Invasion History
First Non-native North American Tidal Record: 1957First Non-native West Coast Tidal Record: 1977
First Non-native East/Gulf Coast Tidal Record: 1957
General Invasion History:
Codium fragile is believed to have originated in the Northwest Pacific in waters around Japan. In Europe, it was first collected on the west coast of Ireland in 1845, but not recognized as an introduced species until around 1900 (Chapman 1999; Provan et al. 2008). A morphotype, C. f. subsp. atlanticum, of uncertain taxonomic and invasion status, was collected even earlier in 1839, in Ireland, but has had a limited range in Europe (Provan et al. 2008). The more typical C. fragile was first collected in the Mediterranean in 1950 (Verlaque 1994). In North America, Codium fragile was first collected on Long Island, New York in 1957 (Bouck and Morgan 1957). This seaweed spread rapidly to the north and south, reaching Nova Scotia in 1991 (Begin and Scheibling 2003); the Magdalen Islands, in the Gulf of St. Lawrence, Quebec, by 2003 (Drouin et al. 2011); and the south coast of Newfoundland by 2012 (Matheson et al. 2014). To the south, it colonized Beaufort Inlet, North Carolina in 1981 (Searles et al. 1984) and the current southernmost record is Cape Fear Inlet, North Carolina (Geraldi et al. 2014).
On the West Coast, at least one separate species of Codium or a separate subspecies of C. fragile is native from Baja California to Alaska, but an introduced population of C. fragile was discovered in San Francisco Bay in 1977 (Silva 1979; Cohen and Carlton 1995). Other invasions by C. fragile are widely scattered in space and time, including the Falkland Islands in 1849 (Provan et al. 2008); Cape Horn in1842; New Zealand in 1841 (Provan et al. 2008); Cape Town, South Africa in 1884 (Provan et al. 2008); Tasmania in 1890 (Provan et al. 2008); Iceland, before 1985 (South and Tittley 1986); Azores in 1993 (Cardigos et al. 2006); and Chile in 1998 (Castilla et al. 2005). Some of these populations were named as new subspecies, but were found, by genetic methods, to belong to C. fragile subsp. fragile (Provan et al. 2008).
North American Invasion History:
Invasion History on the West Coast:
Early Codium specimens from the West Coast of North America were identified as C. mucronatum forma californicum ( J. Agardh 1887), later known as C. fragile subsp. californicum (J. Agardh) C.A. Maggs & J. Kelly (Guiry and Guiry 2016). This form of Codium is found from Baja California to Alaska, mostly on the open coast (Abbott and Hollenberg 1976; Silva 1979; Miller et al. 2011). In 1977, a population of C. fragile, then identified as subspecies tomentosoides, was found only at Coyote Point in San Francisco Bay (Silva 1979). Codium fragile was found at Coyote Point and Redwood City in 1978-1983 (Josselyn and West 1985). In 1993-94, Cohen and Carlton (1995) found it growing on floating docks from Richmond to San Leandro, and a Pier 39, in San Francisco Harbor (Cohen and Carlton 1995). This seaweed has also been collected in Tomales Bay (Miller 2004; Miller et al. 2011).
Invasion History on the East Coast:
Codium fragile's first appearance in Northwest Atlantic waters was in Gardiners Bay, Long Island in 1957 (Bouck and Morgan 1957). Its introduction has been attributed to ship fouling, ballast water, or to the introduction of European or Japanese oysters. The first mode seems likeliest, because precautions were taken to prevent introduction of fouling organisms with European oysters planted experimentally in 1949 (Loosanoff 1975; cited by Carlton and Scanlon 1985) and because the dates and sites of oyster plantings do not correspond with those of C. fragile. The spotty nature of its spread in East coast waters suggests a diversity of transport mechanisms. Codium fragile spp. fragile was first collected in East Marion New York on the Eastern Fork of Long Island, in Gardiners's and Peconic Bays in 1957 (Bouck and Morgan 1957). It reached the Connecticut side of Long Island Sound by 1961 and Rhode Island by 1962-68. It was then brought to Chatham and Cotuit on Cape Cod in 1961 with transplanted oysters from Long Island. By the early 70's, it was widespread on the south side of Cape Cod (Carlton and Scanlon 1985).
