The Effects of Different Light Spectra, UV and Extreme Temperature on the Physiology of Endosymbiotic Jellyfish <i>Cassiopea andromeda</i>

ABSTRACT The endosymbiotic jellyfish Cassiopea andromeda represents a yet untapped marine species that could be targeted as a new source for bioproducts, including food and feed. Also, the potential use of contained valuable ingredients, such as carotenoids and other antioxidants, under controlled aquaculture conditions might be a particularly promising pathway. However, this requires close knowledge about physiology and culture conditions. In this study, the effects of different stress parameters such as different light spectra, light intensities, UV and extreme temperatures on C. andromeda were investigated. The following response parameters were measured: pigments, photosynthetic efficiency, bell pulsation rate, antioxidant activity (AOA) and respiration. The carotenoid peridinin and chlorophyll a were detected as dominant light‐harvesting pigments. Three different experiments were performed. Over a four week treatment interval under four different light conditions, C. andromeda that were exposed to light spectra lacking blue color ( λ = 400–500 nm) showed a decreasing content of chlorophyll, peridinin and all other detected pigments, while photosynthetic efficiency and AOA were not affected by any light spectra changes. Critical thresholds for both photosynthetic efficiency and respiration were detected beyond 39°C. UV seemed to have a similar effect on respiration as low temperatures, while UV did not seem to significantly affect bell pulsation rate and symbiont density. This study contributes to the development of an environmentally controlled C. andromeda indoor aquaculture system, revealing optimal temperature and light regimes. Accordingly, C. andromeda holds promise as a resource for pigment production that may offer value as a supplement for functional foods and nutraceuticals.