Alveolates (Dinoflagellata)
Dinophysis norvegica (dinoflagellate) is described as an Arctic – boreal species found throughout the north Atlantic and north Pacific (Okolodkov and Dodge 1996). It has been collected in ballast-water samples from international vessels entering the ports of the Estuary and Gulf of St. Lawrence (Harvey et al. 1999), and from international vessels visiting the Laurentian Great Lakes and upper St Lawrence River (Subba Rao et al. 1994). Dinophysis norvegica produces okadaic acid, a toxin that accumulates in shellfish and can lead to Diarrhetic Shellfish Poisoning in humans who eat them. Symptoms usually begin within 30 minutes to a few hours after eating contaminated shellfish. The illness, which usually is not fatal, is characterised by incapacitating diarrhea, nausea, and vomiting, abdominal cramps and chills (Kleindinst 2001).
Annelida
Hydroides dianthus (a serpulid polychaete) is native to the east coast of North America. It was described in the fouling fauna of Naples, Italy, in 1865 (Nolan 1994), and is now widely distributed in harbours and coastal lagoons throughout the Mediterranean (Zibrowius 1994). It was discovered in Southampton Water, England, in 1970 but has apparently not spread further. H. dianthus is most likely to be a hull-fouling invader but its larvae might also be transported in ballast-water. H. dianthus is a nuisance fouler, and in its native range may also kill young oysters by overgrowing them (Eno et al. 1997).
Marenzelleria viridis (red-gilled mud worm) is native to
the east coast of North America. It
was discovered in the Firth of Forth and Firth of Tay, Scotland, in 1982 and
1984, and in the Ems estuary, Germany in 1983 (Eno et al. 1997). It has subsequently been discovered at
several sites throughout the Baltic: along the coasts of Germany, Poland, Sweden
and Finland in 1985, 1988, 1990 and 1992 respectively (Jansson 1994; Gollasch et al. 1999). It was first collected from San Francisco Bay
in 1991, and is now widespread throughout the Bay area (Cohen and Carlton
1995).
Marenzelleria viridis competes for food and space with native species in European waters,
possibly causing a negative impact on the food web of commercial fish
species. It has also been recorded
feeding on the larvae of native species.
It digs deeper than most native species and thus increases the thickness
of the populated surface sediment layer and depth limit of bioturbation. This burrowing in deep sediments may
enhance denitrification and exchange of material and energy in the
sediment-water interface, causing local benthic production to increase up to 10
fold. Its larvae and young adults
may be beneficial for benthic fish providing an additional food source (Gollasch
et al. 1999; Gollasch and Leppäkoski
1999), although its ability to live in deep burrows may actually reduce
predation on this species. M. viridis is
generally acknowledged to be a ballast-water invader, transported as either
larvae or adults.
Chordata
Liza ramada (thinlip mullet) is native to the eastern Atlantic: from southern Norway to Morocco, including the Mediterranean and the Black Sea. It has been recorded in ballast-water samples taken from commercial vessels sailing from Israel to the United States (Wonham et al. 2000) but to date does not appear to have established outside its native range. Liza ramada is a confirmed host of Epitheliocystis sp., an exotic pathogen of quarantine importance to Australia. Epitheliocystis is a common, widely distributed and readily transmitted chronic chlamydial infection of the skin and gills of freshwater and marine fish species. It causes hypertrophy of infected cells, impairing respiration. Infection may lead to death, especially in hatchery-reared young fish (Humphrey 1995). Epitheliocystis sp. has been recorded in Atlantic salmon farms in Tasmania (Nowak and Clark 1999) but is not widespread in Australia.
Neogobius melanostomus (round goby) tolerates both fresh
and marine waters. It is native to
the coasts and estuaries of the Black, Azov, Caspian and Marmara Seas (Miller
1986). Its native distribution may
also include the Mediterranean (Carlton and Geller 1993). In 1990, a three- or four-year old
specimen was discovered in the Bay of Gdansk, Poland; three years later several hundred
specimens were caught in the bay.
