Alien & Invasive Species in the Aegean
Overview
The environmental impacts of invasive species has raised global concern as their presence has the potential to cause devastation to biodiversity and benthic community structure. These species are threatening due to their ability to outcompete native species for food and niche. This often results in the impeding faunal and floral species eventually replacing local individuals.
It is vital that we track the spread of these invasive species, in order to preserve community structures endemic to the Mediterranean. Invasive species have become such a threat that more than 5% of the marine species in the Mediterranean are now considered non-native species. This amounts to over 986 alien species, of which 775 were found specifically in the eastern Mediterranean.
Partners
FISH
- Abudefduf vaigiensis
- Alepes djedaba
- Apogonichthyoides pharaonis
- Atherinomorus forskalii
- Callionymus filamentosus
- Enchelycore anatina
- Fistularia commersonii
- Hemiramphus far
- Lagocephalus sceleratus
- Parupeneus forsskali
- Pempheris rhomboidea
- Planiliza haematocheilus
- Plotosus lineatus
- Pterois miles
- Sargocentron rubrum
- Saurida lessepsianus
- Scarus ghobban
- Scomberomorus commerson
- Siganus luridus
- Siganus rivulatus
- Sphyraena chrystotaenia
- Stephanolepis diaspros
- Torquigener flavimaculosus
- Upeneus pori
Common Name
Indo-Pacific sergeant
Scientific Name
Abudefduf vaigiensis
Description
Small compressed oval body covered in small, fine scales. Vibrant coloration of yellow to pale-blue/green with 5 vertical stripes down their sides.
Habitat
Shallow water (<20m), associated with a variety of substrate.
diet
Zooplankton, benthic algae and invertebrates
Size
5-15cm
Status according to ELNAIS
Alien – Casual
Pathway of Origin
Unaided
Origin
Lessepsian migrant, native to the Indo-Pacific, potentially via shipping activity
first sighting in greek waters
Disputed because of confusion with similar species, potentially 2018
edible?
No
Impacts
Shows some evidence of hybridisation with native species, diminishing the strength of native gene pools.
further information
The males remain at spawning sites to guard and aerate the eggs
Common Name
Shrimp scad
Scientific Name
Alepes djedaba
Description
Sleek body adapted for open water swimming. Bright, golden yellow/green body with many bold vertical bands down their sides as juvenilles, which may fade during adulthood. Their fins display a pale yellow coloration.
Habitat
Shallow inshore reefs and sandy substrates
diet
Invertebrates such as shrimps and crustacean larvae, and sometimes small fish
Size
25cm
Status according to ELNAIS
Alien – Established
Pathway of Origin
Unaided
Origin
Lessepsian migrant, native to the Red Sea
first sighting in greek waters
Zakynthos, 1960
edible?
Yes
Impacts
They school with T.mediterraneus, and share the same dietary niches
further information
Possibly overexploited in its native areas, e.g., India, for human consumption
Common Name
Pharaoh cardinalfish
Scientific Name
Apogonichthyoides pharaonis
Description
The Pharaoh cardinalfish has a streamlined body with striking red and orange colouration dorsally and a palewhite or yellow underside. A thin, black stripe runs vertically through their eye, with a wider black line extending from their grill cover over the lateral line to the caudal fin.
Habitat
Worldwide distribution with a preference for rocky substrates and shallow waters
diet
Nocturnal planktivorous predator
Size
4-6cm
Status according to ELNAIS
Alien – Established
Pathway of Origin
Unaided
Origin
Lessepsian migrant, native to the Red Sea
first sighting in greek waters
Rhodes, 2002
edible?
No
Impacts
Outcompete Apogon imberbis
further information
Mouth-brooder
Common Name
Red Sea hardyhead silverside
Scientific Name
Atherinomorus forskalii
Description
These fish are characterized by a bright, iridescent silvery-blue body with several prominent yellow to golden horizontal stripes running along their streamlined body. The dorsal fin is located closer to the tail end of the body and is typically marked with a series of small spots.
Habitat
Tropical, often associated with reefs and other sheltered habitats
diet
Opportunistic feeder, prey includes zooplankton and benthic invertbrates
Size
10-12cm
Status according to ELNAIS
Alien – Established
Pathway of Origin
Unaided
Origin
Lessepsian migrant
first sighting in greek waters
Kos, 1986
edible?
Yes
Impacts
Diet overlap with Atherina boyeri and Belone belone
further information
Can form schools of thousands
Common Name
Blotchfin dragonet
Scientific Name
Callionymus filamentosus
Description
The blotchfin dragonet is a light brown fish that has darker brown spots. Males have a dorsal spine before the first dorsal fin. For both sexes, the second dorsal fin is noticably longer than the first.
Habitat
Sandy and muddy substrate in coastal areas to around 100m, although they have been recorded at depths as great as 350m
diet
Feeds on small benthic invertebrates, mainly crustaceans and marine worms.
Size
Up to 20cm
Status according to ELNAIS
Alien – Established
Pathway of Origin
Unaided
Origin
Lessepsian migrant, native to the Indo-West Pacific
first sighting in greek waters
Ionian sea, 2003
edible?
No
Impacts
As their population size has increased rapidly closely related species have seen massive population declines.
further information
Callionymus filamentosus are victims of a castrating parasite, Obruspora papernae that is found in most of the Mediterranean population. Despite this, they remain one of the most abundant fish species represented in shallow trawler fishery landings on the Israeli Mediterranean coast.
Common Name
Fangtooth moray
Scientific Name
Enchelycore anatina
Description
These morays have large teeth resembling fangs, and are typically dark brown or black with white or yellow spots. They have an elongated body and an absence of pectoral and pelvic fins, as well as a lack of scales.
