Screening for Health-Promoting Fatty Acids in Ascidians and Seaweeds Grown under the Influence of Fish Farming Activities.

The present study aimed to contrast the fatty acid (FA) profile of ascidians (Ascidiacea) and seaweeds (sea lettuce, Ulva spp. and bladderwrack, Fucus sp.) occurring in a coastal lagoon with versus without the influence of organic-rich effluents from fish farming activities. Our results revealed that ascidians and seaweeds from these contrasting environments displayed significant differences in their FA profiles. The n-3/n-6 ratio of Ascidiacea was lower under the influence of fish farming conditions, likely a consequence of the growing level of terrestrial-based ingredients rich on n-6 FA used in the formulation of aquafeeds. Unsurprisingly, these specimens also displayed significantly higher levels of 18:1(n-7+n-9) and 18:2n-6, as these combined accounted for more than 50% of the total pool of FAs present in formulated aquafeeds. The dissimilarities recorded in the FAs of seaweeds from these different environments were less marked (≈5%), with these being more pronounced in the FA classes of the brown seaweed Fucus sp. (namely PUFA). Overall, even under the influence of organic-rich effluents from fish farming activities, ascidians and seaweeds are a valuable source of health-promoting FAs, which confirms their potential for sustainable farming practices, such as integrated multi-trophic aquaculture.

Unravelling the fatty acid profiles of different polychaete species cultured under integrated multi-trophic aquaculture (IMTA).

Polychaetes can be successfully employed to recover otherwise wasted nutrients present in particulate organic matter (POM) of aquaculture effluents. The present study describes the fatty acid (FA) profile of four different polychaete species cultured in sand filters supplied with effluent water from a marine fish farm. The FA profile of cultured and wild Hediste diversicolor was compared and revealed a ≈ 24.2% dissimilarity, with cultured biomass displaying a higher content in two essential n-3 highly unsaturated FA (HUFA) (EPA [20:5 n-3] and DHA [22:6 n-3]-eicosapentaenoic and docosahexaenoic acid, respectively). The comparison of the FA profile of cultured H. diversicolor with that of other polychaete species whose larvae successfully settled on the sand filters (Diopatra neapolitana, Sabella cf. pavonina and Terebella lapidaria) revealed that their FA profile, which is here described for the first time, displayed high levels of EPA and DHA (≈ 1.5-4.8 and 1.0-1.1 µg mg-1 DW, respectively). The highest concentration of total FA per biomass of polychaete was recorded in H. diversicolor and T. lapidaria, with both species being the ones whose FA profiles revealed a lowest level of dissimilarity and more closely resembled that of the aquafeed used in the fish farm. In the present work it was demonstrated that it is possible to produce polychaetes biomass with high nutritional value through an eco-design concept such as integrated multi-trophic aquaculture (IMTA). Indeed, this framework promotes a cleaner production and, in this specific case, allowed to recover essential fatty acids that are commonly wasted in aquaculture effluents.

Recovering wasted nutrients from shrimp farming through the combined culture of polychaetes and halophytes.

The bioremediation and biomass production of organic extractive organisms (polychaetes Arenicola marina, Hediste diversicolor and halophyte Salicornia ramosissima) was assessed in an integrated multi-trophic aquaculture (IMTA) framework. Culture trials were performed outdoors using the nutient rich effluent from a shrimp farm employing recirculated aquaculture systems. Similar bioremediation efficiencies were obtained in cultures using a single polyculture tank (1 T) or two trophic levels separated tanks (2 T; ≈ 0.3 and 0.6 m2 operational area, respectively), with a reduction of 74-87% for particulate organic matter (POM), 56-64% for dissolved inorganic nitrogen (DIN) and 60-65% for dissolved inorganic phosphorus (DIP). Hediste diversicolor adapted well to culture conditions, reaching densities up to 5.000 ind. m-2 (≈ 78-98 g m-2). Arenicola marina failed to cope with water temperature that exceeded the species thermal limits, displaying a survival < 10% (20 °C often pointed as the maximum thermal threshold for this species). Productivity of S. ramosissima with 1 T was about twice that obtained with 2 T (≈ 150-170 and ≈ 60-90 g FW m-2 edible aboveground biomass, respectively). The yellowish coloration of cultured plants was likely due to the chemical oxidation and rapid sand filtration pre-treatment applied to the brackish groundwater used in the aquaculture facility, that removed iron (and probably other essential elements). Overall, 1 T design combining H. diversicolor and S. ramosissima displayed the best bioremediation performance and biomass production, while also allowing reducing in half the operational area required to implement this IMTA framework.

