Alla Khosrovyan

Comparative performances of eggs and embryos of sea urchin (Paracentrotus lividus) in toxicity bioassays used for assessment of marine sediment quality.

The potential toxicity of sediments from various ports was assessed by means of two different liquid-phase toxicity bioassays (acute and chronic) with embryos and eggs of sea urchin Paracentrotus lividus. Performances of embryos and eggs of P. lividus in these bioassays were compared for their interchangeable applicability in integrated sediment quality assessment. The obtained endpoints (percentages of normally developed plutei and fertilized eggs) were linked to physical and chemical properties of sediments and demonstrated dependence on sediment contamination. The endpoints in the two bioassays were strongly correlated and generally exhibited similar tendency throughout the samples. Therein, embryos demonstrated higher sensitivity to elutriate exposure, compared to eggs. It was concluded that these tests could be used interchangeably for testing toxicity of marine sediments. Preferential use of any of the bioassays can be determined by the discriminatory capacity of the test or vulnerability consideration of the test subject to the surrounding conditions.

Several benthic species can be used interchangeably in integrated sediment quality assessment

The selection of the best management option for contaminated sediments requires the biological assessment of sediment quality using bioindicator organisms. There have been comparisons of the performance of different test species when exposed to naturally occurring sediments. However, more research is needed to determine their suitability to be used interchangeably. The sensitivity of two amphipod species (Ampelisca brevicornis and Corophium volutator) to sediments collected from four different commercial ports in Spain was tested. For comparison the lugworm, Arenicola marina, which is typically used for bioaccumulation testing, was also tested. Chemical analyses of the sediments were also conducted. All species responded consistently to the chemical exposure tests, although the amphipods, as expected, were more sensitive than the lugworm. It was found that C. volutator showed higher vulnerability than A.brevicornis. It was concluded that the three species can be used interchangeably in the battery of tests for integrated sediment quality assessment.

Comparative analysis of two weight-of-evidence methodologies for integrated sediment quality assessment

The results of sediment quality assessment by two different weight-of-evidence methodologies were compared. Both methodologies used the same dataset but as criteria and procedures were different, the results emphasized different aspects of sediment contamination. One of the methodologies integrated the data by means of a multivariate analysis and suggested bioavailability of contaminants and their spatial distribution. The other methodology, used in the dredged material management framework recently proposed in Spain, evaluated sediment toxicity in general by assigning categories. Despite the differences in the interpretation and presentation of results, the methodologies evaluated sediment risk similarly, taking into account chemical concentrations and toxicological effects. Comparison of the results of different approaches is important to define their limitations and thereby avoid implications of potential environmental impacts from different management options, as in the case of dredged material risk assessment. Consistent results of these two methodologies emphasized validity and robustness of the integrated, weight-of-evidence, approach to sediment quality assessment. Limitations of the methodologies were discussed.

Effects of simulated CO2 escape from sediments on the development of midge Chironomus riparius

The acidification of freshwater caused by potential CO2 gas seepage from sediment layers has not previously been studied, although freshwater is likely to be affected by the accidental escape of this gas from onshore storage facilities. In this study, two riparian sediments with different contamination levels were subjected to acidification via direct injection of CO2 gas, simulating the potential leak of CO2. Tests with the midge Chironomus riparius larvae were used to assess metal fluxes and vulnerability of benthic invertebrates to the effects of acidification. The midges were grown in whole sediments over 28d after which midge emergence and ability to reproduce were tested. The results revealed that acidification is an important factor controlling the development of the midges. Although larval development and emergence were affected by neither acidity (pH 7.5 and 7.0) nor contamination levels, none of the eggs, laid during the exposure, hatched. In less contaminated sediment, Chironomus larvae succumbed to the impact of pH 6.5 and 6.0, showing suppressed growth and metamorphosis and consequently, no emergence. In highly contaminated sediment, pH 6.5 level retarded larval growth and inhibited emergence, while pH 6.0 caused mortality. The latter could also be attributed to metal mobilization effects facilitated by an increase in the ambient acidity. Experimentation on clean sediments at pH 6.5 and 6.0 also showed absence of emergence during the experimental period. These results suggest that acidity factor could seriously diminish the vitality of midge larvae and ability of midge to produce offspring, challenging the commonly known tolerance of midges to high acidity (up to pH 3.5). Whilst larval midges can survive acidity and/or metal exposure, stimulated by creeping CO2 gas, and even emerge as adults, physiological impairments may take place which may seriously threaten the resilience of C. riparius population and subsequently lead to the decline of the population size and disruption of their function in ecosystems. Suggestions on using more sensitive endpoints than emergence when testing acidification effects are made.

