Browsing by Author "Madeira, Carolina"
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- Conserved fatty acid profiles and lipid metabolic pathways in a tropical reef fish exposed to ocean warming – An adaptation mechanism of tolerant species?Publication . Madeira, Carolina; Madeira, Diana; Ladd, Nemiah; Schubert, Carsten J.; Diniz, Mário S.; Vinagre, Catarina; Leal, Miguel C.Climate warming is causing rapid spatial expansion of ocean warm pools from equatorial latitudes towards the subtropics. Sedentary coral reef inhabitants in affected areas will thus be trapped in high temperature regimes, which may become the "new normal". In this study, we used clownfish Amphiprion ocellaris as model organism to study reef fish mechanisms of thermal adaptation and determine how high temperature affects multiple lipid aspects that influence physiology and thermal tolerance. We exposed juvenile fish to two different experimental conditions, implemented over 28 days: average tropical water temperatures (26 °C, control) or average warm pool temperatures (30 °C). We then performed several analyses on fish muscle and liver tissues: i) total lipid content (%), ii) lipid peroxides, iii) fatty acid profiles, iv) lipid metabolic pathways, and v) weight as body condition metric. Results showed that lipid storage capacity in A. ocellaris was not affected by elevated temperature, even in the presence of lipid peroxides in both tissues assessed. Additionally, fatty acid profiles were unresponsive to elevated temperature, and lipid metabolic networks were consequently well conserved. Consistent with these results, we did not observe changes in fish weight at elevated temperature. There were, however, differences in fatty acid profiles between tissue types and over time. Liver showed enhanced α-linolenic and linoleic acid metabolism, which is an important pathway in stress response signaling and modulation on environmental changes. Temporal oscillations in fatty acid profiles are most likely related to intrinsic factors such as growth, which leads to the mobilization of energetic reserves between different tissues throughout time according to organism needs. Based on these results, we propose that the stability of fatty acid profiles and lipid metabolic pathways may be an important thermal adaptation feature of fish exposed to warming environments.
- Different sensitivity to heatwaves across the life cycle of fish reflects phenotypic adaptation to environmental nichePublication . Madeira, Diana; Madeira, Carolina; Costa, Pedro M.; Vinagre, Catarina; Portner, Hans-Otto; Diniz, Mario S.Predicting responses of marine organisms to global change requires eco-physiological assessments across the complex life cycles of species. Here, we experimentally tested the vulnerability of a demersal temperate fish (Sparus aurata) to long-lasting heatwaves, on larval , juvenile and adult life-stages. Fish were exposed to simulated coastal (18 degrees C), estuarine (24 degrees C) summer temperatures, and heatwave conditions (30 degrees C) and their physiological responses were assessed based on cellular stress response biomarkers (heat shock protein 70 kDa, ubiquitin, antioxidant enzymes, lipid peroxidation) and phenotypic measures (histopathology, condition and mortality). Life-stage vulnerability can be ranked as larvae > adults > juveniles, based on mortality , tissue pathology and the capacity to employ cellular stress responses, reflecting the different environmental niches of each life stage. While larvae lacked acclimation capacity, which resulted in damage to tissues and elevated mortality, juveniles coped well with elevated temperature. the rapid induction of cytoprotective proteins maintained the integrity of vital organs in juveniles, suggesting adaptive phenotypic plasticity in coastal and estuarine waters. Adults displayed lower plasticity to heatwaves as they transition to deeper habitats for maturation, showing tissue damage in brain, liver and muscle. Life cycle closure of sea breams in coastal habitats will therefore be determined by larval and adult stages.
- Differential effects of food restriction and warming in the two-spotted goby: impaired reproductive performance and stressed offspringPublication . Lopes, Ana F.; Murdoch, Robyn; Martins-Cardoso, Sara; Madeira, Carolina; Costa, Pedro M.; Félix, Ana S.; Oliveira, Rui F.; Bandarra, Narcisa M.; Vinagre, Catarina; Lopes, Ana R.; Gonçalves, Emanuel J.; Faria, Ana MargaridaClimate change is a growing threat to marine organisms and ecosystems, and it is already modifying ocean properties by, for example, increasing temperature and decreasing pH. Increasing water temperature may also lead to an impairment of primary productivity and an overall depletion of available zooplankton. Understanding how the crossover between warming and zooplankton availability impacts fish populations has paramount implications for conservation and mitigation strategies. Through a cross factorial design to test the effects of ocean temperature and food availability in a temperate marine teleost, Pomatochistus flavescens, we showed that hindered feeding impacted sheltering and avoidance behaviour. Also, low food availability impaired fish reproduction, particularly male reproduction, as the expression of cyp11b1, a gene with a pivotal role in the synthesis of the most important fish androgen, 11-ketotestosterone, was significantly reduced under a low food regime. In contrast, temperature alone did not affect reproductive success, but offspring showed increased saturated fatty acid content (embryos) and increased lipid peroxidation (larvae). Altogether, food availability had a stronger effect on fitness, showing that coping with elevated temperatures, an ability that may be expected in shallow-water fish, can be indirectly impacted, or even overwhelmed, by the effects of ocean warming on primary productivity and downstream ecological processes.
