Integration of physical, geochemical and biological analyses as a strategy for coastal lagoon biomonitoring.

Coastal lagoons are complex environments threatened by natural and anthropogenic stressors. Here, we tested the effectiveness of combining physical, geochemical and chemical measurements with biomarker data obtained in field-exposed marine mussels (Mytilus galloprovincialis) as a biomonitoring strategy for a highly pressured lagoon (Pialassa Baiona, Ravenna, Italy). Data showed a spatial trend of sediment contamination by Hg, Pt, Au, Ag, Mo, Re, Cd, Pd and Zn. Local conditions of high water temperature/low conductivity were detected among selected sites. After a 30-day in situ exposure, Ag and Hg were the most bioaccumulated elements (10 and 5 folds, respectively) in mussels followed by Sb, Al, Ti and Fe. Decreased survival, lysosomal dysfunctions, increased metallothionein content and peroxisome proliferation were observed in mussels in relation to metal spatial distribution and physico-chemical fluctuations. Overall, this study provides a further confirmation of the role of biomonitoring to reliably assess the environmental quality of highly pressured lagoons.

Exposure of mussels to a polluted environment: insights into the stress syndrome development.

Coastal environments are often subjected to contamination, whose biological impact is profitably evaluated through sentinel organisms and biomarkers. mRNA profiling was also proposed as a potential biomarker, whose relevance is still under discussion. Indeed, correlation between molecular and cell-organism responses need further investigations, especially under field conditions. In this study, we followed the development of physiological alterations in Mytilus galloprovincialis transplanted into a polluted coastal lagoon for 2, 4, 7, 14 and 30 days. Three consolidated biomarkers were measured, i.e. lysosomal membrane stability, lipofuscin and metallothionein contents. In parallel, the expressions of stress-related genes encoding metallothioneins (mt10 and mt20), 70-kDa heat shock proteins (MgHSC70 and MgHSP70), and Multi Xenobiotic Resistance-related transporters (MgPgp, MgMrp2, and MgMvp) were analyzed, to have a greater insight into the time-related evolution of the response. Significant (p<0.05) biomarker responses were induced after 7 days of exposure and further increased with time, whereas gene expression profiles were dramatically altered 2 days after transplanting. Biomarkers and gene expression profiles indicated a stress syndrome development in mussels, although with different temporal patterns. Their combined application provided insights into the molecular and cellular basis of mussel responses to challenging environments, and may have far-reaching implications for monitoring environmental health.

A biological and geochemical integrated approach to assess the environmental quality of a coastal lagoon (Ravenna, Italy).

The assessment of the environmental quality of coastal lagoons is rather difficult as their intrinsic high variability limits the power of analytical chemistry and ecotoxicological approaches. Aim of the present work was to integrate geochemical and biological data which were simultaneously collected from the Pialassa Baiona lagoon (Ravenna, Italy), and evaluate the usefulness of a biomonitoring strategy based on sentinel organisms and biomarkers. Geochemical analysis on suspended, surface, and subsurface sediments were performed at five different sites of the lagoon; moreover the heavy metal bioaccumulation and a battery of biomarkers was evaluated in Mytilus galloprovincialis transplanted in the same sites. Heavy metals appeared to be diffused throughout the lagoon reaching higher levels in the southernmost sites, and mainly concentrated in suspended sediments. Lysosome membrane stability, neutral lipid and lipofuscin accumulation, and metallothionein levels in mussels indicated the development of a stress syndrome in animals exposed to the polluted sites.

Bioaccumulation of cyclopenta[cd]pyrene and benzo[ghi]fluoranthene by mussels transplanted in a coastal lagoon.

The bioaccumulation of two isomeric non-alternant non-priority polycyclic aromatic hydrocarbons (PAHs), namely cyclopenta[cd]pyrene and benzo[ghi]fluoranthene, was investigated in caged mussels (Mytilus galloprovincialis) exposed for 30 days in three sites of a coastal lagoon (Pialassa Baiona, Ravenna, Italy) contaminated by pyrogenic PAHs. The concentration of cyclopenta[cd]pyrene and benzo[ghi]fluoranthene increased from undetectable levels in reference mussels withdrawn from the Adriatic sea to 10-30 ng g(-1) dry weight in transplanted mussels. Other contaminants bioaccumulated by caged mussels included pyrene, fluoranthene and mercury. Whilst the isomer concentration ratio pyrene/fluoranthene in biota was comparable to that observed in sediments, the cyclopenta[cd]pyrene/benzo[ghi]fluoranthene ratio was much lower in mussels than in sediments. The lower sediment biota accumulation factor of cyclopenta[cd]pyrene with respect to that of benzo[ghi]fluoranthene was tentatively attributed to the greater biological activity of the former compound, which contains a reactive olefinic bond in the cyclopenta fused ring moiety. Given the higher mutagenic activity of cyclopenta[cd]pyrene with respect to other priority PAHs, its bioaccumulation from contaminated sediments may rise considerably the overall toxicity of PAH residues in exposed biota.