Page 24 - Invasive_Species_2013

Origin and dispersal of marine

invasives

The most important factor that may have contributed to 304 m² in 1869, 1,800 m² in 1962 and 3,600 m² in 1980, is
the disparity in the richness and identity of recorded alien at present 5,200 m².
species in different parts of the Mediterranean basin is
human-associated transport mechanisms. Vectors and The Suez Canal Authority is currently evaluating a new
pathways, the magnitude of transfer and the geographic proposal for increasing the canal’s depth or doubling
sources of the species clearly differ from one region to its width to attract loaded very-large crude carriers
another, affecting both the species pool and the number (VLCCs) and ultra-large crude carriers (ULCCs)
of propagules delivered. This variation is perhaps most (www.suezcanal.gov.eg). A deeper, wider canal will
pronounced between the eastern and the western basins enlarge the saltwater passage to the Mediterranean and
of the Mediterranean. The majority of alien species consequently enable the migration of more Red Sea
recorded in the Levant entered through the Suez Canal, species. With the continuous removal of high salinity
whereas mariculture and shipping have been more barriers and the canal’s expansion over the years, the influx
important means of alien species introduction in the of these aliens has not abated; quite the opposite, since
north-western Mediterranean and the Adriatic Sea. they have recently been recorded spreading to even
deeper waters in the Mediterranean, increasing the spatial
Suez Canal extent of invasion not only to coastal ecosystems but also
to adjacent environments.
The Suez Canal has supplied the largest number of
successfully established aliens in the Mediterranean Sea Shipping
in terms of magnitude, frequency and duration of transfer.
For decades, the ongoing migration of marine species Ships can transport alien species in ballast water, as hull
through the Suez Canal has helped to explain the richness fouling or as solid ballast (i.e. with sand, rocks, soil, etc.).
of Red Sea alien species in the eastern Mediterranean Hull fouling on ships was recognized as a vector for alien
Sea, particularly in the Levant area (from Libya and Egypt introductions when non-native serpulid polychaetes were
in the south to Israel, Lebanon and Syria in the east). found for the first time in the Mediterranean. It is likely that
some, perhaps many, other early introductions have been
Since its opening in 1869, the canal has undergone several overlooked.
major enlargements over the years. Its most recent
expansion, completed in January 2010, increased its Shipping has been implicated in the dispersal of numerous
depth to allow the passage of vessels with drafts of up to neritic organisms, from micro-organisms and macrophytes
66 ft. The canal’s typical cross-sectional area, which was to fish. Ballast is usually taken into dedicated ballast tanks

Fig. 12. Map of maritime transportation routes in the Mediterranean. Sources: REMPEC; Beilstein, M., Bournay, E., Environment and
Security in the Mediterranean: Desertification, ENVSEC, 2009. By R. Pravettoni - GRID-Arendal

Monitoring Marine Invasive Species in Mediterranean MPAs: A strategy and practical guide for managers 21