Habitat
Rocky reef crevices, concealing itself for elusive predation, juveniles can also be found at great depths
diet
Hunts fish and cephalopods
Size
120cm
Status according to ELNAIS
Unknown
Pathway of Origin
Unknown
Origin
Migrated through the Strait of Gibraltar from the eastern-central Atlantic
first sighting in greek waters
Elafonissos Island, 2002
edible?
No
Impacts
Muraena helena occupy the same niche.
further information
These are solitary animals
Common Name
Bluespotted cornetfish
Scientific Name
Fistularia commersonii
Description
The bluespotted cornetfish with very elongated and highly compressed body structure, often confused with drifting seagrass in the deep waters. Body color typically greenish-grey with a whiter underside, it features subtle blue stripes or dots.
Habitat
Occurs at depths between 0-132m on shallow coral and rocky reefs and sandy bottoms as well as Posidonia and Cymodocea meadows
diet
Feeds predominently on other fish, as well as shrimp and isopods.
Size
160cm
Status according to ELNAIS
Alien – Invasive
Pathway of Origin
Unaided
Origin
Lessepsian migrants, native to the Pacific and Indian Oceans
FIRST SIGHTING IN GREEK WATERS
Crete, 2001
edible?
Yes, in high demand
Impacts
Spicara smaris, Boops boops, and Mullidae species were found to be their most common prey type by weight
further information
A widespread species, found from Japan to the Meditteranean, it is related to pipefish and seahorses.
Common Name
Black-barred halfbeak
Scientific Name
Hemiramphus far
Description
A long, thin fish with a long beak-like lower jaw that protudes outwards from its body. It’s shorter upper jaw can be described as triangular and lacking scales. Mainly silver with a bluer dorsal region, a number of black vertical lines are found along the side of the body.
Habitat
Epiepelagic (0-6m), coastal waters
diet
Variable feeding habits, but mainly zooplankton and unmoored seagrass blades in surface waters.
Size
Up to 45 cm
Status according to ELNAIS
Alien – Established
Pathway of Origin
Unaided
Origin
Lessepsian migrant, native to the Indo-West Pacific
first sighting in greek waters
Rhodes, 1943
edible?
Yes
Impacts
Negligible or unreported.
further information
One of the first lessepsian migrants to the Mediterranean
Common Name
Silver-cheeked toadfish
Scientific Name
Lagocephalus sceleratus
Description
This toadfish boasts a greenish body adorned with dark spots enveloping its upper half. A distinct white belly is set apart from the spotty upper portion by a silver encircling line.
Habitat
Found in warm, shallow waters, with sandy and muddy substrates
diet
Demersal carnivores, feed mainly on non-native species molluscs and crustaceans
Size
40-60cm
Status according to ELNAIS
Alien – Invasive
Pathway of Origin
Unaided
Origin
Lessepsian migrants, possibly transported in ship ballast water
first sighting in greek waters
Zakynthos, 2005
edible?
No, it is incredibly toxic
Impacts
In part due to their lethal toxicity, silver cheeked toadfish are massively succesful predators within Eastern Meditteranean waters. They have inhabited the niche of many native top predators of the ecosystem that have dissappeared due to overfishing. Surprisingly, they do seem to benefit the ecosystem by predating many other invasive species.
further information
An important part of the ecological sucess of L. sceleratus is due to their having one of the most advanced forms of teeth in the animal kingdom. The ‘first generation teeth’ are coated with recurring toothbands which are continously regenerated by stem cells.
Common Name
Red Sea goatfish
Scientific Name
Parupeneus forsskali
Description
In addition to the two chin barbels typical of goatfish, this fish can be identified with its elongated body and a bold black stripe that runs from the upper lip through the eye and along the upper body, ending near the second dorsal fin. Above the stripe, the body is grayish-green with yellow scale edges, while below, coloration is white with reddish scale edges.
Habitat
Sandy bottoms and coral reefs, often in the vicinity of seagrass meadows. Found at depths of up to 45m
diet
Carnivorous, mostly preys on small benthic crustaceans and molluscs
Size
25cm
Status according to ELNAIS
Alien – Established
Pathway of Origin
Unaided
Origin
Lessepsian migrants native to Atlantic, Indian and Pacific oceans.
first sighting in greek waters
Rhodes, 2017
edible?
Yes
Impacts
This invasive mullid competes with native mullid species.
further information
Probes the sand with sensory organ-carrying hyoid barbels.
Common Name
Fish in this genus are commonly referred to as sweepers, but this species has no common name
Scientific Name
Pempheris rhomboidea
Description
Elongated, slender body with scales displayed in a diamond formation. The diamond pattern is outlined in black, making it stand out from their pale body.
Habitat
Pelagic/neritic, minimum depth of 20m
diet
Zooplankton
Size
Up to 13.2cm
Status according to ELNAIS
Alien – Established
Pathway of Origin
Unaided
Origin
Lessepsian migrant, native to the Red Sea
first sighting in greek waters
Rhodes, 1983
edible?
Rarely consumed
Impacts
Reported to be populous underneath offshore fish farms in the Aegean, altering the dispersal and biodiversity of native fish due to human intervention.
further information
Exhibits underwater soniferoius behaviour
Common Name
So-iuy mullet
Scientific Name
Planiliza haematocheilus
Description
The fusiform body can be silver to brown in colour on the top of the body, however the bottom half is colourless. It has an caudal fin that has a stronger, more bolder colouration compared to the rest of the body. It has two separate dorsal fins and a small mouth with a thick upper lip.
Habitat
Euryhaline species that displays high ecological plasticity, typically found in near-shore water
diet
Omnivorous, often consumes detritus
Size
50cm
Status according to ELNAIS
Alien – Established
Pathway of Origin
Unaided
Origin
Native to north-east Asia, escaped from fisheries
first sighting in greek waters
Rhodes, 1998
edible?