The species probably arrived in the Baltic in 1987 as eggs or larvae in
ballast-water discharges in the harbours and shipyards of Gdansk, though it
might have arrived by natural dispersal through the canals and rivers that
connect the Baltic with the Black and Caspian seas, although this seems less
likely (Jansson 1994; Skora 1997).
Since 1990 it has spread west through the Baltic, and in 1999 was
reported off the German island of Rugen (Gollasch et al. 1999). N. melanostomus was also introduced into
the Laurentian Great Lakes, again via ballast-water: it was first discovered in
1990 in and near the St Clair River on the Michigan-Ontario border. Since then, it has
spread through the Lakes region and into Illinois, Indiana, Ohio, Pennsylvania,
Wisconsin, Minnesota and New York (Fuller and Benson
2001).
Neogobius melanostomus is an aggressive, voracious feeder, eating eggs, fry, other small
fish, molluscs and crustaceans. It
causes extensive changes in the food chains of the areas that it invades and
competes with native fish for food, space and spawning grounds. In the Great Lakes it has disrupted the
spawning of native fish by habitat displacement, causing their numbers to
decrease (Jude 1996). However, N. melanostomus may also have a positive
impact by providing alternative commercial and recreational fisheries. (Gollasch
et al. 1999; Fuller and Benson 2001).
Pagrus major (red seabream) is native to Japan. It was accidentally introduced into Italy in the 1980s but did not establish there (Arthington et al. 1999). The vector of this introduction to Italy is unknown – we have included it here as a precaution, as P. major is a confirmed host of two exotic pathogens of quarantine importance to Australia: Epitheliocystis sp. (see Liza ramada) and Pasteurella piscicidia. Pasteurella spp. are associated with septicaemic infections of marine and estuarine fish species, and cause severe disease in farmed and wild fish. Japan has reported high mortalities in cultured Japanese yellowtail, with similar problems reported in sea bass culture (Greece), and in wild striped bass and white perch (United States) (Humphrey 1995).
Siganus rivulatus (marbled spinefoot) is native to the Red Sea and Gulf of Aden. With the opening of the Suez Canal, it spread throughout the eastern Mediterranean and can now be found on the shores of Cyprus, Greece, Israel, Libya, Syria, Tunisia and Turkey (Ktari and Ktari 1974; Arthington et al. 1999; CIESM 2001). It has also been identified in ballast-water samples taken from commercial vessels ballasting in Israel bound for the United Sates (Wonham et al. 2000). Siganus rivulatus is herbivorous and probably exerts a strong influence on the functional processes of the eastern Mediterranean, a sea with a low level of herbivory (Boudouresque 1994; pers. comm. C. F. Boudouresque, Centre d’Océanologie de Marseille, March 2001). The spines of S. rivulatus are slightly venomous causing a painful, but non-lethal, sting.
Tridentiger bifasciatus (Shimofuri goby) tolerates both fresh and brackish waters but is unable to survive in full marine salinities. It is native to Asian estuaries from Hokkaido (Japan) to Hong Kong (Matern and Fleming 1995). In 1985 it was identified from the Sacramento-San Joaquin Estuary in California and in 1989 it was the most abundant larval fish species in the upper estuary. It has since spread over 500 km by the water pumping of the California State Water Project through the California Aqueduct (Matern 2001). The species probably arrived in the estuary via ballast-water (Cohen and Carlton 1995). The diet and habitat preferences of Tridentiger bifasciatus potentially place it in direct competition with the endangered tidewater goby Eucyclogobius newberryi. Laboratory experiments conducted by Swenson and Matern (cited in Matern and Fleming 1995) demonstrated that T. bifasciatus will prey upon, disrupt the spawning of, and reduce the feeding of tidewater gobies
Cnidaria
Blackfordia virginica (Black Sea jellyfish) is native to the Black and Caspian seas. It was discovered in Chesapeake Bay in 1904 and the Ganges River at Calcutta in 1926 (Carlton 1985). In the 1970s it was discovered in San Francisco Bay but remained misidentified until 1993 (Cohen and Carlton 1995). It is thought to have been introduced to these areas via hull fouling or ballast-water. Blackfordia virginica eats mainly barnacle nauplii, copepods, tanaids and other invertebrates (Mills and Sommer 1995) and therefore has the potential to substantially alter the food web when it swarms (pers. comm. S. Gollasch, Institut für Meereskunde, March 2001). For this reason, Gollasch and Leppäkoski (1999) list this species as harmful.
