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Top predators such as most shark species are extremely vulnerable to amassing high concentrations of contaminants, but not much is known about the effects that the contaminant body burden imparts on these animals. Species like the blue shark (Prionace glauca) are very relevant in this regard, as they have high ecological and socioeconomic value, and have the potential to act as bioindicators of pollution. This work aimed to assess if differences in contaminant body burden found in blue sharks from the Northeast Atlantic would translate into differences in stress responses. Biochemical responses related to detoxification and oxidative stress, and histological alterations were assessed in the liver and gills of 60 blue sharks previously found to have zone-related contamination differences. Similar zone-related differences were found in biomarker responses, with the sharks from the most contaminated zone exhibiting more pronounced responses. Additionally, strong positive correlations were found between contaminants (i.e., As, PCBs, and PBDEs) and relevant biomarkers (e.g., damaged DNA and protective histological alterations). The present results are indicative of the potential that this species and these tools have to be used to monitor pollution in different areas of the Atlantic., This study had the support of Fundação para a Ciência e a Tecnologia (FCT) through the project BLUESHARKER (PTDC/CTAAMB/29136/2017), co-financed by COMPETE2020 (POCI-01-0145-FEDER-029136), the Strategic Project granted to MARE – Marine and Environmental Sciences Centre (UIDB/04292/2020 and UIDP/04292/2020), the project granted to the Associate Laboratory ARNET (LA/P/0069/2020), and the grant awarded to Luís Alves (SFRH/BD/122082/2016). Vanessa F. Fonseca was supported by FCT, via research contract 2021.00244.CEECIND. Sara Novais is funded by national funds (OE), through FCT, in the scope of the framework contract foreseen in the numbers 4, 5, and 6 of the article 23, of the Decree-Law 57/2016, of August 29, changed by Law 57/2017, of July 19.

Chemical pollution is a major threat to marine ecosystems, and top predators such as most shark species are extremely vulnerable to being exposed and accumulating contaminants such as metals and persistent organic pollutants (POPs). This work aimed to study the degree, composition, and the sources of contamination in the blue shark (Prionace glauca) inhabiting the Northeast Atlantic, as well as the potential risk faced by human consumers. A total of 60 sharks were sampled in situ aboard fishing vessels, and the concentrations of a set of metals and POPs were analysed in various tissues and complemented with stable isotope analyses. High levels of contaminants were found in most sharks sampled. The concentrations of most metals were higher in the muscle when compared with the liver. Regarding the dangers to consumers posed by the concentrations of arsenic (As), mercury (Hg), and lead (Pb), over 75% of the sharks presented muscle concentrations of at least one contaminant above the legal limits for human consumption, and a risk assessment determined that consumption of meat of these sharks exceeding 0.07 Kg per week could potentially expose human consumers to dangerous amounts of methylmercury (MeHg). Additionally, the assessment of single contaminants may lead to an underestimation of the risk for the human health. Finally, the overall accumulation of contaminants seems to be mostly influenced by the sharks’ geographical distribution, rather than sex, size, or trophic level of their prey., This study had the support of Fundaçao ˜ para a Ciˆencia e a Tecnologia (FCT) through the project BLUESHARKER (PTDC/CTAAMB/29136/ 2017), co-financed by COMPETE2020 (POCI-01-0145-FEDER-029136), the grant to MARE – Marine and Environmental Sciences Centre (UIDB/ 04292/2020 and UIDP/04292/2020) and the Associate Laboratory ARNET (LA/P/0069/2020), the grant awarded to Luís Alves (SFRH/BD/ 122082/2016), and the transitory norm contract to Filipe Ceia (DL57/ 2016/CP1370/CT90). Sara Novais is funded by national funds (OE), through FCT, in the scope of the framework contract foreseen in the numbers 4, 5, and 6 of the article 23, of the Decree-Law 57/2016, of August 29, changed by Law 57/2017, of July 19