Yes
Impacts
A danger to native mullet species, they bring exotic parasites that have a wider influence on all nearby fauna and are often found in close proximity with Liza aurata, allowing parasite transfer.
further information
Native to an area with many cyclic changes in water composition; can hibernate in winter
Common Name
Striped eel catfish
Scientific Name
Plotosus lineatus
Description
This species of catfish has a cylindrical, elongated body covered in a mucus layer. Brrownish grey stripes run vertically along the body, with a set of 4 barbels by the mouth. It has a single venomous spine on each of the pectoral and dorsal fins.
Habitat
Mainly associated with reefs, with a depth range from 1- 60m
diet
Carnivorous, search sand for molluscs, worms, fish and crustaceans
Size
25cm
Status according to ELNAIS
Unknown
Pathway of Origin
Unknown
Origin
Lessepsian migrant, native to the Indo-Pacific
first sighting in greek waters
Dodecanese, 2016
edible?
Edible with caution, due to being one of the most venomous species globally
Impacts
Compete with Trachinus draco and Mullus sp for prey
further information
Juvenilles form dense aggregations of around 100 fish, in a distinctive ball shape
Common Name
Common lionfish, Devil firefish
Scientific Name
Pterois miles
Description
This fish is well-known for its invasive propensity and is easily recognized with red, white, and black stripes and long spines that are very toxic. It typically swims slowly, passively drifting in the water while hunting for prey.
Habitat
Will settle in a majority of habitat types, but prefers rocky caves and crevices (often previously occupied by groupers) up to 150m deep
diet
Generalist predator that consumes a range of teleosts and crustaceans, some of which have high economic value, thus competeing with fisheries.
Size
30-40cm
Status according to ELNAIS
Alien – Invasive
Pathway of Origin
Unaided
Origin
Lessepsian migrants native to the Red Sea and Indian Ocean
first sighting in greek waters
Kalymnos, 2009
edible?
Yes
Impacts
They inhabit the same range as Pempheris species, Apogon species and Sarcocentron rubrum, pushing them out of their native habitat or consuming them; Spicara smaris, Sparisoma cretense, Chromis chromis, are all target species for lionfish consumption.
further information
They can live up to 30 years and have few predators.
Common Name
Redcoat
Scientific Name
Sargocentron rubrum
Description
The main body is enveloped by brownish-red and white stripes and has a dark red dorsal fin that is interrupted by white blotches on the membrane. Additionally, five vertical stripes adorn its cheek, extending from the back of the cheek to its large eyeball, running perpendicular to the body stripes.
Habitat
Nocturnal; rocky substrate from 0-40m, pelagic when juvenile then migrate to rocky inshore habitat after losing juvenile spines, and are found in caves during the day.
diet
Mainly on decapod crustaceans
Size
Up to 32cm
Status according to ELNAIS
Alien – Established
Pathway of Origin
Unaided
Origin
Lessepsian migrant, native to the Red Sea
first sighting in greek waters
Rhodes, 1948
edible?
Yes
Impacts
Competes with Apogon imberbis, they inhabit the same rocky ground nocturnally
further information
Sharp, long, venomous spines line its cheeks
Common Name
Lessepsian lizardfish
Scientific Name
Saurida lessepsianus
Description
The Lessepsian lizardfish is recognized by its triangular dorsal fin with 11-12 rays, long pectoral fins, and a caudal fin bearing 3-8 black spots. Its belly has a front portion ranging from pale grey to black, while the rear is whitish. Notably, it features a large mouth with a series of teeth that grow larger towards the back.
Habitat
Depth range of 20-100m, sandy and muddy marine substrates
diet
Piscivorous, low diet plasticity
Size
Up to 28cm
Status according to ELNAIS
Alien – Established
Pathway of Origin
Unaided
Origin
Lessepsian migrant, native to the Red Sea
first sighting in greek waters
Dodecanese, 1971 (potentially prior)
edible?
Yes
Impacts
High diet overlap with native Synodus saurus
further information
Only identified in scientific literature in 2015, before specimens were thought to be of similar species.
Common Name
Blue-barred parrotfish
Scientific Name
Scarus ghobban
Description
This parrotfish has an elongated, compressed body, with a beak-shaped mouth used for grazing on hard substrates. It has extremely striking colouration; an anterior of vibrant blue or green meets an oragne or pink posterior.
Habitat
0-90m, Adults are found among coral reefs, while juveniles prefer algae covered inshore habitats.
diet
Like other parrotfish, it feeds by scraping algae from rock and coral
Size
Usually 30cm, but up to 75cm has been recorded
Status according to ELNAIS
Alien – Casual
Pathway of Origin
Unaided
Origin
Lessepsian migrant, native to the Red Sea
first sighting in greek waters
2014
edible?
Yes
Impacts
Crushing and consumption of native corals and algae
further information
Maximum age of 13 years
Common Name
Narrow-barred Spanish mackerel
Scientific Name
Scomberomorus commerson
Description
With a body shape specifically adapted for speed, they have a pointed head and several dorsal and ventral fins to aid stability. They have a silvery, bluish-green body with many slim, vertical bars which may vary between black and deep blue. Their underside is most commonly white or silver.
Habitat
Pelagic, continental shelves to shallow coastal areas between 10-70m
diet
Low diet plasticity with their main food source being the anchovy, Engraulis encrasicolus, They also eat squid and shrimps.
Size
120cm
Status according to ELNAIS
Unaided
Pathway of Origin
Unaided
Origin
Lessepsian migrant, native to the Indian Ocean
first sighting in greek waters
Ionian Sea, 2008
edible?
Yes, in high demand
Impacts
E. encrasicholus, Boops boops, T. mediterraneus; all are native prey species
further information
Can live up to 22 years
Common Name
Dusky spinefoot
Scientific Name
Siganus luridus
Description
This fish’s colouration is a mottled dark green and brown, with stronger pigmentation in the top half of their body. The anterior spines are slender yet powerful; the posterior spines are stout, all are venomous.
