Statistical calibration of the Carlit indexin the Pontine Island of Zannone

The Water Framework Directive (WFD) 2000 ⁄ 60 ⁄ EC, adopted by the European Community in 2000 requires that member states achieve and maintain a good ecological status of all water bodies by 2015. In the marine context, the ecological status has to be quantified applying indexes based on appropriate key biological elements, which allow the categorization of water bodies into five Ecological Status (ES) classes. The CARLIT index is a cartographic monitoring tool enabling the Ecological Quality Ratio (EQR) to be calculated using macroalgae in coastal hard bottoms as a key biological element; at present it is being applied in Spain, France and Italy. In this work we investigate the role of a key macroalgae (Cystoseira amentacea) involved in the index definition. We analyze the relation between the algae presence and geomorphological information in the area of Pontine Islands trough standard logistic regression and autologistc models to account for spatial correlation. Results are compared in terms of goodness of fit and predictive capability. Our work is developed in areas where the water quality is known (chemical analyzes available) to be excellent, however the associated Carlit value does not classify them as such.