An assessment of metal contamination along the Irish coast using the seaweed Ascophyllum nodosum (Fucales, Phaeophyceae)

Ascophyllum nodosum (Linnaeus) Le Jolis from Arctic: Its Biochemical Composition, Antiradical Potential, and Human Health Risk

Ascophyllum nodosum is a brown seaweed common in Arctic tidal waters. We have collected A. nodosum samples from the Barents Sea (BS), Irminger Sea (IS), and Norwegian Sea (NS) in different reproductive stages and have evaluated their biochemical composition, radical scavenging potential, and health risks. The total content of dominating carbohydrates (fucoidan, mannitol, alginate, and laminaran) ranged from 347 mg/g DW in NS to 528 mg/g DW in BS. The proportion of two main structural monosaccharides of fucoidan (fucose and xylose) differed significantly between the seas and reproductive phase, reaching a maximum at the fertile phase in the BS sample. Polyphenols and flavonoids totals were highest in NS A. nodosum samples and increased on average in the following order: BS < IS < NS. A positive correlation of free radical scavenging activity for seaweed extracts with polyphenols content was observed. The concentration of elements in A. nodosum from the Arctic seas region was in the following order: Ca > Mg > Sr > Fe > Al > Zn > As total > Rb > Mn > Ba > Cu > Co. Seaweeds from BS had the lowest metal pollution index (MPI) of 38.4. A. nodosum from IS had the highest MPI of 83. According to the calculated target hazard quotient (THQ) and hazard index (HI) values, Arctic A. nodosum samples pose no carcinogenic risk to adult and child health and are safe for regular consumption. Our results suggest that the Arctic A. nodosum has a remarkable potential for food and pharmaceutical industries as an underestimated source of polysaccharides, polyphenols, and flavonoids.

Exploring uranium bioaccumulation in the brown alga Ascophyllum nodosum: insights from multi-scale spectroscopy and imaging

Legacy radioactive waste can be defined as the radioactive waste produced during the infancy of the civil nuclear industry's development in the mid-20th Century, a time when, unfortunately, waste storage and treatment were not well planned. The marine environment is one of the environmental compartments worth studying in this regard because of legacy waste in specific locations of the seabed. Comprising nearly 70% of the earth's service, the oceans are the largest and indeed the final destination for contaminated fresh waters. For this reason, long-term studies of the accumulation biochemical mechanisms of metallic radionuclides in the marine ecosystem are required. In this context the brown algal compartment may be ecologically relevant because of forming large and dense algal beds in coastal areas and potential important biomass for contamination. This report presents the first step in the investigation of uranium (U, an element used in the nuclear cycle) bioaccumulation in the brown alga Ascophyllum nodosum using a multi-scale spectroscopic and imaging approach. Contamination of A. nodosum specimens in closed aquaria at 13 °C was performed with a defined quantity of U(VI) (10-5 M). The living algal uptake was quantified by ICP-MS and a localization study in the various algal compartments was carried out by combining electronic microscopy imaging (SEM), X-ray Absorption spectroscopy (XAS) and micro X-ray Florescence (μ-XRF). Data indicate that the brown alga is able to concentrate U(VI) by an active bioaccumulation mechanism, reaching an equilibrium state after 200 h of daily contamination. A comparison between living organisms and dry biomass confirms a stress-response process in the former, with an average bioaccumulation factor (BAF) of 10 ± 2 for living specimens (90% lower compared to dry biomass, 142 ± 5). Also, these results open new perspectives for a potential use of A. nodosum dry biomass as uranium biosorbent. The different partial BAFs (bioaccumulation factors) range from 3 (for thallus) to 49 (for receptacles) leading to a compartmentalization of uranium within the seaweed. This reveals a higher accumulation capacity in the receptacles, the algal reproductive parts. SEM images highlight the different tissue distributions among the compartments with a superficial absorption in the thallus and lateral branches and several hotspots in the oospheres of the female individuals. A preliminary speciation XAS analysis identified a distinct U speciation in the gametes-containing receptacles as a pseudo-autunite phosphate phase. Similarly, XAS measurements on the lateral branches (XANES) were not conclusive with regards to the occurrence of an alginate-U complex in these tissues. Nonetheless, the hypothesis that alginate may play a role in the speciation of U in the algal thallus tissues is still under consideration.

Comparative study of the chemical composition and antifungal activity of commercial brown seaweed extracts

INTRODUCTION

A sustainable agriculture and the great increase in consumers of organic products in the last years make the use of natural products one of the main challenges of modern agriculture. This is the reason that the use of products based on seaweed extracts has increased exponentially, specifically brown seaweeds, including Ascophyllum nodosum and Ecklonia maxima.

