Optimizing the knowledge on life cycle control and cryopreservation of Porphyra umbilicalis in function of the potential in mariculture
van der Linden, A. (2022). Optimizing the knowledge on life cycle control and cryopreservation of Porphyra umbilicalis in function of the potential in mariculture. MSc Thesis. Universiteit Antwerpen/Ghent University/Vrije Universiteit Brussel: Antwerpen/Gent/Brussel. 40 pp.
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Document type: Dissertation
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| Keywords |
Porphyra umbilicalis Kützing, 1843 [WoRMS]
Marine/Coastal |
| Abstract |
Macroalgae, also called seaweeds, are found in the littoral and sublittoral zones all around the world where they fulfill key ecological functions. However, the potential of seaweeds in the food, feed, agricultural, cosmetical, pharmaceutical and biotechnological industries as raw or processed products is gaining more recognition. Asian countries have been cultivating seaweeds for over a 100 years, while European interest is growing but large scale cultivation is still in its starting stages. Before being able to upscale seaweed aquaculture in the European region, increasing knowledge on the life cycle control and optimal growing conditions for local species is required. The genera Porphyra, also referred to as ‘nori’, contains promising aquaculture species that are locally found in European waters although their complex lifecycles are not yet fully understood and cultivation bottlenecks, such as the mass release of conchospores, still remain. is a species showing great potential for aquaculture due to its high nutrient uptake and assimilation rates together with high growth rates. Further, asexual strains of the species are found which have potential to circumvent some of the bottlenecks in the sexual lifecycle that still occur. The goal of this study was to optimize and improve the current knowledge on the life cycle control and optimal growing conditions of an asexual strain of P. umbilicalis. Further, I tested the tolerance of the species to being frozen in function of cryopreservation. Experiments conducted tested the effects of temperature (10°C, 15°C, 18°C and 23°C) and photoperiod (16:8 light:dark and 8:16 light:dark) on the daily growth rates, time until maturity and time until spore release. Another experiment, tested the effect of freezing at -20°C on P. umbilicalis blades and their released neutral spore quantity and quality. Lastly, I studied the effects of different nutrient ratios on the daily growth rates and carbon:nitrogen ratio of the tissue. Daily growth rates, time until maturity and time until spore release were significantly affected by temperature and photoperiod. Freezing had no significant effect on neutral spore quality and quantity. Further, I found a significant effect of different nutrient ratios on the C:N ratios of samples tissue but not on their daily growth rates. Optimal growing conditions for are identified as being temperatures between 15°C and 18°C while using a long day 16:8 photoperiod. A short photoperiod with cooler temperatures between 10°C and 15°C are identified as inducing maturation and spore releases. To optimize the protein content within the seaweed blades, I identified a 5:1 N:P ratio with ammonia as the main nitrogen source for rapid uptake. |
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