This study had the support of Fundação para a Ciência e Tecnologia (FCT), through project PROTEOME (PTDC/AAG-MAA/1302/2014) cofunded by COMPETE (POCI-01-0145-FEDER-016773) and the Strategic Project UID/MAR/04292/2013 granted to MARE, and the grants awarded to Luís Alves (SFRH/BD/122082/2016) and Sara Novais (SFRH/BPD/94500/2013), and also FCT and Deutscher Akademischer Austauschdienst (DAAD) program for bilateral cooperation funding Global Invaders and Stream Cukes. The authors also wish to acknowledge the Integrated Program of SR&TD “Smart Valorization of Endogenous Marine Biological Resources Under a Changing Climate” (reference Centro-01-0145-FEDER-000018), co-funded by Centro 2020) program, Portugal 2020, European Union, through the European Regional Development Fund. The Leibniz project budget 6057 granted financial support for Holger Kühnhold. A NAM-fellowship was awarded to Lisa Indriana for a prolonged research stay in Germany. We thank Christiane Hassenrück for helpful advice concerning data analyses and interpretation. Moreover, we thank Kai Lorkowski, Nico Steinel and Christian Brandt for technical support and Sofia Esteves da Silva and Hugo Morais for great SCUBA diving support. The notion that thermal specialists from tropical regions live closer to their temperature limits than temperate eurytherms, seems too generalized. Species specific differences in physiological and biochemical stress reactions are linked to key components of organism fitness, like metabolic capacity, which indicates that acclimation potential across latitudes might be highly diverse rather than simplistic. In this study the exposure of a tropical (Holothuria scabra) and a temperate (Holothuria forskali) sea cucumber species to identical cold- and warmacclimation stress was compared using the key metabolic parameters, respiration rate, enzyme activity (ETS, LDH, IDH), and energy reserve fractions (lipid, carbohydrate and protein). Results show much broader respiratory adjustments, as response to temperature change, in H. scabra (2–30 μgO2*gww−1 *h−1) compared to H. forskali (1.5–6.6 μgO2*gww−1 *h−1). Moreover, the tropical species showed clearly pronounced up and down regulation of metabolic enzymes and shifts in energy reserves, due to thermal acclimation, while the same metabolic indicators remained consistent in the temperate species. In summary, these findings indicate enhanced metabolic plasticity in H. scabra at the cost of elevated energy expenditures, which seems to favor the tropical stenotherm in terms of thermal acclimation capacity. The comparison of such holistic metabolic analyses between conspecifics and congeners, may help to predict the heterogeneous effects of global temperature changes across latitudinal gradients. info:eu-repo/semantics/publishedVersion

Acknowledgements : This study had the support of Fundaçao ˜ para a Ciˆencia e a Tecnologia (FCT) through the Strategic Project UID/MAR/04292/2020 granted to MARE – Marine and Environmental Sciences Centre, project BLUESHARKER (PTDC/CTA-AMB/29136/2017), co-financed by COMPETE2020 (POCI-01-0145-FEDER-029136), and grant awarded to Luís Alves (SFRH/BD/122082/2016). Sara Novais is funded by national funds (OE), through FCT – Fundação para a Ciência e a Tecnologia, I.P., in the scope of the framework contract foreseen in the numbers 4, 5 and 6 of the article 23, of the Decree-Law 57/2016, of August 29, changed by Law 57/2017, of July 19. The project was also partially funded by the Integrated Programme of SR&TD “SmartBioR” (reference Centro-01-0145-FEDER-000018), co-funded by Centro 2020 program, Portugal2020, European Union, through the European Regional Development Fund. Authors would also like to acknowledge the fishermen enabling access to the samples, and all the members of Lemos Lab research group that helped in the laboratory during the dissection and sampling. 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. info:eu-repo/semantics/publishedVersion

