ESTM - Mestrado em Aquacultura
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Percorrer ESTM - Mestrado em Aquacultura por orientador "Alexandra Pereira Lourenço , Sílvia"
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- Marine heatwave effects on Pacific oyster (Magallana gigas Thunberg, 1793) growth, condition, soft body colour, and texturePublication . Lourenço, Rodrigo Pereira; Alexandra Pereira Lourenço , Sílvia; Joaquina da Cunha Pinheiro, Maria; Margarida Paulino Violante , AnaThe Pacific oyster Magallana gigas is a highly sought-after seafood, considered a superfood and delicacy worldwide. Most of the oyster market supply comes from aquaculture, despite that, this sector faces increasing threats due to climate change. Marine heatwave events have become more frequent, causing widespread mass mortality events. Even when marine heatwaves aren’t severe enough to cause such a deadly impact, sublethal effects may be noticed, specifically in growth performance and quality. The main aim of this study was to evaluate the effects of a simulated heatwave on M. gigas growth, condition, and flesh colour and texture. Additionally, a complementary trial was conducted to evaluate the effects of traditional handling practices on the same parameters. In both studies, oysters were obtained at Exporsado and maintained in two identical RAS, separating the control and experimental groups. In oysters subjected to handling practices, a higher condition index was observed compared to the control (11.03% higher), alongside a tendency for improved shell growth, although no statistical significance was observed. A slight decrease in textural properties was observed under handling conditions, while colourimetry analysis revealed a subtle yet consistent shift, resulting in a darker flesh tone (10.31% lower in Luminosity). In the heatwave experiment, the experimental group was exposed for 10 days to a simulated heatwave event of 24ºC, with a gradual increase from and subsequent return to 18ºC. In the experiment where handling was evaluated, light tumbling was applied alongside desiccation periods, periodically throughout the course of 30 days. To evaluate effects, morphological, conditioning, colourimetric and texturometrical data were collected in both groups during the two trials. Oysters exposed to the simulated heatwave showed reduced growth (less 5.42% in height and less 8.45% in weight) and lower condition indices, particularly in the AFNOR index, compared to the control treatment (less 28,72%). Soft tissues' properties were also affected, with altered colourimetric patterns and lower texture values observed in the heatwave treatment. These results demonstrate that both handling practices and marine heatwave events influence M. gigas growth, condition, and soft tissue colour and texture. Furthermore, these findings highlight that handling practices may enhance performance, while also highlighting the importance of sublethal effects associated with Marine heatwave events in oyster aquaculture.