Habitat
Shallow water with hard substrates such as coral and rocky reefs. In Posidonia meadows in Rhodes.
diet
Herbivores that graze on algae in the subrate as well as larger brown algae
Size
20-30cm
Status according to ELNAIS
Alien – Established
Pathway of Origin
Unaided
Origin
Lessepsian migrant, native to the western Indian Ocean
first sighting in greek waters
Crete, 1964
edible?
Toxic spines, but if prepared properly can be consumed
Impacts
Their algal grazing encourages urchin activity
further information
Around Santorini, this species accounted for 90% of the total abundance of herbivores
Common Name
Marbled spinefoot
Scientific Name
Siganus rivulatus
Description
The marbled spinefoot has a body with brown, green or grey coloration and a lateral midline. The fish’s eyes are silver or gold and notably it has protruding venomous dorsal spines that are displayed when threatened.
Habitat
Prefers sheltered areas such as shallow waters with hard substrates and strong algal communities
diet
Herbivorous, algae grazer
Size
20-27cm
Status according to ELNAIS
Alien – Invasive
Pathway of Origin
Unaided
Origin
Lessepsian migrants; native to the Indian Ocean and the Red Sea to the Mediterranean
first sighting in greek waters
Crete, 1925
Edible?
Yes
Impacts
These fish have the same dietary niche as Sarpa salpa, Sparisoma cretense, and many juvenile native fish; Siganids are far more abundant in the Mediterranean than other native herbivores
further information
This species has competitve superiority stemming from greater adaptability, rapid growth, higher fecundity and early sexual maturity.
Common Name
Yellowstripe barracuda
Scientific Name
Sphyraena chrystotaenia
Description
Like many barracudas this fish has a very elongated body with two dorsal fins and a forked tail. The underside of the fish is silvery with a darker dorsal coloration and a lateral stripe.
Habitat
Pelagic, from 1 – 50m
diet
Carnivorous, mainly preys on fish and crustaceans.
Size
20-25cm
Status according to ELNAIS
Alien – Established
Pathway of Origin
Unaided
Origin
Lessepsian migrant, native to the Indo-West Pacific
first sighting in greek waters
Crete, 1995
edible?
Yes, becoming commercially important in the Mediterranean
Impacts
Consumes small fish that are also targeted by regional fisheries.
further information
Forms large schools
Common Name
Reticulated leatherjacket
Scientific Name
Stephanolepis diaspros
Description
A laterally compressed species with rough olive coloured scales. The first dorsal fin has a large spine, the second is filamentous and the caudal fin is rounded. It has a pointed snout and many incisor-like teeth.
Habitat
0-50m in demersal, tropical waters, around rocky substrate with vegetation, the immature individuals found on sandy and muddy substrates, sometimes found quite far off the coast.
diet
Preys on small invertebrates off rocks, omnivorous and opportunistic predators
Size
Up to 25cm
Status according to ELNAIS
Alien – Established
Pathway of Origin
Unaided
Origin
Lessepsian migrant, native to the Red Sea
first sighting in greek waters
Messenia, 1943
edible?
Yes
Impacts
Will consume marine plants to aid in digestion of its main prey.
further information
First described by Alec Frederick Fraser-Brunner in 1940
Common Name
Yellowspotted puffer
Scientific Name
Torquigener flavimaculosus
Description
This species has large eyes with a yellow ring surrounding the blue centre. It has a bulbous body covered in hexagonal plates for protection. It has yellow markings allowing camouflage with sand.
Habitat
Found in depths of 3-57m, near reefs, seagrass beds and soft substrates
diet
Carnivorous, preference for invertebrates with limited mobility
Size
Up to 16cm
Status according to ELNAIS
Alien – Established
Pathway of Origin
Unaided
Origin
Lessepsian migrant, native to the Indian Ocean
first sighting in greek waters
Rhodes, 2006
edible?
Contain tetrodotoxin, not edible and lethal if consumed
Impacts
Predator of many native species
further information
Unique foraging strategy in which they can suck hermit crabs out of their shells
Common Name
Por’s goatfish
Scientific Name
Upeneus pori
Description
Slender body that is flattened on the underside. Their coloration is red/orange and pale silver underneath. The caudal fin has orange and silver stripes on the upper half and is solid orange on the other half, and can be distinguished by barbels underneath the mouth.
Habitat
Demersal species, found in soft and hard substrates in coastal areas between 20-52m
diet
Forages for benthic invertebrates with barbels
Size
Up to 19cm
Status according to ELNAIS
Alien – Established
Pathway of Origin
Unaided
Origin
Lessepsian migrant
first sighting in greek waters
Iskenderun Bay, 2003
edible?
Yes, in high demand
Impacts
Competes with native mullidae sp.
further information
Has spread as far west as Sicily
MACROINVERTEBRATES
- Aplysia dactylomela
- Aplysia parvula
- Bursatella leachii
- Callinectes sapidus
- Cassiopea andromeda
- Cerithium scabridum
- Chama pacifica
- Conomurex persicus
- Dendostrea folium
- Diadema setosum
- Herdmania momus
- Oculina patagonica
- Percnon gibbesi
- Pinctada radiata
- Rapana venosa
- Rhopilema nomadica
- Ruditapes philippinarum
- Sepioteuthis lessoniana
- Spondylus spinosus
- Synaptula reciprocans
Common Name
Spotted Sea hare
Scientific Name
Aplysia dactylomela
Description
Large sea slug with distinctive black rings of varying sizes covering the body which can have a pale green to yellow and dark brown base coloration. Head with four “horns”.