Codium fragile was first collected north of Cape Cod in Boothbay Harbor Maine in 1964, where it was probably introduced with transplanted oysters (Carlton and Scanlon 1985). Its spread in Cape Cod Bay occurred later. It reached the Cape Cod Canal by 1969, and successively was found in Barnstable Harbor, MA in 1972; Wellfleet Harbor, MA in 1974; Duxbury Bay in 1981; and Provincetown in 1981. By 1983, it was collected at Appledore Island, Isles of Shoals, Maine (Carlton and Scanlon 1985). However, it was present to the north, at Bar Harbor, Maine by the late 1970's or early 1980's (Bird et al. 1993). The northward spread was spotty, with first records in Massachusetts Bay (Salem) in 2000 (MIT Sea Grant 2003), and in Great Bay, New Hampshire in 1985 (Mathieson et al. 2003). Codium fragile was first collected in Mahone Bay, on the central Atlantic coast of Nova Scotia in 1991. It has not yet been seen in the Bay of Fundy, although it was found in Sam Orr's Pond, a tributary of Passamaquoddy Bay, New Brunswick in 2009 (Saunders et al. 2013). It may have been brought to Nova Scotia, with transplanted shellfish, as packing material for bait, or by Gulf Stream eddies from New England (Bird et al. 1993).
In 1996, Codium fragile was collected for the first time in the Gulf of St. Lawrence, in Caribou Harbour, on the Northumberland Straits (Garbary et al. 1997). Since then, the spread has continued, both in the Gulf of St. Lawrence, and on the Atlantic Coast of Nova Scotia and Newfoundland. Codium fragile has been spreading through Northumberland Straits, in Nova Scotia, New Brunswick and on the Straits and Gulf Side of Prince Edward Island (Hubbard and Garbary 2002; Garbary et al. 2004). One population in Malpeque Bay included plants with the morphology of C. f. subsp. atlanticum (Hubbard and Garbary 2002). In the Gulf, it has spread as far north as the Magdalen Islands, Quebec in 2002 (Simard et al. 2005; Drouin et al. 2011, 47.3 N). Codium fragile is now patchily distributed on the whole Atlantic Coast of Nova Scotia, from Cape Sable Island, at the southwestern end to Canso, a distance of 450 km (Hubbard and Garbary 2002; Watanabe et al. 2010). In 2012, C. fragile was found at several sites in Placentia Bay, Newfoundland (Matheson et al. 2014, 47.8 N).
Between 1957 and 1968, C. fragile became widespread and abundant in Long Island Sound (Carlton and Scanlon 1985). It was first found in Barnegat Bay in 1966 and was widely distributed by 1969 (Taylor et al. 1969). The next southern record was in Assateague Channel, part of Chingcoteague Bay, Virginia in 1976 (Hillson 1976). Surprisingly, C. fragile was not collected at other estuaries in the region until much later. It was found washed up on the beach in Poquoson Neck, Virginia, on the western side of the lower Chesapeake Bay in 1995 (Scott Godwin, personal communication). It was found at Cape Henry, Virginia in 1999 (Ruiz et al., unpublished data), and was found in Atlantic coastal bays from Indian River Bay, Delaware to Hog Island Bay, Virginia in 2000-2003 (Thomsen 2004; Miller and Brown 2005; Thomsen and McGlathery 2006). However, we have no records from Delaware Bay. Codium fragile approached its southernmost limit at Topsail Inlet, south of Cape Hatteras, North Carolina in 1979, Masonboro Inlet in 1982, and Beaufort Inlet in 1981 (Searles et al. 1984). It was found growing abundantly on artificial substrates in Cape Fear Sound, near Wilmington, North Carolina in 2009 (Geraldi et al. 2014).
Invasion History Elsewhere in the World:
Codium fragile was an early invader to European waters, but was unrecognized. The possibly synonymous or related C. f. subsp. atlanticum was collected in Ireland in 1839 (Provan et al. 2008). However, taxonomists disagree on whether this form is introduced or native in Europe (Silva 1955; Provan et al. 2008; Guiry and Guiry 2016). It has a mostly European distribution from Norway to Spain, but 'atlanticum-like' plants have been found in Nova Scotia and the Azores (Hubbard and Garbary 2002; Tittley and Neto 2005). The typical C. fragile was collected on the west coast of Ireland in 1845, but was mistaken for the native C. tomentosum (Provan et al. 2008). It and other early C. fragile herbarium specimens were re-identified using chloroplast DNA (Provan et al. 2008). Codium fragile was recognized as a non-native species when it was collected in the Netherlands in 1900 (Silva 1955). However, it had already been collect in Devon, England in 1853 (Provan et al. 2008). It has spread extensively along the coast of Europe, reaching Sweden by 1939, the Danish Kattegatt (Baltic mouth) by 1985 (Chapman 1999), and Galicia, Spain by 1989 (Pérez-Cirera et al. 1989). It was first collected in the Mediterranean in France in 1950 (Verlaque 1994) and has spread east, reaching the Turkish Aegean by 1985 (Ribera and Boudouresque 1995). In the eastern Atlantic, C. fragile was established in Iceland by 1985 (South and Tittley 1987), the Canary Islands by 1990 (Haroun et al. 2002) and the Azores by 1993 (Tittley and Neto 2005).
