Elutriate preparation affects embryo development test with Paracentrotus lividus: An in-depth study on the differences between two protocols and three different sediment/water mixing times.

Coastal areas are under continuous and increasing pressure from different human activities. A mixture of contaminants (e.g. hydrocarbons, pesticides, persistent organic pollutants (POPs), emerging contaminants, and others), originating mainly from populated, industrialised and agricultural areas, can reach the marine environment through different means such as wastewater discharge, soil runoffs, leaching from agriculture, and volatilisation/deposition. In this context, marine sediments have increasingly been considered repositories for a variety of pollutants that can accumulate and be stored for long periods, acting as a secondary source of contaminants during subsequent dredging operation or vessel manoeuvring. Chemical and ecotoxicological analyses of sediments are routinely conducted to evaluate the potential hazard/risk to the environment, either on bulk sediment or elutriate. In general, sediment elutriates are commonly prepared according to ASTM Guide even if alternative protocols are proposed by USACE for the various condition that they have to represent. The goal of the present study was to determine if the toxicological properties of ASTMprepared elutriates are comparable to those obtained from the USACE protocol. Sediment coming from 3 harbours (Olbia, Cagliari, and Toulon), as part of the "Se.D.Ri.Port" Interreg Project, were processed to obtain elutriates according to ASTM Guide and USACE Dredging Elutriate protocol and tested with the sea urchin Paracentrotus lividus embryo development test. Moreover, the significance of different stirring times of water/sediment mixture (1 h, 3 h, and 24 h) was tested with both the ASTM and USACE protocol. In addition to the biological analysis, for each sediment sample, heavy metals concentration, granulometry, and organic matter were determined. Even if for the ports of Toulon and Cagliari, the ASTM and USACE elutriates showed comparable results with P. lividus bioassay, for the port of Olbia the two protocols showed different criticalities. Preliminary results show that for the site Olbia elutriates prepared with the USACE protocol resulted in higher toxicity than elutriates obtained with ASTM (p < 0.001). In conclusion, differences in preparation protocols appear to be significant and can lead to different results in biological testing. To overcome this problem and to obtain more reliable evaluations of risk to the environment, standardisation and regulation must be the next goals in sediment management procedure.

Larval development ratio test with the calanoid copepod Acartia tonsa as a new bioassay to assess marine sediment quality.

The copepod Acartia tonsa was used as a model species to assess marine sediment quality. Acute and chronic bioassays, such as larval development ratio (LDR) and different end-points were evaluated. As a pelagic species, A. tonsa is mainly exposed to water-soluble toxicants and bioassays are commonly performed in seawater. However, an interaction among A. tonsa eggs and the first larval stages with marine sediments might occur in shallow water environments. Here we tested two different LDR protocols by incubating A. tonsa eggs in elutriates and sediments coming from two areas located in Tuscany Region (Central Italy): Livorno harbour and Viareggio coast. The end-points analyzed were larval mortality (LM) and development inhibition (DI) expressed as the percentage of copepods that completed the metamorphosis from nauplius to copepodite. Aims of this study were: i) to verify the suitability of A. tonsa copepod for the bioassay with sediment and ii) to compare the sensitivity of A. tonsa exposed to different matrices, such as water and sediment. A preliminary acute test was also performed. Acute tests showed the highest toxicity of Livorno's samples (two out of three) compared to Viareggio samples, for which no effect was observed. On the contrary, LDR tests with sediments and elutriates revealed some toxic effects also for Viareggio's samples. Results were discussed with regards to the chemical characterization of the samples. Our results indicated that different end-points were affected in A. tonsa, depending on the matrices to which the copepods were exposed and on the test used. Bioassays with elutriates and sediments are suggested and LDR test could help decision-makers to identify a more appropriate management of dredging materials.

Environmental quality assessment of Grand Harbour (Valletta, Maltese Islands): a case study of a busy harbour in the Central Mediterranean Sea.