METHODS

In this study, the chemical composition of 20 commercial seaweed extract products used as biostimulants and their antifungal activity against two common postharvest pathogens (Botrytis cinerea and Penicillium digitatum) from fruits were evaluated. Data were processed using chemometric techniques based on linear and non-linear models.

RESULTS AND DISCUSSION

The results showed that the algae species and the percentage of seaweed had a significant effect on the final composition of the products. In addition, great disparity was observed between formulations with similar labeling and antifungal effect of most of the analyzed products against some of the tested pathogens. These findings indicate the need for further research.

Current knowledge and future perspectives of the use of seaweeds for livestock production and meat quality: a systematic review

The effects of dietary macroalgae, or seaweeds, on growth performance and meat quality of livestock animal species are here reviewed. Macroalgae are classified into Phaeophyceae (brown algae), Rhodophyceae (red algae) and Chlorophyceae (green algae). The most common macroalga genera used as livestock feedstuffs are: Ascophyllum, Laminaria and Undaria for brown algae; Ulva, Codium and Cladophora for green algae; and Pyropia, Chondrus and Palmaria for red algae. Macroalgae are rich in many nutrients, including bioactive compounds, such as soluble polysaccharides, with some species being good sources of n-3 and n-6 polyunsaturated fatty acids. To date, the incorporation of macroalgae in livestock animal diets was shown to improve growth and meat quality, depending on the alga species, dietary level and animal growth stage. Generally, Ascophyllum nodosum can increase average daily gain (ADG) in ruminant and pig mostly due to its prebiotic activity in animal's gut. A. nodosum also enhances marbling score, colour uniformity and redness, and can decrease saturated fatty acids in ruminant meats. Laminaria sp., mainly Laminaria digitata, increases ADG and feed efficiency, and improves the antioxidant potential of pork. Ulva sp., and its mixture with Codium sp., was shown to improve poultry growth at up to 10% feed. Therefore, seaweeds are promising sustainable alternatives to corn and soybean as feed ingredients, thus attenuating the current competition among food-feed-biofuel industries. In addition, macroalgae can hinder eutrophication and participate in bioremediation. However, some challenges need to be overcome, such as the development of large-scale and cost-effective algae production methods and the improvement of algae digestibility by monogastric animals. The dietary inclusion of Carbohydrate-Active enZymes (CAZymes) could allow for the degradation of recalcitrant macroalga cell walls, with an increase of nutrients bioavailability. Overall, the use of macroalgae as feedstuffs is a promising strategy for the development of a more sustainable livestock production.

Spatio-temporal trace element fingerprinting of king scallops (Pecten maximus) reveals harvesting period and location

A rapidly growing human population is increasingly relying on seafood as a source of protein and other essential nutrients. Bivalve shellfish, both from wild populations and aquaculture, will undoubtedly continue to account for a significant portion of overall seafood production, but consumption of such shellfish carries potential health risks. Biotoxins, disease causing organisms and pollution contribute to this risk, as shellfish are indiscriminate, passive filter feeders. While government bodies, industry regulators and producers are capable of managing this risk, counterfeit produce can risk public safety, in turn damaging the reputation of the entire industry. Traceability tools provide a means to uphold food safety standards and mitigate remaining risk to consumers. Here, we show how the use of trace element (TE) signatures in shells and soft tissues of king scallops combined, can predict geographic origin with 100% accuracy. Importantly, we explore the temporal stability of this method, successfully classifying 100% of individuals correctly between two dates just 42 days apart from the same harvesting location. The most important elements in the trace element signatures of the scallops, discriminating between harvesting sites and dates were barium, boron, chromium, lead, manganese, molybdenum and selenium. The traceability tool described here offers a viable method to trace produce to its source, empowering industry regulators, government authorities, aquaculture practitioners and retailers in terms of tracking shellfish throughout the supply chain, which would comply with legislation and boost consumer confidence.

Trace element fingerprinting of blue mussel (Mytilus edulis) shells and soft tissues successfully reveals harvesting locations

Globally, aquaculture products are expected to account for >60% of total seafood produce by 2030. In the European Union, the seafood sector is of considerable economic importance to member states with household spending on seafood produce totalling €54.8 billion in 2016. Within the EU, shellfish aquaculture supports livelihoods and employment in many rural communities throughout the region. Harmful algal blooms pose considerable risk to consumer safety and in turn, stability of the shellfish market. If contaminated produce was to make it to the market the health risk to the public could be considerable, but the damage to the sector through loss of trust in producers would also be significant. Mytilus edulis account for a considerable portion of the aquaculture sector in the Northeast Atlantic. At present, no scientific tool is available to industry regulators, to allow them to trace mussel produce to its source, uphold food safety standards and ensure consumer confidence. The present study uses chemical analysis of shells and soft tissues to classify individual M. edulis to their site of harvest. The use of random forest classification of trace element composition has revealed location specific elemental signatures for all examined sites. This led to the correct classification of 100% of individuals sampled to their respective harvesting locations, including two sites located just 6 km apart within the same bay. The protocol demonstrated here provides the basis for a scientifically driven traceability framework for shellfish produce.

