Assessment of ecological quality of coastal lagoons with a combination of phytobenthic and water quality indices.

Coastal lagoons are ecotones between continents and the sea. Coastal lagoons of Western Greece, subjected to different human pressures, were classified into four different types based on their hydromorphological characteristics and monitored over a three year period for their biotic and abiotic features. Six ecological indices based on water quality parameters (TSI-Chl-a, TSI-TP, TRIX), benthic macrophytes (E-MaQI, EEI-c) and an integrated index TWQI, were applied to assess the ecological status of studied lagoons under real conditions. The trophic status ranged from oligotrophic to hypertrophic according to the index applied. The ecological quality of transitional water ecosystems can be better assessed by using indices based on benthic macrophytes as changes in abundance and diversity of sensitive and tolerant species are the first evidence of incoming eutrophication. The multi-parametric index TWQI can be considered appropriate for the ecological assessment of these ecosystems due to its robustness and the simple application procedure.

A bioaccumulation model for herbicides in Ulva rigida and Tapes philippinarum in Sacca di Goro lagoon (Northern Adriatic).

A bioaccumulation model to predict concentrations of s-triazine herbicides in the macroalgae Ulva rigida and in clams Tapes philippinarum has been implemented, calibrated and validated. The model uses input data from a 3D biogeochemical model that provides biomasses in the different compartments, i.e. phytoplankton, zooplankton and bacteria; and from a 3D fate model that provides the herbicides concentrations in the water column as well as in the sediments. Simulated data were compared with experimental data collected during a set of sampling campaigns carried out in 2004 and 2005 in the Sacca di Goro lagoon (Northern Adriatic). The model predicts correctly the concentrations of herbicides measured in Ulva rigida and reproduces with good agreement the values of concentration of herbicides found in clams. Furthermore, the simulated spatial and temporal dynamics in the biota compartment, following those of the water and sediments, are also in agreement with the experimental data. This integrated approach combining biogeochemical, fate and bioaccumulation models provide an overall assessment of the importance of the different environmental compartments and it can also support the testing of different management strategies to improve ecosystem state and functioning. Further research is necessary to elucidate the role and importance of the metabolism of these compounds by clams.