The relevance of the community approach linking chemical and biological analyses in pollution assessment

Source risk, ecological risk, and bioeffect assessment for polycyclic aromatic hydrocarbons (PAHs) in Laizhou Bay and Jiaozhou Bay of Shandong Peninsula, China

In order to incorporate the contribution of pollution sources to ecological risks into environmental monitoring, positive matrix factorization-risk quotient (PMF-RQ) was used to quantify the contribution of different PAH sources to ecological risks, which indicated that the unburned petroleum, vehicular emissions, and diesel combustion were the main sources of PAHs in Laizhou Bay and Jiaozhou Bay, and they were caused by petrochemical industry, maritime shipping, and urban traffic exhaust as the major sources of PAHs for ecological risk. Meanwhile, integrated biomarker response (IBR) and multi-biomarker pollution index (MPI) suggested that September was the most polluted month for PAHs in Laizhou Bay and Jiaozhou Bay and the pollution in Laizhou Bay was significantly higher than that in Jiaozhou Bay. This research was dedicated to explore the monitoring pattern for PAH pollution from the source to bioeffects, and it may have contributed a scientific support to monitoring and governance of marine PAH pollution.

Which Micropollutants in Water Environments Deserve More Attention Globally?

Increasing chemical pollution of aquatic environments is a growing concern with global relevance. A large number of organic chemicals are termed as "micropollutants" due to their low concentrations, and long-term exposure to micropollutants may pose considerable risks to aquatic organisms and human health. In recent decades, numerous treatment methods and technologies have been proposed to remove micropollutants in water, and typically several micropollutants were chosen as target pollutants to evaluate removal efficiencies. However, it is often unclear whether their toxicity and occurrence levels and frequencies enable them to contribute significantly to the overall chemical pollution in global aquatic environments. This review intends to answer an important lingering question: Which micropollutants or class of micropollutants deserve more attention globally and should be removed with higher priority? Different risk-based prioritization approaches were used to address this question. The risk quotient (RQ) method was found to be a feasible approach to prioritize micropollutants in a large scale due to its relatively simple assessment procedure and extensive use. A total of 83 prioritization case studies using the RQ method in the past decade were compiled, and 473 compounds that were selected by screening 3466 compounds of three broad classes (pharmaceuticals and personal care products (PPCPs), pesticides, and industrial chemicals) were found to have risks (RQ > 0.01). To determine the micropollutants of global importance, we propose an overall risk surrogate, that is, the weighted average risk quotient (WARQ). The WARQ integrates the risk intensity and frequency of micropollutants in global aquatic environments to achieve a more comprehensive priority determination. Through metadata analysis, we recommend a ranked list of 53 micropollutants, including 36 PPCPs (e.g., sulfamethoxazole and ibuprofen), seven pesticides (e.g., heptachlor and diazinon), and 10 industrial chemicals (e.g., perfluorooctanesulfonic acid and 4-nonylphenol) for risk management and remediation efforts. One caveat is that the ranked list of global importance does not consider transformation products of micropollutants (including disinfection byproducts) and new forms of pollutants (including antibiotic resistance genes and microplastics), and this list of global importance may not be directly applicable to a specific region or country. Also, it needs mentioning that there might be no best answer toward this question, and hopefully this review can act as a small step toward a better answer.

Integration of chemical and biological methods: A case study of polycyclic aromatic hydrocarbons pollution monitoring in Shandong Peninsula, China

Polycyclic aromatic hydrocarbons (PAHs), as persistent toxic substances (PTS), have been widely monitored in coastal environment, including seawater and sediment. However, scientific monitoring methods, like ecological risk assessment and integrated biomarker response, still need massive researches to verify their availabilities. This study was performed in March, May, August and October of 2018 at eight sites, Yellow River estuary (S1), Guangli Port (S2), Xiaying (S3), Laizhou (S4), Inner Bay (S5), Outer Bay (S6), Hongdao (S7) and Hongshiya (S8) of Shandong Peninsula, China. The contents of 16 priority PAHs in local seawater and sediment were determined, by which ecological risk assessment risk quotient (RQ) for seawater and sediment quality guidelines (SQGs) were calculated to characterize the PAHs pollution. Meanwhile, multiple biomarkers in the digestive gland of clam Ruditapes philippinarum were measured to represent different biological endpoints, including ethoxyresorufin-O-deethylase (EROD), glutathione S-transferase (GST), sulfotransferase (SULT), superoxide dismutase (SOD) and lipid peroxidation (LPO), by which integrated biomarker response (IBR) was calculated to provide a comprehensive assessment of environmental quality. Taken together, these results revealed the heaviest pollution at S2 as both PAHs concentrations and biomarkers responses reflected, and supported the integrated biomarker response as a useful tool for marine environmental monitoring, through its integration with SQGs.

