Styela clava

Invasion History

First Non-native North American Tidal Record: 1933
First Non-native West Coast Tidal Record: 1933
First Non-native East/Gulf Coast Tidal Record: 1970

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General Invasion History:

Styela clava is native to the Northwest Pacific, from Shanghai to the Sea of Okhotsk and the southeastern Bering Sea (Benyaminson, in Golikov et al. 1976; Nishikawa 1991). It has become widely distributed in coastal waters, through ship fouling and transport with oysters (Crassostrea gigas; Buizer 1980; Cohen and Carlton 1995; Lutzen 1999). The morphology of this tunicate, with its great attachment strength, and streamlined body, is well adapted for transport on the hulls of moving ships (Murray et al. 2012). In 1933, it was first collected in the Northeast Pacific in Newport Beach California, and has subsequently spread south to San Diego (in 1959), and north to San Francisco Bay (in 1949), Coos Bay Oregon (in 1993) and Vancouver Island, British Columbia (in 1995; Carlton and Cohen 1995). On the East Coast of North America, it was first collected in 1970 in Beverly, Massachusetts and Portsmouth, New Hampshire, and has subsequently spread south to Chincoteague, Virginia and north to Prince Edward Island and Nova Scotia (Berman et al. 1992; U.S. National Museum of Natural History 2002-2012; Locke et al. 2007; Paul Fofonoff, personal observations 2013; Moore et al. 2014). In the northeast Atlantic, it was recorded in Plymouth, England in 1953, and has subsequently spread east, along the southern North Sea to the Limfjord and Kattegat in Denmark and south to Portugal and a Mediterranean lagoon (Buizer 1999; Lutzen 1999; Davis and Davis 2005; Davis and Davis 2007). In 1972, it invaded Port Philip Bay, Australia, and in 1977, Sydney Harbour (Hewitt et al. 1999). In 2005, it was discovered in New Zealand (Biosecurity New Zealand 2005a; Biosecurity New Zealand 2005b).

North American Invasion History:

Invasion History on the West Coast:

Styela clava was first collected on the West Coast in Newport, California in 1933 (Carlton 1979) and in Elkhorn Slough in 1935 (Carlton 1979; Lambert and Lambert 1998; Wasson et al. 2001). Styela clava was found at Point Richmond, in San Francisco Bay, in 1949, King Harbor (Redondo Beach) and Mission Bay (San Diego) in 1971, and San Diego Bay in 1972 (Carlton 1979; Cohen and Carlton 1995; Lambert and Lambert 1998; Nichols et al. 2023)). It was also collected in 1972 in Morro Bay, but has not been seen there since (Carlton 1979; Needles 2007). Surprisingly, although it has been established for 50 years in San Francisco Bay, it has not been reported from nearby Tomales Bay (Fairey et al. 2002), and is a recent invader in Bodega Harbor and Humboldt Bay (reported in 2000, Boyd et al. 2002).

North of California, Styela clava was first reported in Coos Bay, Oregon in 1993 (Cohen and Carlton 1995), and Vancouver Island, British Columbia and Drayton Harbor, in Blaine, Washington (on Georgia Straits) in 1998 (Lambert 2003). In 2001, it was collected in Neah Bay, Juan de Fuca Straits, on the Olympic Peninsula, Washington (deRivera et al. 2005), and in 2005 in the Hood Canal, part of Puget Sound (Center for Aquatic Resource Studies 2009).

Invasion History on the East Coast:

In the Northwest Atlantic, Styela clava was first collected in 1970 in Beverly, Massachusetts and in Portsmouth Harbor, New Hampshire (Berman et al., 1992). South of Cape Cod, the earliest record appears to be from 1973, on Long Island (Carlton, 1989). It was established in Narragansett Bay by 1976 (Fofonoff, personal observation; Plough 1978), and is now found throughout southern New England (Whitlatch and Osman 2000; MIT Sea Grant 2003; Carman et al. 2007; Carman et al. 2009). In 1998 it was found in Kennebunkport and Boothbay Harbor, Maine (Whitlatch and Osman 2000), and in 2000, in Portland Harbor, Casco Bay, Maine. In 1998, S. clava appeared in the Brudenell River, Prince Edward Island, in the Gulf of St. Lawrence, Canada, where it has caused serious problems by fouling cultured mussels and the lines and racks used in their rearing (Locke et al. 2007). This tunicate has spread to several estuaries on Prince Edward Island (Ramsay et al. 2008; Arsenault et al. 2009). In 2012-2013, it was found at several sites in the Canso Canal, between the mainland of Nova Scotia and Cape Breton Island, and on the Atlantic coast of Nova Scotia, in Halifax and Lunenburg harbors (Moore et al. 2014). 

