Browsing by Author "Madeira, Diana"
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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.
- 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.