Codium fragile was introduced to several locations in the Southern Hemisphere in the 18th century, including Cape Horn, Chile in 1842; the Falkland Islands in 1849; Bay of Islands, New Zealand in 1841; and the Cape of Good Hope, South Africa in 1884 (Provan et al. 2008). We have not found information on established populations in Atlantic South America, but C. fragile is established in several locations on the northern and central coasts of Chile (Castilla et al. 2005; Neill et al. 2006). Codium fragile is established on the southern Atlantic coast of South Africa, but its range is unclear, because of confusion with presumed native forms of Codium (Mead et al. 2011b). The South African form was described as C. f. capensis, but the type specimen proved to be genetically identical to C. fragile (Provan et al. 2008). Similarly, in New Zealand, a native subspecies, C. f. nova-zelandiae was described in 1935, but the type specimen was found to actually be C. fragile (Provan et al. 2008). Prior to this discovery, the introduced C. fragile was thought to have been introduced to New Zealand in 1973 and to have a limited range near Auckand (Dromgoole and Foster 1983; Trowbridge 1995). In Australia, Codium fragile subsp. tasmanicum was described from Tasmania in 1889, but was also found to be identical to typical C. fragile (Provan et al. 2008). A herbarium specimen of C. fragile was collected in Port Philip Bay in 1890 (Provan et al. 2008), but the first reported discovery of this plant was made in 1996 (Campbell 1999). It was subsequently found near Sydney in 2001 (NIMPIS 2015); in West Lakes, South Australia in 2002 (Wiltshire et al. 2010); and Albany, Western Australia in 2008 (McDonald et al. 2015).
Description
Codium fragile has thick, spongy, finger-like and forking branches, which extend from an irregular holdfast. The branches are covered with densely packed, short hairs, giving the plant a felt-like appearance and slimy texture. The tips of the branches are tapered. A plant may be about 0.5-1 m tall, with about 12 orders of branching, and weigh up to 3 kg. The branches are buoyant in the water due to the production of oxygen inside the plant. Older branches are dark green, while the tips and newer branches are a bright lighter green. Dead branches are whitish-yellow and resemble thick spaghetti. This species has many descriptive common names, including 'Dead-Man's Fingers', 'Green Fleece', Sponge Weed', 'Sponge Fingers', ‘Sputnik Weed’, 'Staghorn Weed' and 'Oyster Thief'. Oyster Thief describes the tendency of the oxygen-filled weeds to float and carry away oysters, while Sputnik Weed refers to its mysterious appearance around Long Island in 1957, soon after the launching of the Russian satellite.
The body of a green alga is called a thallus, a mass of undifferentiated filaments ('siphons'). In the genus Codium, the thallus is thick and spongy, and formed into the distinctive dichotomous branches. The internal structure of the thallus is comprised of a medulla, densely packed colorless siphons, surrounded by a green palisade-like layer of vesicles called utricles. The siphons are coenocytic and lack walls between the cells. The uitricles are the outer tips of these filaments. The holdfast is composed of a web of rhizoids (root-like filaments). The utricles in C. fragile are club-shaped, with a small pointed tip. Utricles bear one or two hairs below the tip, 25-60 µm long, 50-600 µm long. The dense field of hairs gives the branches a fuzzy appearance. The growth form is highly variable. This description is based on: Silva 1955, Bold and Wynne 1978, Gosner 1978, Schneider and Searles 1991, Trowbridge 1998, Van Patten 2006, Fisheries and Oceans Canada 2011, and Guiry and Guiry 2016.