The southern extent of the range of S. clava is poorly known. It has been found in a New Jersey coastal inlet ~50 km north of Cape May (McDermott, personal communication, 1999). In November 2003, several S. clava were found washed ashore on Cape Henlopen, at the mouth of Delaware Bay (Fofonoff, unpublished data). In the Chesapeake Bay region, in 1994, a single specimen of S. clava (Catalog number 20711) was collected in Chincoteague VA (U.S. National Museum of Natural History 2002; Linda Cole, personal communication). We have not collected this species in Chesapeake Bay proper, but in 2013 we found established populations in the Indian River Inlet, Delaware; Ocean City Inlet, Maryland; and Chincoteague Inlet, Virginia (Paul Fofonoff and Kristen Larson, personal observations).

Invasion History Elsewhere in the World:

In Europe, Styela clava was first collected during 1953 in Plymouth, England, where it was mistakenly described as a new species, S. mammiculata (Carlsile 1954 cited by Lutzen 1999). It spread east along the English Channel (record in 1957 from Southampton) and across to France (record in 1968 from Dieppe) into the North Sea (record in 1974 from Den Helder, Netherlands) and to Denmark by 1991 (Buizer 1980; Lutzen 1999). In Ireland, it was first collected in Cork Harbor in 1971, and has spread north to a marina near Dublin on the Irish Sea, and to Kerry on the Atlantic Coast (Minchin et al. 2006). Styela clava spread south along the Atlantic coast of Europe, reaching Brest and Roscoff in Brittany in 1973 (Lutzen 1999) and Arcachon, France on the Bay of Biscay (Davis and Davis 2005). It now occurs at many locations on the Biscay and Atlantic coasts of Spain, with a current southern limit at Cascais, Portugal (Davis and Davis 2005). In 2006, it was found in a lagoon (Bassin de Thau) in Sete, France on the Mediterranean Sea. This basin is used intensively for oyster culture (Davis and Davis 2008). In 2004, S. clava was reported in Romanian waters of the Black Sea, as a 'casual' fouling organism, presumably not established (Micu and Micu 2004, cited by Skolka and Preda 2010). In 2012, an established population was found in the Sea of Marmara, Turkey, connecting the Black and Mediterranean Seas (Cinar 2016).

In 1972, Styela clava was found in Port Phillip Bay, Victoria, Australia, where it has become quite abundant. In 1977, it was found in Sydney Harbour, New South Wales. However, S. clava was not found in a 2000 port survey (Australian Museum Business Services 2002). In 2005, S. clava was found in several locations in New Zealand, including Auckland, Littleton, and Christchurch (Biosecurity New Zealand 2005a).

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Description

Styela clava is a solitary tunicate with a leathery, but thin, and bumpy tunic. Its body is cylindrical or club-shaped and narrows posteriorly to a stalk that is anchored to the substrata by a disk shaped holdfast. The wrinkled or creased looking stalk is often 20-50% of the total body length. Styela clava can grow up to 150 mm in length. Colors can range from yellowish to reddish to brownish. The oral and atrial siphons are located close together and are directed anteriorly. Both siphons have four lobes and appear striped with alternating dark and light brownish to purplish bands (Kott 1985; Nishikawa 1991; Lambert 2003).

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Taxonomy

Ecology

General:

Life History- A solitary tunicate is ovoid, elongate or vase-like in shape, with two openings or siphons. Most solitary tunicates attach to substrates by their side or base, but some attach with a conspicuous stalk. They are sessile filter feeders with two siphons, an oral and an atrial siphon. Water is pumped in through the oral siphon, where phytoplankton and detritus is filtered by the gills, and passed on mucus strings to the stomach and intestines. Waste is then expelled in the outgoing atrial water.