Acknowledgements : We would like to thank the Instituto da Conservação da Natureza e Florestas (ICNF) for permits and logistical support (lodging) to conduct this work. All applicable international, national, and/or institutional guidelines for the care and use of animals were followed and all necessary approvals have been obtained from the ICNF. Special thanks to the wardens, Paulo Crisostomo ´ and Eduardo Mourato (Reserva Natural das Berlengas). We would like to thank Jos´e Seco for valuable inputs during earlier drafts of the manuscript. LMFA and JMP acknowledge their grants (SFRH/BD/122082/2016, SFRH/BD/123499/2016, respectively) attributed by the Foundation for Science and Technology (FCT; Portugal). This study benefited from the strategic program of MARE, financed by FCT (MARE - UID/MAR/04292/2020) and the transitory norm contracts DL57/2016 to FRC (DL57/2016/CP1370/ CT90), ACN (DL57/2016/CP1370/CT89), VHP (SFRH/BPD/85024/2012) and SCN (SFRH/BPD/94500/2013). Financial support provided by FCT and MARE through a PhD grant attributed to MIL (UI/BD/150956/2021) and the project ECOLIND – Seabirds and fish as ecological indicators of contaminants and health in the North Atlantic relevant to ocean resources assessment (MFM/2017/0003) Multidisciplinary approaches are essential to diligently assess environmental health status of ecosystems. In this study, year-round chemical elements’ exposure and impacts were assessed on the wide-ranging Cory’s shearwater Calonectris borealis breeding in Berlenga Island, offshore Portugal, North Atlantic Ocean. The aim was to identify potential contamination and oxidative stress sources associated with trophic ecology, habitat and spatial use, and foraging patterns. A set of 20 chemical elements were quantified, along with oxidative stress biomarkers, stable isotope analyses, and GPS tracking data. Birds presented higher accumulation to some nonessential elements along the year (i.e. arsenic, As; cadmium, Cd; mercury, Hg; lead, Pb; and strontium, Sr), in which concentrations were similar or surpassed other procellariform seabird populations all over the world. No significant differences were found for any of the elements between different periods within the breeding season, with exception of Hg. However, a Principal Component Analysis taking into consideration a group of elements showed differences between pre-laying and chick-rearing periods, with overall higher concentrations in the former. Individuals spending more time engaging in an intensive search for food, and in more coastal environments, presented overall higher element concentrations, and particularly Hg. Contrary to expectations, no relationships were found between chemical elements and oxidative stress. On the other hand, spatial use and foraging patterns of Cory’s shearwaters influenced their oxidative stress responses. Our results highlight the need for multidisciplinary approaches to deepen understanding of the large-scale vulnerability of bioindicators such as seabirds and, by extension, the overall environmental health of ecosystems in which they rely. info:eu-repo/semantics/publishedVersion

Acknowledgments : We are thankful to the Air Force Base No. 6 of Montijo (Portugal) for allowing the field study in their military establishment. We are also grateful to Marilia Freire and Daniel Alves for the valuable assistance during field work. This study was funded by the Science and Technology Foundation, Portugal, project PTDC/BIA-BMA/29662/2017; strategic projects UID/MAR/04292/2020 to A.F. and M.C.P.A. by MARE and UID/BIA/00329/2020 to P.J.F. by cE3c; grant SFRH/BD/115562/2016 to M.V. Marine traffic is themost common and chronic source of ocean noise pollution. Despite the evidence of detrimental effects of noise exposure on fish, knowledge about the effects on the critical early life stages - embryos and larvae - is still scarce. Here, we take a natural habitat-based approach to examine potential impacts of boat noise exposure in early life stages in a wild fish population of the Lusitanian toadfish (Halobatrachus didactylus). In-situ experiments were carried out in the Tagus estuary, an estuary with significant commercial and recreational boat traffic. Nestswith eggswere exposed to either ambient (control) or boat noise (treatment), for 1 fortnight. Eggs were photographed before being assigned to each treatment, and after exposure, to count number of eggs and/or larvae to assess survival, and sampled to study development and oxidative stress and energy metabolism-related biomarkers. Data concerns 4 sampling periods (fortnights) from 2 years. Results indicate that offspring survival did not differ between treatments, but boat noise induced a detrimental effect on embryos and larvae stress response, and on larvae development. Embryos showed reduced levels of electron transport system (ETS), an energy metabolism-related biomarker, while larvae showed higher overall stress responses, with increased levels of superoxide dismutase (SOD) and DNA damage (oxidative stress related responses), ETS, and reduced growth. With this study,we provided the first evidence of detrimental effects of boat noise exposure on fish development in the field and on stress biomarker responses. If these critical early stages are not able to compensate and/or acclimate to the noise stress later in the ontogeny, then anthropogenic noise has the potential to severely affect this and likely other marine fishes, with further consequences for populations resilience and dynamics. info:eu-repo/semantics/publishedVersion