An integrated approach using chemical ecological risk assessment and multi-integrated biomarker indexes approach to assess pollution: A case study of Ruditapes philippinarum in four bays on the Shandong Peninsula in China

Considering the ecological risks of polycyclic aromatic hydrocarbons (PAHs) to the marine environment, it is urgent to find scientific and effective monitoring methods. In this study, an integrated approach combining chemical ecological risk assessment and multi-integrated biomarker indexes approach was used to assess the marine environment. Samples included seawater, sediments, and clam Ruditapes philippinarum were collected from four bays on the Shandong Peninsula, China in the four seasons of 2019. The concentrations, composition, potential sources, and ecological risk of PAHs were investigated in seawater and sediments. Risk quotient (RQ) and sediment quality guidelines (SQGs) were calculated to assess the ecological risks of PAHs in seawater and sediment, respectively. And then, clam Ruditapes philippinarum's multi-level biological response, including its ethoxyresorufin-O-deethylase (EROD), glutathione S-transferase (GST), superoxide dismutase (SOD), lipid peroxidation (LPO), and acetylcholinesterase (AChE) were investigated in-depth, by which multi-integrated biomarker indexes approach were calculated to evaluate marine environmental quality. Taken together, the results showed that the concentration of PAHs was in good agreement with the response of biomarkers, and the usefulness of the combined use of chemical ecological risk assessment and integrated biomarker indexes to assess PAHs pollution was verified.

Biomonitoring of polycyclic aromatic hydrocarbons (PAHs) from Manila clam Ruditapes philippinarum in Laizhou, Rushan and Jiaozhou, bays of China, and investigation of its relationship with human carcinogenic risk

This study examined the marine environment and seafood safety using chemical monitoring and multiple biomarkers. Samples were collected from three bays on the Shandong Peninsula in China, Laizhou, Rushan and Jiaozhou, in March, May, August, and October of 2018 and 2019. The polycyclic aromatic hydrocarbon (PAH) concentrations in sediments and tissue samples from the clam Ruditapes philippinarum and multiple biomarkers were measured. All the sampling sites were found to be medium-PAH-contaminated areas (100-1000 ng/g d.w.). According to the correlation analysis, ethoxyresorufin-o-deethylase (EROD) and superoxide dismutase (SOD) activity in the clam's digestive gland were sensitive to PAHs (p < .05), but the incremental lifetime cancer risk (ILCR) was lower than the priority risk level (10^-4) at most sampling sites. EROD, SOD and acetylcholinesterase activity exhibited significant correlations with the ILCR values (p < .01), suggesting that they may serve as good indicators for assessing safe seafood consumption levels for human beings.

The use of epilithic biofilms as bioaccumulators of pesticides and pharmaceuticals in aquatic environments

Biofilms are a consortium of communities of organisms that live in syntrophic relationships and present a higher organization level than that of individual cells. Biofilms dominate microbial life in streams and rivers, enable crucial ecosystem processes, contribute to global biogeochemical flows and represent the main active bacterial life form. Epilithic biofilms are the main biomass found in rivers; their exposure to contaminants can lead to changes in their structure and composition. The composition of these communities is influenced by physicochemical factors, temperature, light and prior exposure to pollutants, among other factors, and it can be used for water quality monitoring purposes. The heterogenous composition of biofilms enables them to accumulate compounds in an integrative manner. Moreover, the availability of several sorption sites and their likely saturation can contribute to bioaccumulation. In aquatic environments, biofilms are also susceptible to the acquisition of antibiotic resistance genes and participate in their dissemination. Anthropic pressure intensification processes continuously expose water resources and, consequently, biofilm communities to different contamination sources. Therefore, the use of biofilms to indicate environmental pollution is reinforced by the progress of studies on the subject. Biofilm communities' response to pollutants in aquatic environments can be mainly influenced by the presence of different organisms, which may change due to community development or age. The current research aims to review studies about biofilm contamination and highlight the importance of biofilm use to better evaluate and maintain the quality of water bodies.

A verification of correlation between chemical monitoring and multi-biomarker approach using clam Ruditapes philippinarum and scallop Chlamys farreri to assess the impact of pollution in Shandong coastal area of China

Biogeochemical monitoring coupled with multi-biomarker approach were performed for the assessment of marine environment, using clam Ruditapes philippinarum and scallop Chlamys farreri to indicate contamination status in sediments and seawater respectively. The bivalves were collected from three stations, Jiaozhou Bay, Rushan Bay and Laizhou Bay, of Shandong coastal area. A series of contaminants (PAHs and TBBPA) and biomarkers (AhR, EROD, GST, SOD, GPx, CAT, DNA damage) were measured. Multi-biomarker pollution index (MPI) and integrated biomarker response (IBR) were carried out to evaluate contamination status and both indexes showed that Rushan Bay was most polluted, where the pollution level of sediments reached "highly polluted" in August, followed by Jiaozhou Bay and Rushan Bay which reached "lightly polluted". The correlation of IBR values with contaminants' concentrations was verified through the Pearson correlation coefficient (p < 0.05), consolidating this scientific assessment method for marine environment.

