Metadata of the article that will be visualized in OnlineFirst _____________________________________________________________________________________ _____________________________________________________________________________________Please note: Images will appear in color online but will be printed in black and white. 1 Article Title Seaweed extracts as antimicrobial agents in aquaculture 2 Article Sub- Title 3 Article Copyright - Springer Science+Business Media Dordrecht 2014 Year (This will be the copyright line in the final PDF) 4 Journal Name Journal of Applied Phycology 5 Family Name Vatsos 6 Particle 7 Given Name Ioannis N 8 Corresponding Suffix 9 Author Organization University of Nordland 10 Division Faculty of Biosciences and Aquaculture 11 Address Post Office Box 1490, Bodø 8049, Norway 12 e-mail [email protected] 13 Family Name Rebours 14 Particle 15 Given Name Celine 16 Suffix 17 Author Organization Bioforsk, Norwegian Institute for Agricultural and Environmental Research 18 Division 19 Address Frederik A. Dahlsvei 20, Ås 1430, Norway 20 e-mail [email protected] 21 Received 21 July 2014 22 Schedule Revised 10 December 2014 23 Accepted 11 December 2014 24 Abstract In the last 20 years, there has been an increasing interest in using various seaweed extracts as prophylactic and/or therapeutic agents in aquaculture. Up until now, most studies on the direct antimicrobial effect of seaweeds have taken place in various parts of Asia, particularly in India. All groups of seaweeds exhibit significant antimicrobial properties against many infectious agents of fish and shrimp, but the genera that appear to exhibit a broader range of antibacterial properties are Asparagopsis spp. (red seaweed) and Sargassum spp. (brown seaweed). The activity can be affected by many factors and the method of extraction is one of the most important ones, as the extracts that are produced using organic solvents appear more efficient. In fish, almost all published information on bacterial pathogens comes from in vitro screenings, where extracts of different seaweed species were tested against many bacterial species. On the other hand, in shrimp, the studies have been focusing on the antimicrobial effects of seaweed extracts mainly against many Vibrio species. Regarding the viral pathogens, in fish, there is only one published study on fish viruses (IHNV and IPNV), while in shrimp there are many studies on WSSV. There are only two published studies on fish parasites (Ichthyophonus hoferi and Neobendenia spp.) and no studies on pathogenic fish and shrimp fungi. Interestingly, there are no published studies on salmons and carps, the main fish species that are extensively farmed. When the antimicrobial properties were studied in vivo, the seaweed extracts were either incorporated directly in the feeds (dry or live) or added directly into the water in which the fish and shrimp were reared. In the last case, the water-soluble antimicrobial seaweed substances affected the communication between the bacterial pathogens, rather than their growth. The development of parasites was also affected. In addition, one study indicated that short-term immersion of shrimp in seaweed extracts appeared to have a therapeutic effect against Vibrio parahaemolyticus. On the other hand, incorporation of the extracts into the feeds appeared to be an effective delivery method for the prevention and treatment of different infectious diseases. Up until now, there are no complete studies on the pharmacodynamics and pharmacokinetics of seaweed extracts in fish or shrimp. However, the findings indicate that they can reduce the bacterial load within the tissues. Another issue that has not been examined yet is the applicability of using these extracts on a commercial scale. Currently, the increased extraction cost inhibits the extensive use of these extracts. Other methodologies, such the production of synthetic analogues with similar properties, may decrease the production cost. Based on the published studies, seaweed extracts exhibit promising antimicrobial properties, but further research is needed before the complete potential of seaweed extracts is assessed. 