The genus Codium is challenging taxonomically. At least 130 species are recognized, mostly in tropical and subtropical zones (Appeltans et al. 2016). For example, the occurrence of C. fragile in Europe was overlooked for at least 50 years after its introduction, because of its similarity to the native European C. tomentosum (Provan et al. 2008). The taxonomy of C. fragile is also complex at the subspecies level. At least 17 subspecies have been recognized, from different parts of the world, but the status of these is uncertain. Codium fragile was originally described by Suringa, from specimens collected in Japan, in a book by Hariot et al. 1889 (cited by Provan et al. 2008). European specimens were identified as Codium fragile subspecies tomentosoides, based on the type from the Netherlands, collected in 1900 (Silva 1955). This name was widely applied to introduced populations in many parts of the world, including the East Coast of North America (Bouck and Morgan 1957), San Francisco Bay (Silva 1979), Australia (Campbell 1999), and New Zealand (Trowbridge 1998). A worldwide genetic survey of the subspecies of C. fragile concluded that the invasive C. f. subsp. tomentosoides was identical to the original type form, and should be known as C. f. subsp. fragile, or simply C. fragile (Provan et al. 2008; Guiry and Guiry 2016).
Specimens of three named geographical subspecies, including subsp. capensis from South Africa, subsp. novae-zelandiae from New Zealand, and subsp. tasmanicum proved to be C. fragile (Provan et al. 2008). One or more apparently native Codium species grow on the West Coast of North America from Alaska to Mexico, with a sporadic distribution on rocks of the outer coast. The apparently native plants have been known as C. f. subsp. californicum, and appear to be distinct from the introduced C. fragile growing in San Francisco Bay (Silva 1979; Trowbridge 1998; Miller et al. 2011). However, Provan et al. (2009) found that one herbarium specimen, marked as C. f. subsp. californicum from Washington State belonged with the other C. fragile populations. Armitage et al. (2017) did find that a small sample of C. f. ssp. californicum was geneticall distinct (Armitage et al. 2017). More extensive study of West Coast populations is needed.
Two nominal subspecies, C. f. subsp. atlanticum, and C. f. subsp. scandinavicum coexist with C. fragile in Europe and are of uncertain taxonomic and introduction status. They are not regarded as invasive. Codium fragile subsp. atlanticum is smaller (usually 15-25 cm high) and has much smaller utricle tips than typical C. fragile (Silva 1955). Some herbarium specimens, labelled as atlanticum were genetically distinct, while others matched typical C. fragile (Provan et al. 2008). One population, morphologically resembling atlanticum, was found in Malpeque Bay, Prince Edward Island, Canada (Hubbard and Garbary 2002). Codium fragile subsp. scandinavicum has a limited reported range in Norway and Sweden. Provan et al. (2008) found that herbarium specimens of scandinavicum were genetically identical to C. fragile. Both of these subspecies may be synonymous and are best regarded as ecotypes. ‘The degree of both genotypic variation reported (small) and phenotypic variation described (large) makes the described subspecies and varieties unsustainable and it would be better to recognize one variable species for all practical purposes.’ - Wendy Guiry (29 Dec. 2007, in Guiry and Guiry 2016). A recent moleclular analysis of the DNA barcoding marker tufA suggests that there at least 2 species within the Codium fragile clade, but the authors suggest hat more genetic research is needed to divide C. fragile into native and introduced clades throughout its worldwide range (Verbruggen et al. 2016).