Maeotias marginata (Black Sea jellyfish), also known as Maeotias inexpectata, is another ballast-water or hull-fouling invader native to the Black Sea. It was discovered in Chesapeake Bay in 1968 (Carlton 1985) and in San Francisco Bay in 1992. It is also known from South Carolina and France (Cohen and Carlton 1995). Maeotias marginata, like Blackfordia virginica, feeds exclusively on small crustaceans: barnacle nauplii, copepods (eggs and nauplii) and crab larvae. It is considered harmful for similar reasons (Gollasch and Leppäkoski 1999; pers. comm. S. Gollasch, Institut für Meereskunde, March 2001). In 1993 M. marginata swarmed in San Francisco Bay, infesting tributaries of the bay and causing considerable public alarm (Fuller 2001).
Ampelisca abdita is native to the northwest Atlantic from Maine to the eastern Gulf of Mexico. Its invasion history is presumably linked with oyster movements and there is also the potential for it to be transported via ballast-water. It was first transported to the east coast of the USA in the early 1950s, although confusion over taxonomy may have hidden its introduction for many years prior to then. It occurs in very high densities throughout the San Francisco Bay and other surrounding areas, but has not yet been recorded further north or south (Cohen and Carlton 1995). In the Atlantic, A. abdita is commonly found amongst oyster beds and forms extensive mats within the sediments of protected bays. In San Francisco Bay, the high abundance of A. abdita allows it to interfere with the native mollusc Macoma balthica through predation, physical processes or competition for food (Nichols and Thompson 1985). It also has been suggested by Santos and Simon (1980) that A. abdita may limit recruitment and disrupt the feeding of established organisms.
The native range of Balanus eburneus (ivory barnacle) stretches from Massachusetts to the West Indies and Brazil. It has since been reported in the North Sea, Black Sea and Caspian Sea, and from India, Japan, West Africa and the Pacific side of the Panama canal (Walford and Wicklund 1973; Carlton 1985; Gollasch and Leppäkoski 1999). It is known to be a hull fouling species and may also be transported in ballast-water. Balanus eburneus is a nuisance fouler, fouling oysters in BonSecour Bay, Alabama, which increases labour costs for market preparation (Athanas and Rouse 1996). Balanus species may also cause significant changes to ecological processes by increasing the area and volume available for associated meio- and macro-fauna, and enhancing the detritus-based food chains by supplying their habitat with particulate detritus (Gollasch and Leppäkoski 1999).
Callinectes sapidus (blue crab) is an important fisheries species from its native Atlantic coast of North America, south to Uruguay. It has been introduced to the Netherlands, Israel, Japan, Germany and the Mediterranean (Wolff 1954; Walford and Wicklund 1973; Carlton 1985; Nolan 1994), possibly through hull fouling but more likely in ballast-water. It has also been introduced to the Nordic area, but did not establish there (Gollasch and Leppäkoski 1999). In its introduced populations in Bardawil Lagoon, Northern Sinai, it is also an important fishery species. C. sapidus has been reported to mutilate fish caught in traps and trammel nets, and to tear nets (CIESM 2001). As its preferred prey is clams, mussels and oysters, it may also impact commercial fisheries.
