Biochemical composition and condition of Crassostrea gigas (Thunberg, 1793) in relation to integrated multi-trophic aquaculture (IMTA) feed sources

• Main Author: Schupp, Maximilian Felix
• Format: Thesis
• Language: unknown
• Published: Universität Rostock 2015
• Subjects: Imta; Pacific; Crassostrea gigas; Pacific oyster; Turbot
• Online Access: https://epic.awi.de/id/eprint/42312/; https://epic.awi.de/id/eprint/42312/1/Masterthesis_Maximilian_Felix_Schupp_2016.pdf; https://hdl.handle.net/10013/epic.49040; https://hdl.handle.net/10013/epic.49040.d001

Offshore aquaculture has the potential to satisfy some of the rising demand for animal protein and, using an integrated multi-trophic aquaculture (IMTA) approach, to do so in a sustainable, ecologically friendly and economically valuable way. This approach relies heavily on the bio-extraction capacity of filter-feeding organisms like the Pacific oyster, Crassostrea gigas (Thunberg, 1793), to turn excess particles of higher trophic cultured organism like fish, into valuable biomass. This study investigates the incorporation of IMTA related feeds by C. gigas based on changes in its biochemical composition. To accomplish this objective, a laboratory based feeding experiment was conducted, using five prepared diets. These consisted of a commercial turbot feed, turbot feces and the microalgae Tetraselmis chui and were mixed to simulate different open water feeding scenarios. Oysters feeding on high energy turbot feed, as part of their diet, managed to significantly increase their condition index (CI), while condition in the other groups remained unaffected. Lower carbon-to-nitrogen (C/N) ratio in oysters feeding solely on low energy turbo feces implied a depletion of energy reserves after the experiment, whereas oysters feeding on a mixture of turbot feed and feces showed no such signs. Changes in fatty acid (FA) composition of oysters were particularly apparent in animals feeding on turbot feed. Composition and abundance of saturated and mono-unsaturated FA changed, in part, in relation to diet composition. Changes are believed to be the result of biosynthesis of non-methylene-interrupted (NMI) FA. The results presented in this study indicate that C. gigas will incorporate particulate fish waste and are even able to increase their condition while doing so. This suggests that they will be able to absorb excess nutrients released from aquaculture sites and become another valuable product of an IMTA system.