Chemical mixtures and fluorescence in situ hybridization analysis of natural microbial community in the Tiber river

The Water Framework Directive (WFD) regulates freshwater and coastal water quality assessment in Europe. Chemical and ecological water quality status is based on measurements of chemical pollutants in water and biota together with other indicators such as temperature, nutrients, species compositions (phytoplankton, microalgae, benthos and fish) and hydromorphological conditions. However, in the current strategy a link between the chemical and the ecological status is missing. In the present WFD, no microbiological indicators are foreseen for integrating the different anthropogenic pressures, including mixtures of chemicals, nutrients and temperature changes, to provide a holistic view of the freshwater ecosystem water quality. The main aim of this work was to evaluate if natural microbial populations can be valuable indicators of multiple stressors (e.g. chemical pollutants, temperature, nutrients etc.) to guide preventive and remediation actions by water authorities. A preliminary survey was conducted to identify four sites reflecting a contamination gradient from the source to the mouth of a river suitable to the objectives of the European Marie Curie project, MicroCoKit. The River Tiber (Italy) was selected as a pilot case study to investigate the correlation between bacteria taxa and the chemical status of the river. The main physicochemical parameters, inorganic elements, organic pollutants and natural microbial community composition were assessed at four selected sites corresponding to pristine, agricultural, industrial and urban areas for three consecutive years. The overall chemical results indicated a correspondence between different groups of contaminants and the main contamination sources at the selected sampling points. Phylogenetic analysis of the microbial community analyzed by Fluorescence In Situ Hybridization method (FISH) revealed differences among the four sampling sites which could reflect an adaptive bacterial response to the different anthropogenic pressures.

Contribution of trace metallic elements to weakly contaminated lacustrine sediments: effects on benthic and pelagic organisms through multi-species laboratory bioassays

Surficial sediments exhibit higher levels of contamination than overlying water, especially from persistent contaminants such as trace metallic elements (TMEs). While sediments could in turn act as sources of contamination for the water column, their ecotoxicology is yet rarely assessed in a multi-compartments perspective. This study aims at assessing the response of benthic and pelagic organisms exposed to weakly contaminated sediments using a multi-species laboratory assay by focusing on TMEs (Cd, Cr, Cu, Ni, Pb, and Zn) contamination. Chironomus riparius larvae, Daphnia magna, and Lemna minor were simultaneously exposed for 10 days to six sediments sampled from the littoral of a large French lake (Lake Bourget). The endpoints consisted in the survival and growth rates and the bioconcentration factor (BCF). Significant negative relationships between sediment TME concentrations and survival rates of C. riparius and growth rates of C. riparius and D. magna suggested that both benthic and pelagic macro-invertebrates were impacted by sediment contamination, which was not observed in L. minor. Significant relationships of the sediment with the internal TME concentrations were positive while negative with the BCFs, suggesting an increase in biological regulation processes in all organisms with the increase of sediment TME concentrations. These results underline the importance of including both benthic and pelagic organisms in ecotoxicological assessment of low contaminated sediments and the relevance of the relationship BCFs/sediment contamination as prior biomarkers than higher life history traits.

Towards a multi-bioassay-based index for toxicity assessment of fluvial waters

Despite their proven reliability for revealing 'acceptable' degrees of toxicity in waste- and reclaimed waters, bioassays are rarely used to assess the toxicity of hazardous contaminants present in natural waters. In this study, we used organisms from different trophic levels to assess the toxicity of water samples collected from four different South Korean rivers. The main objective was to develop a multi-descriptor index of toxicity for undiluted river water. The responses of six test organisms (Aliivibrio fischeri, Pseudokirchneriella subcapitata, Heterocypris incongruens, Moina macrocopa, Danio rerio and Lemna minor) after laboratory exposure to water samples were considered for this index, as well as the frequency of teratologies in diatom assemblages. Each individual test was attributed a toxicity class and score (three levels; no toxicity = 0, low toxicity = 1, confirmed toxicity = 2) based on the organism's response after exposure and a total score was calculated. The proposed index also considers the number of test organisms that received the highest toxicity score (value = 2). An overall toxicity category was then attributed to the water sample based on those two metrics: A = no toxicity, B = slight toxicity, C = moderate toxicity; D = toxicity and E = high toxicity. The susceptibility of the test organisms varied greatly and the sensitivity of their response also differed among bioassays. The combined responses of organisms from different trophic levels and with different life strategies provided multi-level diagnostic information about the intensity and the nature of contamination.

Histological and Genotoxic Biomarkers in Prochilodus lacustris (Pisces, Prochilodontidae) for Environmental Assessment in a Protected Area in the Northeast of Brazil

The quality of aquatic environments all around the world is being altered by different human activities that represent direct threat to the ecological system and the aquatic biota. This study aimed to evaluate the occurrence of histological and genotoxic alterations in Prochilodus lacustris as indicators of anthropic impacts in a lacustrine environment in northeast Brazil. The histological alterations were evaluated using the histological alteration index, and the genotoxic alterations were detected using the micronuclei test, at three sampling stations (S1, S2 and S3). The gills presented lesions with three stages of severity, with mild lesions more frequent in the specimens collected at station S1. Mild hepatic tissue lesions were the most frequent type in both areas. Micronucleus analysis showed that station S3 was the most affected. The biological responses observed indicated that the fish are under influence of environmental changes. It is important to highlight that the organisms collected at station S3 had a more compromised health status.