25 Keywords Seaweed - Antimicrobial - Fish - Shrimp - Aquaculture separated by ' - ' 26 Foot note information JrnlID 10811_ArtID 506_Proof# 1 - 20/12/2014 J Appl Phycol DOI 10.1007/s10811-014-0506-0 1 3 5TH CONGRESS OF THE INTERNATIONAL SOCIETY FOR APPLIED PHYCOLOGY 2 4 Seaweed extracts as antimicrobial agents in aquaculture 67 Ioannis N Vatsos & Celine Rebours 8 9 Received: 21 July 2014 /Revised and accepted: 10 December 2014 10 # Springer Science+Business Media Dordrecht 2014 OF 11 Abstract In the last 20 years, there has been an increasing directly in the feeds (dry or live) or added directly into the 38 12 interest in using various seaweed extracts as prophylactic and/ water in which the fish and shrimp were reared. In the last 39 13 or therapeutic agents in aquaculture. Up until now, most case, the water-soluble antimicrobial seaweed substances af- 40 14 studies on the direct antimicrobial effect of seaweeds have fected the communicationPRO between the bacterial pathogens, 41 15 taken place in various parts of Asia, particularly in India. All rather than their growth. The development of parasites was 42 16 groups of seaweeds exhibit significant antimicrobial proper- also affected.D In addition, one study indicated that short-term 43 17 ties against many infectious agents of fish and shrimp, but the immersionE of shrimp in seaweed extracts appeared to have a 44 18 genera that appear to exhibit a broader range of antibacterial therapeutic effect against Vibrio parahaemolyticus.Onthe 45 19 properties are Asparagopsis spp. (red seaweed) and other hand, incorporation of the extracts into the feeds ap- 46 20 Sargassum spp. (brown seaweed). The activity can be affected peared to be an effective delivery method for the prevention 47 21 by many factors and the method of extraction is one of the and treatment of different infectious diseases. Up until now, 48 22 most important ones, as the extracts that are produced using there are no complete studies on the pharmacodynamics and 49 23 organic solvents appear more efficient. In fish, almost all pharmacokinetics of seaweed extracts in fish or shrimp. How- 50 24 published information on bacterial pathogens comes from ever, the findings indicate that they can reduce the bacterial 51 25 in vitro screenings, where extracts of different seaweed spe- load within the tissues. Another issue that has not been exam- 52 26 cies were tested against many bacterial species.ORRECT On the other ined yet is the applicability of using these extracts on a 53 27 hand, in shrimp, the studies have beenC focusing on the anti- commercial scale. Currently, the increased extraction cost 54 28 microbial effects of seaweed extracts mainly against many inhibits the extensive use of these extracts. Other methodolo- 55 29 Vibrio species. Regarding the viral pathogens, in fish, there gies, such the production of synthetic analogues with similar 56 30 is only one published study onUN fish viruses (IHNVand IPNV), properties, may decrease the production cost. Based on the 57 31 while in shrimp there are many studies on WSSV. There are published studies, seaweed extracts exhibit promising antimi- 58 32 only two published studies on fish parasites (Ichthyophonus crobial properties, but further research is needed before the 59 33 hoferi and Neobendenia spp.) and no studies on pathogenic complete potential of seaweed extracts is assessed. 60 34 fish and shrimp fungi. Interestingly, there are no published 35 studies on salmons and carps, the main fish species that are Keywords Seaweed . Antimicrobial . Fish . Shrimp . 61 36 extensively farmed. When the antimicrobial properties were Aquaculture 62 37 studied in vivo, the seaweed extracts were either incorporated 63 Introduction 64 I. N. Vatsos (*) Faculty of Biosciences and Aquaculture, University of Nordland, Q1 65 Post Office Box 1490, 8049 Bodø, Norway With an average annual growth rate of 8.9 % since 1970, e-mail: [email protected] aquaculture is considered to be the fastest growing food- 66 producing sector in the world and accounts for about 36 % 67 C. Rebours of the global fish supply and almost 60 % of the global shrimp 68 Bioforsk, Norwegian Institute for Agricultural and Environmental 69 Research, Frederik A. Dahlsvei 20, 1430 Ås, Norway supply (FAO 2014). In terms of quantity, farming of cyprinids e-mail: [email protected] dominates the aquaculture production, with 25.4 million T, 70 JrnlID 10811_ArtID 506_Proof# 1 - 20/12/2014 J Appl Phycol 71 while the production of salmonids and crustaceans (shrimp polysaccharides (e.g. fucoidan), various phytochemicals (e.g. 124 72 and prawns) contributes with 3.2 and 4.3 million T, respec- phlorotannins), carotenoids, minerals, peptides and lipids 125 73 tively (FAO 2014). Diseases, either infectious or non-infec- (Gupta and Abu-Ghannam 2011b;HoldtandKraan2011). It 126 74 tious, are important limiting factors that affect the production is worth mentioning that some of these compounds, as for 127 75 volume and consequently the production cost. In 2006, for example phlorotannins, are not found in terrestrial plants. 128 76 instance, for a global production of 1.6 million T of salmon, The present review focuses on published studies on the 129 77 the cost for sea lice treatments was estimated at 305 million € direct antimicrobial properties of seaweeds and their extracts 130 78 (Costello 2009). It has been estimated