The impacts of climate change on marine life, especially oviparous elasmobranchs remain uncertain. This study assesses the effects of ocean warming on the development of S. canicula embryos and juveniles, with a focus on the neuronal system. Embryos were incubated at 15°C (control), 17°C and 20°C, with some juveniles later transferred to 15°C or maintained at the same elevated temperature for two months. The measured parameters were the mortality, embryonic developmental time, yolk consumption, weight, length, Fulton’s condition factor, hepatosomatic index, freezing behavior, cerebellum cell population and ventilation rate.
The results showed that elevated temperatures increased embryonic mortality and the mortality of juveniles maintained at 17°C. High temperatures also reduced developmental time and accelerated the emergence of freezing behaviors. Yolk consumption, ventilation rate and overall health were not significantly affected by the temperatures. However, high temperatures during embryonic development significantly reduced the number of total cells and neurons in the cerebellum irreversibly. Furthermore, three freezing behaviors were described for the first time in this study, along with the ages at which embryos initiate displaying them.
Further research should be done to deepen our understanding of the impacts of climate change on oviparous elasmobranchs
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