Metals accumulation in edible marine algae collected from Thondi coast of Palk Bay, Southeastern India

This study aimed to monitor the concentrations of metals including Cd, Pb, Cu and Zn in commercially important and commonly edible brown, red and green algal species collected from Thondi coast, southeast India. Green seaweed Chaetomorpha linum contained higher (Cd 8.51 mg kg^-1, Pb 5.24  mg kg^-1, Cu 15.38 mg kg^-1, and Zn 22.34  mg kg^-1) concentrations of metals than other tested seaweed samples. The concentrations of metals significantly varied within and between the investigated species of seaweed samples (P < 0.05). It was revealed that Cd, Pb, Cu and Zn metals were present in the species of seaweeds at different concentration. The residual levels of metals were less than the maximum allowable levels specified for human consumption compared to PTWIs, JECFA, FAO/WHO, FSSAI and EC. This study suggested that exposure to the analysed metals (Cd, Pb, Cu and Zn) through seaweeds consumption does not raise serious health effects to consumers and it is safe for human consumption.

Quantification and feed to food transfer of total and inorganic arsenic from a commercial seaweed feed

Seaweed has a long-associated history of use as a supplemented livestock feed, providing nutrients and vitamins essential to maintaining animal health. Some species of seaweed, particularly the fucoids, are well-known accumulators of the metalloid arsenic (As). Arsenic toxicity to humans is well established even at low exposure levels and is considered a class 1 human carcinogen. As mankind's appetite for livestock produce continues to grow unabated, there is a concern that consumption of livestock produce reared on a diet supplemented with seaweed animal feed (SAF) may pose a threat to the human population due to potentially high levels of As present in seaweed. To address this concern and provide end users, including industry, consumers, policymakers and regulators with information on the exposure associated with As in commercial seaweed animal feed, the estimated daily intake (EDI) of As was calculated to evaluate potential human exposure levels. Using As data from a commercially available seaweed meal over a five-year period (2012-2017) a population exposure assessment was carried out. A Monte Carlo simulation model was developed to characterise the feed to food transfer of As from animal feed to animal produce such as beef, milk, chicken, and eggs. The model examined initial levels in seaweed, inclusion rate in animal feed, animal feeding rates and potential transfer to food produced from a supplemented diet of SAF. The analysis of seaweed animal feed showed that inorganic As was a small fraction of the total As found in seaweed meal (80:1). Statistical analysis found significant differences in the concentration of As in seaweed animal feed depending on the grain size (p < 0.001), with higher As concentrations in smaller sized grain fractions. Due to several detoxification steps and subsequent rapid excretion from the bodies of livestock, a very low carryover rate of As compounds from seaweed animal feed into livestock produce was observed. The EDI calculated in this study for the livestock produce evaluated at the 95th confidence interval was <0.01% of suggested safe levels of inorganic As intake. The threat to the general population as a result of consumption of livestock products reared on a diet consisting of SAF is found to be negligible.

Metabolomic analysis of the toxic effect of chronic exposure of cadmium on rat urine

This study aimed to assess the toxic effect of chronic exposure to cadmium through a metabolomic approach based on ultra-performance liquid chromatography/mass spectrometry (UPLC-MS). Forty male Sprague-Dawley rats were randomly assigned to the following groups: control, low-dose cadmium chloride (CdCl₂) (0.13 mg/kg body weight (bw)), middle-dose CdCl₂ (0.8/kg bw), and high-dose CdCl₂ (4.9 mg/kg bw). The rats continuously received CdCl₂ via drinking water for 24 weeks. Rat urine samples were then collected at different time points to establish the metabolomic profiles. Multiple statistical analyses with principal component analysis and partial least squares-discriminant analysis were used to investigate the metabolomic profile changes in the urine samples and screen for potential biomarkers. Thirteen metabolites were identified from the metabolomic profiles of rat urine after treatment. Compared with the control group, the treated groups showed significantly increased intensities of phenylacetylglycine, guanidinosuccinic acid, 4-pyridoxic acid, 4-aminohippuric acid, 4-guanidinobutanoic acid, allantoic acid, dopamine, LysoPC(18:2(9Z,12Z)), and L-urobilinogen. By contrast, the intensities of creatinine, L-carnitine, taurine, and pantothenic acid in the treated groups were significantly decreased. These results indicated that Cd disrupts energy and lipid metabolism. Meanwhile, Cd causes liver and kidney damage via induction of oxidative stress; serum biochemical indices (e.g., creatinine and urea nitrogen) also support the aforementioned results.