Habitat
Rocky shores and sand with dense algal cover, shallow waters
diet
A herbivore that feeds on green algae
DEPTH
0-40 m
Size
40 cm
Status according to elnais
Unknown
Pathway of Origin
Unaided
Origin
Cape Verde archipelago, the Caribbean and around the Gulf of Mexico, off the coast of Florida, Bermuda, Bahamas, Belize, Brazil, Senegal and the Canary Islands.
first sighting in greek waters
2002
further information
It is nocturnal during the day it hides under large rocks or in crevices. At night, it is usually seen either crawling like an ordinary sea slug on seaweeds, or swimming by undulating its wings. Mantle flattens with swimming and ripples similar to that of cuttle fish. If threatened releases magenta ink to the water
Common Name
Pygmy sea hare
Scientific Name
Aplysia parvula
Description
A small sea slug. Mottled brown or green (sometimes more uniform). Tentacle tips are dark in colour.
Habitat
Intertidal and subtidal habitats.
diet
A herbivore that feeds on red algae
DEPTH
0-50 m
Size
6 cm
Status according to elnais
Questionable
Pathway of Origin
Unaided
Origin
Red Sea and Indian Ocean
first sighting in greek waters
2006
further information
It usually occurs in less than 5 m of water. Found roaming around various species of algae. It is nocturnal.
Common Name
Ragged sea hare
Scientific Name
Bursatella leachii
Description
Large sea slug of grey brown coloration with numerous long, branching, white papillae that give the animal its ragged appearance. A key distinctive feature are the dark brown blotches on the white papillae and bright blue eyespots scattered over the body. It also has two characteristic tentacles originating from the head resembling long ears, and two oral tentacles of similar shape near the mouth.
Habitat
Shallow, sheltered waters, often on sandy or muddy bottom, seagrass beds, and occasionally in harbour environments.
diet
A detritivore that feeds on green aglae, cyanobacteria and Calothrix crustacea
DEPTH
0-30 m
Size
10 cm
Status according to elnais
Alien – Established
Pathway of Origin
Unaided, Transport – Stowaway
Origin
Tropical Atlantic and Indo-Pacific Oceans
first sighting in greek waters
1975
further information
More active during daytime and hides at night. In the early morning sea hares are found together in groups of 8–12 individuals, disperse during the day. They reassemble again at night. Often found around Caulerpa prolifera. Comercial benefits in anti-HIV medicine
Common Name
Atlantic blue crab
Scientific Name
Callinectes sapidus
Description
Decapod crustacean with distinctive blue legs and claws. Back legs are adapted for swimming.
Habitat
Inhabits the crevices of rocks or man-made structures in estuaries and river mouths. Good tolerance to high salinity water to almost fresh water.
diet
An omnivore that feeds on clams, oysters, and mussels as well as almost any vegetable or animal matter.
DEPTH
1 to 90 m
Size
18 cm
Status according to elnais
Alien – Invasive
Pathway of Origin
Transport – Stowaway
Origin
Western Atlantic, from New
England to Uruguay
first sighting in greek waters
Amphipolis and Methonis – North West Aegean Sea (1937)
further information
During times of the year when temperatures are colder, C. sapidus tends to migrate to deeper water. They are active swimmers and have their last pair of walking legs adapted to be shaped like a paddle to accommodate swimming. It is a diurnal animal
Common Name
Upside-down jellyfish
Scientific Name
Cassiopea andromeda
Description
Scyphozoan jellyfish with yellow-brown bell, pale spots and streaks with frilly tentacles. Lies upside down on the seabed, easily mistaken for an anemone.
Habitat
Sandy or clear, warm and shallow waters
diet
Feed on small pelagic species, which are near the seabed. They recieve nutrients from a symbiotic relationship with macroalgae.
DEPTH
> 7.5 m
Size
30 cm
Status according to elnais
Alien – Established
Pathway of Origin
Unaided
Origin
Indo-Pacific
first sighting in greek waters
Therasia Island (1942)
further information
Prey on fish larvae/eggs and could therefore negatively affect fisheries
Common Name
None
Scientific Name
Cerithium scabridum
Description
Sea snail with brown to green coloration and long proboscis. Shell is long and gets wider close to the opening and tapers to the end.
Habitat
Intertidal or shallow water zone sandy mud, rock pools in sheltered places, and lagoons.
diet
A herbivore that feeds on graze on algae and dertitus
DEPTH
2 – 25 m
Size
7 cm
Status according to elnais
Alien – Established
Pathway of Origin
Unaided
Origin
Red Sea, Persian Gulf, western and southern India
first sighting in greek waters
2007
further information
Nocturnal – does its foraging at night
Common Name
Jewel box oyster
Scientific Name
Chama pacifica
Description
White to pinkish-red with pale-rose blotches. Large, ovoid-shaped oyster. Usually thick and irregularly rounded.
Habitat
Rocky shores and hard substrates, thrive in harbour environments
diet
A filter feeder that feeds on phytoplankton & bacteria
DEPTH
0 – 40 m
Size
8 – 10 cm
Status according to elnais
Alien – Established
Pathway of Origin
Unaided
Origin
Indo-Pacific
first sighting in greek waters
Rhodes Island (2005)
further information
Singly or together with Erythrean spiny oyster can form dense aggregations, producing solid reefs at some sites and completely replacing native species.
Common Name
Persian conch
Scientific Name
Conomurex persicus
Description
Elongated white shell, densely covered in a brown sstriped pattern.
Habitat
Sandy bottoms between 1 and 10 m deep
diet
A herbivore that feeds on algae
DEPTH
3 – 8 m
Size
4 – 7 cm
Status according to elnais
Alien – Invasive
Pathway of Origin
Unaided, Transport – Stowaway
Origin
Western Indian Ocean
first sighting in greek waters
Rhodes Island (1988)
further information
Buries itself during the winter months starting in October/November and ends its dormant state in April. Poisonous. It is a nocturnal species.
