The Gulf of Naples has an extension of ca 870 kmq and an average depth of 170 m. The coastal area, which is inhabited since pre-Roman age, is densely populated and small factories are actively growing. In the Gulf, polluted areas (Sarno river mouth, harbours) coexist with pristine areas, including some Protected Marine Areas. Research on marine organisms has started before since the beginning of 1800, but first ecological studies date back to the 70ies of the last century. A long-term monitoring station (LTER-MC, 49°49’N, 14°15’E) is located 2 nm off Naples city (depth ca 75 m) at the boundary between eutrophied coastal waters and oligotrophic Tyrrhenian waters. Larger areas of the Gulf have been sampled occasionally in several cruises. The main research at these sites addresses plankton variability in response to environmental forcing. Plankton samples are collected along with environmental data at a weekly scale, and species identification is performed with traditional methods coupled with Electron microscopy and molecular tools. Phytoplankton species are often grown in the lab for experimental work or taxonomic analyses, which have led to the discovery of about 15 new microalgal species. Special investigations have addressed, among other topics, the role of viruses in the demise of algal blooms, the rate of dinoflagellate cyst production over the seasons, the rhythm of sexual reproduction in diatoms and grazing of meso- and microzooplankton. The MC data set represents one of the few plankton time series available in the Mediterranean Sea, and it is certainly one of the longest. Extensive seagrass meadows are located around the flegrean islands: the endemic Posidonia oceanica (L.) Delile infact can grow both on rock and sand substrates. In this area, in the last decades a reduction in shoot density has been detected, as a result of anchoring, the impact of the local fishery and water quality. Around the island of Ischia (within a Marine Protected Area), Posidonia oceanica forms a continuous belt (0.5-38 m depth), covering about 17 km2 of the seafloor. The best known meadow (Station LTER-LA), studied since 1979, is located in the northern part of the island (40°41,582 N, 13°53,361 E). Only in this station, the meadow is continuous from 0.5 m down to 32 m depth, covering an area of about 3 kmq. Other meadows have also been monitored. In recent years at the station Castello Aragonese (40°43,51 N, 13°57,55 E), where natural CO2 emissions allow for the study of ecosystem responses to ocean acidification, is under monitoring.The main research lines are focused on the responses of marine plants and associated communities to environmental variability and changes. Plant-animal interactions, spanning from biodiversity and distribution patterns in space and time to phylogenetic and phylogeographic traits, from trophic-chemical relationships to life-history features and molecular phylogeography and speciation are also investigated.