Endocrine disruption in aquatic systems: up-scaling research to address ecological consequences

Endocrine‐disrupting chemicals (EDCs) can alter biological function in organisms at environmentally relevant concentrations and are a significant threat to aquatic biodiversity, but there is little understanding of exposure consequences for populations, communities and ecosystems. The pervasive nature of EDCs within aquatic environments and their multiple sub‐lethal effects make assessments of their impact especially important but also highly challenging. Herein, we review the data on EDC effects in aquatic systems focusing on studies assessing populations and ecosystems, and including how biotic and abiotic processes may affect, and be affected by, responses to EDCs. Recent research indicates a significant influence of behavioural responses (e.g. enhancing feeding rates), transgenerational effects and trophic cascades in the ecological consequences of EDC exposure. In addition, interactions between EDCs and other chemical, physical and biological factors generate uncertainty in our understanding of the ecological effects of EDCs within aquatic ecosystems. We illustrate how effect thresholds for EDCs generated from individual‐based experimental bioassays of the types commonly applied using chemical test guidelines [e.g. Organisation for Economic Co‐operation and Development (OECD)] may not necessarily reflect the hazards associated with endocrine disruption. We argue that improved risk assessment for EDCs in aquatic ecosystems urgently requires more ecologically oriented research as well as field‐based assessments at population‐, community‐ and food‐web levels.

A multi-biomarker approach in scallop Chlamys farreri to assess the impact of contaminants in Qingdao coastal area of China

A multi-biomarker approach was carried out to classify the environmental quality and the adverse effects of contaminants on scallop Chlamys farreri. The scallops were collected from three sampling stations in Qingdao coastal area of China in March, May, August and October of 2015. A suite of environmental factors and biomarkers, including temperature, salinity, pH, the concentrations of polycyclic aromatic hydrocarbons (PAHs), tetrabromobisphenol A (TBBPA) and metals (Cr, Mn, Cu, Zn, Cd, Pb, As) in seawater and soft tissue, mRNA expression of aryl hydrocarbon receptor (AhR) and P-glycoprotein (P-gp), 7-ethoxyresorufin O-deethylase (EROD), glutathione-S-transferase (GST), uridine-diphosphate-glucuronyl-transferase (UGT), sulfotransferase (SULT), metallothionein (MT), Superoxide dismutase (SOD), glutathione peroxidase (GPx), catalase (CAT), lipid peroxidation (LPO) and protein carbonyl (PC) contents and DNA strand breaks, were measured in the gill and digestive gland. The results showed that S2 was the most polluted while S1 was identified the least polluted. Despite the differentiation of pollution levels and environmental parameters the selected biomarkers responded efficiently to contaminants. Principal component analysis (PCA) revealed that EROD for PAHs, AhR for TBBPA, MT for Cr, Pb and Mn, LPO and PC for Zn were the effective biomarkers respectively. This study demonstrated that the application of multi-biomarker approach in conjunction with the traditional analysis of environmental parameters and contaminants provided valuable information in environmental risk assessment.

Sewage sludge hazardous assessment: chemical evaluation and cytological effects in CHO-k1 cells

Application of sewage sludge in agricultural lands is a growing practice in several countries due to its numerous benefits to soil and crops, where chemical and pathogen levels are determined by corresponding legislation. However, the presence of contaminants in residues must always be controlled before application due to their dangerous effects over the ecosystem and potential risks to human health. The main objective of this study was to integrate biological and chemical analysis in order to help elucidating the residue potential toxic, cytotoxic, and mutagenic effects. We evaluate samples of sewage sludge before and after the sanitizing treatment with lime in cytokinesis-block assay using CHO-k1 culture cells. The sanitizing treatment promoted a decrease in pathogen levels, which is the main purpose of this process. Even with chemical levels below the established by environmental agencies, results showed sewage sludge ability to enhance genotoxic and mutagenic effects, proving that residue should be handled with caution in order to minimize its environmental and human risk.

Application of the micronucleus test and comet assay in Trachemys callirostris erythrocytes as a model for in situ genotoxic monitoring

Trachemys callirostris is a turtle species endemic to northern South America. In northern Colombia it occurs in the middle and lower Magdalena River drainage and its principal tributaries (lower Cauca and San Jorge rivers) and in other minor drainages such as the lower Sinú River. In recent years, industrial, agricultural, and mining activities have altered natural habitats in Colombia where this species occurs, and many of the pollutants released there are known to induce genetic alterations in wildlife species. The micronucleus test and comet assay are two of the most widely used methods to characterize DNA damage induced by physical and chemical agents in wildlife species, but have not been employed previously for genotoxic evaluations in T. callirostris. The goal of this study was to optimize these genotoxic biomarkers for T. callirostris erythrocytes in order to establish levels of DNA damage in this species and thereby evaluate its potential as a sentinel species for monitoring genotoxic effects in freshwater environments in northern Colombia. Both genotoxic techniques were applied on peripheral blood erythrocytes from 20 captive-reared T. callirostris individuals as a negative control, as well as from samples obtained from 49 individuals collected in Magangué (Magdalena River drainage) and 24 individuals collected in Lorica (Sinú River drainage) in northern Colombia. Negative control individuals exhibited a baseline frequency of micronuclei of 0.78±0.58 and baseline values for comet tail length and tail moment of 3.34±0.24µm and 10.70±5.5, respectively. In contrast, samples from both field sites exhibited significantly greater evidence of genotoxic effects for both tests. The mean MN frequencies in the samples from Magangué and Lorica were 8.04±7.08 and 12.19±12.94, respectively. The mean tail length for samples from Magangué and Lorica were 5.78±3.18 and 15.46±7.39, respectively. Finally, the mean tail moment for samples from Magangué and Lorica were 23.59±18.22 and 297.94±242.18, respectively. The frequency of micronuclei in the samples was positively related to comet tail length and tail moment. Thus, this study showed that both genotoxicity biomarkers may be applied to T. callirostris erythrocytes as a sentinel organism for assessing the effects of environmental pollutants in freshwater ecosystems in northern South America.