Differences in Metal Accumulation in the Growing Shoot Tips and Remaining Shoot Tissue in Three Species of Brown Seaweeds

In this study we compared the accumulation of eight metals and two metalloids in the growing tips and the remaining shoot tissue of three species of brown seaweeds commonly used in biomonitoring studies (Fucus ceranoides, Fucus spiralis and Ascophyllum nodosum). Regression analysis of the data obtained showed that there was no statistically significant difference in accumulation in numerous cases; although most of the relationships were significant, many of the coefficients of determination were low. However, the concentrations of Mn and Zn in the growing tips were closely related to the concentrations in the rest of the tissue in all three species, possibly due to redistribution of these elements. Interspecies differences in bioconcentration of the elements may be partly explained by differences in the relative growth rates.

Talitrus saltator as a biomonitor: An assessment of trace element contamination on an urban coastline gradient

This study reports the first ever application of the trace element pollution index (TEPI) along a coastal, urban gradient using trace element concentrations (Ti, Mn, Co, Cu, As, Mo, Ag, Cd, Pb, Cr, Fe, Zn and Se) in the amphipod crustacean Talitrus saltator. Samples were collected from 10 sites in Galway Bay (Ireland) and concentrations of Pb showed the greatest spatial variation, likely due to the proximity of some sites to a former landfill and busy harbour. The TEPI used alongside the quartile method allowed for the assigning of sites to contamination level categories. Mapping these class levels allowed for straightforward visualisation of trace element contamination along the urban gradient. In addition, this study presents trace elements levels in T. saltator form the Atlantic Coast of Europe for the first time and the concentrations observed were comparatively lower than previously reported for T. saltator from the Baltic and Mediterranean seas.

Assessment and Characterisation of Ireland's Green Tides (Ulva Species)

Enrichment of nutrients and metals in seawater associated with anthropogenic activities can threaten aquatic ecosystems. Consequently, nutrient and metal concentrations are parameters used to define water quality. The European Union’s Water Framework Directive (WFD) goes further than a contaminant-based approach and utilises indices to assess the Ecological Status (ES) of transitional water bodies (e.g. estuaries and lagoons). One assessment is based upon the abundance of opportunistic Ulva species, as an indication of eutrophication. The objective of this study was to characterise Ireland’s Ulva blooms through the use of WFD assessment, metal concentrations and taxonomic identity. Furthermore, the study assessed whether the ecological assessment is related to the metal composition in the Ulva. WFD algal bloom assessment revealed that the largest surveyed blooms had an estimated biomass of 2164 metric tonnes (w/w). DNA sequences identified biomass from all locations as Ulva rigida, with the exception of New Quay, which was Ulva rotundata. Some blooms contained significant amounts of As, Cu, Cr, Pb and Sn. The results showed that all metal concentrations had a negative relationship (except Se) with the Ecological Quality Ratio (EQR). However, only in the case of Mn were these differences significant (p = 0.038). Overall, the metal composition and concentrations found in Ulva were site dependent, and not clearly related to the ES. Nevertheless, sites with a moderate or poor ES had a higher variability in the metals levels than in estuaries with a high ES.

Bioaccumulation of metals in ryegrass (Lolium perenne L.) following the application of lime stabilised, thermally dried and anaerobically digested sewage sludge

The uptake and accumulation of metals in plants is a potential pathway for the transfer of environmental contaminants in the food chain, and poses potential health and environmental risks. In light of increased population growth and urbanisation, the safe disposal of sewage sludge, which can contain significant levels of toxic contaminants, remains an environmental challenge globally. The aims of this experiment were to apply municipal sludge, having undergone treatment by thermal drying, anaerobic digestion, and lime stabilisation, to permanent grassland in order to assess the bioaccumulation of metals (B, Al, Ti, V, Cr, Mn, Co, Ni, Cu, Zn, As, Nb, Mo, Sb, Ba, W, Pb, Fe, Cd) by perennial ryegrass over a period of up to 18 weeks after application. The legislation currently prohibits use of grassland for fodder or grazing for at least three weeks after application of treated sewage sludge (biosolids). Five treatments were used: thermally dried (TD), anaerobically digested (AD) and lime stabilised (LS) sludge all from one wastewater treatment plant (WWTP), AD sludge from another WWTP, and a study control (grassland only, without application of biosolids). In general, there was no significant difference in metal content of the ryegrass between micro-plots that received treated municipal sludge and the control over the study duration. The metal content of the ryegrass was below the levels at which phytotoxicity occurs and below the maximum levels specified for animal feeds.

