Phytoplankton community to assess the environmental status of the Adriatic Sea via non-linear partial least squares regression

The pigment spectra and the size structure of phytoplankton communities are considered as informative tools to assess the water quality in the context of the Descriptor 5 (Eutrophication) of the Marine Strategy Framework Directive (2008/56/EC). In this paper we analyse the phytoplankton assemblages in three sectors of the Adriatic Sea, the northernmost part of the Mediterranean, characterized by different trophic conditions and by variables highly correlated. Our main aim is to assess the environmental status of coastal waters by analysing the dependence of the Fp-ratio (index of trophic status by pigment signatures, Claustre in Limnol Oceanogr 39(5):1206–1210, 1994), from the total biomass and the cell size structure of the phytoplankton communities (Chlorophyll a), the salinity and the temperature of the Adriatic Sea via some variants of the partial least squares regression model (Durand in Chemometr Intell Lab Syst 58:235–246, 2001; Lombardo et al. in J Chemometr 23(12):605–617, 2009). The findings of the analysis confirm the utility of the Fp-ratio as indicator of the trophic status of the coastal waters.