Common Name
Leaf Oyster
Scientific Name
Dendostrea folium
Description
A red-brown coloured shell with an irregular elongated shape. Two valves – right valve dark purple, left valve white with purple stripes.
Habitat
Shallow, sublittoral, on rocks.
diet
A filter feeder that feeds on bacteria, protozoa, a variety of diatoms and invertebrate larvae
DEPTH
5 – 30 m
Size
Up to 55 mm in height, 30 in length and 10 in width
Status according to elnais
Alien – Invasive
Pathway of Origin
Unaided, Transport – Stowaway
Origin
Indo-West Pacific
first sighting in greek waters
2005
further information
Attached to other living sessile bivalves.
Common Name
Long-spined sea urchin
Scientific Name
Diadema setosum
Description
Echinoid with black test and very long and narrow spines, which can be black, white or banded black and white. It also has 5 characteristic white dots on its body and an orange ring around the periprotcal cone. Mildly venomous.
Habitat
Can be found on sandy area, near seagrass beds or rocks
diet
A herbivore that feeds on green and filamentous algae
DEPTH
0-70 m
Size
Up to 10 cm, spines up to 30 cm
Status according to elnais
Alien – Established
Pathway of Origin
Unaided
Origin
Indian Ocean, East Africa and the Red Sea. Also in South Pacific Islands and Japan.
first sighting in greek waters
2010
further information
Lives in a group or alone. Hides in crevices and under overhangs by day, and forages at night, at a distance of a few meters away from its daytime hideout. It is nocturnal.
Common Name
Giant pink ascidian
Scientific Name
Herdmania momus
Description
A large ascidain that is translucent with pink/red colouration. Inflated, spherical body with two short, cylindrical siphons on the top and side. Tiny calcareous spicules lie under the surface of the outer tunic and internal structures.The gut can sometimes be distinguished through the transparent body, forming a loop
Habitat
Smooth artificial substrates such as breakwaters, jetties and artificial reefs
diet
A filter feeder that feeds on plankton and small organisms
DEPTH
up to 20 m
Size
18 cm
Status according to elnais
Alien – Established
Pathway of Origin
Unaided
Origin
Indo-Pacific
first sighting in greek waters
2010
further information
Have not yet been shown to outcompete native species or invade natural ecosystems. Its potential invasive status is uncertain.
Common Name
None
Scientific Name
Oculina patagonica
Description
A stoney colonial coral that is yellow-brownish in colour. Tubular skeletons of the polyps are crowded, up to 5 mm
Habitat
Natural pristine sites as well as in
marinas, harbours and heavily polluted areas.
diet
Stony colonial coral that
can harbour zooxanthellae
DEPTH
0-40 m
Size
5 mm
Status according to elnais
Unknown
Pathway of Origin
Transport – Stowaway, Transport – Contaminant
Origin
The eastern Atlantic
first sighting in greek waters
2002
further information
The colonies are generally encrusting, thicker in the centre with a thin edge spreading over the substrate.
Common Name
Sally light foot crab
Scientific Name
Percnon gibbesi
Description
Decapod of brownish colour with characteristic green and yellow
rings on the legs. Eye stalks and claws are orange.
Habitat
In the crevices of rocks or on man-made structures such as ports and marinas at shallow depths.
diet
A herbivore that feeds on filamentous and calcareous algae.
DEPTH
0.5 – 4 m
Size
3 cm
Status according to elnais
Alien – Invasive
Pathway of Origin
Transport – Stowaway
Origin
Pacific (California to Chile)
and Atlantic (Florida to Brazil) American coasts. Atlantic coast of Africa
first sighting in greek waters
–
further information
Often hides under stones and within man made structures such as marinas and docks. It is nocturnal.
Common Name
Rayed pearl oyster
Scientific Name
Pinctada radiata
Description
Bivalve with brown-purple shell occasionally mixed with green, pale yellow or white. The shape of the shell is rounded and irregular, with the two valves being flattened and developing obliquely in one direction.
Habitat
Attached to hard surfaces (natural or artificial) such as rocks, nets, buoys and docks, as well as in seagrass meadows on sandy-muddy sediments
diet
A filter feeder that feeds on microscopic plankton and organic particles.
DEPTH
5-25 m
Size
5-10 cm
Status according to elnais
Alien – Invasive
Pathway of Origin
Escape from Confinement, Transport – Stowaway (hull fouling)
Origin
Shallow waters in the Indo-Pacific region
first sighting in greek waters
1961
further information
Creates extensive oyster beds
Common Name
Rapa whelk
Scientific Name
Rapana venosa
Description
Large sea snail with rounded and heavy shell of grey to reddish brown coloration. Ornamental axial ribs, with a whorl and as a short spire.
Habitat
On sandy and rocky mixed bottoms in marine and brackish estuarine
diet
A carnivore that feeds on Bivalve molluscs
DEPTH
0.5-25 m
Size
3 – 16.5 cm
Status according to elnais
Alien – Casual
Pathway of Origin
Unaided
Origin
Northeast Pacific
first sighting in greek waters
Thessaloniki (1986)
further information
Often lies buried in the sand to avoid predators and preys on other mollusc species. Nocturnal.
Common Name
Nomad jellyfish
Scientific Name
Rhopilema nomadica
Description
Scyphozoan jellyfish with eight characteristic large mouth-arms, divided at mid-length into two ramifications with numerous long filaments.
Habitat
Coastal areas
diet
A carnivore that feeds on vast amounts of shrimp, mollusc and fish larvae
DEPTH
0-40 m
Size
The bell of this jellyfish can range from 10 to 90 cm in diameter, usually 40 – 60 cm
Status according to elnais
Alien – Casual
Pathway of Origin
Unaided
Origin
East coast of Africa and the Red Sea
first sighting in greek waters
Peninsula of Mani (2006)
further information
Dense in summer months
but found all year round.