Taxonomy
Taxonomic Tree
Kingdom: | Plantae | |
Phylum: | Chlorophycota | |
Class: | Chlorophyceae | |
Order: | Caulerpales | |
Family: | Codiaceae | |
Genus: | Codium | |
Species: | fragile |
Synonyms
Codium fragile ssp. tomentosoides (P. C. Silva, 1955)
Codium mucronotatum var. tomentosoides (Van Goor, 1923)
Acanthcodium fragile (Suringar in Hariot, 1889)
Codium fragile ssp. Atlanticum ( (A.D.Cotton) P.C.Silva, 1912)
Codium fragile ssp. Scandinavicum (P. C. Silva, 1957)
Potentially Misidentified Species
Native to Western Atlantic south of Cape Hatteras to Puerto Rico (Schneider and Seales 1991)
Codium decorticatum
Native to Western Atlantic south of Cape Hatteras to Puerto Rico (Schneider and Seales 1991)
Codium fragile ssp. californicam
Native to Northeast Pacific, Alaska to Baja California (Miller et al. 2011)
Codium ishthmocladium
Native to Western Atlantic south of Cape Hatteras to Brazil (Schneider and Seales 1991)
Codium taylorii
Native to Western Atlantic south of Cape Hatteras to Brazil, also Canary Island and West Africa (Schneider and Seales 1991)
Codium tomentosum
Native in European Atlantic waters (Silva 1955)
Ecology
General:
Sexual reproduction in Codium fragile takes place through the production and release of flagellated swarmers (zoospores). In other species of Codium, reproduction is anisogamic and usually dioecious, with female plants producing spores and males producing smaller spores. The spores are produced by gametangia, reproductive structures protruding from the surface of the utricle. Female gametangia are dark green and lumpy, while male gametangia have an even outline and are brightly-colored (Bold and Wynne 1978). True C. fragile are monecious (Trowbridge 1998; Prince and Trowbridge 2004). Populations of C. fragile in Long Island Sound, Europe, and Japan, reproduce by stem fragmentation and by release of zoospores, of roughly equal size and believed to be female. One population in the Northwest Atlantic (Appledore Island, Maine) produces gametes (Prince 1988). Germination of the spores of all these populations occurred without the fusion of gametes and so was parthogenetic (Ramus 1971; Churchill and Moeller 1972; Bulleri et al. 2007). In Long Island Sound, the release occurs from May to September (Churchill and Moeller 1972). The spores settle and germinate about 24 hours after release and grow into masses of filaments. Mechanical shaking was necessary for growth of primordia in culture, suggesting that tides and currents are needed to stimulate growth (Ramus 1972). In Rhode Island populations, fragmentation was most common in winter, but these winter fragments are probably not viable (Hanisak 1979). In Nova Scotia populations, fragmentation occurred in summer, as a result of wave stress, and these fragments functioned as propagules (Bégin et al. 2003). Strong light exposure results in accumulation of oxygen in the thalli, and favors long-distance dispersal and colonization by the fragments (Gagnon et al. 2014).
Codium fragile is tolerant of a wide range of temperatures (-2-30°C) and salinities (12-42 PSU) (Malinowski and Ramus 1973; Hanisak 1979), but has not colonized tropical regions. It has colonized a wide range of habitats, including rocky and cobble shores, driftwood, jetties, breakwaters, seawalls, docks, piers, and floats. On soft bottoms, it grows on scattered stones and shells (Ramus 1971; Gosner 1978; Bulleri and Airoldi 2005; Geraldi et al. 2014). This seaweed has considerable tolerance to desiccation and extends into the lower intertidal zone. In experiments, it was able to survive periods of emersion of up to 90 days in high relative air humidity, leading to the likelihood on transport in fishnets, boat decks, or fouled shellfish (Schaffelke and Deane 2005). This seaweed quickly recovers normal photosynthesis after short (5-6 h) exposure to desiccation or freshwater (Kim and Garbary 2007). Codium fragile has colonized kelp beds, particularly after disturbance by storms, herbivores such as sea urchins, or the killing of kelps by the invading bryozoan Membranipora membranacea (Harris and Mathieson 2000; Chapman et al. 2002; Scheibling and Gagnon 2006). Eelgrass (Zostera marina) beds are also invaded by C. fragile, often growing on stones or shells (Ramus 1971), but also attaching to roots and rhizomes of the plant. Garbary et al. (2004) has described a growth form which attaches to eelgrass and sends out horizontal axes and vertical branches.
Growth rates of Codium fragile, at an optimum temperature, were greatest at low to moderate light intensities, 30-90 µE m-3s-1, and long photoperiods, 16h L: 8h D, or 24 h L, but fell off a bit at high intensities (150, µE m-3s-1), suggesting best growth under summer conditions. Total daily irradiance, rather than photoperiod appears to be the major feature of light that affects growth. On a daily basis, at 24 C growth rates stopped increasing above 4 µE m-3s-1 (Hanisak 1979). Sporelings were more sensitive to light, with growth saturating at 1.2 µE m-3s-1 -day and declining above 4 µE m-3s-1 -day (Hanisak 1979). Nitrate, nitrite, ammonium, and urea were equally good as nitrogen sources (Hanisak 1979).
