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Effects of ocean warming on the reproduction of the deep-sea octocoral Dentomuricea aff. meteor
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Resumo(s)
The deep sea is the largest and most diverse biome on Earth. Cold-water corals (CWC) are important habitat constructors in deep-sea ecosystems. Scientific research using laboratory experiments is crucial to help us understand climate change impacts on these organisms. Investigating their reproduction under ocean warming will provide essential information on the future of CWC populations. The aims of this dissertation were (1) to explore the influence of coral maintenance in aquaria on the reproductive condition of Dentomuricea aff. meteor; (2) to evaluate the effects of ocean warming scenarios on the reproduction and tissue condition of this species. Coral colonies were collected as bycatch from experimental longline fisheries, sectioned into fragments and placed in aquaria. To assess the potential effects of maintenance in aquaria on their reproductive condition, corals were sampled immediately after collection, and one and two months in aquaria. To evaluate the potential effects of ocean warming, coral fragments were experimentally exposed to 14ºC (control), 16ºC (maximum natural temperature) and 19ºC (IPCC RCP 8.5) and sampled at three and six weeks of exposure to the treatments. Samples were then histologically processed to analyse gamete number and volume. Corals matured their gametes during the first months in the aquaria, with spawning observed during the first four weeks of the ocean warming experiment. Elevated temperatures reduced polyp’s fecundity, with models predicting declines of 7% and 18% per +1ºC in male and female polyps, respectively. Oocyte volume declined under warming, while spermatocysts volume remained unaltered. Male and female corals lost up to 35% and 55% of their tissue (coenenchyma), respectively, at higher temperatures. Increased metabolic rates and energy allocation to mitigate the thermal stress may have impaired the reproductive condition. Oosorption and polyp bail-out behaviour may be responses to thermal stress. These findings are crucial for management measures and conservation efforts.
Descrição
Tese de Mestrado, Ecologia Marinha, 2025, Universidade de Lisboa, Faculdade de Ciências
Palavras-chave
Thermal stress cold-water corals gametogenesis tissue loss aquarium conditions