A. Cristina S. Rocha

Antioxidant response of Phragmites australis to Cu and Cd contamination

Metals are known to induce oxidative stress in plant cells. Antioxidant thiolic compounds are known to play an important role in plants׳ defence mechanisms against metal toxicity but, regarding salt marsh plants, their role is still very poorly understood. In this work, the involvement of non-protein thiols (NPT), such as cysteine (Cys), reduced glutathione (GSH), oxidised glutathione (GSSG) and total acid-soluble SH compounds (total thiols), in the tolerance mechanisms of the marsh plant Phragmites australis against Cu and Cd toxicity was assessed. Specimens of this plant, freshly harvested in an estuarine salt marsh, were exposed, for 7 days, to rhizosediment soaked with the respective elutriate contaminated with Cu (0, 10 and 100 mg/L) or Cd (0, 1, 10 mg/L). In terms of NPT production, Cu and Cd contamination induced different responses in P. australis. The content of Cys increased in plant tissue after plant exposure to Cu, whereas Cd contamination led to a decrease in GSSG levels. In general, metal contamination did not cause a significant variation on GSH levels. Both metals influenced, to some extent, the production of other thiolic compounds. Despite the accumulation of considerable amounts of Cu and Cd in belowground tissues, no visible toxicity signs were observed. So, antioxidant thiolic compounds were probably involved in the mechanisms used by P. australis to alleviate metal toxicity. As P. australis is considered suitable for phytostabilising metal-contaminated sediments, understanding its tolerance mechanisms to toxic metals is important to optimise the conditions for applying this plant in phytoremediation procedures.

Toxicity of seven priority hazardous and noxious substances (HNSs) to marine organisms: Current status, knowledge gaps and recommendations for future research

Shipping industry and seaborne trade have rapidly increased over the last fifty years, mainly due to the continuous increasing demand for chemicals and fuels. Consequently, despite current regulations, the occurrence of accidental spills poses an important risk. Hazardous and noxious substances (HNSs) have been raising major concern among environmental managers and scientific community for their heterogeneity, hazardous potential towards aquatic organisms and associated social-economic impacts. A literature review on ecotoxicological hazards to aquatic organisms was conducted for seven HNSs: acrylonitrile, n-butyl acrylate, cyclohexylbenzene, hexane, isononanol, trichloroethylene and xylene. Information on the mechanisms of action of the selected HNS was also reviewed. The main purpose was to identify: i) knowledge gaps in need of being addressed in future research; and ii) a set of possible biomarkers suitable for ecotoxicological assessment and monitoring in both estuarine and marine systems. Main gaps found concern the scarcity of information available on ecotoxicological effects of HNS towards marine species and their poorly understood mode of action in wildlife. Differences were found between the sensitivity of freshwater and seawater organisms, so endpoints produced in the former may not be straightforwardly employed in evaluations for the marine environment. The relationship between sub-individual effects and higher level detrimental alterations (e.g. behavioural, morphological, reproductive effects and mortality) are not fully understood. In this context, a set of biomarkers associated to neurotoxicity, detoxification and anti-oxidant defences is suggested as potential indicators of toxic exposure/effects of HNS in marine organisms. Overall, to support the development of contingency plans and the establishment of environmental safety thresholds, it will be necessary to undertake targeted research on HNS ecotoxicity in the marine environment. Research should address these issues under more realistic exposure scenarios reflecting the prevailing spatial and temporal variability in ecological and environmental conditions.

SPE sample pre-treatment using a mixed-mode sorbent of reverse-phase and ionic exchange for determination of ALMWOAs in waters

Studies concerning the role of aliphatic low molecular weight organic acids (ALMWOAs) in physical, chemical and biological processes occurring in rhizosphere have been carried out over the last decades. However, the analytical determination of ALMWOAs concentrations in nature is difficult owing to their considerably low levels and the interference of most environmental matrices, which demands pre-concentration steps. For these reasons, a pre-treatment of the sample prior to its analysis is usually required. Herein, a solid phase extraction (SPE) method is given as a sample pre-treatment step for ALMWOAs determination in solutions with plant exudates. A SPE sorbent, with characteristics different from those used until now, was used to overcome matrix interference. High-performance liquid chromatography (HPLC) coupled with a diode array detector (DAD) was used for analysis. Acceptable ALMWOAs recovery percentages were achieved for freshwater matrices and interference of trace metals (Cu, Cd and Ni) was not observed. The developed method was applied to identify and estimate the levels of ALMWOAs released in the solution (freshwater enriched with 10 mg/L Cu, 5 mg/L Ni and 1 mg/L Cd) where roots of Halimione portulacoides and Phragmites australis specimens have been exposed, for 2 hours. Both plants liberated measurable amounts of oxalic acid and P. australis also released into the solution citric and maleic acids.

