Quality assessment of transitional waters using a benthic biotic index: the case study of the Pialassa Baiona (northern Adriatic Sea)

1. Conservation and management of transitional waters require monitoring activities that integrate traditional chemical and physical evaluations with biological assessment. 2. Macrobenthic biotic indices have been proposed as an ecologically based cost-effective tool for the environmental quality assessment. 3. In the present paper, different approaches applicable to the biological assessment of transitional water were discussed. 4. Biotic Coefficient (a biotic index developed for European estuaries) and different metrics, multivariate ordination plots and chemico-physical measures have been applied to the environmental quality assessment of a North Adriatic coastal lagoon. 5. Results of the Biotic Coefficient were positively correlated with values of evenness index (Hill's N10) and with the abundance of the opportunistic polychaete Capitella capitata, while they were negatively correlated with the abundance of the isopod Hidotea balthica. 6. Results of the biotic indices depend on knowledge of the sensitivity of the species and on the assumptions made. Therefore, their development and validation requires a better understanding of population distribution and of assemblage dynamics in response to different natural or anthropogenic disturbances.