Combined effects of drought and the fungicide tebuconazole on aquatic leaf litter decomposition

Loss of biodiversity and altered ecosystem functioning are driven by the cumulative effects of multiple natural and anthropogenic stressors affecting both quantity and quality of water resources. Here we performed a 40-day laboratory microcosm experiment to assess the individual and combined effects of drought and the model fungicide tebuconazole (TBZ) on leaf litter decomposition (LLD), a fundamental biogeochemical process in freshwater ecosystems. Starting out from a worst-case scenario perspective, leaf-associated microbial communities were exposed to severe drought conditions (four 5-day drought periods alternated with 4-day immersion periods) and/or a chronic exposure to TBZ (nominal concentration of 20μgL(-1)). We assessed the direct effects of drought and fungicide on the structure (biomass, diversity) and activity (extracellular enzymatic potential) of fungal and bacterial assemblages colonizing leaves. We also investigated indirect effects on the feeding rates of the amphipod Gammarus fossarum on leaves previously exposed to drought and/or TBZ contamination. Results indicate a stronger effect of drought stress than fungicide contamination under the experimental conditions applied. Indeed, the drought stress strongly impacted microbial community structure and activities, inhibiting the LLD process and leading to cascading effects on macroinvertebrate feeding. However, despite the lack of significant effect of TBZ applied alone, the effects of drought on microbial functions (i.e., decrease in LLD and in enzymatic activities) and on Gammarus feeding rates were more pronounced when drought and TBZ stresses were applied together. In a perspective of ecological risk assessment and ecosystem management for sustainability, these findings stress the need for deeper insight into how multiple stressors can affect the functioning of aquatic ecosystems and associated services.

Metagenomic sequencing of marine periphyton: taxonomic and functional insights into biofilm communities

Periphyton communities are complex phototrophic, multispecies biofilms that develop on surfaces in aquatic environments. These communities harbor a large diversity of organisms comprising viruses, bacteria, algae, fungi, protozoans, and metazoans. However, thus far the total biodiversity of periphyton has not been described. In this study, we use metagenomics to characterize periphyton communities from the marine environment of the Swedish west coast. Although we found approximately ten times more eukaryotic rRNA marker gene sequences compared to prokaryotic, the whole metagenome-based similarity searches showed that bacteria constitute the most abundant phyla in these biofilms. We show that marine periphyton encompass a range of heterotrophic and phototrophic organisms. Heterotrophic bacteria, including the majority of proteobacterial clades and Bacteroidetes, and eukaryotic macro-invertebrates were found to dominate periphyton. The phototrophic groups comprise Cyanobacteria and the alpha-proteobacterial genus Roseobacter, followed by different micro- and macro-algae. We also assess the metabolic pathways that predispose these communities to an attached lifestyle. Functional indicators of the biofilm form of life in periphyton involve genes coding for enzymes that catalyze the production and degradation of extracellular polymeric substances, mainly in the form of complex sugars such as starch and glycogen-like meshes together with chitin. Genes for 278 different transporter proteins were detected in the metagenome, constituting the most abundant protein complexes. Finally, genes encoding enzymes that participate in anaerobic pathways, such as denitrification and methanogenesis, were detected suggesting the presence of anaerobic or low-oxygen micro-zones within the biofilms.

Influence of the natural growth environment on the sensitivity of phototrophic biofilm to herbicide

Ecotoxicological experiments were performed in laboratory-scale microcosms to investigate community-level structural responses of river phototrophic biofilms from different environments to herbicide exposure. Biofilms were initially cultivated on artificial supports placed in situ for 4 weeks at two sites, site M, located in an agricultural watershed basin and site S, located in a forested watershed basin. The biofilms were subsequently transferred to microcosms and, after an acclimatisation phase of 7 days were exposed to alachlor at 10 and 30 μg L(-1) for 23 days. Alachlor effects were assessed by a combination of structural parameters, including biomass (ash-free dry mass and chlorophyll a), molecular fingerprinting of the bacterial community (polymerase chain reaction (PCR)-denaturing gradient gel electrophoresis (DGGE)) and diatom species composition. Alachlor impacted the chlorophyll a and ash-free dry mass levels of phototrophic biofilms previously cultivated at site S. The structural responses of bacterial and diatom communities were difficult to distinguish from changes linked to the microcosm incubation period. Phototrophic biofilms from site S exposed at 30 μg L(-1) alachlor were characterised by an increase of Achnanthidium minutissimum (K-z.) Czarnecki abundance, as well as a higher proportion of abnormal frustules. Thus, phototrophic biofilms with different histories, exhibited different responses to alachlor exposure demonstrating the importance of growth environment. These observations also confirm the problem of distinguishing changes induced by the stress of pesticide toxicity from temporal evolution of the community in the microcosm.

