Recent monitoring data of Posidonia oceanica meadows distributed along the Apulian coasts (Eastern-Central Mediterranean Sea) according to the 2000/60 EC Directive

According to the Water Framework Directive (WFD), a specific monitoring of Posidonia oceanica meadows was carried out along the Apulian coasts by the Regional Agency for the Environmental Prevention and Protection (ARPA Puglia). A total of 17 sites, 11 in the Southern Adriatic Sea and 6 in the Northern Ionian Sea were investigated during two consecutive monitoring cycles (2009-2011 and 2012-2014). Sampling procedures as well as laboratory analyses (phenology and lepidochronology) were carried out according to a common methodological protocol shared at Italian national level (D.M. 260/2010) for the final ecological classification (sensu WFD) using the PREI index. In each meadow, two sampling stations were investigated by scuba divers at the fixed depth of 15 m and in correspondence of the lower bathymetric distribution limit. For each station, 9 shoots counting (40x40 cm square) and 3 covering estimates (around 5 m of radius) were carried out. In addition, 18 orthotropic shoots and a sediment sample were collected as well as some other bio-ecological data (meadow continuity, dead matte presence, bottom type, invasive algae presence, flowering, disturbance sources, lower limit type and depth). The results showed that 29% of sites were classified as “GOOD”, 59% were classified as ”MODERATE” while the remaining 12% as “POOR”, with a general slight improvement of the classification in the last monitoring cycle (2012-2014). Although the ecological quality status of the Apulian Posidonia oceanica meadows (summarized by the PREI index values) reflects the distribution of anthropic pressures on the coast (harbours, industrial and urbanized areas, river’s outlets) along a latitudinal gradient, the classification based on the rules (reference conditions and EQR boundaries for the PREI index) reported in the Italian law (D.M. 260/2010) seems to underestimate the real ecological status. Consequently, a revision of both the actual reference conditions and EQR boundaries is suggested for the BQE Posidonia oceanica in the Apulian marine waters, in order to taking account of the environmental features of two different marine basins as the south-western Adriatic Sea and the north-western Ionian Sea.