Contamination levels by plastic debris, trace elements and persistent organic pollutants were assessed and related to macrobenthic diversity within soft bottoms of Grand Harbour (Malta, Central Mediterranean). Sediment toxicity was evaluated by ecotoxicological method, deploying Bacteria (Vibrio fischeri), Echinodermata (Paracentrotus lividus) and Crustacea (Corophium orientale). Univariate analysis (Pearson's test) was used to test relationships between biodiversity indices, pollutants and grain size. A multivariate approach (PERMANOVA) was applied to investigate for any significant differences among sampling stations concerning plastic abundances and to test the relationship between infaunal abundances and pollutant concentrations (the BIOENV test). Significant differences in the plastic abundances were found between sampling stations. The lowest value for Shannon-Wiener biodiversity index was associated to the highest sediment pollution level. Multivariate analyses suggest that MBT and TBT were factors that most influenced macrozoobenthic abundance and biodiversity. The bivalve Corbula gibba and the introduced polychaete Monticellina dorsobranchialis were the most abundant found species.

Did you consider ammonium? A possible confounding factor in evaluating the toxicity of marine sediments.

Bioassays are a crucial tool for assessing environmental quality, but they face inherent variability due to unexplored confounding factors in marine ecosystems. Ammonium (NH4+) is a vital form of nitrogen in aquatic environments, but it is also a significant focus due to its toxic effects, particularly on marine invertebrates. This study examines the impact of ammonium toxicity on Paracentrotus lividus embryo-development bioassays, which are widely used to evaluate the environmental quality of dredged sediment. The aim is to establish threshold values (EC01, EC05, EC20, and EC50 values) for the correct application of the P. lividus bioassay. The research reveals that ammonium has a significant impact on larval development (EC50 for NH4+ equivalent to 0.81 mg/L). The results emphasize the ecological implications of elevated NH4+ levels in dredged material and highlight the need for precise assessments in environmental management. This study provides essential data for refining guidelines and understanding the complex interactions of this compound in marine ecosystems, ensuring accurate evaluations of environmental quality.

Contaminant accumulation and biomarker responses in caged mussels, Mytilus galloprovincialis, to evaluate bioavailability and toxicological effects of remobilized chemicals during dredging and disposal operations in harbour areas.

Remobilization of chemicals from contaminated sediments is a major risk associated with dredging and disposal operations in harbour areas. In this work caged mussels, Mytilus galloprovincialis, were chosen as bioindicator organisms to reveal the impact and recovery of organisms from these activities in the harbour of Piombino (Tuscany, Italy) where approximately 100,000 m(3) of sediments were removed and disposed in a local confined disposal facility (CDF). Organisms were deployed before, during and after the end of operations, selecting sites differently impacted by these activities. Temporal changes in environmental bioavailability and biological effects of pollutants were assessed by integrating analyses of trace metals and polycyclic aromatic hydrocarbons (PAHs) accumulated in tissues of caged mussels with a wide array of biomarkers reflecting exposure to specific classes of pollutants and different levels of cellular unbalance or toxicity. Such biological responses included levels of metallothioneins, activity of acyl CoA oxidase (AOX) as a marker of peroxisome proliferation, oxidative stress biomarkers (content of glutathione, enzymatic activities of catalase, glutathione S-transferases, glutathione reductase, glutathione peroxidases), total oxyradical scavenging capacity (TOSC) toward peroxyl and hydroxyl radicals, lysosomal membrane stability and genotoxic effects measured as DNA strand breaks and frequency of micronuclei. Obtained results indicated that a general disturbance was already present in the whole harbour area and especially in the inner site before the beginning of operations, when caged mussels exhibited a significant accumulation of PAHs and Pb, lower TOSC values and higher levels of both lysosomal and genotoxic damages. Bioavailability of trace metals and PAHs markedly increased during dredging activities with values up to 40 microg/g for Pb and up to 2200 ng/g for PAHs in tissues of caged mussels, a significant inhibition of antioxidant efficiency and increase of oxidative damages. While bioavailability of trace metals returned to the pre-dredging values after the end of operations, the accumulation of PAHs, oxidative effects and genotoxic damages remained elevated in mussels caged in the inner area and in front of CDF. Overall this study confirmed the utility of caged mussels to assess the remobilization of chemicals from dredged sediments and the onset of potentially harmful biological effects.