Solitary ascidians are hermaphroditic, meaning that both eggs and sperm are released to the atrial chamber. Eggs may be self-fertilized or fertilized by sperm from nearby animals, but many species have a partial block to self-fertilization. Depending on the species, eggs may be externally or internally fertilized. In external fertilizers, eggs and sperm are released through the atrial siphon into the surrounding water column were fertilization takes place. In internal fertilizers, eggs are brooded and fertilized within the atrial chamber and then released into the water column upon hatching. Fertilized eggs hatch into a tadpole larva with a muscular tail, notochord, eyespots, and a set of adhesive papillae. The lecithotrophic (non-feeding, yolk-dependent) larva swims briefly before settlement. Swimming periods are usually less than a day and some larvae settle immediately after release, but the larval period can be longer at lower temperatures. Once settled, the tail is absorbed, the gill basket expands, and the tunicate begins to feed by filtering (Barnes 1983).

In all part of its native and introduced range, S. clava is more frequently reported from anthropogenic stuctures than from natural surfaces, (Simkanin et al. 2012). Dock floats are especially favored habitats, probably because their motion provides rapid water exchange, and a fresh supply of food-laden water (Glasby 2001). Other colonized man-made structures include pilings, piers, aquaculture structures, and boat hulls (Carman et al. 2010; Davidson et al. 2010; Simkanin et al. 2012). Natural habitats include rocky reefs, bivalve colonies, seaweeds, (White and Orr 2011; Simkanin et al. 2012).

Food:

Phytoplankton

Consumers:

snails, fish, crabs, urchins

Trophic Status:

Suspension Feeder

SusFed

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Habitats

General Habitat	Coarse Woody Debris	None
General Habitat	Oyster Reef	None
General Habitat	Marinas & Docks	None
General Habitat	Rocky	None
General Habitat	Vessel Hull	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

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Life History

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Tolerances and Life History Parameters

Minimum Temperature (ºC)	-2	Field data, Denmark (Lutzing 1998)
Maximum Temperature (ºC)	26.6	Field data, Thau Lagoon, France (Davis and Davis 2009)
Minimum Salinity (‰)	18	Experimental data; animals from Denmark, transferred stepwise (Lutzen 1998).
Maximum Salinity (‰)	35	Field data (Lutzen 1998, experimental data (Sims 1984, highest tested)
Minimum Reproductive Temperature	15	Field data, Davis and Davis 2007; Wong et al. 2011
Maximum Length (mm)	90	Kott 1985; Nishikawa 1991; Lambert 2003
Broad Temperature Range	None	Cold temperate-Warm temperate
Broad Salinity Range	None	Polyhaline-Euhaline

General Impacts

Economic Impacts

Fisheries: The largest economic impacts of Styela clava have been seen in Prince Edward Island, Canada, where dense populations of tunicates have fouled cages used for fish aquaculture, and ropes, racks, and other gear used in mussel culture (Locke et al. 2007; Arsenault et al. 2009). The tunicates compete with cultured mussels, reducing mussel harvests by ~50%. The estimated economic impact is 34-88 million $CAN per year (Coulatti et al. 2006). Another negative potential impact of S. clava and other tunicates is that when they foul aquaculture gear and boats, they can retain and transport viable cells and cysts of toxic phytoplankton (Rosa et al. 2013). On the positive side, S. clava is a popular food item in Korea. Styela clava and S. plicata are extensively cultured on long lines in Korea and Japan (Lambert et al. 2016). Fisheries for S. clava, in New England, for the Korean market appear feasible (Karney and Rhee 2009).

Shipping and Industry: Styela clava can grow in very dense populations on boat hulls, docks, fishing gear, and aquaculture equipment.

Ecological Impacts

Competition: Styela clava typically grows in dense populations, dominating large patches in fouling communities. Styela clava is abundant in Southern California harbors, often forming dense patches with 100% cover (Lambert and Lambert 1998; Lambert and Lambert 2003). It and other introduced ascidians have replaced the native species Pyura haustor and Ascidia ceratodes from southern California harbors (Lambert and Lambert 1998). It covered 18.5% of fouling plate surfaces in one-year old assemblages near Avery Point, Connecticut, Long Island Sound (Altman and Whitlatch 2007). It can reduce the growth rate of co-occurring species through its intense filtration of the water column (Osman and Whitlatch 2000). In English waters, the population growth of S. clava was paralleled by a decrease in Ciona intestinalis (Lutzen 1999). Styela clava grows in very dense populations in Port Phillip Bay, Australia, apparently displacing other fouling organisms. Because of its high filtering rate, it was expected to compete for food with other suspension-feeding taxa (Currie et al. 1999); however, this effect was not seen in the experiments conducted by Ross et al. (2007).