Impact of an urban multi-metal contamination gradient: metal bioaccumulation and tolerance of river biofilms collected in different seasons

The aim of this study was to investigate the repeatability and seasonal variability of the biological response of river biofilms chronically exposed to a multi-metal pressure in an urban contamination gradient. Biofilms were grown on immersed plastic membranes at three sites on the Seine river upstream (site 1) and downstream (sites 2 and 3) from Paris (France). They were collected in four different seasons (autumn, spring, summer and winter). Biofilm tolerance to Cu, Ni, Pb and Zn was measured using a PICT (Pollution-Induced Community Tolerance) approach with a previously developed short-term toxicity test based on β-glucosidase (heterotrophic) activity. Metal concentrations in the river and also in the biofilm samples (total and non-exchangeable bioaccumulated metals) were also monitored. Biofilm-accumulated metal concentrations reflected the increase of the multi-metal exposure along the urban gradient. These concentrations were strongly correlated with dissolved and particulate organic carbon and with the total metal fraction in the river water, which recalls the significant influence of the environmental parameters on metal uptake processes in river biofilms. Overall, natural biofilms allow monitoring water quality by integrating the variations of a diffuse metal contamination overtime. Tolerance levels globally increased from site 1 to site 3 reflecting the metal pollution gradient measured in the river water collected at the three sites. Cu tolerance tended to increase during warm seasons but no clear seasonal tendency could be found for Ni, Pb and Zn. Furthermore, principal component analysis clearly discriminated samples collected upstream (site 1) from samples collected downstream (sites 2 and 3) along the first principal component which was correlated to the metal gradient. Samples collected in winter were also separated from the others along the second principal component correlated to parameters like water temperature and Total Suspended Solids concentration. This study shows that chronic in situ exposure to environmental metal concentrations has a significant impact on natural biofilms. Biofilm tolerance to metals and biofilm metal bioaccumulation both reflect metal exposure levels although they remain low when compared to Environmental Quality Standards from the European Water Framework Directive. Yet temperature appears as an important environmental variable shaping community structure and response to toxic exposure which shows that the sampling date is an important parameter to consider when using natural river biofilms to assess the impacts of urban pressure.

Linking community tolerance and structure with low metallic contamination: a field study on 13 biofilms sampled across the Seine river basin

It is difficult to assess the biological consequences of diffuse water contamination by micropollutants which are present in rivers at low, even sublethal levels. River biofilms, which respond quickly to changes of environmental parameters, are good candidates to acquire knowledge on the response of aquatic organisms to diffuse chemical contamination in the field. The study was designed as an attempt to link biofilm metal tolerance and metallic contamination in a field survey covering 13 different sampling sites in the Seine river basin (north of France) with low contamination levels. Cd and Zn tolerance of heterotrophic communities was assessed using a short-term toxicity test based on β-glucosidase activity. Metal tolerance levels varied between sites but there was no obvious correlation between tolerance and corresponding water contamination levels for Cd and Zn. Indeed, metallic contamination at the sampling sites remained subtle when compared to water quality standards (only two sampling sites had either Zn or both Cu and Zn concentrations exceeding the Environmental Quality Standards set by the EU Water Framework Directive). Yet, multivariate analysis of the data using Partial Least Squares Regression revealed that both metallic and environmental parameters were important variables explaining the variability of metal tolerance levels. Automated Ribosomal Intergenic Spacer Analysis (ARISA) was also performed on both bacterial and eukaryotic biofilm communities from the 13 sampling sites. Multivariate analysis of ARISA fingerprints revealed that biofilms with similar tolerance levels have similar ARISA profiles. Those results confirm that river biofilms are potential indicators of low, diffuse contamination levels of aquatic systems.

Characterization and evolution of natural aquatic biofilm communities exposed in vitro to herbicides

River biofilms are assemblies of autotrophic and heterotrophic microorganisms that can be affected by pollutants such as those found in watersheds and wastewater treatment plants. In the laboratory, experimental biofilms were formed from river water, and their overall composition was investigated. Denaturing gradient gel electrophoresis (DGGE) and cytometry were used to assess the richness and diversity of these communities. The software Cytostack (available on request) was developed to treat and analyze the cytometric data. Measurements of chlorophyll-a and carotenoids were used to assess the global composition of the photoautotrophic community, whereas proteins, polysaccharides (PS) content, and esterase activities were used to assess overall changes in the mixed communities. We evaluated the effects that 3 weeks of treatment with the herbicides diuron and glyphosate (10 μg L(-1)) had on these biofilms. Exposed to diuron, bacterial communities adapted, changing their composition. Glyphosate inhibited growth of one autotrophic community but caused no chlorophyll deficit. As a whole, the biofilm acted as a micro-ecosystem, able to regulate and maintain a constant level of photosynthetic pigment through the structural adaptation of the autotrophic community. These results are one more proof that microbial diversity of aquatic biofilms is influenced by chemical stresses, potentially leading to disturbances within the ecosystems.

