Browsing by Author "Ribeiro, Laura"
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- Early life stage mechanisms of an active fish species to cope with ocean warming and hypoxia as interacting stressorsPublication . Lima, André R.A.; Booms, Emily M.; Lopes, Ana Rita; Martins-Cardoso, Sara; Novais, Sara C; Lemos, Marco F.L.; Ribeiro, Laura; Castanho, Sara; Candeias-Mendes, Ana; Pousão-Ferreira, Pedro; Faria, Ana M.Ocean’s characteristics are rapidly changing, modifying environmental suitability for early life stages of fish. We assessed whether the chronic effects of warming (24 ◦C) and hypoxia (<2–2.5 mg L− 1 ) will be amplified by the combination of these stressors on mortality, growth, behaviour, metabolism and oxidative stress of early stages of the white seabream Diplodus sargus. Combined warming and hypoxia synergistically increased larval mortality by >51%. Warming induced faster growth in length and slower gains in weight when compared to other treatments. Boldness and exploration were not directly affected, but swimming activity increased under all test treatments. Under the combination of warming and hypoxia, routine metabolic rate (RMR) significantly decreases when compared to other treatments and shows a negative thermal dependence. Superoxide dismutase and catalase activities increased under warming and were maintained similar to control levels under hypoxia or under combined stressors. Under hypoxia, the enzymatic activities were not enough to prevent oxidative damages as lipid peroxidation and DNA damage increased above control levels. Hypoxia reduced electron transport system activity (cellular respiration) and isocitrate dehydrogenase activity (aerobic metabolism) below control levels. However, lactate dehydrogenase activity (anaerobic metabolism) did not differ among treatments. A Redundancy Analysis showed that ~99% of the variability in mortality, growth, behaviour and RMR among treatments can be explained by molecular responses. Mortality and growth are highly influenced by oxidative stress and energy metabolism, exhibiting a positive relationship with reactive oxygen species and a negative relationship with aerobic metabolism, regardless of treatment. Under hypoxic condition, RMR, boldness and swimming activity have a positive relationship with anaerobic metabolism regardless of temperature. Thus, seabreams may use anaerobic reliance to counterbalance the effects of the stressors on RMR, activity and growth. The outcomes suggests that early life stages of white seabream overcame the single and combined effects of hypoxia and warming.
- Effects of high pCO2 on early life development of pelagic spawning marine fishPublication . Faria, Ana Margarida; Filipe, Soraia; Lopes, Ana F.; Oliveira, Ana P.; Gonçalves, Emanuel João; Ribeiro, LauraThe present study investigated the effect of elevated pCO2 on the development of early stages of the pelagic spawning marine fish Solea senegalensis, Diplodus sargus and Argyrosomus regius. Eggs and larvae were reared under control (pH 8.0, ,570 matm) and two elevated pCO2 conditions (pH 7.8, ,1100 matm; pH 7.6, ,1900 matm) until mouth opening (3 days post-hatching). Egg size did not change with exposure to elevated pCO2, but hatching rate was significantly reduced under high pCO2 for all three species. Survival rate was not affected by exposure to increased pCO2, but growth rate was differently affected across species, with A. regius growing faster in the mid-level pCO2 treatment compared with control conditions. S. senegalensis and A. regius hatched with smaller yolk sacs under increased pCO2 but endogenous reserves of D. sargus were not affected. Otoliths were consistently larger under elevated pCO2 conditions for all the three species. Differences among egg batches and a significant interaction between batch and pCO2 suggest that other factors, such as egg quality, can influence the response to increased pCO2. Overall, the results support the occurrence of a species-specific response to pCO2, but highlight the need for cautious analysis of potential sensitivity of species from unreplicated observations.
- Effects of water temperature and structural habitat complexity on the routine swimming speed and escape response of post-settlement stage white seabreamPublication . Vicente, Patrícia; Almeida, João; Ribeiro, Laura; Castanho, Sara; Candeias-Mendes, Ana; Pousão-Ferreira, Pedro; M. Faria, AnaCoastal habitats are increasingly threatened by multiple anthropogenic-related activities, which include ocean warming and loss of structural habitat complexity. These two pressures have the potential to severely affect the structure and function of marine biodiversity. Early life stages of many fish species recruit to coastal habitats at the end of their pelagic phase, benefiting from access to food, shelter and protection. However, changes in temperature have been shown to influence ecologically relevant behaviours in post-settlement stage fish, and the loss of structural habitat complexity has been related to low recruitment and deleterious behaviours of fish in coastal habitats. Here, we evaluated the individual and interactive effects of prolonged exposure to increasing temperature and changed structural habitat complexity on routine swimming speed and escape response of post-settlement white seabream, Diplodus sargus (Linnaeus, 1758). Fish were reared under different temperatures (control 19 °C; high 22 °C) and structural habitat complexity (low and high) scenarios, in a cross-experimental design, and the routine swimming and escape responses were analyzed after 6 weeks of exposure. Change in temperature did not induce alterations at the behavioural level, but loss of structural habitat complexity increased speed and distance travelled during routine swimming, and responsiveness to a stimulus during the escape response behaviour. The interaction of the two factors did not influence performance. Determining how species are affected by changes in their environment, and the mechanisms that underlie these changes, will be critical to understanding the fish recruitment and populations’ fitness and survival.