The Collective Article "New

PERSEUS project aims to identify the most relevant pressures exerted on the ecosystems of the Southern European Seas (SES), highlighting knowledge and data gaps that endanger the achievement of SES Good Environmental Status (GES) as mandated by the Marine Strategy Framework Directive (MSFD). A complementary approach has been adopted, by a meta-analysis of existing literature on pressure/impact/knowledge gaps summarized in tables related to the MSFD descriptors, discriminating open waters from coastal areas. A comparative assessment of the Initial Assessments (IAs) for five SES countries has been also independently performed. The comparison between meta-analysis results and IAs shows similarities for coastal areas only. Major knowledge gaps have been detected for the biodiversity, marine food web, marine litter and underwater noise descriptors. The meta-analysis also allowed the identification of additional research themes targeting research topics that are requested to the achievement of GES.

The Collective Article ‘New Mediterranean Biodiversity Records’ of the Mediterranean Marine Science journal offers the means to publish biodiversity records in the Mediterranean Sea. The current article is divided in two parts, for records of native and alien species respectively. The new records of native species include: the neon flying squid Ommastrephes bartramii in Capri Island, Thyrrenian Sea; the bigeye thresher shark Alopias superciliosus in the Adriatic Sea; a juvenile basking shark Cetorhinus maximus caught off Piran (northern Adriatic); the deep-sea Messina rockfish Scorpaenodes arenai in the National Marine Park of Zakynthos (East Ionian Sea, Greece); and the oceanic puffer Lagocephalus lagocephalus in the Adriatic Sea.The new records of alien species include: the red algae Antithamnionella elegans and Palisada maris-rubri, found for the first time in Israel and Greece respectively; the green alga Codium parvulum reported from Turkey (Aegean Sea); the first record of the alien sea urchin Diadema setosum in Greece; the nudibranch Goniobranchus annulatus reported from South-Eastern Aegean Sea (Greece); the opisthobranch Melibe viridis found in Lebanon; the new records of the blue spotted cornetfish Fistularia commersonii in the Alicante coast (Eastern Spain); the alien fish Siganus luridus and Siganus rivulatus in Lipsi Island, Dodecanese (Greece); the first record of Stephanolepis diaspros from the Egadi Islands Marine Protected Area (western Sicily); a northward expansion of the alien pufferfish Torquigener flavimaculosus along the southeastern Aegean coasts of Turkey; and data on the occurrence of the Lessepsian immigrants Alepes djedaba, Lagocephalus sceleratus and Fistularia commersonii in Zakynthos Island (SE Ionian Sea, Greece).

Fish catch composition in 21 gill net samplings performed between 2014 and 2015 at Rhodes Island (Aegean Sea, Greece) was analysed, with the aim to contribute in filling scattered information on coastal fish assemblages in a Mediterranean region heavily impacted by biological invasions. A total biomass of 183 kg was collected comprising 1070 fish individuals, distributed along 43 native and six Lessepsian migrant species. The alien Siganus luridus prevailed in terms of frequency of occurrence, followed by the native Sparisoma cretense, which exhibited the higher abundance and biomass, followed by S. luridus, Scorpaena scrofa and Siganus rivulatus. Ratios between alien and native species as well as between their abundance and biomass are discussed.