Codium fragile is a potentially important food item for marine herbivores, a substrate for epiphytes and epifauna, and a refuge for mobile animals. For some generalist herbivores, it is a low-quality food, however. Herbivores feeding or growing poorly on this alga include the amphipod Ampithoe longimana (Cruz-Rivera and Hay 2001) and the Green Sea Urchin Strongylocentrotus droebachiensis (Prince and LeBlanc 1992; Scheibling and Anthony 2001). However, the introduced Asian Shore Crab Hemigrapsus sanguineus preferred C. fragile and Ulva spp. to Chondrus crispus, Fucus spp., and Ascophyllum nodosum (Bourdeau and O'Connor 2003). Grazing by the introduced Common Periwinkle (Littorina littorea) may control C. fragile in the intertidal zone (Scheibling et al. 2008). Saccoglossan seaslugs include specialized herbivores on green algae. Placida dendritca (probably a complex of several cryptic species) is a major herbivore on Codium fragile in the Gulf of Maine (Bleakney 1989; Trowbridge et al. 1998; Harris and Jones 2005).
Consumers:
Placida dendritica (sea slug)
Trophic Status:
Primary Producer
PrimProdHabitats
General Habitat | Grass Bed | None |
General Habitat | Unstructured Bottom | None |
General Habitat | Oyster Reef | None |
General Habitat | Marinas & Docks | None |
General Habitat | Rocky | None |
Salinity Range | Polyhaline | 18-30 PSU |
Salinity Range | Euhaline | 30-40 PSU |
Tidal Range | Subtidal | None |
Tidal Range | Low Intertidal | None |
Vertical Habitat | Epibenthic | None |
Life History
Tolerances and Life History Parameters
Minimum Temperature (ºC) | -2 | Field data, New England (Malinowski and Ramus 1972) |
Maximum Temperature (ºC) | 30 | Experimental data growth of thalli (Hanisak 1979) |
Minimum Salinity (‰) | 12 | Experimental data, growth of thalli at 24 C (Hanisak 1979) |
Maximum Salinity (‰) | 42 | Experimental data, growth of thalli at 24 C ( (Hanisak 1979) |
Minimum Reproductive Temperature | 12 | Experimental data, growth of sporelings (Hanisak 1979) |
Maximum Reproductive Temperature | 24 | Experimental data, growth of sporelings (Hanisak 1979) |
Minimum Reproductive Salinity | 18 | Experimental data, growth of sporelings (Hanisak 1979) |
Maximum Reproductive Salinity | 48 | Experimental data, growth of sporelings (Hanisak 1979) |
Maximum Length (mm) | 1,000 | More typically to 500 mm or less (Silva 1955; Gosner 1978; Schneider and Searles 1991; Van Patten 2006) |
Broad Temperature Range | None | Cold temperate-Warm temperate |
Broad Salinity Range | None | Polyhaline-Euhaline |
General Impacts
Codium fragile is widely regarded as a troublesome invader. The DAISIE website lists it as one of the '100 worst' invaders in Europe (DAISIE 2009), as does a species list for the Mediterranean (Streftaris and Zeneros 2006). Common economic impacts include interference with fishing gear and aquaculture, and aesthetic impacts on recreation, due to masses of the slimy weed washed up on beaches (Ramus 1971; Boudouresque 1994). Codium fragile's invasion of productive marine habitats such as kelp and seagrass beds may have impacts on fisheries, but these are difficult to measure (Ramus 1971; Schmidt and Sheibling 2006; Kelly et al. 2011).
Economic Impacts
Fisheries - Codium fragile can attach to shellfish, interfering with movement in scallops and causing shellfish, mussels, and oysters to be washed ashore with the buoyant seaweed (Ramus 1971). The weed also frequently fouls fishing lines and nets in shallow waters (Galtsoff 1964; Boudouresque 1994; Campbell 1999; Garbary et al. 2004). In Chile, it overgrew red algae (Gracilaria chilensis), being cultured for agar, reducing the harvest of the crop (Neill et al. 2006).
Aesthetic - Accumulations of Codium fragile on beaches are unattractive and unpleasant to walk on, perhaps more so than most seaweeds. On public beaches, the seaweeds are regularly removed by cleaning crews (Fofonoff personal observation). On French Mediterranean beaches, in the 1960s, blooms of C. fragile washed ashore, and had to be removed with heavy equipment (Boudouresque 1994).
