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. The long-term monitoring station (LTER-MC, 40°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 MC data set represents one of the few plankton time series available in the Mediterranean Sea, and it is certainly one of the longest.

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.

Researches on marine benthic organisms around the Flegrean islands in the Gulf of Naples have been traditionally performed at the Stazione Zoologica since its foundation in 1872. The peculiarity of this area is strictly related to its geographic location, corrisponding to the winter surface isotherm of 14°C that cuts the Mediterranean Sea into two and represents a climatic boundary barrier for species with different biogeographic affinities. The richness in marine species and habitats of this area (including the islands of Ischia, Procida and Vivara) is preserved by the establishment in 2008 of the Marine Protected Area ‘Regno di Nettuno’. One of the most important habitat of the Gulf of Naples is represented by the Posidonia oceanica beds, an endemic seagrass that forms around the island of Ischia a continuous belt, from 0.5 m down to 38 m in depth, covering about 1700ha of the seafloor. Several meadows have been studied by the Benthic Group, located at Villa Dohrn on the Island of Ischia: Scarrupata di Barano, Cava dell’Isola, La Nave, San Pietro, Castello Aragonese and Lacco Ameno. The best-known meadow is that of Lacco Ameno (LA), studied since 1976, and located in the northern part of the island, in the bay bounded by ‘Monte Vico’ and the city of Lacco Ameno (40,7598 N, 13,900 E). Only in this station, the meadow is continuous from 0.5 m down to 32 m in depth and it covers an area of about 308 ha. In this pilot site (Station LTER-LA), a significant variability at different spatial and temporal scales has been recorded for plant descriptors and associated communities. In particular, at 5 and 10 m depths, a decrease in meadow density (a descriptor of the ecological status of a meadow, widely used by many authors to indicate the plant abundance) is evident since the end of 1980. This fact seems to suggest an increase in the anthropic pressure, even if other factors, such as physical disturbance, topographic complexity and nutrient availability, might operate to modify this system. The high plasticity of P. oceanica, which responds to a wide range of environmental conditions, have driven our researches towards the study of the effects of climatic changes, such as ocean acidifcation, on this vegetated system. Issues associated to climate changes are being approached also by the comparison with another Ischia P.oceanica meadow. This is located at Castello Aragonese (40,73083°N 13,96310°E), on the east side of the island, where a number of vents which release CO2 affect the P. oceanica system. These CO2 vents are unusual in that they are not heated and neither do they produce toxic compounds, providing a natural laboratory for the study of the ecosystem level effects of ocean acidification.