- Does predation exacerbate the risk of endosymbiont loss in heat stressed hermatypic corals? molecular cues provide insights into species-specific health outcomes in a multi-stressor oceanPublication . Madeira, Carolina; Dias, Marta; Ferreira, Ana; Gouveia, Raúl; Cabral, Henrique; Diniz, Mário S.; Vinagre, CatarinaOcean warming has been a major driver of coral reef bleaching and mass mortality. Coupled to other biotic pressures, corals' ability for acclimatization and adaptation may become compromised. Here, we tested the combined effects of warming scenarios (26, 30, and 32 degrees C) and predation (wound vs. no wound) in coral health condition (paleness, bleaching, and mortality), cellular stress responses (heat shock protein 70 kDa Hsp70, total ubiquitin Ub, and total antioxidant capacity TAC), and physiological state (integrated biomarker response index, IBR) of seven Scleractinian coral species, after being exposed for 60 days. Results show that although temperature was the main factor driving coral health condition, thermotolerant species (Galaxea fascicularis, Psammocora contigua, and Turbinaria reniformis) displayed increased paleness, bleaching, and mortality in predation treatments at high temperature, whereas thermosensitive species (Acropora tenuis, Echinopora lamellosa, and Montipora capricornis brown and green morphotypes) all died at 32 degrees C, regardless of predation condition. At the molecular level, results show that there were significant main and interactive effects of species, temperature, and predation in the biomarkers assessed. Temperature affected Hsp70, Ub, and TAC, evidencing the role of protein folding and turnover, as well as reactive oxygen species scavenging in heat stress management. Predation increased Hsp70 and Ub, suggesting the activation of the pro-phenoloxidase system and cytokine activity, whereas the combination of both stressors mainly affected TAC during moderate stress and Ub under severe stress, suggesting that redox balance and defense of homeostasis are crucial in tissue repair at high temperature. IBR levels showed an increasing trend at 32 degrees C in predated coral fragments (although non-significant). We conclude that coral responses to the combination of high temperature and predation pressure display high inter-species variability, but these stressors may pose a higher risk of endosymbiont loss, depending on species physiology and stress intensity.
- Shallow water fish display low phenotypic plasticity to ocean warming and extreme weather events regardless of previous thermal historyPublication . Missionário, Madalena; Almeida, Célia; Fernandes, Joana Filipa; Vinagre, Catarina; Madeira, Carolina; Madeira, DianaShallow water environments have long been recognized by scientists as sentinels for climate change. By analysing the impacts of ocean warming and marine heatwaves (MHW) in species from these areas, we can estimate their plasticity and hence vulnerability to thermal challenges. Pomatoschistus microps is a benthic intertidal fish species inhabiting coastal lagoons where temperature fluctuations are common. Here, we tested the effects of " Present " and " Future summer" scenarios (22 degrees C and 25 degrees C) and their respective heatwaves (27 degrees C and 30 degrees C) versus a " Control " scenario of 19 degrees C on warm (summer)- and cold (winter)- acclimatized fish. Then, we estimated phenotypic plasticity of critical thermal maximum (CTmax), oxygen consumption and cellular stress responses (CSR). Temperature seasonal variation and body weight (as proxy for body size) effects on fish thermal tolerance were also determined. Fish exposed to higher temperature treatments exhibited higher thermal tolerance, with this pattern being consistent for both warm- and cold-acclimatized fish. However, this difference was subtle (<4.6 %), suggesting a low capacity for acclimation. Nonetheless, warm-acclimatized fish (collected in summer) displayed significantly higher CTmax than cold-acclimatized fish (collected in winter), indicating that CTmax is influenced by seasonal thermal variation. Weight also represents a constraint factor for P. microps thermal tolerance, as heavier animals displayed lower CTmax. No alterations in O2 consumption, neither in CSR biomarkers were detected across temperature treatments, suggesting that fish were otherwise relatively insensitive to thermal fluctuations, independently of thermal history, within the thermal scenarios tested. Overall, the studied population of P. microps seems well adapted to temperature variations in their natural environment, exhibiting a large thermal safety margin (average of 11.02 degrees C).
- Warming in shallow waters: Seasonal response of stress biomarkers in a tide pool fishPublication . Vinagre, Catarina; Madeira, Diana; Mendonça, Vanessa; Madeira, Carolina; Diniz, Mário S.Tide pools are rapidly warming environments with low thermal inertia, where organisms are exposed to potentially stressful conditions. This way, tide pools will be among the first and hardest hit environments by climate warming. Studies of thermal stress in situ are rare, but important so that current thermal stress in the wild can be confirmed and serve as reference for the future. This study aims to investigate the seasonal response of stress biomarkers in a common tide pool fish, the blenny Lipophrys trigloides, under natural conditions, in situ. Multiple biomarkers of thermal and oxidative stress were analysed in the tissues of the muscle, visceral mass, gills and brain of L. trigloides, under spring (18.50 +/- 0.71 degrees C) and summer conditions (28.30 +/- 1.30 degrees C), in order to assess tissue-specific seasonal responses to the rapid warming that occurs seasonally in tide pools. It was concluded that L. trigloides seems to be setting in motion relevant thermal stress and antioxidant defences under summer conditions. All tissues analysed were responsive and all biomarkers of thermal and oxidative stress increased in summer conditions, with the exception of SOD, which presented no alterations. The present study offers reference values that will be useful for future comparison during particularly warm summers and in future years as climate warming progresses.