Common Name
Manila clam/Japanese carpet shell
Scientific Name
Ruditapes philippinarum
Description
Bivalve of oval shell, radiating ribs, variable pattern and colour (generally cream coloured).
Habitat
Estuaries and lagoons, on sandy and muddy bottoms
diet
A filter feeder that feeds on plankton
DEPTH
Buries to 10 cm depth
Size
4 – 5.7 cm
Status according to elnais
Unknown
Pathway of Origin
Unknown
Origin
Pacific to the Indian Ocean
first sighting in greek waters
1980
further information
Significantly increase sediment erosion and re-suspension rates and over-enrich sediments with biodeposits, leading to sediment anoxia which inhibits nitrification and kills benthic fauna.
Common Name
Bigfin reef squid
Scientific Name
Sepioteuthis lessoniana
Description
Cephalopod with thick, muscular, oval fins extending around the mantle. Presence of large chromatophores covering the surface of the head.
Habitat
Shallow waters, found on coral reefs and seagrass meadows
diet
A carnivore that feeds on prawns, fish and crustaceans
DEPTH
100 m
Size
3.8 – 33 cm
Status according to elnais
Alien – Established
Pathway of Origin
Unaided
Origin
Indo-Pacific – Japan to Australia and New Zealand coasts, Hawaii to the East African coast, north to Red Sea and south to Madagascar
first sighting in greek waters
2009
further information
Exhibit both schooling and shoaling behaviours. Very young bigfin reef squids will also stay close together (shoaling), but do not swim together parallel to each other (schooling). Unlike most other squid species, bigfin reef squids are rarely cannibalistic. Nocturnal. Commercially important.
Common Name
Spiny oyster
Scientific Name
Spondylus spinosus
Description
Bivalve with rust coloured shell lined with long white spines and multiple eyes around the edge of the mantle.
Habitat
Rocky substrate
diet
A filter feeder that feeds on plankton
DEPTH
2-40 m
Size
7 cm
Status according to elnais
Alien – Casual
Pathway of Origin
Transport – Stowaway (hull fouling)
Origin
Indo-West Pacific
first sighting in greek waters
2008
further information
It can form large populations of up to 15 individuals.
Common Name
Worm Sea Cucumber
Scientific Name
Synaptula reciprocans
Description
Holothurian with a very elongated body of a dark-brown to black coloration, which can appear as a long black rope to the untrained eye. Characteristic mouth surrounded by tentacles.
Habitat
Found on rocky or sandy substrate, usually close to vegetation
diet
An omnivore that feeds on diatoms and other micro-organisms and organic coated particles
DEPTH
From the surface down to 20 m
Size
40 cm
Status according to elnais
Alien – Invasive
Pathway of Origin
Unaided
Origin
Red Sea
first sighting in greek waters
1995
further information
They are surficial modifiers, distribution highly depends on the water currents
MARINE FLORA
- Asparagopsis armata
- Asparagopsis taxiformis
- Caulerpa cylindracea
- Caulerpa scalpelliformis
- Caulerpa taxifolia
- Codium fragile
- Galaxaura rugosa
- Ganonema farinosum
- Halophila stipulacea
- Lophocladia lallemandii
- Stypopodium schimperi
- Undaria pinnatifida
- Womersleyella setacea
Common Name
Red Harpoon Weed
Scientific Name
Asparagopsis armata
Description
This species of marine red algae has two morphologically different stages: The gametophyte stage is pale purplish-red, while the tetrasporophyte stage is brownish-red, filamentous, and highly branched.
Habitat
Epiphytic to algae, especially Corallina spp.
depth
0-40m
Size
Up to 200 mm
Status according to ELNAIS
Alien – Casual
Pathway of Origin
Unaided
Origin
Native to western Australia, mechanism of spread unknown
first sighting in greek waters
Santorini, 1972
Impacts
Asparagopsis armata is noted for its high biomass production and biotechnological potential due to the myriad of produced secondary metabolites. However, it’s also one of the most aggressive invasive seaweed species, causing economic and ecological problems in Europe.
further information
The asexual phase of Asparagopsis armata was once described as a separate species, Falkenbergia rufolanosa.
Common Name
Red Sea Plume
Scientific Name
Asparagopsis taxiformis
Description
This species of red algae has a cosmopolitan distribution in tropical to warm temperate waters.
Habitat
Tropical/subtropical
depth
0-14m
Size
Between 5 to 20 cm
Status according to ELNAIS
Alien – Invasive
Pathway of Origin
Unaided
Origin
Native to southern Australia and New Zealand, mechanism of spread unknown
first sighting in greek waters
1992
Impacts
A.taxiformis erodes the habitat structure and biodiversity of native algal forests in the Mediterranean Sea. The seaweed has been shown to have a positive impact in methane reduction in livestock. Feeding ruminants a diet containing 0.2% A. taxiformis reduced their methane emissions by nearly 99%.
further information
Among 20 types of seaweed tested, A. taxiformis showed the most promise in reducing methane emissions in ruminants, with nearly 99% effectiveness
Common Name
Caulerpa spp. are commonly known as Sea Grapes
Scientific Name
Caulerpa cylindracea
Description
This green macroagae has one main stolon with coarse branchlike structures bearing clusters of miniature grapelike appendages.
Habitat
Colonises a variety of substrata from the intertidal zone to over 60 m in depth
depth
0-70m
Size
From 5 to 30 cm
Status according to ELNAIS
Alien – Invasive
Pathway of Origin
Unaided
Origin
Native to western Australia, mechanism of spread unknown
first sighting in greek waters
1993
Impacts
Caulerpa cylindracea is a key invasive species in the Mediterranean Sea where it has spread widely, raising ecological concerns. It dominating presence has been found to alter indigenous flora and fauna biodiversity, affect the behavior of native species and have adverse repercussions on fish growth and population dynamics.
further information
Caulerpa cylindracea has a unique reproductive strategy, reproducing vegetatively by fragmentation, and sexually through a process known as holocarpy, where the entire organism’s cytoplasm is used up in the creation of gametes.