This study was supported by Fundação para a Ciência e a Tecnologia (FCT) and FEDER through the project BLUESHARKER (PTDC/CTAAMB/29136/2017) and the Strategic Project UID/MAR/04292/2019. The project was also funded by the Integrated Programme of SR&TD “SmartBioR” (Centro-01-0145-FEDER-000018) cofunded by Centro 2020 program, Portugal2020, European Union, through the European Regional Development Fund. Luís M.F. Alves also wishes to L.M.F. Alves, et al. Fisheries Research 230 (2020) 105648 7 acknowledge the financial support given by FCT (SFRH/BD/122082/ 2016). This study was also supported by Oceanário de Lisboa and Oceano Azul Foundation through the project Shark Attract, winner of the first edition of the Ocean’s Conservation Fund. Portugal plays a major role in shark, skate and ray fisheries in the European Union. With the decline of these animals raising concerns amongst scientists all over the world, we set out to provide an updated assessment on elasmobranch landings in Portugal between 1986 and 2017. The dataset analysed in this study consisted of 15,521 records, each with information concerning the species (or higher taxonomic level), port, month, year, and weight of fish landed. A non-parametric change points assessment statistical technique was used to evaluate important changes in landings throughout the time series. Principal components analysis was also performed to mean values of landings per year for the most captured species, and similar analysis was conducted using fishing ports instead of year, for the same sub-set of species / taxa. According to the data, more than 143 thousand metric tons of elasmobranchs were landed in Portuguese ports between 1986 and 2017, divided by 58 taxa of sharks, skates and rays. The most landed taxa were demersal rays and skates (Raja spp.), followed by spotted dogfishes (Scyliorhinus spp.), blue shark (Prionace glauca), Portuguese dogfish (Centroscymnus coelolepis), leafscale gulper shark (Centrophorus squamosus), gulper shark (Centrophorus granulosus) and shortfin mako (Isurus oxyrinchus). Together, these seven taxa accounted for more than 75% of all landings. Several cases of misreporting were identified and discussed. Overall, landings of elasmobranchs in Portugal show marked decreases and changes in composition, with deep-sea sharks being the most influential group during the studied period. info:eu-repo/semantics/publishedVersion

Inhibition of acetylcholinesterase (AChE) activity has been widely used to assess the exposure and effects of anticholinergic environmental contaminants in several species. The aim of this study was to investigate if sublethal concentrations of the organophosphorous pesticide chlorpyrifos (CPF), a well-known AChE inhibitor, would also affect cholinesterases (ChE) in Gibbula umbilicalis and if this inhibition would result in an alteration of its behaviour, in an attempt to link the effects observed at the cellular level with effects at higher levels of ecological relevance. The biochemical properties of ChEs in this species were first characterized through the assessment of different enzymatic forms present in the sea snail, using different substrates and selective inhibitors. The results suggest that G. umbilicalis possess ChEs with characteristics of typical AChE, which should be the main form present. Additionally, in vitro and in vivo effects of CPF on AChE activity were investigated, along with effects on snails' behaviour: the ability of the snails to move/turn after exposure to the contaminant (flipping test). As expected, CPF inhibited AChE activity both in vitro and in vivo conditions. Moreover, the link between AChE activity inhibition and adverse effects on behavioural changes was established: AChE inhibition was positively correlated with the flipping test, indicating a mechanistic relationship between the two endpoints determined in in vivo exposures. This study highlights the importance of linking biochemical endpoints such as AChE activity with higher level endpoints like behavioural alterations, increasing the ecological relevance of the effects observed. © 2019 Elsevier Inc., This study was funded by Fundação para a Ciência e a Tecnologia (FCT) through the Strategic Project UID/MAR/04292/2013, project MARINE INVADERS – The impact and mechanisms of success of the invasive seaweed Asparagopsis armata on coastal environments (POCI-01-0145-FEDER-031144), and the grants awarded to Carla Silva (SFRH/BD/87030/2012), Luís Alves (SFRH/BD/122082/2016) and Sara Novais (SFRH/BPD/94500/2013). The project was also partially funded by the Integrated Programme of SR&TD “SmartBioR” (reference Centro-01-0145-FEDER-000018) cofunded by Centro 2020 program, Portugal2020, European Union, through the European Regional Development Fund.

