combination with maximum food intake and optimum food conversion ratio (FCR). Increasing temperature from 21 °C to 26.5 °C resulted in a 54 % increase in the fish's final weight after 30 days. A water pH of 6.58 resulted in mortality and inhibited both growth and FCR due to physiological disruptions to which the fish could not adapt.

This study shows that alternatives for fishmeal in a fish diet affect not only fish growth but also faeces stability and nitrogen (N) and phosphorus (P) waste production. Wheat gluten diet (WGD), soybean meal extract diet (SBE), soybean meal diet (SBM), duckweed diet (DWD) and single‐cell protein diet (SCP) were evaluated as a fishmeal replacement on a 15% weight weight−1 basis in tilapia diets. Fishmeal replacement affected dry matter (dm), protein, ash and P digestibility significantly. Faeces recovery (6.8–11.2%) was not significantly affected, although the amount of non‐recovered faeces and total faeces showed significant differences. Duckweed diet and SCP resulted in the largest amounts of non‐recovered and total faeces (199–210, 224–225 g dm kg−1 feed dm). Compared with fishmeal diet (FMD), the WGD and SBE resulted in similar growth, but higher non‐faecal N losses (471–495 vs. 416 g N kg−1 N). Soybean meal diet, DWD and SCP resulted in lower growth but less non‐faecal loss (409–450 g N kg−1 N). The DWD and FMD had the highest N retention (480 g N kg−1 N) compared with the other diets (431–451 g N kg−1 N). Carbon retention, faecal and non‐faecal losses and P retention were similar for all diets (302–358, 142–176 and 489–523g C kg−1 C, 606–704 g P kg−1 P). Phosphorus faecal loss was lower for all diets (329–381 g P kg−1 P) than for the FMD (401 g P kg−1 P).

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