Charybdis japonica (lady crab) is a native of Japan, Malaysia and China, where it is a commercially important species. A fisherman discovered a live, mature, male specimen of C. japonica in Adelaide’s Port River in December 2000. A subsequent search for more of the species did not find any more in the area (pers. comm., J. Gilliland, Primary Industries and Resources, South Australia). The vector of introduction in this case is unknown but ballast-water or hull-fouling are likely candidate. Charybdis japonica is known to be a host or carrier of the White Spot Syndrome Virus (WSSV) (Maeda et al. 1998). WSSV is a serious fisheries threat: it infects a broad spectrum of crustaceans, and can cause cumulative mortalities of up to 100% within 3 to 10 days of the first signs of the disease. Some infected individuals do not succumb to the disease but act as carriers that are able to spread the pathogen (Lightner 1996).
The native range of Hemigrapsus penicillatus stretches from Northern Japan to China. It was first discovered in France in 1994 in the estuary of Charente Maritime close to La Rochelle. It can now be found north of La Rochelle, and south to the shallow-water habitats of the Bay of Biscay (Spain), often in densities of 20 specimens/m2 (Gollasch and Leppäkoski 1999). H. penicillatus is undoubtedly having an effect on other organisms on the rocky shore through predation and other competitive interactions, particularly where it occurs in high densities (Noel et al. 1997; Gollasch 1999). It is known to be a hull-fouling species – six juveniles were found on the hull of a car-carrier in a German dry dock in 1993 (Gollasch and Leppäkoski 1999) – but it could also be transported through ballast-water.
Hemigrapsus sanguineus (Japanese shore crab) is native to the Asian shores of the north Pacific Ocean. The crab was first reported on the east coast of North America in 1988, near Cape May, New Jersey. Since then it has spread north to Cape Cod (Massachusetts) and south to Chesapeake Bay. In some regions it has replaced the previously introduced Carcinus maenas through competition with juveniles for intertidal habitat (Carlton and Geller 1993; Gollasch & Leppäkoski 1999; Jensen et al. 2000).
Hemigrapsus sanguineus is a known host or carrier of the WSSV (Maeda et al. 1998). It is an omnivore, feeding on commercially important molluscs (such as clams, scallops, mussels and oysters) as well as fish larvae and many species of algae . It has displaced native crabs on the mid-Atlantic coast of North America (Lohrer and Whitlatch 1997; Gerard et al. 1999) and is thought to compete with native xanthid mud crabs for habitat (McDermott 1991). In laboratory trials, H. sanguineus was the dominant competitor for food and space (Jensen et al. 2000). H. sanguineus is generally acknowledged to be a ballast-mediated invader.
Limulus polyphemus (horseshoe crab) is native to the east coast of North America, from Nova Scotia to the Florida Keys. It is also occasionally found along the coastline of the Gulf of Mexico and the Yucatan peninsula. It is sporadically found in European waters (a couple of records per decade), but in very low numbers, and has not established (Gollasch and Leppäkoski 1999). A single specimen was found in 1908 in New Zealand (Cranfield et al. 1998). As its life cycle includes a pelagic larval stage, it could be spread via ballast-water. There have been no recorded impacts of Limulus polyphemus because it has not established in any of the areas to which it has been introduced. However, in its native range it feeds on commercially important species, such as thin-shelled clams and bivalves (Botton 1984a, 1984b), and may therefore pose a threat to such fisheries if it were to establish in a new area.
Nippoleucon hinumensis (a Japanese cumacean) is native to Japan. It was first recorded on the Pacific coast of North America (Coos Bay, Oregon) in 1979, and has since been confirmed in the Umpqua River, Columbia River, Yaquina Bay, San Francisco Bay, Grizzly Bay and Puget Sound (Cohen and Carlton 1995; Cohen et al. 1998). It is thought to be a ballast-water invader. No negative environmental impacts have been recorded for Nippoleucon hinumensis in its introduced range, however, it is numerically dominant in areas such as San Francisco Bay and Yaquina Bay, where it occurs in densities of hundreds to thousands of individuals per square metre (Cohen & Carlton 1995; Castillo et al. 2000). It is therefore very likely that N. hinumensis competes with native species for resources and changes the availability of prey for native pelagic feeders.