Habitat Change: The dense aggregations frequently formed by Styela clava exclude other organisms but also provide secondary substrate for other fouling organisms. The tunics of S. clava are frequently fouled by colonial tunicates. In experimental studies, soft sediment fauna from Port Phillip Bay, Australia, showed idiosyncratic responses to increased Styela density, with crustaceans and tanaids, decreasing, while the deposit-feeding bivalve Laternula rostrata increased (Ross et al. 2007).

Predation: Styela clava can inhibit settlement of co-occurring fouling organisms through predation on planktonic larvae, as a result of high filtering rates (Osman and Whitlatch 2000).

Food/Prey: Newly settled S. clava in Long Island Sound are prone to intense predation by the snails Astyris lunata (= Mitrella lunata) and Costoanachis translirata (= Anachis lafresnayi of authors) (Osman and Whitlatch 2000; Whitlatch and Osman 2009). Older juveniles are subject to predation by fishes, mostly Tautog (Tautoga onitis) and Cunner (Tautogolabrus adspersus) (Osman and Whitlatch 2000).

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Regional Impacts

NEP-V	Northern California to Mid Channel Islands		Economic Impact	Fisheries
Common oyster fouling organism (Carlton 1979)
NEP-V	Northern California to Mid Channel Islands		Economic Impact	Shipping/Boating
Common hull and dock fouling oganism (Carlton 1979)
P090	San Francisco Bay		Economic Impact	Shipping/Boating
Common dock and hull fouling organism.
M040	Long Island Sound		Ecological Impact	Competition
Styela clava is frequently abundant and often the dominant fouling organism in harbors. It covered 18.5% of fouling plate surface in one-year old assemblages near Avery Point, CT (Altman and Whitlatch 2007). It can reduce the growth rate of co-occurring species through its intense filtration of the water column (Osman and Whitlatch 2000).
NA-S3	None		Economic Impact	Fisheries
Fouling of aquaculture cages (Arsenault et al. 2009). Competition with cultured mollusks for food and space. Reduces mussel harvests by ~50%, estimated impact 34-88 miliion $CAN per year (Coulatti et al. 2006).
NA-ET3	Cape Cod to Cape Hatteras		Ecological Impact	Competition
Styela clava is frequently abundant and often the dominant fouling organism in harbors. It covered 18.5% of fouling plate surfaces in one-year old assemblages near Avery Point, Connecticut, Long Island Sound (Altman and Whitlatch 2007). It can reduce the growth rate of co-occurring species through its intense filtration of the water column (Osman and Whitlatch 2000). Styela clava is abundant in harbors with varying water quaility, including those with poor, fair and good quality (Carman et al. 2007).
NA-ET2	Bay of Fundy to Cape Cod		Economic Impact	Fisheries
Farming Styela clava for the Korean market appears feasible (Karney and Rhee 2009).
NA-S3	None		Ecological Impact	Competition
Competition with cultured mussels for food and space (Coulatti et al. 2006; Gittenberger 2009; Comeau et al. 2015).
NA-ET3	Cape Cod to Cape Hatteras		Ecological Impact	Predation
Styela clava can inhibit settlement of co-occurring fouling organisms through predation on planktonic larvae, as a result of high filtering rates (Osman and Whitlatch 2000).
AUS-VIII	None		Ecological Impact	Habitat Change
In experimental studies with various densities of Styela clava, fauna from Port Phillip Bay showed idiosyncratic responses to increased Styela density, with crustaceans, and tanaids, as a group decreasing, while the deposit-feeding bivalve Laternula rostrata increased. These changes appeared to be due to subtle changes in hydrodynamics, sediment quality, emigration or altered survival in Styela rather than community-wide effects (Ross et al. 2007).
NEP-VI	Pt. Conception to Southern Baja California		Ecological Impact	Competition
Styela clava is abundant in Southern California harbors, often forming dense patches with 100% cover (Lambert and Lambert 1998; Lambert and Lambert 2003). It and other introduced ascidians have replaced the native species Pyura haustor and Ascidia ceratodes in southern California harbors (Lambert and Lambert 1998).
P020	San Diego Bay		Ecological Impact	Competition
Styela clava is abundant in Southern California harbors, often forming dense patches with 100% cover (Lambert and Lambert 1998; Lambert and Lambert 2003). It and other introduced ascidians have replaced the native species Pyura haustor and Ascidia ceratodes in southern California harbors (Lambert and Lambert 1998).