Acknowledgements : We would like to thank the Instituto da Conservação da Natureza e Florestas (ICNF) for permits and logistical support (lodging) to conduct this work. All applicable international, national, and/or institutional guidelines for the care and use of animals were followed and all necessary approvals have been obtained by the ICNF. Special thanks to the wardens, Paulo Crisóstomo and Eduardo Mourato (Reserva Natural das Berlengas) and Silverio (Parque Natural da Ria Formosa). We would like to thank José Seco for valuable inputs during earlier drafts of the manuscript. FRC, LMFA, JGC, ACN, VHP and SCN acknowledge their grants (SFRH/BPD/95372/2013, SFRH/BD/122082/2016, PD/BD/ 127991/2016, SFRH/BPD/108197/2015, SFRH/BPD/85024/2012, SFRH/BPD/94500/2013, respectively) attributed by the Foundation for Science and Technology (FCT; Portugal) and the European Social Fund (POPH, EU). This study benefited from the strategic program of MARE, financed by FCT (MARE - UID/MAR/04292/2020) and financial support provided by FCT and MARE through the project ECOLIND – Seabirds and fish as ecological indicators of contaminants and health in the North Atlantic relevant to ocean resources assessment (MFM/2017/0003). Metal pollution is currently a major issue in marine ecosystems, as organisms, and particularly seabirds, are exposed and accumulating increased levels from several anthropogenic sources. A set of 13 metals were quantified in two gull species breeding in sympatry, and in two distinct colonies separated by ca. 400 km. Oxidative stress was measured, and stable isotope analyses were used to link metal contamination and oxidative stress with the trophic ecology of each species/population. There was a clear segregation of metal contamination between the two species and to a much lesser extent between colonies. Overall, Audouin's gull was the most contaminated species for most metals, once this species relies mainly on fish and other marine resources. The Yellow-legged gull feeds regularly on terrestrial food sources besides fish, which may dilute contamination levels. Oxidative stress responses were related with birds' trophic ecology and foraging habitat, but apparently not with metal contamination. info:eu-repo/semantics/publishedVersion

This work was partly funded by the EU Transnational Territorial Cooperation programme INTERREG IVB NWE projects (PILLS project 008B & “noPILLS in our waters”); and A. Aderemi was also funded by a PhD studentship from SEBE, Glasgow Caledonian University. This study also had the support of the Fundação para a Ciência e a Tecnologia (FCT) Strategic Project UID/MAR/04292/2013 granted to MARE, project ProTEoME - PROteomic Tools to assess Endocrine disruptiOn MEchanisms ((PTDC/AAG-MAA/1302/2014), and the post-doc grant to Sara C. Novais (SFRH/BPD/94500/2013). The project was also partially funded by the Integrated Programme of SR&TD “SmartBioR” (reference Centro-01-0145-FEDER-000018) cofunded by Centro 2020 program, Portugal2020, European Union, through the European Regional Development Fund. The individual effect of four human antibiotics on the microalgae Raphidocelis subcapitata was investigated following a 120-h exposure. The effects were assessed by analyzing growth, and biochemical parameters related with: 1) antioxidant capacity and oxidative damage by measuring superoxide dismutase (SOD) activity and lipid peroxidation (LPO) levels; and 2) cellular energy allocation (CEA) by quantifying the content in energy reserves, which represents the energy available (Ea), and the electron transport system activity that represents a measure of oxygen and cellular energy consumption (Ec). Growth yield inhibitory concentrations of sulfamethoxazole (18-30%), clarithromycin (28.7%), ciprofloxacin (28%) and erythromycin (17-39%) were found to elicit a considerable increase in Ec, thereby causing a significant decrease in the CEA. The elevated Ec can be a result of the need to respond to oxidative stress occurring under those conditions given the significant increase in SOD activity at these levels. For sulfamethoxazole, erythromycin and ciprofloxacin, the antioxidant responses do not seem to be enough to cope with the reactive oxygen species and prevent oxidative damage, given the elevated LPO levels observed. A stimulatory effect on growth yield was observed (up to 16%) at ciprofloxacin lowest concentration, which highly correlated with the increase in CEA. Based on the no observed effect concentration (NOECs) and/or effective concentration (EC10) results, Ec, SOD and CEA were more sensitive than the classical endpoint of growth rate for all the tested antibiotics. By revealing the antibiotic stress effects in R. subcapitata at the cellular level, this study suggests CEA as a more reliable indicator of the organisms' physiological status. info:eu-repo/semantics/publishedVersion

