Potentially toxic elements (PTEs) are of major concern due to their high persistence and toxicity. Recently, rare earth elements (REEs) concentration in aquatic ecosystems has been increasing due to their application in modern technologies. Thus, this work aimed to study, for the first time, the influence of REEs (lanthanum, cerium, praseodymium, neodymium, europium, gadolinium, terbium, dysprosium and yttrium) and of salinity (10 and 30) on the removal of PTEs (Cd, Cr, Cu, Hg, Ni and Pb) from contaminated waters by living macroalgae (Fucus spiralis, Fucus vesiculosus, Gracilaria sp., Osmundea pinnatifida, Ulva intestinalis and Ulva lactuca). Experiments ran for 168 h, with each macroalga exposed to saline water spiked with the six PTEs and with the six PTEs plus nine REEs (all at 1 μmol L⁻¹) at both salinities. Results showed that all species have high affinity with Hg (90–99% of removal), not being affected neither by salinity changes nor by the presence of other PTEs or REEs. Cd showed the lowest affinity to most macroalgae, with residual concentrations in water varying between 50 and 108 μg L⁻¹, while Pb removal always increased with salinity decline (up to 80% at salinity 10). REEs influence was clearer at salinity 30, and mainly for Pb. No substantial changes were observed in Ni and Hg sorption. For the remaining elements, the effect of REEs varied among algae species. Overall, the results highlight the role of marine macroalgae as living biofilters (particularly U. lactuca), capable of lowering the levels of top priority hazardous substances (particularly Hg) and other PTEs in water, even in the presence of the new emerging contaminants - REEs. Differences in removal efficiency between elements and macroalgae are explained by the contaminant chemistry in water and by macroalgae characteristics.

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.

The aim of the present study was to optimize the protocol for sampling marine macroalgae to be used to biomonitor heavy metal contamination in marine ecosystems. For this purpose, we collected 50 subsamples of the brown seaweed Fucus vesiculosus at random in each of three sampling sites (SS) and determined the concentrations of Al, As, Cd, Co, Cr, Cu, Fe, Hg, N, Ni, Pb, Zn and δ15N. We used semivariograms to explore the possible existence of spatial structure in the concentrations of the elements. Spatial structure was observed in 88% of the semivariograms studied, with element concentrations varying longitudinally and transversally along the SS. Using randomization techniques, we estimated that in each SS, a minimum of 30 evenly distributed subsamples should be collected within three bands parallel to the coastline (and also at different heights on the rocks if necessary), and analyzed in a single composite sample representative of the intra-SS variability.

Bismuth is a heavy metal whose biogeochemical behaviour in the marine environment is poorly defined. In this study, we exposed three different species of macroalga (the chlorophyte, Ulva lactuca, the phaeophyte, Fucus vesiculosus, and the rhodophyte, Chondrus crispus) to different concentrations of Bi (up to 50 μg L⁻¹) under controlled, laboratory conditions. After a period of 48-h, the phytotoxicity of Bi was measured in terms of chlorophyll fluorescence quenching, and adsorption and internalisation of Bi determined by ICP after EDTA extraction and acid digestion, respectively. For all algae, both the internalisation and total accumulation of Bi were proportional to the concentration of aqueous metal. Total accumulation followed the order: F. vesiculosus > C. crispus > U. lactuca; with respective accumulation factors of about 4200, 1700 and 600 L kg⁻¹. Greatest internalisation (about 33% of total accumulated Bi) was exhibited by C. crispus, the only macroalga to display a phytotoxic response in the exposures. A comparison of the present results with those reported in the literature suggests that Bi accumulation by macroalgae is significantly lower than its accumulation by marine plankton (volume concentration factors of 10⁵ to 10⁷), and that the phytotoxicity of Bi is low relative to other heavy metals like Ag and Tl.

The Estarreja Channel, Ria de Aveiro, Portugal, received industrial effluents for over 70years. Despite the discharges stopped a decade ago, a recent study showed negative ecological effects still associated with the metal and metalloid contaminated sediments. In contaminated versus reference channels, this study compared the benthic macrofauna collected with corer and mesh-bags for community structure and synthesis descriptors, namely taxa richness (S), Shannon-Wiener diversity (H′), taxonomic (AMBI and M-AMBI) and non-taxonomic (ISS) biotic indices and functional indicators (decomposition rates). The corer infauna dominated community and the associated S, H′, M-AMBI and ISS indices detected significant differences between contaminated and reference channels, otherwise undistinguished by the decomposition rates and the mesh-bags epifauna dominated community and associated indices. This suggests that sediment contamination in the deeper layers is not being transferred to the surface layers, explaining the non-affectation of the benthic macrofauna communities sampled in the leaf-bags.