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Pseudodiaptomus marinus (Asian copepod) is a euryhaline copepod native to China, Japan and Pacific Russia. It has been introduced to Hawaii, Mauritius and California, most probably through ballast-water (Carlton 1985; Carlton and Geller 1993; Cohen and Carlton 1995). Pseudodiaptomus marinus has been implicated in the decline of native copepods and fish in San Francisco Bay. Because it is more efficient at avoiding predation by the larvae of the delta smelt Hypomesus transpacificus than are native copepods, and its swimming behaviour makes it less attractive to the larvae, the larvae are weakened and made more vulnerable to starvation and predation (Kanim and Taniguchi 1993). P. marinus is thought to have displaced P. euryhalinus (Cohen & Carlton 1995) and contributed to the decline of the delta smelt.
Rhithropanopeus harrisii (dwarf crab or Harris mud crab) is native to the estuaries of the northwest Atlantic from New Brunswick to Florida and from the Mississippi to Veracruz in Mexico. It has a long history of invasion mediated by oyster movements and shipping (ballast-water and/or hull fouling). It was first transported to the Netherlands some time before 1874. It has since been described from the Pacific coast of North America (Lake Merritt, Oakland and San Francisco Bay, 1937; Coos Bay, Oregon, 1950; Netarts Bay, 1976; Yaquina Bay and Umpqua River, 1978), the Panama canal (1969), and at various locations throughout Europe (Baltic coast of Poland, 1951; Copenhagen, 1953; Azov, Black and Caspian Seas, 1958; southern Spain 1980s) (Wolff 1954; Walford and Wicklund 1973; Carlton 1985; Jansson 1994; Cohen and Carlton 1995; Gonzalez-Gordillo et al. 1990). In the Atlantic, R. harrisi is commonly found amongst oyster beds. Gollasch and Leppäkoski (1999) list it as ‘harmful’ because it may feed on newly settled mussels and oysters (spat) (pers. comm. S. Gollasch, Institut für Meereskunde, Kiel, February 2002).
Tortanus dextrilobatus is a large calanoid copepod that preys on other smaller copepods. It is native to the brackish waters of southern China, and has recently been described in South Korea (Ohtsuka et al. 1992). It was discovered in San Francisco Bay in 1993, where it is now one of the most abundant copepods in areas of the estuary where the salinity is about 15 psu (Kimmerer et al. 1999), and has been implicated in the decline of native copepods such as Diaptomus novamexicanus, D. siciloides, and D. pallidus (Cohen and Carlton 1995; Orsi and Ohtsuka 1999). It is thought to be a ballast-water introduction.
Crepidula fornicata (slipper limpet) is native to the
east coast of North America from the Gulf of St Lawrence to northern
Mexico. It was
first introduced into the United Kingdom in the late 19th century with imports of the American oyster Crassostrea
virginica, and since has spread throughout the country as far north as
Pembrokeshire and Yorkshire (Eno et al. 1997), with occasional reports further
north. C. fornicata spread
from the south coast of England to other areas of western Europe, and has
successfully invaded the North Sea and Atlantic coasts of Sweden, Norway,
Denmark, Germany, the Netherlands, Belgium and France. It was discovered in
the Mediterranean around Sicily and Calabria, in the early 1970s, and in the Languedoc
lagoons on the coast of France in 1989 (di Natale 1982; Zibrowius 1994; Jansson
1994). It has
also been introduced to the Pacific coast of North America from Puget Sound
south to San Francisco Bay (Carlton 1992), and has been reported from Uruguay
and Japan (Gollasch et al. 1999).
