• Paranthura japonica
P. japonica Richardson 1909 is a marine isopod currently established in the whole
Mediterranean basin (Goulletquer, 2016). Most individuals were recorded on shallow
water (3-6 m) hard bottoms, with a maximum density of 180 specimens m
-
² in Genoa,
and 760 specimens m
-
² in La Spezia; in addition, few specimens were recorded in the
soft bottom cores performed at 16-35 m depth in different localities of the centralwestern Ligurian Sea. More than 1/3 of the collected individuals were eggs-carrying
females; this fact, together with the elevated density of specimens in the harbour and the
new records along the coasts, suggest an ongoing and quick colonization of the
Mediterranean basin by this recently arrived invader.
• Branchiomma luctuosum
B. luctuosum (Grube 1870) is a tube-building polychaete entered from the Red Sea. A
maximum density of 320 individuals m
-
² was recorded in the Genoa harbour, and 280
individuals m
-
² in La Spezia at the end of the summer period. The species is therefore
extremely common in port environments, and can be found also in natural bays,
representing a successful NIS in the Ligurian basin.
• Paraleucilla magna
The calcareous sponge P. magna Klautau, Monteiro & Borojevic, 2004, native from the
Brazilian coast, is common in the lower infralittoral communities, and mainly occurs on
artificial hard substrata (floats) of port ecosystems, where the water movements are
reduced, or in mussels and oysters farms. In 2021 in Genoa harbour, this species has
been recorded on plastic panels with a maximum coverage percentage of 2,39%.
Discussion
The Ligurian Sea, thanks to its geographical, morphological and hydrographical
features, represents one of the coldest portions of the Mediterranean basin, thus it is
relatively preserved by NIS invasions; nevertheless, the increasing diversity, frequency
and spatial distribution of alien species recently observed in the Ligurian basin indicate
a rapidly progressing invasion, which ecosystemic consequence are yet to be fully
understood.
Acknowledgements
This research was financially supported by ARPAL and ISPRA.
Bibliography
GOULLETQUER P. (2016) - Guide des Organismes Exotiques Marins: Littoral Atlantique et
Littoral Méditerranéen. Belin Editeur.
2nd Mediterranean Symposium on the Non-Indigenous Species (Genoa, Italy, 22-23 September 2022)
112
P. japonica Richardson 1909 is a marine isopod currently established in the whole
Mediterranean basin (Goulletquer, 2016). Most individuals were recorded on shallow
water (3-6 m) hard bottoms, with a maximum density of 180 specimens m
-
² in Genoa,
and 760 specimens m
-
² in La Spezia; in addition, few specimens were recorded in the
soft bottom cores performed at 16-35 m depth in different localities of the centralwestern Ligurian Sea. More than 1/3 of the collected individuals were eggs-carrying
females; this fact, together with the elevated density of specimens in the harbour and the
new records along the coasts, suggest an ongoing and quick colonization of the
Mediterranean basin by this recently arrived invader.
• Branchiomma luctuosum
B. luctuosum (Grube 1870) is a tube-building polychaete entered from the Red Sea. A
maximum density of 320 individuals m
-
² was recorded in the Genoa harbour, and 280
individuals m
-
² in La Spezia at the end of the summer period. The species is therefore
extremely common in port environments, and can be found also in natural bays,
representing a successful NIS in the Ligurian basin.
• Paraleucilla magna
The calcareous sponge P. magna Klautau, Monteiro & Borojevic, 2004, native from the
Brazilian coast, is common in the lower infralittoral communities, and mainly occurs on
artificial hard substrata (floats) of port ecosystems, where the water movements are
reduced, or in mussels and oysters farms. In 2021 in Genoa harbour, this species has
been recorded on plastic panels with a maximum coverage percentage of 2,39%.
Discussion
The Ligurian Sea, thanks to its geographical, morphological and hydrographical
features, represents one of the coldest portions of the Mediterranean basin, thus it is
relatively preserved by NIS invasions; nevertheless, the increasing diversity, frequency
and spatial distribution of alien species recently observed in the Ligurian basin indicate
a rapidly progressing invasion, which ecosystemic consequence are yet to be fully
understood.
Acknowledgements
This research was financially supported by ARPAL and ISPRA.
Bibliography
GOULLETQUER P. (2016) - Guide des Organismes Exotiques Marins: Littoral Atlantique et
Littoral Méditerranéen. Belin Editeur.
2nd Mediterranean Symposium on the Non-Indigenous Species (Genoa, Italy, 22-23 September 2022)
112