Marine contamination is an ever-growing problem, with contaminants such as metals constantly being introduced in the ecosystems. To understand the effects these contaminants exert in marine organisms, there is a need to connect the measured contamination levels with biological endpoints that can give an indication of stress or susceptibility. Sharks tend to bioaccumulate and biomagnify different contaminants throughout their long lives, mainly by feeding on smaller animals containing different levels of such pollutants. Being very abundant and heavily fished, these animals have the potential to be used in marine biomonitoring studies. Moreover, the fact that they are used for human consumption ads further relevance to the study of their contamination levels. The present study aimed to assess the levels of metal contamination in the catshark Scyliorhinus canicula while also addressing stress effects using biochemical biomarkers to understand possible consequences of such contamination. The sharks were sampled right after being caught off the coast of Portugal, aboard a commercial trawling boat. Metals were quantified in different tissues and the levels of biochemical parameters related with detoxification, oxidative stress, and energy metabolism were measured for each individual. Some of the metals were preferentially accumulated in liver, when compared to muscle. Significant correlations were observed between physiological parameters and contaminant accumulation levels and some suitable biomarker candidates were identified. This study further highlights the effectiveness of combining biochemical parameters and pollutant body burden determinations to assess effects of contamination and demonstrates the great potential of sharks to be used in biomonitoring studies of the marine environment. info:eu-repo/semantics/publishedVersion

Cholinesterases (ChE) are a family of enzymes that play an essential role in neuronal and motor functions. Because of the susceptibility of these enzymes to anticholinergic agents and to other contaminants, their activity is frequently used as biomarker in pollution monitoring studies. The three known types of ChE in fish are acetilcholinesterase (AChE), butyrylcholinesterase (BChE) and propionylcholinesterase (PChE). The presence of these enzymes in each tissue differs between species, and thus their usage as biomarkers requires previous enzyme characterization. Sharks, mostly acting as apex predators, help maintain the balance of fish populations performing a key role in the ecosystem. Blue sharks (Prionace glauca) are one of the most abundant and heavily fished sharks in the world, thus being good candidate organisms for ecotoxicology and biomonitoring studies. The present study aimed to characterize the ChE present in the brain and muscle of the blue shark using different substrates and selective inhibitors, and to assess the in vitro sensitivity of these sharks' ChE to chlorpyrifos-oxon, a metabolite of a commonly used organophosphorous pesticide, recognized as amodel anticholinesterase contaminant. The results suggest that the brain of P. glauca seems to contain atypical ChEs, displayingmixed properties of AChE and BChE, and that the muscle tissue seems to contain mainly AChE. In vitro exposures to chloropyrifosoxon inhibited blue shark's ChE in both tissues, the brain being the most sensitive tissue and therefore the most suitable for detection of exposure to low concentrations of anticholinergic compounds in the environment. This study indicates that ChE activity in blue sharks has the potential to be used as a sensitive and reliable biomarker in marine biomonitoring programs. info:eu-repo/semantics/publishedVersion

Holothuria scabra is the most valued and cultured tropical sea cucumber, given the great demand of this species for human consumption. However, despite its ecological and economic relevance, little is known regarding its immune responses under thermal stress. Here, the main goal was to study the response of sea cucumbers to temperature stress, assessing sub-organismal alterations and acclimation capacities of juveniles to temperature changes. After changing temperature (1 °C/day) for 6 days, organisms were exposed to temperature conditions of 21 °C (cold), 27 °C (control), and 33 °C (warm) over a 30 day period. At each 15-day interval (T0, T15, and T30), six replicates per condition were killed for biochemical analysis. Immune responses were addressed by studying the activity of phenoloxidase (PO) and prophenoloxidase (ProPO) in the coelomic fluid. Antioxidant defence responses—catalase (CAT), superoxide dismutase (SOD), and glutathione reductase (GR) enzymatic activities—were measured in the muscle and respiratory tree tissues, whereas oxidative damage was evaluated by measuring levels of superoxide radicals (ROS), DNA-strand breaks and lipid peroxidation (LPO). Juvenile H. scabra increased SOD and PO activities when temperature was elevated, and revealed low levels of ROS and damage in both cold and warm treatments throughout the experiment, confirming the organism’s moderate thermal stress. After the short acclimation period, the immune and antioxidant responses prevented damage and maintained homeostasis. This multi-biomarker approach highlights its usefulness to monitor the health of H. scabra and to gain insight concerning the use of this high-valued species in global-scale aquaculture from different temperature regions.