Prioritization of chemicals in the aquatic environment based on risk assessment: analytical, modeling and regulatory perspective

The extensive and intensive use of chemicals in our developed, highly technological society includes more than 100,000 chemical substances. Significant scientific evidence has lead to the recognition that their improper use and release may result in undesirable and harmful side-effects on both the human and ecosystem health. To cope with them, appropriate risk assessment processes and related prioritization schemes have been developed in order to provide the necessary scientific support for regulatory procedures. In the present paper, two of the elements that constitute the core of risk assessment, namely occurrence and hazard effects, have been discussed. Recent advances in analytical chemistry (sample pre-treatment and instrumental equipment, etc.) have allowed for more comprehensive monitoring of environmental pollution reaching limits of detection up to sub ng L(-1). Alternative to analytical measurements, occurrence models can provide risk managers with a very interesting approach for estimating environmental concentrations from real or hypothetical scenarios. The most representative prioritization schemes used for issuing lists of concerning chemicals have also been examined and put in the context of existing environmental policies for protection strategies and regulations. Finally, new challenges in the field of risk-assessment have been outlined, including those posed by new materials (i.e., nanomaterials), transformation products, multi-chemical exposure, or extension of the risk assessment process to the whole ecosystem.

Biodiversity and structure of spider communities along a metal pollution gradient

The objective of the study was to determine whether long-term metal pollution affects communities of epigeal spiders (Aranea), studied at three taxonomic levels: species, genera, and families. Biodiversity was defined by three indices: the Hierarchical Richness Index (HRI), Margalef index (D(M)) and Pielou evenness index (J). In different ways the indices describe taxa richness and the distribution of individuals among taxa. The dominance pattern of the communities was described with four measures: number of dominant species at a site, percentage of dominant species at a site, average dominant species abundance at a site, and the share of the most numerous species (Alopecosa cuneata) at a site. Spiders were collected along a metal pollution gradient in southern Poland, extending ca. 33 km from zinc and lead smelter to an uncontaminated area. The zinc concentration in soil was used as the pollution index.The study revealed a significant effect of metal pollution on spider biodiversity as described by HRI for species (p = 0.039), genera (p = 0.0041) and families (p = 0.0147), and by D(M) for genera (p = 0.0259) and families (p = 0.0028). HRI correlated negatively with pollution level, while D(M) correlated positively. This means that although broadly described HRI diversity decreased with increasing pollution level, species richness increased with increasing contamination. Mesophilic meadows were generally richer. Pielou (J) did not show any significant correlations. There were a few evidences for the intermediate disturbance hypothesis: certain indices reached their highest values at moderate pollution levels rather than at the cleanest or most polluted sites.

Use of polar organic chemical integrative samplers to assess the effects of chronic pesticide exposure on biofilms

The responses of aquatic organisms to chronic exposure to environmental concentrations of toxicants, often found in mixtures, are poorly documented. Here passive sampler extracts were used in experimental contamination of laboratory channels, to investigate their effects on natural biofilm communities. A realistic mixture of pesticides extracted from Polar Organic Chemical Integrative Samplers was used to expose biofilms in laboratory channels to total pesticide concentrations averaging 0.5 ± 0.1 μg l⁻¹. The level of exposure was representative of field conditions in terms of relative proportions of the substances but the exposure concentration was not maintained (decreasing concentrations between contamination occasions). The impact on the structural as well as the functional characteristics of the autotrophic and heterotrophic components was determined, using biofilm grown in uncontaminated conditions (reference site) and in sites exposed to pesticides (contaminated site). The exposure imposed did not significantly modify the structure or functions of reference biofilms, nor did it modify tolerance as measured by mixture EC₅₀ (EC₅₀ mix). In contrast, the communities from the more contaminated downstream section lost tolerance following decreased dose exposure, but community composition remained fairly stable. Overall, these results indicate that low levels of contamination did not lead to strong changes in community structure, and 14-day changes in tolerance seemed to depend mainly on physiological adaptation, suggesting that other environmental factors or longer-lasting processes prevailed. This study reports the first attempt to use passive sampler extracts as a realistic composite contaminant for experimental exposure of biofilms, with promising perspectives in further ecotoxicology studies.

Presence and biological effects of emerging contaminants in Llobregat River basin: a review

Llobregat River (North-East Spain) is the most important drinking water source for Barcelona and its surrounding area. As one of the only water sources in the area the river water have been overexploited and effluents from more than 30 urban wastewater treatment plants, industries and agriculture runoffs have been discharged into the river. This article reviews the presence of emerging contaminants published during the last decades, emphasizing on the observed effects on ecosystems caused by the contamination. Pesticides, surfactants, estrogens, pharmaceuticals and personal care products and even abuse drugs are the main groups detected in different studies, reporting alterations in species composition, abundance or biomass and endocrine disruption measured by alterations in enzymatic activity or specific protein production. The information available provides an overview of the river status according to the Water Framework Directive.

The effects of the nitrofuran furaltadone on Ulva lactuca

The use of pharmaceuticals in the food production industry as prophylatic and therapeutic agents is necessary to promote animal health, but may entail significant consequences to natural ecosystems, especially in the cases of overdosing and use of banned pharmaceuticals. The vast effects that antibiotics released into the environment have on non-target organisms are already under the scope of researchers but little attention has been given to primary producers such as macroalgae. The present study assessed furaltadone's, an antibacterial agent illegally used for veterinary purposes, uptake capacity by Ulva lactuca and its effect in the growth of this cosmopolitan macroalgae. Differences in macroalgal growth were shown when submitted to prophylactic and therapeutic concentrations of furaltadone in the water (16 and 32 μg mL⁻¹, respectively). The therapeutic concentration caused higher growth impairment than the prophylactic treatment did, with 87.5% and 58% reductions respectively. Furthermore, together with data collected from the accumulation assays, with values of internal concentrations as high as 18.84 μg g⁻¹ WW, suggest that the macroalgae U. lactuca should be included in field surveys as a biomonitor for the detection of nitrofurans.