Crepidula fornicata has mainly been
spread through transporting of oysters but it may also be carried on ship hulls
and in ballast-water (in its pelagic larval phase). Along the European
coasts of France, England and the Netherlands, it is a serious oyster pest. It competes for food
and space, deposits mud on the substratum making it unsuitable for the spat, and
in heavily infested areas disrupts dredging and harvesting (Eno et al. 1997;
Blanchard 1997).
C.
fornicata is a habitat modifier and may therefore have other ecological
impacts. In the
Solent Estuary, England, for example, it has completely changed the nature of
the benthos by producing a dense layer of dead and living shell over the former
sediments (Solent Forum 2000). It may also encourage the deposition of mud
through its accumulated faeces and pseudofaeces (Eno et al.
1997).
The native range of Ensis directus (Atlantic jack-knife clam) stretches along the Atlantic coast of North America from southern Labrador to South Carolina. It was introduced to the Elbe estuary in the German Bight in 1978 as larvae in the ballast-water of tankers (Gollasch et al. 1999). From here it spread rapidly around the North Sea coasts of Denmark, Sweden and the Netherlands, reaching France in 1986 and England in 1989 (Jansson 1984; Eno et al. 1997). Ensis directus can occur in dense populations in both intertidal and subtidal sand flats, where its burying activities may have an impact on the sediment structure and may decrease the stock of other filterfeeders such as cockles and mussels (Armonies and Reise 1999). The sharp shells of E. directus can damage bottomtrawl nets and make deep cuts in people’s feet or hands, leading to bacterial infections (Gollasch et al. 1999).
Limnoperna fortunei (golden mussel) is native to the
rivers and lakes of China. The species has very broad environmental
tolerances; it is known to occur in estuaries and harbours (Morton 1996), and is
thought to be capable of surviving in marine ballast-water and hypersaline
conditions (Darrigran and de Drego 2000). It was introduced into Hong Kong in the early
1970’s in supplied potable water, and has subsequently been reported from Japan
and Taiwan. In
1991 it was described from the estuary of the Rio de la Plata in Argentina, as a
ballast-water invader.
Within two years, dense colonies of up to ~82,000 mussels m-2 were found at littoral sites along 100 km or so of
the estuary. It
is continuing to spread through Argentina and has recently colonised the Uruguay
and Parana rivers (Morton 1996; pers. comm. R. Willan, Museum and Art Gallery of the
Northern Territory, October 2000).
Limnoperna fortunei is a filter feeder
and may alter phytoplankton and zooplankton stocks, nutrient cycling and the
normal flow of the rivers it invades. This could lead to an increase in macrophyte
growth and sedimentation rates, and a decrease in dissolved oxygen. Its introduction
into South America has led to the displacement of two common gastropods, one of
which is apparently extinct and the other is described as rare (Darrigran and de
Drago 2000). It is also a serious biofouling nuisance of municipal drinking
water and industrial water systems which increases operational costs due to
decreased pump efficiency, increased tube corrosion and increased frequency of
shutdowns for cleaning and filter changes (Ricciardi 1998).
Mya arenaria (soft-shelled clam) is native to the Atlantic coast of North America and Alaska north of the Aleutian peninsula (Cohen and Carlton 1995). It was introduced into Scandinavia possibly as early as the 11th or 12th Century by Vikings, who may have used the clam as food or bait (Petersen et al. 1992). Today it is common on the east and west coasts of Sweden. It spread from here to the Black Sea in the early 1960s, probably through ballast-water discharges (Jansson 1994). It was collected in San Francisco Bay in 1874, having been introduced with transcontinental shipments of Atlantic oysters. It is present in the fossil record of the Pacific coast well before this, but appears to have become extinct sometime before the Pleistocene (Cohen and Carlton 1995). M. arenaria spread, either naturally or via anthropogenic means, to various other sites along the Pacific coast from Juneau, Alaska, to Monterey Bay (Walford and Wicklund 1973). By 1880 it formed the basis of a substantial commercial and recreational fishery on the Pacific coast that lasted until 1948 (Cohen and Carlton 1995).