Marine ecosystems are constantly being threatened by contaminants produced by human activities. There is an urge to better understand their impacts on marine organisms and develop reliable tools for biomonitoring studies, while also assessing their potential impacts on human health.Given their position on top of food webs, sharks are particularly susceptible to bioaccumulation, making thempotential sentinel species ofmarine contamination. Themain objective of this studywas to find suitable biomarkers for futuremarine pollution biomonitoring studies by correlating biochemical responses with tissue contaminant body burden in blue sharks (Prionace glauca), a species heavily caught and consumed by humans, while also addressing their general health. The chemical contaminants analysed comprised different persistent organic pollutants (POPs) families from polychlorinated compounds to brominated flame retardants (BFRs) and perfluorinated compounds (PFCs) and different trace and heavymetals. Concentrations of some contaminants in sharks' tissueswere found to be above the legally allowed limits for human consumption. A canonical correspondence analysis (CCA) was performed and some strong associations were found between biochemical responses and contaminants' accumulation levels. DNA damage and lipid peroxidation levels, as well as the inhibition of the antioxidant enzyme glutathione peroxidase, were the main effects and consequences of contamination. The impact of contamination on these vital macromolecules underlines the suboptimal conditions of the sampled P. glauca, which can ultimately lead to the degradation of core ecological aspects, such as swimming, feeding, and reproduction. It can be concluded that P. glauca demonstrates great potential to be used as environmental sentinel and suitable biomarker candidates were identified in this work.Moreover, this study also highlights the risks that the consumption of blue shark derived products can pose to human health, which is of upmost interest as the sampled organismswere still juveniles and already presented values above regulatory limits. info:eu-repo/semantics/publishedVersion

Funding source : FRC, LMFA, ACN and SCN acknowledge their grants (SFRH/BPD/95372/2013, SFRH/BD/122082/2016, SFRH/BPD/108197/2015 and SFRH/BPD/94500/2013, respectively) attributed by the Foundation for Science and Technology (FCT; Portugal) and the European Social Fund (POPH, EU). This study benefited from the strategic program of MARE, financed by FCT (MARE – UID/MAR/04292/2020) and financial support provided by FCT and MARE through the project ECOLIND – Seabirds and fish as ecological indicators of contaminants and health in the North Atlantic relevant to ocean resources assessment (MFM/2017/0003). The project was also partly funded by the Integrated Programme of SR&TD “SmartBioR” (reference Centro-01-0145-FEDER-000018) cofounded by Centro 2020 program, Portugal2020, European Union, through the European Regional Development Fund. The funding source had no involvement in this study. Sardines (Sardina pilchardus) and mackerels (Scomber spp. and Trachurus spp.) are amongst the most common fish caught along the Iberian coast for human consumption and, as mid-trophic level organisms, they constitute essential prey in the diet of several marine predators. Thus, the assessment of trophic ecology, contamination exposure, and stress responses in such organisms provides valuable information on the environmental health in the mid-trophic chain and the potential risks for consumers. This study aims to contribute for an integrative mercury assessment of the marine ecosystem by measuring stable isotopes, mercury levels, and oxidative stress parameters in five commercial fish species in the northeast Atlantic. Samples of muscle and liver were collected from a total of 116 individuals in two fisheries assessment surveys (Spring and Autumn) along the whole Portuguese coast. Mercury concentrations and stable isotope analysis (δ13C and δ15N) were performed in the muscle, while oxidative stress parameters (lipid peroxidation and DNA damage) were measured in both muscle and liver. Mercury concentrations were found to be considerably lower than values recorded in previous studies and the limits set by the European Union law, which confirms the non-toxic status of these species along the Portuguese coast, concerning this harmful element. Interestingly, no differences were found among the three genera, despite clear differences in trophic niches. Still, mercury concentrations were significantly higher during Autumn than Spring, possibly due to upwelling events during the Summer. Moreover, no relationships between the mercury concentrations and oxidative stress parameters were found. Overall, this work provided an integrative mercury assessment of commercial fishes from the mid-trophic chain, particularly from pelagic (and neritic) regions in the northeast Atlantic, showing that mercury concentration in these species is low. However, it is important to note that this study focused on small- and medium-sized specimens (overall ranging from 13–25 cm in length), and thus higher concentrations of mercury may be present in larger fish due to bioaccumulation. info:eu-repo/semantics/publishedVersion