World Aquaculture March 2019

36 MARCH 2019 • WORLD AQUACULTURE • WWW.WA S.ORG LEFT, FIGURE 9. Example of the green seaweed fouling in the Gracilaria tikvahiae cultures after five weeks in the study (Photo: Megan Davis, FAU HBOI). RIGHT, FIGURE 10. Processing crude agar extract (Photo: Megan Davis, FAU HBOI). LEFT, FIGURE 11. Megan Davis, HBOI research professor, restocking Gracilaria into one of the seaweed study tanks (Photo: Brian Cousin, FAU HBOI). RIGHT, FIGURE 12. Megan Davis and Tyler Bianchine discussing the seaweed study (Photo: Brian Cousin, FAU HBOI). As a generality, as the sunlight intensity decreased agar yield increased. The agar yield was 33 percent at 100 percent sunlight intensity, 40 percent at 50 percent sunlight intensity, and 42 percent at 25 percent sunlight intensity. These results were similar to the crude agar yields obtained by Gunasekera (1963). Based on these initial results, Gracilaria grown in the HBOI IMTA system appears to yield sufficient agar that could be used for making sea moss drinks. Summary The HBOI IMTA system is suitable for growing Gracilaria to produce a product for human consumption. The seaweed is an important product of the system because it uses the waste products and nutrients produced by the fish and other species grown in the system, and returns lower nutrient water to the fish. Reducing the sunlight to the Gracilaria summer crop cultures produced a marketable product with a desirable rich dark red-brown color and sturdy fronds. The lower light also reduced fouling, although the growth rate was not as high as in the full sunlight cultures. The nutritional profile of the seaweed indicated a high level of carbohydrate, protein, and ash and a very low level of fat. Therefore, the Gracilaria grown in the IMTA system was nutritious and could be used for salads and added to other culinary dishes. Based on the gelling of the crude agar produced from the seaweed grown in the IMTA system, it would be ideal for making sea moss drinks. Overall, we recommend growing seaweed in an IMTA system because it captures nutrients from the fed species in the system and results in high-quality sustainable products for human consumption. Developing seaweed markets more fully could significantly enhance the economic viability and commercial success of IMTA systems. Acknowledgments This research was supported by the Link Foundation and the Aquaculture Specialty License Plate Program granted through the Harbor Branch Oceanographic Institute Foundation. The authors thank the following for their contributions to the study: Rich Mulroy, Richard Baptiste, Ryan Winant, Zack Nilles, Patrick Monaghan, Liberta Scotto, Brian Cousin, Casey Den Ouden, Ethan Weber, Patrick Keller, Pete Stock, and Jack Lee.