Patrícia Anacleto

Nutritional quality and safety of cooked edible crab (Cancer pagurus).

Edible crab (Cancer pagurus) is one of the most important crustaceans consumed in Southern European countries, either as boiled or steamed cooked product. So far, the majority of studies assessing health benefits and risks associated to seafood consumption have been carried out in raw products, despite being generally cooked before consumption, and mostly in muscle tissue. Therefore, the aim of this study was to assess the effect of steaming and boiling on the chemical safety and nutritional value of C. pagurus caught in spring and summer. Generally, chemical and elemental composition of brown meat (tissue in the body cavity comprising mainly gonads and hepatopancreas) differed significantly from muscle (white meat in claws and legs). Additionally, the same tissue revealed differences in chemical and elemental composition of raw and cooked C. pagurus, likely due to water leaching. In contrast, few variations between seasons were observed. The results revealed that the consumption of cooked edible crab muscle should be promoted, whereas brown meat ingestion should be done parsimoniously.

Toxic elements and speciation in seafood samples from different contaminated sites in Europe

The presence of cadmium (Cd), lead (Pb), mercury (THg), methylmercury (MeHg), arsenic (TAs), inorganic arsenic (iAs), cobalt (Co), copper (Cu), zinc (Zn), nickel (Ni), chromium (Cr) and iron (Fe) was investigated in seafood collected from European marine ecosystems subjected to strong anthropogenic pressure, i.e. hotspot areas. Different species (Mytilus galloprovincialis, n=50; Chamelea gallina, n=50; Liza aurata, n=25; Platichthys flesus, n=25; Laminaria digitata, n=15; and Saccharina latissima, n=15) sampled in Tagus estuary, Po delta, Ebro delta, western Scheldt, and in the vicinities of a fish farm area (Solund, Norway), between September and December 2013, were selected to assess metal contamination and potential risks to seafood consumers, as well as to determine the suitability of ecologically distinct organisms as bioindicators in environmental monitoring studies. Species exhibited different elemental profiles, likely as a result of their ecological strategies, metabolism and levels in the environment (i.e. seawater and sediments). Higher levels of Cd (0.15-0.94 mg kg(-1)), Pb (0.37-0.89 mg kg(-1)), Co (0.48-1.1 mg kg(-1)), Cu (4.8-8.4 mg kg(-1)), Zn (75-153 mg kg(-1)), Cr (1.0-4.5 mg kg(-1)) and Fe (283-930 mg kg(-1)) were detected in bivalve species, particularly in M. galloprovincialis from Ebro and Po deltas, whereas the highest content of Hg was found in P. flesus (0.86 mg kg(-1)). In fish species, most Hg was organic (MeHg; from 69 to 79%), whereas lower proportions of MeHg were encountered in bivalve species (between 20 and 43%). The highest levels of As were found in macroalgae species L. digitata and S. latissima (41 mg kg(-1) and 43 mg kg(-1), respectively), with iAs accounting almost 50% of the total As content in L. digitata but not with S. latissima nor in the remaining seafood samples. This work highlights that the selection of the most appropriate bioindicator species is a fundamental step in environmental monitoring of each contaminant, especially in coastal areas. Furthermore, data clearly shows that the current risk assessment and legislation solely based on total As or Hg data is limiting, as elemental speciation greatly varies according to seafood species, thus playing a key role in human exposure assessment via food.

Effect of Season on the Chemical Composition and Nutritional Quality of the Edible Crab Cancer pagurus

Cancer pagurus is most appreciated in southern Europe for its muscle and brown meat content. In Portugal, consumption occurs mostly in summer and at Christmas. In this study the seasonal nutritional quality of edible tissues of female and male C. pagurus was determined. Tissue composition was affected by season and sex. All tissues had a well-balanced essential amino acid composition. Muscle and gonads of females had n-3/n-6 ratios in the range of the usual recommended values, and all tissues had PUFA/SFA above the recommended level. Autumn was the season with the highest brown meat yield, total essential amino acids (muscle), taurine (all tissues), EPA (male gonads), and n-3/n-6 ratio (gonads). However, it was also the season with the highest fat content and cholesterol concentration in ovaries. Therefore, people with restricted diets should moderate the consumption of ovaries in autumn. The remaining tissues pose no risks with respect to their proximate chemical composition.