Measuring loads of bioavailable metals is important for environmental assessment near mines and other industrial sources. In this study, a setup of monitoring buoys was tested to assess loads of bioavailable metals near a former Pb–Zn mine in West Greenland using transplanted seaweed, mussels and sea snails. In addition, passive DGT samplers were installed. After a 9-day deployment period, concentrations of especially Pb, Zn and Fe in the species were all markedly elevated at the monitoring sites closest to the mine. Lead concentrations in all three species and the DGT-Pb results showed a significant linear correlation. Zinc and Fe concentrations were less correlated indicating that the mechanisms for Zn and Fe accumulation in the three species are more complex. The results show that there is still a significant load of metals from the mine and that such buoys can be an adequate method to assess present loads of bioavailable metals.

Eutrophication is a major threat to aquatic ecosystems, because excessive nutrient enrichment may result in the loss of ecosystem services. Fjord systems are specifically under pressure due to nutrient input from land (agriculture) and sea (aquaculture). In this bioassay study, we have analyzed the effect of different nutrient sources, as well as their combination, on growth, nutrient composition and recruitment of habitat-forming and ephemeral macrophytes. We found that agricultural fertilizer increased growth for all algae (except Fucus), while the fish farm effluents mainly increased growth of Ulva. The C:N ratio was hardly affected by the fish farm, but decreased significantly in all algae when agriculture fertilizer was added. Most interestingly, however, distance to the fish farm modulated the algal response to the fertilizer. Our results demonstrate the importance of studying effects of multiple stressors in aquatic ecosystems to sustainably manage the consequences of anthropogenic impacts.

Time series of ¹³⁷Cs and ⁹⁹Tc activity concentrations in the brown seaweed Fucus vesiculosus and seawater, gathered at three locations on the eastern Irish coastline during the period 1988–2008, have been modelled using a novel approach incorporating a variable uptake rate in the seaweed. Seasonal variations in the time series, identified using spectral analysis, were incorporated into the model which was used to determine transfer kinetic parameters and to predict ¹³⁷Cs and ⁹⁹Tc concentrations in seaweed, as influenced by levels in ambient seawater. An optimisation method combining evolutionary and grid search minimisation techniques was adopted to determine the best values for the model parameters, from which concentration factors (CF) and biological half-lives (tb₁/₂) for ¹³⁷Cs and ⁹⁹Tc in F. vesiculosus were calculated. CF values of 170–179 and 1.1×105lkg⁻¹ (dry weight) were obtained for ¹³⁷Cs and ⁹⁹Tc, respectively, while the corresponding tb₁/₂ values were 39–47 and 32days, respectively.

Biofouling by marine organisms can result in a variety of negative environmental and economic consequences, with decontamination procedures remaining problematic, costly and labour-intensive. Here, we examined the efficacy of direct steam exposure to induce mortality of selected biofouling species: Mytilus edulis; Magallana gigas; Semibalanus balanoides; Fucus vesiculosus; and an Ulva sp. Total mortality occurred at 60-sec of steam exposure for M. edulis and juvenile M. gigas, at 30-sec for S. balanoides, while 300-sec was required for adult M. gigas. Application of steam reduced the biomass of F. vesiculosus and significantly reduced Ulva sp. biomass, with complete degradation being observed for Ulva sp. following 120-sec of exposure. Accordingly, it appears that steam exposure can cause mortality of biofouling organisms through thermal shock. Although preliminary, our novel and promising results suggest that steam applications could potentially be used to decontaminate niche areas and equipment.

The natural abundance of 15N (δ15N) has been widely used to detect anthropogenically derived N loads in environmental impact studies. The present study involved retrospective analysis of subsamples of Fucus vesiculosus L. collected during a period of three years (2008–2010) from two sites: a control site, within a coastal reference area, and an area affected by the effluents of a marine land-based fish farm. The isotopic signal in different subsamples of the macroalgae thalli (tissue that has grown during the same period) varied depending on the age of the tissue. Moreover, the isotopic signal decreased significantly with the age of the frond to within a certain range. The δ15N of F. vesiculosus is temporally unstable; therefore, measurement of the δ15N of macroalgal tissues does not allow reliable retrospective biomonitoring of environmental pollution. Further knowledge about the growth and other biological aspects of this species is required.