56 DECEMBER 2013 • WORLD AQUACULTURE • WWW.WAS.ORG Global Macroalgae Aquaculture with Reference to Potential in Turkey Gamze Turan Macroalgaee — also known as “seaweeds,” “aquatic plants” or “sea vegetables”e — form a large group of aquatic plants that are widely used for human food in China, Japan and Korea. It is also an ingredient in animal feeds (including aquafeeds), cosmetics and fertilizers (McHugh 2003). Various macroalgae are also used to produce hydrocolloids (or phycocolloids) such as alginate, agar and carrageenan that are used as thickening and gelling agents. Macroalgal extracts are found in a wide range of common products in daily use, such as toothpaste, shaving foam, ice cream, cheeses, candy, beer, shower gels, bacteriological agar and paper. Increasingly, macroalgae are being investigated for the biological activity of extracts, which are finding applications in pharmaceuticals, biotechnology and food preservatives (Schuenhoff et al. 2006). In addition, macroalgal products are used in textiles and printing to achieve the desired consistency of dyes, paints and inks. There are many macroalgae companies producing a range of seaweed based marine spa therapy (thalassotherapy) products that include seaweed bath salts, bubble bath, shampoos, shower gel, soaps, facial scrubs, body masks, moisturizers and foot bath salts (De Roeck-Holtzhauer 1991, Turan and Cirik 2008). Developments in the paper pulp industry have made macroalgae a practical alternative to trees (De Poli et al. 1994, You 2008). There are also potential uses for macroalgae in wastewater treatment because they can absorb nutrients and heavy metal ions, such as zinc and cadmium, from polluted water (Ryther et al. 1975, Schramm 1991a). Physiologically macroalgae can be viewed as biosystems that take up nutrients like sponges absorb water. By periodically harvesting nutrient-rich macroalgal biomass, a large quantity of nutrients can be removed from coastal waters and the regrowth of new biomass can continue the nutrient scrubbing process (Fei 2004). For this reason, macroalgae is used in integrated multi-trophic aquaculture (IMTA) systems to bioremediate the coastal-water nutrification by cage fishculture (Chopin et al. 2001, 2008) and landbased culture (Neori et al. 2004). Offshore or open-ocean cultivation refers to growing macroalgae in waters that are generally too deep for even giant kelp to survive on their own and that are free from the direct influence of land. Open-ocean macroalgae cultivation systems are large farms located in areas with natural or artificial upwelling of deep ocean waters for nutrient supply. Macroalgae Aquaculture Macroalgae aquaculture represents 23 percent of global aquaculture production, but its potential is far from fully exploited. Macroalgae cultivation techniques are standardized, routine and efficient. Despite the variety of life forms and the thousands of macroalgal species described, only about 100 taxa are used in seaweed aquaculture. The genera Laminaria, Undaria, Porphyra, Eucheuma/Kappaphycus, and Gracilaria account for about 98 percent of global production (Sahoo and Yarish 2005, Yarish and Pereira 2007). However, cultivation of other commercially important species, such as Palmaria, Chondrus, Gigartina, Gelidium, Pterocladia, Hypnea, Asparagopsis/Falkenbergia, Ecklonia, Macrocystis, Sargassum, Cystoseira, Monostroma, Ulva and Caulerpa takes place in many different places (Kain-Jones 1991, Schramm 1991b, Critchley and Ohno 1997, 1998, 2001, FAO 2003, McHugh 2003, Critchley et al. 2006, Troell et al. 2006). The global macroalgae industry produces over 15 million tons (fresh weight) annually with a total value of over US$ 7 billion (FAO 2006). The value of food products for human consumption contributes US$ 4-5 billion of this, with Porphyra (nori) the single most valuable crop, worth over US$1.3 billion. Hydrocolloids extracted from macroalgae account for a large part of the remaining value, while smaller miscellaneous uses, such as fertilizers and animal feed additives, make up the remainder. Over 90 percent of the market is supplied by cultivation. The farming of macroalgae has expanded rapidly as demand has outstripped the supply available from natural resources. Large-scale macroalgae culture is attractive because low-cost production technologies have been practiced for decades and the product has multiple uses as food, feed, chemicals and biofuel. Yields of macroalgae can be as high as 80 t dry weight ha-1 y-1 in modern intensive pond farms, while extensive low technology coastal farms regularly get yields above 20 t dry weight ha-1 y-1 (Neori et al. 2004). Macroalgae can take up 29 t carbon ha-1 y-1 in modern intensive farms and 7.3 t carbon ha-1 y-1 in low-technology farms (Sinha et al. 2001). China is the largest producer of macroalgae (10.9 million tons wet weight) followed by the Philippines (1.5 million t), Indonesia (0.91 million t), the Republic of Korea (0.77 million t) and Japan (0.49 million t) (FAO 2009). While the bulk of China’s contribution mainly comes from the cultivation of Laminaria japonica, 50 percent of Korean production is contributed by Undaria pinnatifida and 75 percent of Japan’s contribution comes from the cultivation of Porphyra sp. The Philippines and Indonesia are involved mainly in the cultivation of Kappaphycus alvarezii and Eucheuma denticulatum (carragenophytes) as well as Gracilaria species (agarophytes). Macroalgae and IMTA Feed is the main expense in most finfish and shrimp aquaculture operations, but most feed nutrients are excreted as waste to water (Troell et al. 2003). Integrated multi-trophic aquaculture is an innovative solution for environmental sustainability, economic diversification and social acceptability. The practice combines the cultivation of finfish with shellfish and macroalgal species as an ecologically-balanced aquaculture management approach. Integrated multi-trophic aquaculture increases the long-term
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