Software, Data and Modelling News: SQA: a software tool for integrated sediment quality evaluation based on the Weight-Of-Evidence procedure

A new software tool for integrative sediment quality assessment is developed. The program is based on WOE methodologies which together may be used for assessing degree of contamination in marine sediment. Statistical analysis of field-collected and lab-based data is performed by means of commercial statistical software package Statistica 6.0. The designed tool provides user-friendly interface, is extremely easy in use, greatly simplifies statistical analysis process, interprets the results in text and graphical format.

Dredged material characterization and management frameworks: A case study at the port Vilagarcia (NW, Spain).

The potential impact of dredged sediment has been assessed at sixteen areas of the high-traffic port of Vilagarcia (Northwest Spanish Atlantic coast). The assessment has been done by three weight-of-evidence tools, which integrated data on sediment characteristics and toxicity responses of Ampelisca brevicornis, Vibrio fischeri and eggs and embryos of Paracentrotus lividus. Two of the tools also represented management options regarding the disposal of dredged material. The comparison of the logic in these tools revealed essential differences in the type and the necessity of bioassays and threshold values for chemical concentrations. However, despite this difference, assessment results and the derived management options coincided in most of the sediments. The potential toxicity of sediments was relatively low especially for eggs and embryos possibly due to different contaminant availability in solid and liquid phases. The importance of a battery of toxicity tests in the dredged material quality assessment has been emphasized to avoid an underestimation of sediment toxicity for solid phase organisms, if only liquid phase responses are considered. The potential false implications, which may result from the application of the third tool, were highlighted. The strengths and weaknesses of the tools were discussed from the dredged material management perspective.

The influence of ph and waterborne metals on egg fertilization of the blue mussel (Mytilus edulis), the oyster (Crassostrea gigas) and the sea urchin (Paracentrotus lividus)

This study evaluated the combined effect of pH and metals on the egg fertilization process of two estuarine species, the blue mussel (Mytilus edulis), the oyster (Crassostrea gigas) and a marine species, the sea urchin (Paracentrotus lividus). The success of egg fertilization was examined after exposure of gametes to sediment extracts of various degrees of contamination at pH 6.0, 6.5, 7.0, 7.5 and 8.0. At the pH levels from 6.5 to 8.0, the egg fertilization of the different species demonstrated different sensitivity to metal and/or acidic exposure. In all species, the results revealed that egg fertilization was almost completely inhibited at pH 6.0. The egg fertilization of the blue mussel M. edulis was the least sensitive to the exposure while that of the sea urchin P. lividus demonstrated a concentration-dependent response to the pH levels from 6.5 to 8.0. The results of this study revealed that acidity increased the concentration of several metal ions (Cr, Ni, Cu, Zn, Cd, and Pb) but reduced its availability to the organisms, probably related to the reactivity of the ions with most non-metals or to the competition among metals and other waterborne constituents.

Clastogenecity evaluation of water of Lake Sevan (Armenia) using Tradescantia micronucleus assay

The clastogenic effects of water samples in seven locations of Lake Sevan (Armenia) with the application of Trad-MCN (micronuclei) bioassay using Tradescantia (clone 02) were investigated. A significant increase in the frequency of micronuclei in tetrads of pollen microspores and tetrads with micronuclei exposed to the test samples compared to the control has been revealed. A multivariate analysis indicated linkage between the frequencies of occurrence of micronuclei in the cells and Ni and Co ions. The results were compared with the endpoints of another Tradescantia-based test system (stamen hair mutation test) performed on the same water samples and generation of the plant: occurrences of micronuclei in sporogenic cells coincided with that of non-surviving stamen hair.

Effects of a hypothetical escape of CO 2 gas from subterranean storage sites on water flea Daphnia magna

The impacts of a hypothetical CO2 gas leak from freshwater sediments on the survival and reproduction of freshwater flea Daphnia magna were analyzed. Another objective was to assess the performance of standard toxicity testing protocols for CO2-induced acidification research in freshwaters. Four pH levels (7.5, 7.0, 6.5, and 6.0) and two sediments with different contamination level were tested. The results revealed that the D. magna are susceptible to a gradual but relatively rapid CO2 enrichment of the water column causing a change from circumneutral to acidic conditions. Standard 48-h immobilization test with D. magna tended to underestimate the toxicity at CO2-induced acidity condition. Dissolved aluminum may be implicated in the toxicity to the parental daphnids exposed. Metal outflux from sediments and behavior in elutriate have been discussed.