P030	Mission Bay		Ecological Impact	Competition
Styela clava is abundant in Southern California harbors, often forming dense patches with 100% cover (Lambert and Lambert 1998; Lambert and Lambert 2003). It and other introduced ascidians have replaced the native species Pyura haustor and Ascidia ceratodes in southern California harbors (Lambert and Lambert 1998).
P023	_CDA_P023 (San Louis Rey-Escondido)		Ecological Impact	Competition
Styela clava is abundant in Southern California harbors, often forming dense patches with 100% cover (Lambert and Lambert 1998; Lambert and Lambert 2003). It and other introduced ascidians have replaced the native species Pyura haustor and Ascidia ceratodes in southern California harbors (Lambert and Lambert 1998).
P027	_CDA_P027 (Aliso-San Onofre)		Ecological Impact	Competition
Styela clava is abundant in Southern California harbors, often forming dense patches with 100% cover (Lambert and Lambert 1998; Lambert and Lambert 2003). It and other introduced ascidians have replaced the native species Pyura haustor and Ascidia ceratodes in southern California harbors (Lambert and Lambert 1998).
P040	Newport Bay		Ecological Impact	Competition
Styela clava is abundant in Southern California harbors, often forming dense patches with 100% cover (Lambert and Lambert 1998; Lambert and Lambert 2003). It and other introduced ascidians have replaced the native species Pyura haustor and Ascidia ceratodes in southern California harbors (Lambert and Lambert 1998).
P050	San Pedro Bay		Ecological Impact	Competition
Styela clava is abundant in Southern California harbors, often forming dense patches with 100% cover (Lambert and Lambert 1998; Lambert and Lambert 2003). It and other introduced ascidians have replaced the native species Pyura haustor and Ascidia ceratodes in southern California harbors (Lambert and Lambert 1998).
P060	Santa Monica Bay		Ecological Impact	Competition
Styela clava is abundant in Southern California harbors, often forming dense patches with 100% cover (Lambert and Lambert 1998; Lambert and Lambert 2003). It and other introduced ascidians have replaced the native species Pyura haustor and Ascidia ceratodes in southern California harbors (Lambert and Lambert 1998).
P062	_CDA_P062 (Calleguas)		Ecological Impact	Competition
Styela clava is abundant in Southern California harbors, often forming dense patches with 100% cover (Lambert and Lambert 1998; Lambert and Lambert 2003). It and other introduced ascidians have replaced the native species Pyura haustor and Ascidia ceratodes in southern California harbors (Lambert and Lambert 1998).
P064	_CDA_P064 (Ventura)		Ecological Impact	Competition
Styela clava is abundant in Southern California harbors, often forming dense patches with 100% cover (Lambert and Lambert 1998; Lambert and Lambert 2003). It and other introduced ascidians have replaced the native species Pyura haustor and Ascidia ceratodes in southern California harbors (Lambert and Lambert 1998).
P065	_CDA_P065 (Santa Barbara Channel)		Ecological Impact	Competition
Styela clava is abundant in Southern California harbors, often forming dense patches with 100% cover (Lambert and Lambert 1998; Lambert and Lambert 2003). It and other introduced ascidians have replaced the native species Pyura haustor and Ascidia ceratodes in southern California harbors (Lambert and Lambert 1998).
M040	Long Island Sound		Ecological Impact	Predation
Styela clava can inhibit settlement of co-occurring fouling organisms through predation on planktonic larvae, as a result of high filtering rates (Osman and Whitlatch 2000).
M040	Long Island Sound		Ecological Impact	Food/Prey
Newly settled Styela clava in Long Island Sound are prone to intense predation by the snails Astyris lunata (= Mitrella lunata) and Costoanachis translirata (= Anachis lafresnayi of authors) (Osman and Whitlatch 2000; Whitlatch and Osman 2009). Older juveniles are subject to predation by fishes, mostly Tautog (Tautoga onitis) and Cunner (Tautogolabrus adspersus; Osman and Whitlatch 2000).
M010	Buzzards Bay		Ecological Impact	Competition
Styela clava is abundant in harbors with poor and fair as well as good water quality (Carman et al. 2007).
N185	_CDA_N185 (Cape Cod)		Ecological Impact	Competition
