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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.

2021Journal article

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Biodiversity of intertidal food webs in response to warming across latitudes

Publication . Gauzens, Benoit; Rall, Bjoern C.; Mendonca, Vanessa; Vinagre, Catarina; Brose, Ulrich

Global warming will affect food-web structure and species persistence, and real world data is needed for better prediction. Combining species counts and temperature data from rock pools with dynamic modelling predicts biodiversity increases in arctic to temperate regions and declines in the tropics. Global warming threatens community stability and biodiversity around the globe. Knowledge of the mechanisms underlying the responses to rising temperatures depends heavily on generic food-web models that do not account for changes in network structure along latitudes and temperature gradients. Using 124 marine rock-pool food webs sampled across four continents, we show that despite substantial variation in ambient temperature (mean 11.5-28.4 degrees C), similar empirical food-web and body-mass structures emerge. We have used dynamic modelling to test whether communities from warmer regions are more sensitive to warming and found a general hump-shaped relationship between simulated biodiversity and temperature (gradient from 0-50 degrees C). This implies that an expected anthropogenic global warming of 4 degrees C should increase biodiversity in arctic to temperate regions while biodiversity in tropical regions should decrease. Interestingly, simulations of synthetic networks did not yield similar results, which stresses the importance of considering the specificities of natural food webs for predicting community responses to environmental changes.

2020-03Journal article

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Environmental factors impacting the abundance and distribution of amphipods in intertidal rock pools

Publication . Carvalho, Jéssica; Mendonça, Vanessa; Vinagre, Catarina; Silva, Ana

Intertidal rock pools are considered critical habitats along coastal shores. Amphipods play an important role in intertidal rock pool ecosystems, as food resources for higher trophic levels and sometimes by enriching nutrients through grazing. However, the environmental factors driving their rockpool occupation remain largely unknown. We aimed to examine the importance of the large-scale wave action variation and meso-scale shore variation on the abundance and diversity of rockpool amphipods. A total of 32 intertidal rock pools on four Portuguese shores were studied during the summer spring tide of 2015. We applied multivariate analysis to evaluate the potential impact of wave action (sheltered versus wave exposed shores), physical pool structure (length, width, and depth), and relationships within the pool community on the abundance and diversity of amphipods. Wave exposure significantly influenced amphipod abundance and diversity, and some substrata and biodiversity features of the pool were important in explaining the amphipod abundance. The percentage and composition of coverage and physical features of the rock pools had no significant effect on amphipod abundance and diversity. We showed that the amphipod rockpool community displayed a clear positive response of biodiversity and abundance to the extrinsic factor wave action, and a varied and complex response to within-rockpool biotic variables. In addition, we recorded the presence of the invasive Ampithoe valida for the first time on rocky shores of Portugal. Further investigation into the influence that wave action has on associated pool biota (i.e., dislodgment or deposition of species) could give additional insight into the role of the biotic community in the regulation of amphipod populations within intertidal rock pools

2021Journal article

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