In other regions of the world, however, the occurrence of Mya arenaria has been less beneficial. In the Black Sea, tons of decaying and stinking specimens are washed ashore in some tourist resort areas, having to be removed every morning from the beach during summer to avoid disturbing holiday-makers (Gollasch and Leppäkoski 1999). It changes sulphur-reduction rates in the sediments around its burrows, probably by enriching the sediment with its organic excretions (Hansen et al. 1996), and has transformed the benthic communities of the Black Sea, prevailing over all native bivalves such as Corbula mediterranea. In recent years its abundance has decreased for no known reason (Strasser 1999).
Perna perna (brown mussel) can be found along the Atlantic coast of South America in Brazil, Venezuela and Uruguay, and the West Indies. It may also occur in cooler waters south of Rio de la Plata, Argentina, to the Straits of Magellan. It is common along the Atlantic coast of Africa, from Luderitz Bay north into the Mediterranean, from Gibraltar to the Gulf of Tunis, and on the East coast of Africa, southern India and Sri Lanka (Hicks et al. 2001). It seems unlikely that such a cosmopolitan distribution could be the result of natural dispersion, however, it is unclear which of these regions is the native or introduced range of this species (Siddall 1980). In 1990 it was discovered in Port Aransas, on the Gulf of Mexico coast of Texas, having been introduced through live shellfish imports or ballast-water discharges. A year later it was found at Port Mansfield some 230 km to the south (Hicks and Tunnell 1993). It now occurs along 1700 km of coastline from Freeport, Texas, to southern Veracruz in Mexico (Hicks et al. 2001). P. perna is a highly adaptable species, with a wide salinity tolerance. It is also a nuisance fouler: it colonises jetties, petroleum platforms, wrecks and other artificial hard substrata. Its fouling biomass has been known to sink navigation buoys, threatening the safety of ships (Hicks and Tunnell 1995).
The native range of Perna viridis (asian green mussel) stretches across the Indo-Pacific encompassing the Persian Gulf, India, Papua New Guinea and the South Pacific Islands, and north to Japan (Siddall 1980). It is successfully cultivated for food in Thailand, Malaysia, Singapore, the Philippines, India, Pakistan and southern China (Huang et al. 1983). It was discovered in Trinidad in the early 1990’s, and Venezuela a few years later (Crochet et al. 2000). In 1999 P. viridis was discovered in Tampa Bay, Florida, where it is now firmly established – again ballast-water is thought to be responsible (Florida Marine Research Institute 2000). Perna viridis can be a serious biofouling nuisance. In India it causes problems for power plants that use seawater as a coolant, as they block the flow of cooling water. This damages the pumps, reduces the heat-transfer efficiency, clogs condenser tubes and increases their rate of corrosion (Rajagopal et al. 1994, 1996, 1998).
The native range of Petricolaria pholadiformis (false angel-wing) stretches along the northwestern Atlantic coast of North America from the Gulf of St Lawrence to the Gulf of Mexico (Cohen and Carlton 1995). It was introduced into the United Kingdom by 1890 in shipments of the American oyster Crassostrea virginica (Eno et al. 1997). It was first reported in Denmark in 1905, from where it has spread by its pelagic larvae to the coasts of Belgium and the Netherlands (CIESM 2000). It was discovered in the Mediterranean in 1963, but the vector in this instance is unknown (Boudouresque 1994). During or before 1927, it was found in San Francisco Bay on the Pacific coast of North America; in 1947 it was later reported in Willapa Bay and in 1972 in Newport Bay. Again, the most likely vector in these instances is oyster shipments, although ballast-water is a possibility (Cohen and Carlton 1995). No serious environmental harm has been attributed to the introduction of P. pholadiformis in the United Kingdom. In Belgium and the Netherlands, however, it has almost completely replaced the native species Barnea candida (Pholas candida) (Eno et al. 1997). It bores into clay, peat, mud, sand and other soft sediments, and may therefore modify habitats, and can often be found in oyster beds (Cohen & Carlton 1995).