Ecological Impacts
Competition - In invaded areas, C. fragile has often been reported to invade native plant communities and to partially replace native species. The extent of this competition seems to vary greatly in different regions and different plant communities. It appears to do best as a colonizer of bare surfaces, such as artificial structures, and areas cleared by storms, grazers (such as sea urchins), or the overgrowing bryozoan Membranipora membranacea, and rarely invades areas of undisturbed, established vegetation, such as kelp or seagrass beds (Malinowski and Ramus 1973; Harris and Tyrell 2001; Chapman et al. 2002; Scheibling et al. 2006). Its advantages over native seaweeds include rapid growth and longevity, since most native marine plants are annuals. It rapidly responds to added nutrients, giving it an advantage in eutrophic areas (Ramus 1971). In European waters, it was reported to be replacing the native C. tomentosum and C. vermilaria (Farnham 1980), but in a later survey, native Codium were found to dominate on natural surfaces, while C. fragile dominated on docks and breakwaters (Trowbridge and Farnham 2009). A similar pattern was seen in North Carolina, with C. fragile replacing the native C. decorticatum on artificial substrates (concrete, bulkheads, and granite seawalls), while the native species remains abundant on natural substrates such as oysters (Geraldi et al. 2014).
Habitat Change - Codium fragile is an 'ecosystem engineer', and can alter coastal habitats in multiple ways, especially in regions like the Northeast coast of North America, where no native Codium is present, and where no other alga has a similar growth form. Codium fragile, and its buoyant branches, can interfere with the movement of scallops, help waves wash mussels and stones on to beaches, and float oysters away from their beds (Ben-Avraham 1971; Ramus 1971). On the other hand, they also provide a substrate for epiphytes and epifauna, and a refuge for mobile prey, although often differing in structure, food quality, and physical characteristics from native seaweeds and sea grasses.
Codium fragile is widely thought to provide inferior habitat to native seaweeds and seagrasses, but the evidence for this is mixed. Codium fragile in the Gulf of Maine replaced kelp canopy with less favorable habitat and supported fewer juvenile fishes (Cunner, Tautogolabrus adspersus). This was attributed to the inferior food quality of C. fragile, and a scarcity of epiphytes (Levin et al. 2002). However, experiments elsewhere suggest more complex effects, with different species responding differently to changes in plant communities. In Narragansett Bay, C. fragile supported a more diverse and dense community of native and introduced epiphytic algae, than the native algae Fucus vesiculosus (Jones and Thornber 2005). In Cranberry Cove, Nova Scotia, C. fragile had a greater density (but not diversity) of epiphytes than kelps (Laminaria spp.). The differing structure of a C. fragile canopy permits greater survival of juvenile fishes and crabs than in barren regions or kelp beds (Schmidt and Scheibling 2006). However, these changes were transient in regions off Nova Scotia, where the large growths of C. fragile were removed by winter storms and recolonized by native kelps (Kelly et al. 2011). Small bivalves and amphipods were most abundant in the C. fragile-dominated state, compared to amphipods and small gastropods in the kelp-dominated state (Kelly et al. 2011). In Magdalen Islands, Quebec, eelgrass beds (Zostera marina) had greater diversity and abundance of invertebrates and fishes when invaded by C. fragile (Drouin et al. 2011). In the Adriatic Sea, C. fragile increased the recruitment and survival of Mediterranean Mussels (Mytlilus galloprovincialis) on breakwaters, offering an irregular surface, colonized by filamentous epiphytic algae, favorable for settlement, and buffering mussels from thermal stress and desiccation (Bulleri et al. 2006).
Food/Prey - For many generalized herbivores C. fragile is an inferior food. However, it can support edible epiphytic algae and it also hosts some saccoglossan slugs, which are green-alga-specialists (Trowbridge 1988). Among East Coast species showing poor feeding, growth, or reproduction on C. fragile were the snail Lacuna vincta (Northern Lacuna), the amphipod Ampithoe longimana (Cruz-Rivera and Hay 2001), and the Green Sea Urchin Strongylocentrotus droebachiensis (Prince and LeBlanc 1992; Scheibling and Anthony 2001). However, the introduced Asian Shore Crab Hemigrapsus sanguineus preferred C. fragile to several native seaweeds (Bourdeau and O'Connor 2003). The herbivorous saccoglossan sea-slug Pacifia dendritica feeds on C. fragile, and can control the seaweed's populations, but is vulnerable to predators, including the introduced Green Crab (Carcinus maenas) (Harris and Jones 2005). This cosmopolitan sea slug (probably a species complex) may have been present, but rare on the East Coast, before the Codium invasion, but is now abundant (Bleakney 1989; Harris and Jones 2005).
