WWW.WAS.ORG • WORLD AQUACULTURE • DECEMBER 57 (CONTINUED ON PAGE 58) sustainability and profitability per cultivation unit because wastes of the main cultured species are biomitigated through conversion into aquafeed and biofuel for additional commercially valuable species. Macroalgae are an integral part of IMTA (Bushmann et al. 1994, 2001, 2008, Chopin 2006, Chopin et al. 1999b, 2001 and 2008, Cirik et al. 2006, Neori 2007 and 2008, Neori et al. 1996, 2000 and 2004, Neori and Shpigel 1999, Schuenhoff et al. 2003 and 2006, Shpigel and Neori 1996, Shpigel et al. 1993a, Troell et al. 1997, 1999, 2003 and 2006, Turan et al. 2006, Whitmarsh et al. 2006 and Yang et al. 2004). The IMTA approach diminishes some of the possible environmental impacts of aquaculture (Yang et al. 2006). Effluent from fish farms contains nutrients that can cause problems to other aquatic life in adjacent waters. Macroalgae can often use such nutrients, so trials have been undertaken to farm macroalgae in areas adjacent to fish farms (Krom and Neori 1989, Cohen and Neori 1991, Neori and Shpigel 1999, Neori et al. 1989, 1996, 2004, Nunes et al. 2003, Fei 2004, Kang et al. 2007, Xu et al. 2008). Integrated multi-trophic aquaculture provides new opportunities for valuable crops of macroalgae. In this way, otherwise costly waste mitigation processes become revenuegenerating cultivation components, which, by their harvest, remove nutrients of carbon, nitrogen and phosphorus from the coastal ecosystem. It is estimated that 830 tons of CO2 can be taken up annually by a 1000 t fish + 2000 t shellfish + 500 t macroalgae farm and 1230 t of CO2 can be taken up annually by a 1000 t fish + 7000 t macroalgae farm (Neori 2008). The macroalgae component of IMTA may include species of Gracilaria, Porphyra, Eucheuma/Kappaphycus, Laminaria, Undaria, Ecklonia, Macrocystis, Ulva, and Caulerpa. Other commercially important species, such as Palmaria, Chondrus, Gigartina, Hypnea, Sargassum, Cystoseira, Asparagopsis/ Falkenbergia also have high potential in IMTA systems. Today, several IMTA projects are being conducted in different parts of the world. The goal is to develop suitable modern IMTA macroalgae farming components for different aquaculture environments. Integrated multi-trophic aquaculture technologies are one of the macroalgae culture approaches that are bound to play a major role worldwide in sustainable expansion of aquaculture operations within balanced ecosystem, to respond to a worldwide increasing fuel demand with a new paradigm in the design of efficient CO2 removal systems against global warming (Turan and Neori 2010). Macroalgae for Aquafeeds The long-term sustainability of aquaculture may be limited by its dependence on fishmeal and fish oil (FAO 2002). Furthermore, fish feeding represents over 50 percent of operating costs in intensive aquaculture, with protein being the most expensive dietary component (Lovell 2002). For this reason, during these last decades an intensive effort has been made to evaluate the potential of alternative protein sources in aquafeeds (Alexis 1997). Although several studies have evaluated the replacement of fishmeal by plant ingredients in diets of marine fish species, data about the potential use of macroalgae in fish diets is limited (Appler 1985, Nakagawa et al. 1987, Hashim and Mat Saat 1992, Davies et al. 1997, Wahbeh 1997). FIGURE 1. A brown seaweed, Cystoseira barbata. FIGURE 2. A green seaweed, Ulva rigida. FIGURE 3. Cystoseira beds on a coastal area of Turkey.
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