A Test Battery Approach for the Ecotoxicological Evaluation of Estuarine Sediments

Radiation and Environmental Science Centre, FOCAS Institute, Dublin Institute of Technology, Ireland.
Ecotoxicology (Impact Factor: 2.71). 11/2005; 14(7):741-55. DOI: 10.1007/s10646-005-0022-8
Source: PubMed


The purpose of this study was to evaluate the overall sensitivity and applicability of a number of bioassays representing multiple trophic levels, for the preliminary ecotoxicological screening (Tier I) of estuarine sediments. Chemical analyses were conducted on sediments from all sampling sites to assist in interpreting results. As sediment is an inherently complex, heterogeneous geological matrix, the toxicity associated with different exposure routes (solid, porewater and elutriate phases) was also assessed. A stimulatory response was detected following exposure of some sediment phases to both the Microtox and algal bioassays. Of the bioassays and endpoints employed in this study, the algal test was the most responsive to both elutriates and porewaters. Salinity controls, which corresponded to the salinity of the neat porewater samples, were found to have significant effects on the growth of the algae. To our knowledge, this is the first report of the inclusion of a salinity control in algal toxicity tests, the results of which emphasise the importance of incorporating appropriate controls in experimental design. While differential responses were observed, the site characterised as the most polluted on the basis of chemical analysis was consistently ranked the most toxic with all test species and all test phases. In terms of identifying appropriate Tier I screening tests for sediments, this study demonstrated both the Microtox and algal bioassays to be more sensitive than the bacterial enzyme assays and the invertebrate lethality assay employing Artemia salina. The findings of this study highlight that salinity effects and geophysical properties need to be taken into account when interpreting the results of the bioassays.

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    • "Performing a battery of bioassays provides a wider view of the ecotoxic potential of the matrix investigated. However, it must be adapted according to the matrix considered (Davoren et al., 2005; Perrodin et al., 2011). The present study was performed in the framework of preliminary research focusing on the characterization of the toxicity of CSOs according to a matrix approach (Angerville, 2013). "
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    ABSTRACT: Combined Sewer Overflows (CSO) in small peri-urban streams and rivers are potentially toxic for their biocenosis. Improving the management of CSO discharges requires better knowledge of their dynamics and toxicity. In view to characterizing this toxicity, we sampled the different compartments (benthic and hyporheic zone) of a peri-urban stream located near the city of Lyon in France. The samples were taken at different distances from a CSO and at three period characteristic of different hydrological conditions. Their toxic effects were assessed by bioassays on the dissolved fraction (D. magna, V. fisheri and B. calyciflorus bioassays) and on the particle fraction (V. fisheri and H. incongruens bioassays). The results highlighted significant toxicity of the particulate fraction for the benthic and hyporheic samples, in particular downstream of the CSO, but with high spatio-temporal variability. This variability can first be attributed to the variability of CSO discharge sampling as a function of season and rainfall, and the dynamics of polluted particles (trapping of transported particles in infiltration zones, mobilization during floods). These parameters play a fundamental role in the distribution of pollutants according to the geomorphology of stream facies. Regarding dissolved pollutants, the chemical exchanges taking place at the “water-sediment” interface trigger the transfer of pollutants from one phase to another, after which the dispersion of these pollutants is governed by hydraulic flows. Finally, critical zones and periods are identified for the peri-urban river toxicity studied: benthic sediments under mean flow downstream; hyporheic sediments after a storm event downstream, close to the CSO. Recommendations are made on the basis of the knowledge obtained to optimize the management of these discharges.
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    • "Recently, long-term toxicity test on Artemia sp. were proposed as an alternative to Daphnia sp. for the assessment of the aquatic compartment [5] [6]. In spite of these advantages, the use of Artemia sp. is controversial for some authors, particularly to its supposed inadequate sensitivity to chemical exposure due to the intrinsic resistance to extreme salinity conditions [7] [8]. "
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    ABSTRACT: The study aimed to assess the short-term effects exerted by two inorganic arsenic species (arsenite and arsenate) on Artemia salina after 24, 48 and 72 h. The dose-lethality curves obtained indicate that the lethality induced by arsenite was higher than by arsenate. The lowest observed effect concentration for arsenite (0.5 μg÷mL) is similar with the no observed effect concentration for arsenate, thus indicating that the toxicity of arsenite is higher compared with arsenate. Also, the lethal concentration 50 values confirm that arsenite induced about 1.24-fold higher toxicity than arsenate at 24 h and about three-fold higher toxicity at 48 h and 72 h of exposure. Both LC50 (lethal concentration 50) values are indicating negligible effects exhibited by arsenic at this trophic level after short-term exposure. The predicted no effect concentration in the surface aquatic compartment corresponds to 10.38 μg÷L, similar to the limit imposed by Directive 98÷83÷EC.
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    • "Many authors have shown that bioassays provide a general indication of metal bioavailability/toxicity in sediments (Latif and Licek 2004; Harikumar and Nasir 2010; Baran and Tarnawski 2013; Besser et al. 2014). Bioassays are a useful tool whose application enables a fuller classification of ecological risk resulting from the presence of chemical substances in sediments, their bioavailability, and interactions (Mankiewicz-Boczek et al. 2008; Nendza 2002; Davoren et al. 2005; Narracci et al. 2009; Buitrago et al. 2013). Many authors emphasize that bioassays are a good complement to chemical analyses in procedures of sediment quality assessment (Wadhia and Thompson 2007; Mamindy-Pajany et al. 2011). "
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    ABSTRACT: The aim of this study was to assess heavy metals mobility and toxicity in sediments collected from a dam reservoir in the conditions of intensive human impact by using chemical fractionation and a battery of bioassays. In the studies, the test organisms were exposed to substances dissolved in water (Microtox, Phytotestkit) as well to substances absorbed on the surface of solid particles (Phytotoxkit, Ostracodtoxkit F). The studies showed that sediments from the Rybnik reservoir are toxic, but the tested organisms showed different sensitivity to heavy metals occurring in the bottom sediments. The sediment samples were classified as toxic and very toxic. Moreover, the studies showed a higher toxicity in solid phases and whole sediment than in pore water. The lowest sensitivity was observed in H. incongruens (solid phases) and V. fischeri (pore water, whole sediment). The studies revealed that the toxicity of the sediments is caused mainly by heavy metal forms associated with the solid phase of the sediments. The studies did not confirm the metals occurring in fraction I (exchangeable) to be bioavailable and toxic to living organisms because most correlations between the metal concentration in fraction I and the response of the organisms were negative. The highest mobility from the bottom sediments was found in zinc, average mobility-in copper, cadmium and nickel, and low mobility-in chromium and lead. Organic matter is likely to be the most important factor controlling metal distribution and mobility in the studied sediments.
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