Rhodophyta
Grateloupia doryphora is a large, foliose red alga found in the Pacific Ocean, the Mediterranean Sea and the Atlantic Ocean from the British Isles to Angola and from Florida to Uruguay (see Villalard-Bohnsack and Harlin 1997). It is repeatedly reported to be invasive and is thought to originate from the Pacific Ocean, possibly Japan (see Villalard-Bohnsack and Harlin 1997 and refs therein). In the mid 1990s it was reported from the northeast of the USA at Narragansett Bay at Rhode Island (Villalard-Bohnsack and Harlin 1997). Possible vectors for this species include ballast water and hull fouling. A third possible vector is importation in connection with the initiation of oyster mariculture – this being the probable origin of populations on the shores of France and England (Ribera and Boudouresque 1995). The blades of G. doryphora are fast growing, and can grow up to one metre long, giving it the potential to impact fisheries and become a fouling nuisance. The large size of the blade, and its demonstrated ability to colonise new areas, are clear indicators of its potential to dominate and outcompete indigenous flora (pers. comm. J. Lewis, May 2002).
Womersleyella setacea is a pan-tropical red macroalga found throughout the Indo-Pacific-Caribbean. In 1987 it was reported at Var on the French Mediterranean coast, and has since been reported as common at other places throughout the eastern and western Mediterranean (Athanasiadis 1997). Its recent discovery and rapid spread through the Mediterranean suggests that it probably was introduced into the region via hull fouling (Ribera and Boudouresque 1995). W. setacea can form dense, filamentous, monospecific turf layers up to 5 cm thick (Rindi et al. 1999) overgrowing native algae (Airoldi 2000). It also infests and clogs fishing nets, thereby increasing labour costs (Verlaque 1989).
Stramenopiles
The native range of Chaetoceros concavicornis (centric diatom) appears to be the cold and temperate waters of the Northern Hemisphere (Rines 2001a). It has been collected in ballast-water samples from commercial vessels entering the ports of the Estuary and Gulf of St. Lawrence (Harvey et al. 1999), and from vessels leaving Oakland harbour (California) bound for Japan, China and Taiwan (Zhang and Dickman 1999). In the Pacific northwest, Chaetoceros concavicornis is often implicated in large kills of pen-reared salmon when it occurs in concentrations of about 5 cells/mL of seawater (Albright et al. 1993). Its thick, siliceous setae armed with small barbs, break off and clog the gills of salmon. The salmon eventually die from suffocation or secondary infection. Since no toxin is known to be involved, the problem is considered to be essentially mechanical in nature (Albright et al. 1993; Rines 1998).
Chaetoceros convolutus (centric diatom) is a temperate to cold-water species found in both the northern and southern hemispheres (Rines 2001b), but is not yet known from Australia (pers. comm. G. Hallegraeff, University of Tasmania. September 2000). It has been collected in ballast-water samples from international vessels entering the ports of the Estuary and Gulf of St. Lawrence (Harvey et al. 1999), and from international vessels visiting the Laurentian Great Lakes and upper St Lawrence River (Subba Rao et al. 1994).
Chaetoceros convolutus, like C. concavicornis, has been implicated in large fish-kills in the Pacific northwest – it has long, barbed spines/setae that cause excess mucus production when they become lodged in the gills of penned salmon, resulting in suffocation and death (Albright et al. 1993). It has also been implicated in the death of red king crabs in Alaska. The gill surfaces of the dead crabs were covered with a mucus layer embedded with debris: C. convolutus cells and spines were identified on the gill membranes (Tester and Mahoney 1995).
Psuedo-nitschia seriata (pennate diatom) is a temperate and cold water species found throughout the Northern Hemisphere (Hasle et al. 1996). It has been retrieved from the ballast-tank sediments of international vessels entering the Estuary and Gulf of St Lawrence (Harvey et al. 1999).
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