Occurrence Map
OCC_ID | Author | Year | Date | Locality | Status | Latitude | Longitude |
---|---|---|---|---|---|---|---|
756385 | Introduced Species Study | 2005 | 2005-07-06 | Coyote Point | Non-native | 37.5920 | -122.3210 |
756386 | Introduced Species Study | 2005 | 2005-07-08 | Richmond Marina | Non-native | 37.9137 | -122.3504 |
756387 | Introduced Species Study | 2005 | 2005-09-09 | Coyote Point Marina | Non-native | 37.5905 | -122.3177 |
760772 | Cohen et al. 2005; University and Jepson Herbaria Specimen Portal Database 2018 | 2004 | 2004-05-23 | Brisbane Lagoon, San Francisco Bay | Non-native | 37.6862 | -122.3906 |
760773 | Cohen et al. 2005 | 2004 | 2004-05-25 | Presidio Yacht Club, San Francisco Bay | Non-native | 37.8326 | -122.4741 |
760774 | Cohen et al. 2005 | 2004 | 2004-05-26 | Richmond Marina Boat Ramp, San Francisco Bay | Non-native | 37.9139 | -122.3542 |
760775 | Cohen et al. 2005 | 2004 | 2004-05-27 | Coyote Point Marina, San Francisco Bay | Non-native | 37.5907 | -122.3180 |
760776 | Silva 1979; Carlton and Scanlon 1985; Carlton et al 1990 | 1977 | Coyote Point | Non-native | 37.5921 | -122.3211 | |
760777 | Josselyn and West 1985 | 1985 | Palo Alto | Non-native | 37.4633 | -122.1019 | |
760778 | Josselyn and West 1985 | 1985 | Redwood City, San Francisco Bay | Non-native | 37.5501 | -122.2287 | |
760779 | Josselyn and West 1985 | 1985 | Coyote Point | Non-native | 37.5921 | -122.3211 | |
760780 | Cohen and Carlton 1995 | 1993 | Pier 39, San Francisco Bay | Non-native | 37.8114 | -122.4109 | |
760781 | Cohen and Carlton 1995 | 1994 | Pier 39, San Francisco Bay | Non-native | 37.8114 | -122.4109 | |
760782 | Cohen and Carlton 1995 | 1993 | San Leandro, South San Francisco Bay | Non-native | 37.6946 | -122.1930 | |
760783 | Cohen and Carlton 1995 | 1994 | San Leandro, South San Francisco Bay | Non-native | 37.6946 | -122.1930 | |
760784 | Cohen and Carlton 1995 | 1993 | Richmond, Central San Francisco Bay | Non-native | 37.9078 | -122.3933 | |
760785 | Cohen and Carlton 1995 | 1994 | Richmond, Central San Francisco Bay | Non-native | 37.9078 | -122.3933 | |
760786 | Silva 1979; University and Jepson Herbaria Specimen Portal Database 2018 | 1977 | 1977-08-02 | Coyote Point | Non-native | 37.5921 | -122.3211 |
760787 | Silva 1979; University and Jepson Herbaria Specimen Portal Database 2018 | 1977 | 1977-12-06 | Coyote Point | Non-native | 37.5921 | -122.3211 |
760788 | Silva 1979; University and Jepson Herbaria Specimen Portal Database 2018 | 1975 | 1975-03-24 | Coyote Point | Non-native | 37.5921 | -122.3211 |
760789 | University and Jepson Herbaria Specimen Portal Database 2018 | 2004 | 2004-01-20 | Richmond Marina | Non-native | 37.9129 | -122.3492 |
760790 | University and Jepson Herbaria Specimen Portal Database 2018 | 1993 | Pier 39, San Francisco Bay | Non-native | 37.8114 | -122.4109 | |
760791 | University and Jepson Herbaria Specimen Portal Database 2018 | 1987 | 1987-07-07 | Berkeley Marina | Non-native | 37.8666 | -122.3151 |
760792 | University and Jepson Herbaria Specimen Portal Database 2018 | 1989 | 1989-12-10 | Coyote Point | Non-native | 37.5921 | -122.3211 |
760793 | University and Jepson Herbaria Specimen Portal Database 2018 | 1976 | 1976-12-12 | Robert W. Crown Memorial State Beach | Non-native | 37.7536 | -122.2506 |
760794 | Miller 2004 | 2004 | Tomales Bay | Non-native | 38.1664 | -122.9080 |
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