Effect of warming on protein, glycogen and fatty acid content of native and invasive clams

Human bivalve consumption in Europe has steadily increased in the last years, particularly during summer months when seawater temperature increases. Since ocean warming is among the current global environmental threats affecting aquatic organisms, it is of paramount importance to investigate its effect on the nutritional quality of seafood products. In this context, the aim of this study was to investigate differences in the nutritional quality (in terms of protein, glycogen and fatty acid, FA, content) and condition of a native (grooved carpet shell, Ruditapes decussatus) and an invasive (Japanese carpet shell, Ruditapes philippinarum) clam species, subjected to warming. Our results clearly reveal that temperature significantly affected the nutritional quality of both clam species, particularly the FA composition. Both clam species responded similarly to warming, by significantly decreasing the content of some fatty acids, but not protein and glycogen levels. A predominance of polyunsaturated FA (PUFA) over saturated FA (SFA) and monounsaturated FA (MUFA) was observed throughout the experiment, as well as high n-3/n-6 and PUFA/SFA ratios. The native clam always revealed higher values of these fatty acids, indicating that this species has a better nutritional quality in comparison to the invasive one. Nonetheless, the loss of n-3 PUFA (in native species), eicosapentaenoic (EPA; in both species) and docosahexaenoic (DHA; in invasive species) acids was considered as the major negative outcome derived from warming, since it contributes to the loss of prime quality fatty acids for human health. However, atherogenic, thrombogenic and hypocholesterolemic/hypercholesterolemic indices (AI, TI and h/H, respectively) remained low in both species, even in warming conditions, suggesting that these food items can be used in a cardio-protective and hypocholesterolemic diet. This study provides new insights to understand and foretell the effects of climate change on nutritional quality of marine organisms.

Total Arsenic Content in Seafood Consumed in Portugal

Marine organisms are known to accumulate arsenic (As) in the range of 1–100 mg kg−1 from their environment and food sources. The majority of arsenic is present as organoarsenic compounds, metabolized from inorganic arsenic present in seawater or accumulated from food sources such as algae or other fish. The aim of this study was to evaluate total arsenic content in the muscle of eight fish species, three cephalopods, and one crustacean consumed in Portugal. The measurement of total arsenic (10 individuals of each species) was carried out by EDXRF (Energy Dispersive X-Ray Fluorescence Method). The highest concentrations were found in Norway lobster (30.3 ± 8.7 mg kg−1 wet weight), followed by common octopus (25.9 ± 8.4 mg kg−1 wet weight). Within fish species, wild gilthead sea bream, anglerfish, and megrim species presented values around 12 mg kg,−1 and in the others the average was lower than 10 mg kg−1. Taking into consideration the tolerable daily intake recommended by the World Health Organization (WHO; 0.05 mg As kg−1 body weight), the obtained results of total arsenic in the studied species do not represent a hazard for human consumption.

Ecophysiology of native and alien-invasive clams in an ocean warming context.

Both climate change and biological invasions are among the most serious global environmental threats. Yet mechanisms underlying these eventual interactions remain unclear. The aim of this study was to undertake a comprehensive examination of the physiological and biochemical responses of native (Ruditapes decussatus) and alien-invasive (Ruditapes philippinarum) clams to environmental warming. We evaluated thermal tolerance limits (CTMax), routine metabolic rates (RMRs) and respective thermal sensitivity (Q10 values), critical oxygen partial pressure (Pcrit), heat shock response (HSP70/HSC70 levels), lipid peroxidation (MDA build-up) and antioxidant enzyme [glutathione-S-transferase (GST), catalase (CAT) and superoxide dismutase (SOD)] activities. Contrary to most studies that show that invasive species have a higher thermal tolerance than native congeners, here we revealed that the alien-invasive and native species had similar CTMax values. However, warming had a stronger effect on metabolism and oxidative status of the native R. decussatus, as indicated by the higher RMRs and HSP70/HSC70 and MDA levels, as well as GST, CAT and SOD activities. Moreover, we argue that the alien-invasive clams, instead of up-regulating energetically expensive cellular responses, have evolved a less demanding strategy to cope with short-term environmental (oxidative) stress-pervasive valve closure. Although efficient during stressful short-term periods to ensure isolation and guarantee longer survival, such adaptive behavioural strategy entails metabolic arrest (and the enhancement of anaerobic pathways), which to some extent will not be advantageous under the chronically warming conditions predicted in the future.

Elemental composition of four farmed fish produced in Portugal

Farmed gilthead sea bream (Sparus aurata), European sea bass (Dicentrarchus labrax), rainbow trout (Oncorhynchus mykiss) and turbot (Psetta maxima) produced in Portugal were analysed in order to characterize their elemental composition. Atomic absorption (flame and cold vapour) and molecular absorption spectrometry techniques were used to determine all the studied elements. Similar patterns of macro, trace and ultra trace elements were observed for all fish species. The main elements were potassium (K), sodium (Na), phosphorus (P), magnesium (Mg) and calcium (Ca), followed by zinc (Zn), iron (Fe), copper (Cu), chromium (Cr), manganese (Mn) and nickel (Ni). Cadmium (Cd), mercury (Hg) and lead (Pb) concentrations, obtained in this study, allow concluding that these species do not present a hazard for human consumption. In addition, they contain almost all essential elements at concentrations sufficient to suit the dietary reference intake. Nevertheless, P. maxima nutritious trace element content is relatively low compared with the other three species.

