Browsing by Author "Choulis, Ioannis Emmanouil"
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- Management of the purple sea urchin (Paracentrotus lividus, Lamark 1816) gametogenic cycle through the manipulation of photoperiod, temperature and feedingPublication . Choulis, Ioannis Emmanouil; Cabrita, Elsa; Soares, FlorbelaSea urchins’ gonads are considered as a delicacy, with certain countries such as Japan, Honk Kong and United States, having the highest import rate worldwide. The rising demand has led to an unsustainable exploitation of the wild sea urchins’ stocks. This situation led to the development of echinoculture, covering the ongoing demand and alleviating the fishing pressure. Past studies have shown encouraging results on the somatic and gonadal development, when the feed availability isn’t a limiting factor. In this study, 308 individuals of Paracentrotus lividus were tested in four (4) distinguished methods: a) natural (non-manipulated) photoperiod and temperature, corresponding to the experiment’s time period, with natural diet (Ulva spp.), b) natural photoperiod and temperature with a formulated diet (pellets), c) manipulated photoperiod and temperature with natural diet (Ulva spp.), corresponding to the environmental conditions starting from January until June and d) manipulated conditions with pellets as feed. Data regarding monthly: feed intake, gonadosomatic index and the state of the gonad maturation, were gathered and statistically analyzed. GSI was increased in all the groups regardless of the treatment. Significant differences were found in the sea urchins fed with pellets which had the highest final GSI, compared to the sea urchins fed with Ulva spp. There was no correlation between GSI and the natural or manipulated environmental conditions. The sea urchins in manipulated photoperiod and temperature, after the spawning period in December 2021 – January 2022, had advanced in their gametogenic cycle, compared to the sea urchins in natural environmental conditions. Overall, the experiment verified past studies in were by manipulating the rearing conditions (photoperiod, water temperature), the gametogenic cycle of P. lividus progressed faster, supporting the world echinoculture industry.