1993

TS-hulls

Transverse ark

It is a suspension-feeding bivalve and feeds on phytoplankton found in sandy and muddy subtidal bottoms (<25m depth), in polyhaline-euhaline salinities. Arks occasionally attach to rocks and shells with byssus threads. This bivalve has planktonic veliger larvae.

No impact on biodiversity has been reported to date.

Ecological impacts: In the Adriatic Sea, the rapid increase and numerical dominance of A. transversa is suggestive of competition. The attachment of juvenile A. transversa to snails and bivalves may restrict their movement and habitat use.

Yes

No

1986

UNA

Red Sea hardyhead silverside

It forms large schools along sandy shorelines and reef margins. Feeds on a wide variety of plankton and small benthic invertebrates.

No impact on biodiversity has been reported to date.

No impacts on health and ecosystem services have been recorded.

 Yes

 No

1992

UNA

Growing on hard substrate in low intertidal and upper subtidal, exposed to moderate and strong wave action.

No impact on biodiversity has been reported to date.

2010

UNA

Red harpoon weed

The species usually develops on infralittoral rocky bottoms around the seawater surface to around 40m of depth. Marine algae like A. armata are considered “autogenic ecosystem engineers” as they are at the very bottom of the food chain and control resource availability to other organisms in the ecosystem.

No impact on biodiversity has been reported to date.

1975

UNA, TS

Typical inhabitant of hard substrata. Suspension feeders. Lives in shallow water attached by its byssus to rocks and stones, mostly in clusters. It is a filter feeder, filtering suspended food from the water, mainly phytoplankton or suspended organic detritus.

No impacts on biodiversity have been reported.

Yes

No

2003

UNA

Red Sea hardyhead silverside

Gametangial phase usually sublittoral or occasionally low littoral. Tetrasporangial phase usually epiphytic in lower littoral and sublittoral to 8 m.

1942

UNA

Upside-down jellyfish

Lives in shallow, sandy-muddy, warm, clear waters. Reaches sizes of ≈30 cm.
Feeds on pelagic animals, and on small animals living close to the sea floor. Symbiotic microalgae provide nutrients.

Venomous and can kill fish and other marine organisms that come into contact.
Impact on other species is unknown.

Jellyfish causing a mild sting upon contact. Not highly dangerous.
Predation upon fish larvae and eggs could potentially cause impacts on fisheries.
Appealing for snorkelers/divers.

No

No (painful sting)

1993

UNA

The species has been recorded on a variety of substrates and benthic assemblages (0-70 m depth), in both polluted and unpolluted areas, and proliferated rapidly showing high adaptability to physical stressors maintaining an high eco-physiological rates between 25 °C and 29 °C. It can spread by fragmentation sexual reproduction and its spherical branchlets can also act as propagules.

Caulerpa cylindracea exerts negative effects on marine macrophytes, and can alter the behavior of native species, with putative adverse repercussions on patterns of fish growth and population dynamics.

2010

UNA

The species occurs in high abundances and dominated the benthic community, suggesting that has the potential to become a major pest in the Mediterranean. It was also observed over a very wide depth range, from the sea surface to at least 100 m depth, on a variety of natural soft and hard substrates as well as abandoned fishing nets, suggesting a broad environmental plasticity.

1947

TS

Bluecrab

Lives in a wide range of environments, but more often seen in estuaries. Capable of swimming, but also burrows in muddy-sandy bottoms. Reaches sizes of ≈20 cm. An omnivore that is active and abundant in shallow habitats. Highly cannibalistic.

High ecological impact is expected on coastal ecosystems, by competition or predation.
It is considered to affect seagrass communities, by feeding on seedlings and live plant, bioturbation and unrooting.

Very aggressive, but there are no official reports on humans being injured. The species is a commercial one. Yet, it is responsible for destruction of fishing gear and fish being caught on nets. Moreover, it preys upon other exploited species thus leading to reduced catches.

Yes

Yes (aggressive behavior)