Performance of polychaete assisted sand filters under contrasting nutrient loads in an integrated multi-trophic aquaculture (IMTA) system.

Polychaete assisted sand filters (PASFs) allow to combine a highly efficient retention of particulate organic matter (POM) present in aquaculture effluent water and turn otherwise wasted nutrients into valuable worm biomass, following an integrated multi-trophic aquaculture (IMTA) approach. This study evaluated the bioremediation and biomass production performances of three sets of PASFs stocked with ragworms (Hediste diversicolor) placed in three different locations of an open marine land-based IMTA system. The higher organic matter (OM) recorded in the substrate of the systems which received higher POM content (Raw and Df PASFs - filtered raw and screened by drum filter effluent, respectively) likely prompted a superior reproductive success of stocked polychaetes (final densities 2-7 times higher than initial stock; ≈1000-3000 ind. m-2). Bioremediation efficiencies of ≈70% of supplied POM (≈1.5-1.8 mg L-1) were reported in these systems. The PASFs with lower content of OM in the substrate (Df + Alg PASFs - filtered effluent previously screened by drum filter and macroalgae biofilter) differed significantly from the other two, with stocked polychaetes displaying a poorer reproductive success. The PASFs were naturally colonized with marine invertebrates, with the polychaetes Diopatra neapolitana, Terebella lapidaria and Sabella cf. pavonina being some of the species identified with potential for IMTA.

Valuing Bioactive Lipids from Green, Red and Brown Macroalgae from Aquaculture, to Foster Functionality and Biotechnological Applications.

Marine edible macroalgae have functional proprieties that might improve human health and wellbeing. Lipids represent a minor fraction of macroalgae, yet with major interest as main carriers of omega 3 polyunsaturated fatty acids and intrinsic bioactive properties. In this study, we used lipid extracts from the green macroalgae Ulva rigida and Codium tomentosum; the red Gracilaria gracilis,Palmaria palmata and Porphyra dioica; and the brown Fucus vesiculosus, produced in a land-based integrated multitrophic aquaculture (IMTA) system. We determined the lipid quality indices based on their fatty acid profiles and their bioactivities as putative antioxidant, anti-inflammatory and antiproliferative agents. The results reveal to be species-specific, namely U. rigida displayed the lowest atherogenicity and thrombogenicity indices. Palmaria palmata and F. vesiculosus lipid extracts displayed the lowest inhibitory concentration in the free radical scavenging antioxidant assays. Ulva rigida, C. tomentosum, P. palmata and P. dioica inhibited COX-2 activity by up to 80%, while P. dioica and P. palmata extracts showed the highest cytotoxic potential in the MDA-MB-231 breast cancer cells. This work enhances the valorization of macroalgae as functional foods and promising ingredients for sustainable and healthy diets and fosters new applications of high-valued algal biomass, in a species-specific context.

Nutrient availability affects the polar lipidome of Halimione portulacoides leaves cultured in hydroponics.

Halophytes are increasingly regarded as suitable extractive species and co-products for coastal Integrated Multi-Trophic Aquaculture (IMTA) and studying their lipidome is a valid means towards their economic valorization. Halimione portulacoides (L.) Aellen edible leaves are rich in functional lipids with nutraceutical and pharmaceutical relevance and the present study aimed to investigate the extent to which its lipidome remains unchanged under a range of dissolved inorganic nitrogen (N) and phosphorus (P) concentrations typical of aquaculture effluents. Lipidomics analysis, done by hydrophilic interaction liquid chromatography coupled to high resolution mass spectrometry, identified 175 lipid species in the lipid extract of leaves: 140 phospholipids (PLs) and 35 glycolipids (GLs). Plants irrigated with a saline solution with 20-100 mg DIN-N L-1 and 3-15.5 mg DIP-P L-1 under a 1-week hydraulic retention time displayed a relatively stable lipidome. At lower concentrations (6 mg DIN-N L-1 and 0.8 mg DIP-P L-1), plants exhibited less PLs and GLs per unit of leaves dry weight and the GLs fraction of the lipidome changed significantly. This study reveals the importance of analyzing the lipidomic profile of halophytes under different nutritional regimens in order to establish nutrient-limitation thresholds and assure production conditions that deliver a final product with a consistent lipid profile.

