No abstract

The intense shipping traffic characterising the Adriatic Sea favours the spread of marine organisms. Yet, a study of 12 Adriatic ports (4 on the western side and 8 on the eastern side of the basin) found that non-indigenous species (NIS) accounted for only 4% of the benthic communities settled on hard substrates. The cirripeds Amphibalanus amphitrite and Balanus trigonus, found in 8 harbours, were the most common invaders followed by Amphibalanus eburneus, the ascidian Styela plicata, and the bivalve Magallana gigas. The highest percentage of NIS was recorded in Venice and Ploče, the harbours with the least rich native communities; the lowest percentage was retrieved in Trieste, Koper, Pula, and Rijeka, the harbours hosting the highest species diversity. In contrast, the ports of Bari and Ancona showed both high NIS percentages and highly diversified communities.

Morphological analysis, molecular characterization, and information on distribution and density of Anadara kagoshimensis (Tokunaga, 1906) specimens collected in the Adriatic Sea were here carried out as based on various material and data from five surveys conducted from 2010 to 2014, for a total of 329 bottom trawl hauls. The morphological and molecular analyses allowed to clarify the confused taxonomy regarding the biggest ark clam alien species invading the Italian waters and the Mediterranean Sea. The analysis on distribution and density revealed that A. kagoshimensis mostly occurs along the Italian coast at depths from 8 to 50 m, with a catch frequency of more than 98% in all hauls performed on silty-clay sediment at  8-30 m depth. The hotspot map clearly shows a reduction of its distribution area from 2010 to 2012.

Non-indigenous species (NIS) in the Mediterranean Sea. It presents a report on the softbottom macrobenthos from the five Adriatic ports: Bari, Ancona (Italy), Koper (Slovenia), Pula, Rijeka (Croatia), with a focus on the presence and contribution of NIS to native assemblages. Out of 451 species identified, only four were common to all ports. A total of eight NIS were recorded, five in surveyed ports and three in the lagoon connected to the Port of Koper. The highest number of NIS was recorded in Bari, and the highest abundance in Ancona and Bari. Generally, the number, abundance and contribution of NIS seems too low to cause a substantial impact on native communities in surveyed ports. The suitability of methods adopted for PBS for soft-bottom NIS was discussed and suggestion for methodological improvement is provided.