A comprehensive study of metal distribution in three main classes of seaweed

This paper provides one of the most comprehensive studies of metal distributions in three main macroalgae species. In this novel study, levels of total, intracellular and surface bound Pb, Zn, As, Cd, Co, Cr, Cu, Mn and Ni associated with Polysiphonia lanosa (L) Tandy, Ascophyllum nodosum (L) Le Jolis, Fucus vesiculosus (L) and Ulva sp. were determined. Additionally, water and sediment metal levels were analysed to gain an insight into the relative uptake efficiencies of different macroalgal species. Samples were collected from a clean site in Fethard-on-Sea, Wexford, Ireland (52°11'53.68'N, 6°49'34.64'W), in May 2008. Results demonstrated that total, intracellular and surface bound metal levels varied according to metal and seaweed species, with the highest proportion of metals found to be intracellular. Inhibition of Mn uptake by Zn was indicated for P. lanosa. Furthermore, P. lanosa had enhanced bioaccumulation ability, with the highest Concentration Factor reported of any seaweed to date.

Impacts of ambient salinity and copper on brown algae: 1. Interactive effects on photosynthesis, growth, and copper accumulation

The effect of copper enrichment and salinity on growth, photosynthesis and copper accumulation of two temperate brown seaweeds, Ascophyllum nodosum and Fucus vesiculosus, was investigated in laboratory experiments. A significant negative impact of reduced salinity on photosynthetic activity and growth was observed for both species. After 15 days at a salinity of 5, photosynthesis of A. nodosum was entirely inhibited and growth ceased at a salinity of 15. Increased copper concentration negatively affected photosynthetic activity of A. nodosum and F. vesiculosus resulting in chlorosis and reduced seaweed growth; 5 mg L⁻¹ copper caused an inhibition of the photosynthesis and the degradation of seaweed tips. Under reduced salinity, copper toxicity was enhanced and caused an earlier impact on the physiology of seaweed tips. After exposure to copper and different salinities for 15 days, copper contents of seaweeds were closely related to copper concentration in the water; seaweed copper contents reached their maximum after 1 day of exposure; contents only increased again when additional, free copper was added to the water. At high water copper concentrations or low salinity, or a combination of both, copper content of A. nodosum decreased. By contrast, copper content of F. vesiculosus increased, suggesting that different binding sites or uptake mechanisms exist in the two species. The results suggest that when using brown seaweeds in biomonitoring in situ, any change in the environment will directly and significantly affect algal physiology and thus their metal binding capacity; the assessment of the physiological status of the algae in combination with the analysis of thallus metal content will enhance the reliability of the biomonitoring process.

Runoff effect on eutrophic lake water quality and heavy metal distribution in recent littoral sediment

Multivariate statistical methods (hierarchical clustering analysis: HCA, and principal component analysis: PCA) were used to study the influence of runoff and other diffuse pollution sources on lake water chemistry of Hough Park lake in Central Missouri. In addition, heavy metal concentrations in lake littoral sediment were evaluated for enrichment and probable ecological risk. The abundance of macronutrients in the lake water column followed the order: Ca > Mg > TIC > K > Na > S > NO₃ - N > Fe > NH₃ - N > TP. Heavy metal concentrations in the lake water column were below acute and chronic level ecological guidelines. TN:TP ratios (range: 4.1-6.8) revealed nitrogen limitation of algal and other photosynthetic plant growth. The HCA showed two major clusters of similarity between the sampling points suggesting different pollution levels for the clusters. PCA 1, 2 and 3 reflected the influence of natural biochemical processes, atmospheric deposition and runoff respectively on lake water chemistry. The abundance of heavy metals and the normalizing element (Li) in littoral sediment (<63 μm fraction) samples analyzed in decreasing order were: Mn > Zn > Cr > Ni > Li > Cu > Pb > Cd > Hg. The average concentration of Cr, Mn and Ni in littoral sediment fraction exceeded the respective lowest effects level (LEL) threshold limit. Metal bioavailability in sediment fraction was low since the most labile metal species contained between 0% and 11% of the total metal content. Using the risk assessment code (RAC) criteria, only Mn posed a medium risk to the lake system.