Effect of High-Pressure Processing (HPP) on the Fatty Acid Profile of Different Sized Ragworms (Hediste diversicolor) Cultured in an Integrated Multi-Trophic Aquaculture (IMTA) System.

Ragworms (Hediste diversicolor) cultured under integrated multi-trophic aquaculture (IMTA) conditions display an improved fatty acids (FA) profile than conspecifics from the wild, thus being more suitable for maturation diets of marine fish and shrimp. Nonetheless, their use may represent a potential pathway for pathogens. The objective of the present study was to determine if high-pressure processing (HPP), as an approach to safeguard microbiological safety, could promote significant shifts on the FA profiles of different sized ragworms. An analysis of similarities (ANOSIM) revealed the existence of significant differences in the FA profile and lipid quality indexes (atherogenicity (AI), thrombogenicity (TI) and polyene (PI)) of control and HPP treated ragworms of all tested sizes (small, medium and large). Saturated (SFA) and monounsaturated FA (MUFA) increased after HPP, while polyunsaturated FA (PUFA; FA with 2 or 3 double bonds) and highly unsaturated FA (HUFA; FA with ≥ 4 double bonds) decreased. The amount of docosahexaenoic acid (DHA) in polychaetes exposed to HPP decreased an average of 25%, when compared with the levels recorded in control groups. The values of PI significantly decreased after HPP, while those of AI and TI displayed a significant increase. Despite the shifts in the FA profile of ragworms exposed to HPP, these still display a superior profile to that of wild specimens, namely the presence of DHA. Therefore, HPP can be considered as a suitable approach to safeguard the biosecurity of cultured polychaetes, without compromising their nutritional value, and support the principles of circular economy through the use of IMTA.

Functional traits of a native and an invasive clam of the genus Ruditapes occurring in sympatry in a coastal lagoon.

The main objective of this study was to evaluate the functional traits regarding bioturbation activity and its influence in the nutrient cycling of the native clam species Ruditapes decussatus and the invasive species Ruditapes philippinarum in Ria de Aveiro lagoon. Presently, these species live in sympatry and the impact of the invasive species was evaluated under controlled microcosmos setting, through combined/manipulated ratios of both species, including monospecific scenarios and a control without bivalves. Bioturbation intensity was measured by maximum, median and mean mix depth of particle redistribution, as well as by Surface Boundary Roughness (SBR), using time-lapse fluorescent sediment profile imaging (f-SPI) analysis, through the use of luminophores. Water nutrient concentrations (NH4-N, NOx-N and PO4-P) were also evaluated. This study showed that there were no significant differences in the maximum, median and mean mix depth of particle redistribution, SBR and water nutrient concentrations between the different ratios of clam species tested. Significant differences were only recorded between the control treatment (no bivalves) and those with bivalves. Thus, according to the present work, in a scenario of potential replacement of the native species by the invasive species, no significant differences are anticipated in short- and long-term regarding the tested functional traits.

New climatic targets against global warming: will the maximum 2 °C temperature rise affect estuarine benthic communities?

The Paris Agreement signed by 195 countries in 2015 sets out a global action plan to avoid dangerous climate change by limiting global warming to remain below 2 °C. Under that premise, in situ experiments were run to test the effects of 2 °C temperature increase on the benthic communities in a seagrass bed and adjacent bare sediment, from a temperate European estuary. Temperature was artificially increased in situ and diversity and ecosystem functioning components measured after 10 and 30 days. Despite some warmness effects on the analysed components, significant impacts were not verified on macro and microfauna structure, bioturbation or in the fluxes of nutrients. The effect of site/habitat seemed more important than the effects of the warmness, with the seagrass habitat providing more homogenous results and being less impacted by warmness than the adjacent bare sediment. The results reinforce that most ecological responses to global changes are context dependent and that ecosystem stability depends not only on biological diversity but also on the availability of different habitats and niches, highlighting the role of coastal wetlands. In the context of the Paris Agreement it seems that estuarine benthic ecosystems will be able to cope if global warming remains below 2 °C.

