Cultivation of Saccharina latissima (Sugar kelp) using sea urchins crush as a nutrient source

Abstract

Saccharina latissima is a species of brown seaweed suitable for cultivation and has different usage such as food, biofuel, and feed. Further, the fisheries industry produces tons of byproducts while processing seafood, which will be discarded as waste. In the sea urchin processing industry, for instance, most parts of a sea urchin, such as shell, spines, and viscera, will be discarded after removal of the commercially used gonads (roe). The thesis aims to investigate the potential of a method of utilizing sea urchin byproducts as fertilizer to enrich the water for the cultivation of S. latissima sporophytes. The young sporophytes were cultivated in (a) 10 (low) versus 50 (high) ml of nutrient concentrations of urchins rough crush solution supplied for a repeated short period (pulse) and (b) 10 (low) ml of nutrient concentration of the urchins rough crush solution supplied pulsed versus continuously. The addition of urchins rough crush solution did not increase the nitrate concentration but considerably increased the phosphate concentration in the water. Results reveal that sporophytes exposed to a different volume of urchins rough crush solution have less length growth than the control (unenriched) treatment. Sporophytes in high concentration of urchins rough crush solution supplied pulsed have the poorest length growth. However, the nutrient exposure period (pulse or continuous), was of negligible impact on the length growth of young sporophytes. Both, the concentration of urchins rough crush solution and exposure duration had a negative impact on the length of a color bleached part of lamina of S. latissima. The sporophytes exposed to high concentration of urchins rough crush as pulsed and low concentration of urchins rough crush supplied continuously have longer part of lamina color bleached than the control. From this study byproducts from the fisheries industry are recognized as potential fertilizer in the cultivation of S. latissima. However, the use of urchins rough crush is less suitable for the length growth of S. latissima and increased the bleaching of S. latissima lamina. Further studies should be done in the analysis of urchins rough crush, to better understand the cause of less length growth and enhanced color bleaching in S. latissima