Styela clava is abundant in harbors with poor and fair as well as good water quality (Carman et al. 2007).
NEA-II	None		Ecological Impact	Competition
Populations increased 'explosively' in the Eastern Scheldt, presumably displacing native species (Buizer 1980). In English waters, the population growth of S. clava was paralelled by a decrease in Ciona intestinalis (Lutzen 1999).
NA-ET3	Cape Cod to Cape Hatteras		Ecological Impact	Food/Prey
Newly settled Styela clava in Long Island Sound are prone to intense predation by the snails Astyris lunata (= Mitrella lunata) and Costoanachis translirata (= Anachis lafresnayi of authors) (Osman and Whitlatch 2000; Whitlatch and Osman 2009). Older juveniles are subject to predation by fishes, mostly Tautog (Tautoga onitis) and Cunner (Tautogolabrus adspersus; Osman and Whitlach 2000).
AUS-VIII	None		Ecological Impact	Competition
Styela clava grows in very dense populations in Port Phillip Bay, apparently displacing other fouling organisms. Because of its high filtering rate, it was expected to compete for food with other suspension-feeding taxa (Currie et al. 1999). This was not seen in experiments conducted by Ross et al. (2007).
N195	_CDA_N195 (Cape Cod)		Economic Impact	Fisheries
Styela clava was found fouling aquaculture gear at 21 sites, and cultured Bay Scallops (Aequipecten irradians) at two sites, of 26 aquaculture sites surveyed on Marthas Vineyard (Carman et al. 2010). This tunicate was also reported at aquaculture sites in Rhode Island (Carman et al. 2010).
NA-ET3	Cape Cod to Cape Hatteras		Economic Impact	Fisheries
Styela clava was found fouling aquaculture gear at 21 sites, and cultured Bay Scallops (Aequipecten irradians) at two sites, of 26 aquaculture sites surveyed on Marthas Vineyard (Carman et al. 2010). Styela clava was also reported to be fouling aquaculture sites in Rhode Island and New York state (Carman et al. 2010).
N195	_CDA_N195 (Cape Cod)		Ecological Impact	Competition
Styela clava is abundant in harbors with poor and fair as well as good water quality (Carman et al. 2007)
NEA-II	None		Economic Impact	Shipping/Boating
Fouling impacts fave been reported for the British Isles (Minchin et al. 2013).
SA-I	None		Ecological Impact	Habitat Change
Styela clavad facilitated the invasion of the seaweed Undaria pinnatifida by providing an attachment site for sporelings (Pereyra et al. 2015;Pereyra et al. 2017)
NEA-III	None		Economic Impact	Fisheries
Fouling of cultured mussels by a variety of non-native tunicates was reported beginning in 2013, and was a serious problem by 2016 (Palanisamy et al. 2018).
NZ-IV	None		Economic Impact	Fisheries
The impact of Styela clava on Greenshell Mussel (Perna canaliculus) aquaculture in New Zealand was estimated at NZ $23.9 million (Soliman and Inglis 2018).
CA	California		Ecological Impact	Competition
Styela clava is abundant in Southern California harbors, often forming dense patches with 100% cover (Lambert and Lambert 1998; Lambert and Lambert 2003). It and other introduced ascidians have replaced the native species Pyura haustor and Ascidia ceratodes in southern California harbors (Lambert and Lambert 1998)., Styela clava is abundant in Southern California harbors, often forming dense patches with 100% cover (Lambert and Lambert 1998; Lambert and Lambert 2003). It and other introduced ascidians have replaced the native species Pyura haustor and Ascidia ceratodes in southern California harbors (Lambert and Lambert 1998).,
CA	California		Economic Impact	Shipping/Boating
Common hull and dock fouling oganism (Carlton 1979), Common dock and hull fouling organism.
CA	California		Economic Impact	Fisheries
Common oyster fouling organism (Carlton 1979)
MA	Massachusetts		Ecological Impact	Competition
Styela clava is abundant in harbors with poor and fair as well as good water quality (Carman et al. 2007)., Styela clava is abundant in harbors with poor and fair as well as good water quality (Carman et al. 2007)., Styela clava is abundant in harbors with poor and fair as well as good water quality (Carman et al. 2007)
MA	Massachusetts		Economic Impact	Fisheries
Styela clava was found fouling aquaculture gear at 21 sites, and cultured Bay Scallops (Aequipecten irradians) at two sites, of 26 aquaculture sites surveyed on Marthas Vineyard (Carman et al. 2010). This tunicate was also reported at aquaculture sites in Rhode Island (Carman et al. 2010).

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