Bioprospecting of Marine Macrophytes Using MS-Based Lipidomics as a New Approach.

The marine environment supports a remarkable diversity of organisms which are a potential source of natural products with biological activities. These organisms include a wide variety of marine plants (from micro- to macrophytes), which have been used in the food and pharmaceutical industry. However, the biochemistry and biological activities of many of these macrophytes (namely macroalgae and halophytes, including seagrasses) are still far from being fully explored. Most popular bioactive components include polysaccharides, peptides, phenolics and fatty acids (FAs). Polar lipids (glycolipids, phospholipids and betaine lipids) are emerging as novel value-added bioactive phytochemicals, rich in n-3 FA, with high nutritional value and health beneficial effects for the prevention of chronic diseases. Polar lipids account various combinations of polar groups, fatty acyl chains and backbone structures. The polar lipidome of macrophytes is remarkably diverse, and its screening represents a significant analytical challenge. Modern research platforms, particularly mass spectrometry (MS)-based lipidomic approaches, have been recently used to address this challenge and are here reviewed. The application of lipidomics to address lipid composition of marine macrophytes will contribute to the stimulation of further research on this group and foster the exploration of novel applications.

Development and validation of an experimental life support system for assessing the effects of global climate change and environmental contamination on estuarine and coastal marine benthic communities.

An experimental life support system (ELSS) was constructed to study the interactive effects of multiple stressors on coastal and estuarine benthic communities, specifically perturbations driven by global climate change and anthropogenic environmental contamination. The ELSS allows researchers to control salinity, pH, temperature, ultraviolet radiation (UVR), tidal rhythms and exposure to selected contaminants. Unlike most microcosms previously described, our system enables true independent replication (including randomization). In addition to this, it can be assembled using commercially available materials and equipment, thereby facilitating the replication of identical experimental setups in different geographical locations. Here, we validate the reproducibility and environmental quality of the system by comparing chemical and biological parameters recorded in our ELSS with those prevalent in the natural environment. Water, sediment microbial community and ragworm (the polychaete Hediste diversicolor) samples were obtained from four microcosms after 57 days of operation. In general, average concentrations of dissolved inorganic nutrients (NO3 (-) ; NH4 (+) and PO4 (-3) ) in the water column of the ELSS experimental control units were within the range of concentrations recorded in the natural environment. While some shifts in bacterial community composition were observed between in situ and ELSS sediment samples, the relative abundance of most metabolically active bacterial taxa appeared to be stable. In addition, ELSS operation did not significantly affect survival, oxidative stress and neurological biomarkers of the model organism Hediste diversicolor. The validation data indicate that this system can be used to assess independent or interactive effects of climate change and environmental contamination on benthic communities. Researchers will be able to simulate the effects of these stressors on processes driven by microbial communities, sediment and seawater chemistry and to evaluate potential consequences to sediment toxicity using model organisms such as Hediste diversicolor.

Ragworm fatty acid profiles reveals habitat and trophic interactions with halophytes and with mercury.

The present study aimed to assess if ragworm fatty acids (FA) profiles could be used to discriminate their spatial distribution in an historically mercury-contaminated estuarine environment, i.e., if it was possible to differentiate ragworms present in salt marsh sediments surrounding plant roots and rhizomes (rhizosediment) from adjacent unvegetated sediment. Additionally, we also tried to determine if ragworms differed in mercury content and if these values could also be used to identify the habitat they occur in. Results show that, within the same area, ragworms can be distinguished using FA profiles and that in halophyte rhizosediment ragworms display more than twice the levels of alpha-linolenic acid (18:3n-3). The ratio cis-vaccenic/oleic acids (18:1n-7/18:ln-9) in ragworms suggests higher carnivory in unvegetated sediments. Our study indicates that ragworm FA profiles can be used to identify their habitat, their trophic interaction with halophytes and reveal a spatially contrasting feeding behaviour, which also reflects mercury accumulation.