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Scyliorhinus canicula (Linnaeus, 1758) metal accumulation: A public health concern for Atlantic fish consumers?

Publication . Marques, Alexandre F.S.; Alves, Luís M.F.; Moutinho, Ariana; Lemos, Marco F.L.; Novais, Sara C.

One of the most landed sharks in Portuguese fisheries is the lesser-spotted dogfish (Scyliorhinus canicula), which is ever-present in Portuguese fish markets and consumed as cheap fish protein source. The focus of this study was to evaluate element contamination in consumed tissues of Atlantic S. canicula, with the intent of safeguarding possible public health issues. A total of 74 specimens were analysed for metals and metalloids in the deeper white muscle and skin. Arsenic, zinc, iron and aluminium were the elements with higher mean values. There was a tendency for higher levels in the skin, with differences between life-stage and gender. Many individuals surpassed stipulated guideline limits for mercury and arsenic, posing a risk for human consumption (according to the health risk assessment performed for the average Portuguese fish consumption) or even for use in feed production. Besides the public health concern, this study also evidences troubling signs on marine contamination status.

2021Journal article

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Global warming overrides physiological anti-predatory mechanisms in intertidal rock pool fish Gobius paganellus

Publication . Paul, Nina; Novais, Sara C.; Silva, Cátia S. E.; Mendes, Susana; Kunzmann, Andreas; Lemos, Marco F.L.

In nature, a multitude of factors influences the fitness of an organismat a given time,whichmakes single stressor assessments far from ecologically relevant scenarios. This study focused on the effects of water temperature and predation stress on the metabolismand bodymass gain of a common intertidal rock pool fish, Gobius paganellus, addressing the following hypotheses: (1) the energy metabolism of G. paganellus under predation stress is reduced; (2) G. paganellus shows thermal compensation under heat stress; and (3) thermal stress is the dominant stressor that may override predation stress responses. Individuals were exposed to simulated predation stress and temperature increase from 20 °C to 29 °C, and both stressors combined. Physiological effects were addressed using biochemical biomarkers related with energy metabolism (isocitrate dehydrogenase, lactate dehydrogenase, energy available, energy consumption rates), oxidative stress (superoxide dismutase, catalase, DNA damage, lipid peroxidation), and biotransformation (glutathione-S-transferase). The results of this study revealed that predation stress reduced the cellular metabolism of G. paganellus, and enhanced storage of protein reserves. As hypothesized, hyperthermia decreased the aerobic mitochondrial metabolism, indicating thermal compensationmechanisms to resist against unfavourable temperatures. Hyperthermia was the dominant stressor overriding the physiological responses to predation stress. Both stressors combined might further have synergistically activated detoxification pathways, even though not strong enough to counteract lipid peroxidation and DNA damage completely. The synergistic effect of combined thermal and predation stress thus may not only increase the risk of being preyed upon, but also may indicate extra energy trade-off for the basal metabolism,which in turnmay have ecologically relevant consequences for general body functions

2021Journal article

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Accumulation of chemical elements and occurrence of microplastics in small pelagic fish from a neritic environment

Publication . Silva, Joana M. da; Alves, Luís M.F.; Laranjeiro, Maria I.; Bessa, Filipa; Silva, Andreia V.; Norte, Ana C.; Lemos, Marco F.L.; Ramos, Jaime A.; Novais, Sara C.; Ceia, Filipe R.

The assessment of contaminant exposure in marine organisms often focuses on the most toxic chemical elements from upper trophic level species. Information on mid-trophic level species and particularly on potentially less harmful elements is lacking. Additionally, microplastics have been considered emergent contaminants in aquatic environments which have not been extensively studied in species from mid-trophic levels in food chains. This study aims to contribute to an overall assessment of environmental impacts of such chemicals in a community of small pelagic fish in the North Atlantic. The concentrations of 16 chemical elements, rarely simultaneously quantified (including minerals, trace elements and heavy metals), and the presence of microplastics were analysed in sardines (Sardina pilchardus) and mackerels (Scomber spp. and Trachurus trachurus) sampled along the Portuguese coast. Biochemical stress assessments and stable isotope analyses were also performed. The chemical element concentrations in S. pilchardus, T. trachurus, and Scomber spp. were relatively low and lower than the levels reported for the same species in the North Atlantic and adjacent areas. No clear relationships were found between chemical elements and oxidative damage in fish. However, the concentration of several chemical elements showed differences among species, being related with the species’ habitat use, trophic niches, and specific feeding strategies. The presence of plastic pieces in the stomachs of 29% of the sampled fishes is particularly concerning, as these small pelagic fish from mid-trophic levels compose a significant part of the diet of humans and other top predators. This study highlights the importance of multidisciplinary approaches focusing on the individual, including position data, stable isotopes, and oxidative stress biomarkers as complementary tools in contamination assessment of the marine mid-trophic levels in food chains.

2022Journal article

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Elasmobranchs as bioindicators of pollution in the marine environment

Publication . Alves, Luís M.F.; Lemos, Marco F.L.; Cabral, Henrique; Novais, Sara C.

Bioindicator species are increasingly valuable in environmental pollution monitoring, and elasmobranch species include many suitable candidates for that role. By measuring contaminants and employing biomarkers of effect in relevant elasmobranch species, scientists may gain important insights about the impacts of pollution in marine ecosystems. This review compiles biomarkers applied in elasmobranchs to assess the effect of pollutants (e.g., metals, persistent organic pollutants, and plastics), and the environmental changes induced by anthropogenic activities (e.g., shifts in marine temperature, pH, and oxygenation). Over 30 biomarkers measured in more than 12 species were examined, including biotransformation biomarkers (e.g., cytochrome P450 1A), oxidative stressrelated biomarkers (e.g., superoxide anion, lipid peroxidation, catalase, and vitamins), stress proteins (e.g., heat shock protein 70), reproductive and endocrine biomarkers (e.g., vitellogenin), osmoregulation biomarkers (e.g., trimethylamine N-oxide, Na+/K+-ATPase, and plasma ions), energetic and neurotoxic biomarkers (e.g., lactate dehydrogenase, lactate, and cholinesterases), and histopathological and morphologic biomarkers (e.g., tissue lesions and gross indices).

2022Journal article

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