An integrated approach to assess the environmental quality of a coastal lagoon (Orbetello, Italy)

The aim of the present study was to assess the environmental quality of Orbetello Lagoon (Tyrrhenian Sea) by an integrated approach using the European eel (Anguilla anguilla) as bioindicator organism. In order to update the ecological status of Orbetello lagoon, spatial and temporal variability of chlorophyll a, temperature, pH and salinity were also studied by remote sensing (Landsat 7 TM data). Phase I and II liver detoxification enzymes were measured and persistent organic pollutants (POPs) (PCBs, DDT and its isomers, HCB, HCHs, PCDD/Fs and PBDEs) were determined in muscle by GC/MS. Principal components analysis (PCA) was used to detect relationships or correlations between POP levels and enzyme activities. To assess the potential risk of these compounds to the reproductive system of the European eel, gonads were studied by light microscopy. Phase I (EROD and MROD) and II (UDPGT and GST) enzyme activities turned out to be particularly low and similar to those of eels from relatively unpolluted sites. Muscle concentrations in the ng/g d.w. range were found except for coplanar PCBs, PCDD/Fs and PBDEs which were in the pg/g d.w. range. Toxic equivalents (TEQs) calculated for mono-, non-ortho PCBs and PCDD/Fs were below risk thresholds established by the European Union. PCA showed a potential role of DDT, especially pp'-DDE, in inducing EROD, MROD and UDPGT activities, suggesting persistence of moderate concentrations of these contaminants in the lagoon. All specimens analysed were females; gonads in advanced stages of development had normal morphology, whereas oocytes in early stages of development showed histological alterations.