Common Name
Fern algae
Scientific Name
Caulerpa scalpelliformis
Description
Delicate, fern structures creating fronds that resemble a comb, they are a bright, dark green.
Habitat
Tropical and subtropical distribution on rocky substrate, often in rock pools.
depth
0-30m
Size
20cm, with fronds around 3cm
status (ELNAIS)
Unknown
Pathway of Origin
Unknown
Origin
Native to western Australia, mechanism of spread unknown
Status according to ELNAIS
1929 (First Mediterranean sighting)
Impacts
Disrupting habitat and ecology of native species with preference for rock pool habitats.
further information
This species can control nutrient levels in the water by absorbing nitrates and phosphates, and are used in aquariums for this reason.
Common Name
Killer Algae
Scientific Name
Caulerpa taxifolia
Description
Caulerpa taxifolia is a light green macroalga with upright leaf/feather-like fronds arising from creeping stolons.
Habitat
This species can be found on a wide variety of substrates from rock, sand and mud to seagrasses. It is usually found in depths of 3-35m, but has been recorded at depths down to 100m in the Mediterranean.
depth
0-100m
Size
Frond diameter is 6-8mm and frond length is usually 3-15cm in the shallows, 40-60cm in deeper situations but can grow up to 2.8m in height
Status according to ELNAIS
Alien – Established
Pathway of Origin
Unaided
Origin
Native to tropical waters of populations naturally occurring in the Pacific Ocean, Indian Ocean and the Caribbean Sea, though not confirmed, its spread in the Mediterranean may be due to accidental release
first sighting in greek waters
2010
Impacts
This invasive species disrupts marine ecosystems by out-competing native species for food and light and due to the toxic effect of its caulerpenyne compounds. It forms large monospecific meadowns and vastly reduces biodiversity and suitable fish habitats. It can get caught and cause damage to fishing gear and accumulation of its toxins in fish populations can impact human consumption of local fish e.g. Mediterranean bream (Sarpa salpa).
further information
Caulerpa taxifolia has been cultivated for use in aquaria since the early 1970s in Western Europe. A cold-resistant clone was bred and later distributed to various aquaria, which eventually led to its escape into the wild and invasive behavior. It’s listed as one of the world’s 100 worst invasive species by the IUCN Invasive Species Specialist Group.
Common Name
Green Sea Fingers/Dead Man’s Fingers
Scientific Name
Codium fragile
Description
A siphonous green algae, it consists of one to several erect fronds with cylindrical, spongy branches and is attached to substrates by a spongy basal disc.
Habitat
Intertidal and shallow subtidal rocky bottoms and sheltered habitats such as harbours and bays.
depth
0-15m
Size
Typically 15 to 40 cm. Can grow up to 1 meter.
Status according to ELNAIS
Alien – Invasive
Pathway of Origin
Transport – Stowaway (angling, fishing equipment)
Origin
Native to the north Pacific Ocean and Japan, spread as a stowaway on transport vessels
first sighting in greek waters
1992
Impacts
This alga can displace native species such as Codium tomentosum. It’s a rapidly spreading invasive species in several regions, creating maintenance challenges for aquaculturists as it attaches to almost any hard surface in the subtidal zone. It can overgrow and smother shellfish beds, clog scallop dredges, foul fishing nets, reduce the amenity of jetties, beaches and wharf pilings and hinder the movement of fish and larger invertebrates.
further information
Codium fragile has been introduced as an invasive largely via shellfish aquaculture and attached to ship hulls. It has two subspecies that are similar in appearance but can be distinguished microscopically. One subspecies, Codium fragile subsp. atlanticum, arrived in the southwest of Ireland around 1808, spreading across Britain and other parts of Europe. Another subspecies, Codium fragile subsp. tomentosoides, is one of the most invasive seaweed species in the world, with extensive trans oceanic and inter-oceanic spread this past century.
Common Name
Sea whip
Scientific Name
Galaxaura rugosa
Description
Branching red algae with cylindrical branches that resemble a whip, often reddish/purple. Bushy growth form, often covered in a carbonate crust giving them a rough texture.
Habitat
Shallow areas with a lot of sunlight, attaching to coral reefs, rocky substrate, and occasionally the tubes of polychaete worms.
depth
0-10m
Size
Around 5cm
Status according to ELNAIS
Unknown
Pathway of Origin
Unknown
Origin
Tropical and subtropical seas of the Atlantic, Carribean and Gulf of Mexico, mechanism of spread unknown
first sighting in greek waters
1995
Impacts
Contributes heavily to protection of invertebrates in natural habitat and of nutrient recycling but may throw off the balance of nutrient cycling in habitats where it is invasive
further information
Currently being studied for their potential use in biotechnology and bioactive compounds for medicinal applications.
Common Name
Chalky weed
Scientific Name
Ganonema farinosum
Description
Deep red branching algae with coral like fronds that spread outwards in a tree-like formation
Habitat
Upper sublittoral zone
depth
0-10m
Size
20cm high
Status according to ELNAIS
Unknown
Pathway of Origin
Unknown
Origin
Native to South America, mechanism of spread unknown
first sighting in greek waters
1931
Impacts
Native biodiversity loss due to change in community structure and function
further information
Studies show that specimens of this species house the highest population density and largest body size of Caprellidae
Common Name
Broadleaf Seagrass
Scientific Name
Halophila stipulacea
Description
Rhizomes fixed to sand by roots, bearing pairs of leaves at regular intervals. Leaves have a serrated edge.
Habitat
Euryhaline with a wide ecological range, preference for warm waters and sandy substrate