Bioaccumulation and elimination of mercury in juvenile seabass (Dicentrarchus labrax) in a warmer environment

Warming is an expected impact of climate change that will affect coastal areas in the future. These areas are also subjected to strong anthropogenic pressures leading to chemical contamination. Yet, the consequences of both factors for marine ecosystems, biota and consumers are still unknown. The present work aims to investigate, for the first time, the effect of temperature increase on bioaccumulation and elimination of mercury [(total mercury (THg) and methylmercury (MeHg)] in three tissues (muscle, liver, and brain) of a commercially important seafood species - European seabass (Dicentrarchus labrax). Fish were exposed to the ambient temperature currently used in seabass rearing (18°C) and to the expected ocean warming (+4°C, i.e. 22°C), as well as dietary MeHg during 28 days, followed by a depuration period of 28 days fed with a control diet. In both temperature exposures, higher MeHg contents were observed in the brain, followed by the muscle and liver. Liver registered the highest elimination percentages (EF; up to 64% in the liver, 20% in the brain, and 3% in the muscle). Overall, the results clearly indicate that a warming environment promotes MeHg bioaccumulation in all tissues (e.g. highest levels in brain: 8.1mgkg(-1) ww at 22°C against 6.2mgkg(-1) ww at 18°C after 28 days of MeHg exposure) and hampers MeHg elimination (e.g. liver EF decreases after 28 days of depuration: from 64.2% at 18°C to 50.3% at 22°C). These findings suggest that seafood safety may be compromised in a warming context, particularly for seafood species with contaminant concentrations close to the current regulatory levels. Hence, results point out the need to strengthen research in this area and to revise and/or adapt the current recommendations regarding human exposure to chemical contaminants through seafood consumption, in order to integrate the expected effects of climate change.

Ecophysiological responses of juvenile seabass (Dicentrarchus labrax) exposed to increased temperature and dietary methylmercury

The ecotoxicological effects of methylmercury (MeHg) exposure have been intensively described in literature. Yet, it is still unclear how marine biota will respond to the presence of MeHg under climate change, namely ocean warming. The present study aimed to investigate, for the first time, fish condition [Fultons K index (K), hepatosomatic index (HIS) and brain-to-body mass ratio (BB-ratio)] and several stress-related responses in an ecologically and commercially important fish species (Dicentrachus labrax) exposed for 28days to dietary MeHg (8.0mg kg-1 dw) and temperature increase (+4°C). Results showed significant impairments on fish condition, i.e. up to 34% decrease on K, >100% increase on HIS and 44% decrease on BB-ratio, compared to control conditions. Significant changes on tissue biochemical responses were observed in fish exposed to both stressors, acting alone or combined, evidencing the relevance of assessing possible interactions between different environmental stressors in ecotoxicological studies. For instance, muscle showed to be the least affected tissue, only revealing significant alterations in GST activity of MeHg-enriched fish. On the other hand, liver exhibited a significant induction of GST (>100%) and CAT (up to 74%) in MeHg-enriched fish, regardless of temperature exposure, as well as decreased SOD activity (19%) and increased HSP70/HSC70 content (87%) in fish exposed to warming alone. Brain showed to be affected by temperature (69% of GST inhibition and >100% of increased CAT activity), MeHg (>100% of increased CAT activity, 47% of SOD inhibition and 55% of AChE inhibition), as well as by the combination of both (GST, SOD and AChE inhibition, 17%, 48% and 53%, respectively). Hence, our data provides evidences that the toxicological aspects of MeHg ca be potentiated by warmer temperatures, thus, evidencing the need for further research combining contaminants exposure and climate change effects, to better forecast ecological impacts in the ocean of tomorrow.

Microbiological composition of native and exotic clams from Tagus estuary: effect of season and environmental parameters.

The influence of seasonal and environmental parameters on the occurrence of bacteria was investigated in two clam species (Venerupis pullastra and Ruditapes philippinarum), water and sediment from the Tagus estuary. Total viable counts (TVC), Escherichia coli, Salmonella spp. and Vibrio spp. were evaluated during one-year. Overall, significant seasonal variations were found in both sampling sites, especially for E. coli and Vibrio spp. levels. In summer, significantly higher Vibrio spp. levels were found in R. philippinarum and sediment samples, but not in V. pullastra clams and water samples. In contrast, significantly higher TVC and E. coli levels were observed in winter months in water and sediment samples. Salmonella spp. was generally isolated when higher levels of E. coli were detected, particularly in R. philippinarum. This study is useful for authorities to develop monitoring strategies for coastal contamination and to estimate human health risks associated with the consumption of bivalves.