Active bio-monitoring of contamination in aquatic systems--an in situ translocation experiment applying the PICT concept

The environmental risk assessment of toxicants is often derived from chemical monitoring, based on single species tests performed in the laboratory. However, to provide ecologically relevant information, community approaches are required. The aim of this study was to causally link prometryn exposure to community-level effects in complex field situations and to identify response times of adaptation to pollution and recovery from pollution. For this reason sensitivity shifts in communities were detected and related to structural changes within the periphyton community. Furthermore, it was intended to illustrate the possibility of a combined approach of community translocation and sensitivity assessment for active monitoring of polluted sites. Periphyton was grown at a reference (R) and at a polluted (P) site of the river Elbe basin for 26 days, was subsequently transferred from the polluted site to the reference site and vice versa. Sensitivity of communities to prometryn was determined according to the pollution-induced community tolerance (PICT)-concept in short-term tests by measuring photosynthesis inhibition and was related to structural changes in algal class and diatom species composition. Exposure to prometryn was determined using polar organic integrative samplers (POCIS), giving time-weighted average concentrations. Environmental concentrations of prometryn were significantly higher at the polluted site compared to the reference site. Communities grown at the polluted site showed a higher tolerance to prometryn in comparison to the reference site. 17 Days after the translocation to the reference site, EC(50) decreased 2-fold compared to the non-translocated P-community of the same age. By contrast, EC(50) of the community grown at the reference site was 5 times higher after 17 days exposure at the polluted site. Furthermore, P-R communities were less sensitive to prometryn (higher EC(50)) than R-P communities, 24 days after translocation. These changes in sensitivity to prometryn were consistent with changes in species composition and clearly indicate that the exposure history of communities is defining the time-response of recovery and adaptation. In conclusion, the PICT-concept is shown to be a suitable tool for analysis of recovery and adaptation processes of communities under natural conditions. Therefore, it improves the link between cause and effect in field situations. In situ translocation studies provide an ecological relevant assessment of pesticide effects under field conditions and could be used as a diagnostic tool in active monitoring for decision-making frameworks as used in the implementation of the European Water Framework Directive (WFD).

Effects of organic herbicides on phototrophic microbial communities in freshwater ecosystems

Over the past 15 years, significant research efforts have been channeled into assessing the effects of organic herbicides on freshwater phototrophic microbial communities. The results of this research are reviewed herein. The main conclusions we have reached after performing this review can be summarized into five points: · Most relevant assessments have dealt with the effects of triazine and phenylurea herbicides. Herbicides from these chemical classes are often considered to be model compounds when photosystem-II inhibitors are studied. · Until the early 2000s, the vast majority of investigations conducted to evaluate herbicide effects on phototropic microbes were performed in microcosms or mesocosms. In such studies, herbicides were usually applied alone, and often at concentrations much higher than those detected in the environment. More recently, the trend has been toward more realistic and relevant studies, in which lower herbicide concentrations were considered, and compound mixtures or successive treatments were tested. Increasingly, in situ studies are being designed to directly evaluate microbial community responses, following chemical exposures in contaminated aquatic environments. · Several biological end points are used to evaluate how organisms in the phototrophic microbial community respond to herbicide exposure. These end points allow the detection of quantitative changes, such as chl a concentrations, total cell counts or periphytic biomass, qualitative changes such as community structure to algal diversity, or functional changes such as photosynthesis and respiration, among others. They may give different and complementary information concerning the responses of microbial communities. · PICT approaches, which have generally combined functional and structural measurements, may prove to be valuable for assessing both an immediate impact, and for factoring in the contamination history of an ecosystem at the community level. · Finally, any relevant assessment of pesticide effects should incorporate a detailed environmental characterization that would include abiotic parameters (light, flow speed, nutrient content), or biotic parameters (diversity and structure of biofilms), because these control the bioavailability of pesticides, and thereby the exposure of microbial communities. To improve the value of ecotoxicological risk assessments, future research is needed in two key areas: first, more information on the effects of pollutants at the community level must be obtained (new tools and new end points), and second, more effort must be directed to reinforce the ecological relevance of toxicological investigations.

Modeling the chemical and toxic water status of the Scheldt basin (Belgium), using aquatic invertebrate assemblages and an advanced modeling method

Self-Organizing Maps have been used on monitoring sites in several Scheldt sub-basins to identify the main aquatic invertebrate assemblages and relate them to the physico-chemical and toxic water status. 12 physico-chemical variables and 2 estimates of toxic risk were available for a dataset made up of a total of 489 records. Two of the five defining clusters reflecting a relatively clean environment were composed by very well diversified functional feeding groups and sensitive taxa. The cleanest assemblage was mainly linked to the sites from the Nete sub-basin. The three other clusters were inversely described with a dominance of oligochaetes and deposit feeders as well as a bad water quality. Such an analysis can be used to support ecological status assessment of rivers and thus might be useful for decision-makers in the evaluation of chemical and toxic water status, as required by the EU Water Framework Directive.