Bioaccumulation of persistent and emerging pollutants in wild sea urchin Paracentrotus lividus

ABSTRACT Marine pollution has been increasing as a consequence of anthropogenic activities. The preservation of marine ecosystems, as well as the safety of harvested seafood, are nowadays a global concern. Here, we report for the first time the contamination levels of a large set of 99 emerging and persistent organic contaminants (butyltins (BTs), polycyclic aromatic hydrocarbons (PAHs), pesticides including pyrethroids, pharmaceuticals and personal care products (PCPs) and flame retardants) in roe/gonads of sea urchin Paracentrotus lividus. Sea urchins are a highly prized worldwide delicacy, and the harvesting of this seafood has increased over the last decades, particularly in South West Atlantic coast, where this organism is harvested mainly for exportation. Sampling was performed in three harvesting sites of the NW Portuguese coast subjected to distinct anthropogenic pressures: Carreço, Praia Norte and Vila Chã, with sea urchins being collected in the north and south areas of each site. Butyltins and pharmaceuticals were not found at measurable levels. Several PAHs, four pyrethroids insecticides, four PCPs and eleven flame retardants were found in roe/gonads of sea urchins, though in general at low levels. Differences among harvesting sites and between areas within each site were found, the lowest levels of contaminants being registered in Carreço. The accumulation of contaminants in sea urchins’ roe/gonads seemed to reflect the low anthropogenic pressure felt in the sampling sites. Nevertheless, taking into account the low accumulated levels of chemicals, results indicate that sea urchins collected in South West Atlantic coast are safe for human consumption. HIGHLIGHTSBioaccumulation of 99 organic contaminants were assessed in wild sea urchin.40 emerging and persistent organic contaminants were detected, generally at low levels.Differences were found between sampling sites, Carreço being the least impacted area.

Data for the analysis of interactive multibiomarker responses of a marine crustacean to long-term exposure to aquatic contaminants

The data presented herein relates to the article entitled “Multibiomarker interactions to diagnose and follow-up chronic exposure of a marine crustacean to hazardous and noxious substances (HNS)” (Abreu et al., 2018). Multibiomarker approaches, including molecular, biochemical, physiological and behaviour parameters, are recognised as valuable and cost-effective to employ in integrated chemical and biological effects monitoring of aquatic contamination. Many biomarkers assessed in such programmes share common physiological pathways, showing concomitant or interdependent responses, which can reflect in increased energy costs related to physiological acclimation. Though, routine single biomarker data analysis, and exploratory principal component analysis, limit information obtained from the data collected and their functional interpretation. Ultimately, this influences the type of management actions taken to protect an affected ecosystem. This article presents data employed to develop an analytical approach accounting for multibiomarker interactions. The method was useful to diagnose and follow-up long-term exposure of the marine green crab (Carcinus maenas) to Hazardous and Noxious Substances (HNS).

Macro and trace elements in Paracentrotus lividus gonads from South West Atlantic areas

Abstract Sea urchin represents one of the most valuable seafood product being harvested and explored for their edible part, the gonads or roe. This species is generally considered a sentinel organism for ecotoxicological studies being widely used in monitoring programs to assess coastal aquatic environments quality, because is directly exposed to anthropogenic contaminants in their habitat. In this context, the aim of this study is to evaluate the concentrations of macro (Cl, K, P, Ca, S) and trace (Zn, Br, Fe, Sr, I, Se, Rb, Cu, Cr, Ni, As, iAs, Cd, Pb, Hg) elements in Paracentrotus lividus gonads from three South West Atlantic production areas subjected to distinct environmental and anthropogenic pressures. In all studied areas, the elements profile in sea urchin gonads was Cl > K > P > Ca > S > Zn > Br > Fe > Sr > I > Rb > Cu > Se > Cr > Ni, suggesting an element guide profile with special interest for sea urchin farming development. Concerning toxic elements, the profile was the following: As > Cd > Pb > Hg > iAs. The results evidenced higher levels of Pb and Hg in open areas. Distinct area characteristics and anthropogenic pressures of production areas evidence the importance of biomonitoring contaminants, particularly toxic elements. In general, the levels of these elements were below maximum levels in foodstuffs (MLs) which pose a minimal health risk to consumers. HighlightsHigh levels of Pb and Hg in sea urchin gonads collected in open areas.Studied areas seem to be suitable for the sustainable exploitation of sea urchin.Levels of toxic elements in gonads were below MLs, not constituting a health risk.

Evaluation of the Potential of Salt Marsh Plants for Metal Phytoremediation in Estuarine Environment

Constant discharge of pollutants into the environment, namely at salt marshes, poses a serious problem. Hence, remediation of these ecosystems is crucial not only for their conservation, but also to prevent the propagation of pollutants into the food web. Salt marsh plants have been suggested as suitable alternatives for soil/sediment remediation, having shown potential for the phytoremediation of metal-polluted media. However, more studies in conditions as close as possible to those found in the environment are needed to really confirm this potential; this is the aim of the two studies reported in this chapter. The first study results showed the capability of the salt marsh plant Halimione portulacoides for accumulating high metal levels from metal-polluted in its tissues, indicating, however, that a high plant biomass will be required for phytoremediating metal-affected areas. The second study results indicate that both Juncus maritimus and Phragmites australis have the capacity to be Cd phytostabilizers indicating that these plants can contribute to the recovery of impacted estuarine areas. More experiments should now be carried out to confirm the phytoremediation applicability in the estuarine environment and to assess ways to improve the capability shown by these plants for phytostabilization of metals.