Development of a sustainable land-based Gracilaria cultivation system

Abstract

Land-based seaweed (Gracilaria) cultivation systems may provide products with high quality and biosafety for human consumption, as well as for other high value applications. However, a limitation for this land based system is high management costs. The objective of this study was to determine if the management costs for Gracilaria cultivation can be reduced without a decrease in productivity by using CO 2 injection along with a high stocking density and high photosynthetically active radiation (PAR), and commercially available fertilizers. When Gracilaria tikvahiae was cultivated at a high stocking density and high PAR, coupled with CO 2 enhancement, the productivity was significantly higher than that at a lower stocking density, low light without CO 2 injection. We also found that G. tikvahiae grown in a medium of commercially available fertilizer (Jack's Special, JS) showed a similar growth rate and productivity to that grown in von Stosch's enriched (VSE) seawater, while the cost for JS media is only 2% of the cost for VSE. These results suggest that CO 2 injection and commercial fertilizer may be a potential way to provide sustainability in land-based Gracilaria cultivation systems.Key Words: carbon dioxide; fertilizer; Gracilaria; land based aquaculture; nutrients, sustainability INTRODUCTIONGracilaria is one of the world's most cultivated seaweeds with over 0.8 million tons of annual production and nearly $160 million annual values (Food and Agriculture Organization of the United Nations 2014). Most of the biomass is used in the phycocolloid industry as the main source of food grade agar (Pereira and Yarish 2008) and as a feed for animals (Qi et al. 2010, Johnson et al. submitted). Gracilaria contributes approximately 66% of the total agar production (Pereira and Yarish 2008). Gracilaria has been cultivated mainly in three different ways, including open water, pond or tank cultures (Hanisak 1987, Abreu et al. 2011. In general, both open water and pond cultures require a nursery (tank culture) system to provide sufficient seedstock through vegetative propagation. One important advantage of tank cultivation is the ease of controlling the culture system (Pereira et al. 2013). This ensures that production meets high quality standards and biosafety for human consumptions, as well as for other high value applications such as cosmeceutical or pharmaceutical products. A limitation for tank culture, however, is high management costs (Hanisak and Ryther 1984, Caines et al. 2014).One way to overcome this challenge is to cultivate seaweed at high stocking densities. However, Lapointe and Ryther (1979) reported that the pH in culture tanks of Gracilaria tikvahiae when grown at a high stocking density increased to ca. 9.0, which resulted in the reduction of yields. Studies on Chondrus crispus revealed that the first inorganic element to be depleted in tank cultures is inorganic carbon, due to rapid absorption of CO 2 /HCO 3 -Received April 10, 2014, Accepted August 26, 2014 *Corresponding Author E-mail: jang.kim@uconn....

The short-term effects of elevated CO2 and ammonium concentrations on physiological responses in Gracilariopsis lemaneiformis (Rhodophyta)

“…We predict that mass production of this species in China will increase in response to OA and eutrophication. Kim and Yarish (2014) indicated that productivity of Gracilaria sp. was enhanced under elevated CO 2 levels with high stocking density and irradiance.…”

Prospects and challenges for industrial production of seaweed bioactives

“…Control of pH and CO 2 is readily achieved with on‐land cultures and pH stress may be an effective tool for influencing real‐time bioactivity content (Kim and Yarish ). Other chemical stresses have been implicated in bioactive content variability and some of these can ethically and cost effectively be applied during on‐land cultivation (e.g., oxidants).…”

Land-based drip-irrigated culture of Ulva compressa: The effect of culture platform design and nutrient concentration on biomass production and protein content

“…In addition, and when practiced in simple plastic film-covered greenhouses, the method allows for day-time introduction of CO 2 -rich flue gases from industrial point sources directly into head-spaces of the plastic-covered greenhouses, providing inexpensive, recycled inorganic carbon to the drip irrigated seaweeds. Moreover, one important advantage also of land-based cultivation, including the drip irrigation methods, is the ease and flexibility of controlling the culture system [ 28 , 29 ]. This ensures that production meets high quality standards and biosafety for human and animal consumption, as well as for other high value applications such as cosmeceutical or pharmaceutical products.…”