Rapana venosa

Invasion History

First Non-native North American Tidal Record: 1952
First Non-native West Coast Tidal Record: 1952
First Non-native East/Gulf Coast Tidal Record: 1998

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General Invasion History:

Rapana venosa is native to the Northeast Pacific, from the southern Pacific coast of Russia, to the Sea of Japan, Yellow Sea, and East China Sea (Golikov et al. 1976; Mann and Harding 2000). In 1947, it was first collected from the Black Sea, in Novorossiysk Bay, where it was probably transported by ships. Within a decade, it dispersed widely in the Black Sea and entered the Sea of Azov (Chukhchin 1984; Zolotarev 1996; Mann and Harding 2000). Between 1977 and 1984, it colonized the westernmost Black Sea and the Sea of Marmara (Turkey) (Kinzelbach 1986). Subsequently, R. venosa has colonized widely separated areas, probably by ship transport. In 1998, it appeared in Chesapeake Bay, Virginia where it has become established (Harding and Mann 1999; Mann and Harding 2000). Juvenile R. venosa were found attached to Loggerhead Sea Turtles (Caretta caretta) in Wassaw Sound, Georgia so populations may exist outside Chesapeake Bay (Harding et al. 2011). Veined Rapa Whelks have been found on the European Atlantic coast, in small numbers, from the North Sea (UK-Netherlands, Kerckhof et al. 2006; Jensen 2010) to Ría de Arousa, Spain (Banon et al. 2008). In 1998. R. venosa was collected in the Rio de la Plata, Uruguay-Argentina where it is now abundant (Pastorino et al. 2000; Giberto et al. 2006). At least three individuals of this whelk have been found on the West Coast, two on imported oysters, and one on a ship's sea-chest cover (Carlton 1979; Sylvester et al. 2011). Genetic comparisons of Asian, Black Sea, Mediterranean, Atlantic European, and Chesapeake specimens indicate that all of the Atlantic populations are derived from the introduced population in the Black Sea (Chandler et al. 2008).

North American Invasion History:

Invasion History on the West Coast:

A few living specimens of R. venosa were collected in Bellingham Bay, Washington (WA) in 1926 (Dall 1926, cited by Carlton 1979) and Willapa Bay, WA in 1952 (Burch 1952 and Hanna 1966; cited by Carlton 1979). Although one specimen was found alive in Willapa Bay as late as 1974 (Carlton 1979), there is no evidence of reproduction on the West Coast. These snails were found in areas of recent Pacific Oyster (Crassostrea gigas) transplants. A single live specimen was found in 2007-2009 fouling surveys, on the sea-chest cover of a ship in Vancouver Harbor, British Columbia (Sylvester et al. 2011).

Invasion History on the East Coast:

In June 1998, two specimens of Rapana venosa were collected in the lower James River, Portsmouth, Virginia (VA). Subsequently, R. venosa was found to have a well-established population in lower western Chesapeake Bay, occurring from the Bay Bridge -Tunnel to the mouth of the Rappahannock River and the opposite Eastern Shore. More than 1000 individuals have been collected, as well as numerous egg-cases (Harding and Mann 1999; Mann and Harding 2000). The expected range of R. venosa within the Bay extends at least to the northern mouth of the Rappahannock River (1 specimen in 1998) (Mann and Harding 2000), and perhaps further up the Bay, since adults tolerate salinities of 9-12 PSU in the Sea of Azov (Chukhchin 1984). Since 2003, three range extensions of R. venosa have been reported within the Bay: (1) seaward along the southern edge of the bay to Cape Henry; (2) upstream in the James River about 10 km, from the VA 258 bridge to Thomas Rock and Brown Shoal (oyster beds); and (3) northward in the bay to Tangier Light (Harding and Mann 2005).

Based on temperature tolerance, Rapana venosa's future Atlantic coast range could extend from Cape Cod, Massachusetts to Cape Hatteras, North Carolina or Charleston, South Carolina. Its long planktonic larval period (14-17 days) and the potential for coastwise ship transport suggest that rapid coastal range expansion is possible (Mann and Harding 2000). Another vector, transport on sea turtles, is indicated by the finding of R. venosa on Loggerhead Sea Turtles (Caretta caretta) in lower Chesapeake Bay (Norfolk, VA) and Wassaw Sound, Georgia. In Georgia, 12 newly settled juvenile whelks were found on the shells of eight breeding turtles. These snails were too young to have been transported from Chesapeake Bay, either by currents or on a turtle's shell, and indicate the presence of an as-yet undiscovered adult population in nearby waters (Harding et al. 2011; Harding and Mann 2017). As of 2009, 27,622 specimens bave been collected at temperatures of 2.45 -29.15°C and salinities of 12-25 PSU (Harding and Mann 2017). A single specimen of R. venosa was collected alive from Fiesta Key, Florida, in 1973, but was not reported until 2015 (USGS Nonindigenous Aquatic Species Program 2017).

Invasion History Elsewhere in the World:

Rapana venosa was first reported in the Black Sea in Novorossiysk Bay, Russia, on the northeastern shore, in 1946 (Chukhchin 1984; Gomiou et al. 2002). It was probably carried from the Russian Pacific coast on ships’ hulls or in ballast water. It spread rapidly through the sea, reaching Sevastopol and Yalta by 1954, the coast of Turkey by 1960, the southern part of the Sea of Azov by 1972, and the Sea of Marmara by 1982 (Kinzelbach 1986; Zolotarev 1996; Gomiou et al. 2002; Cinar et al. 2005). In the Black Sea it reproduced rapidly, and reached high densities, despite low salinity (~18 PSU). It can feed at salinities as low as 12 PSU, characteristic of the southern Sea of Azov (Chukhchin 1984). The spread of R. venosa into the Mediterranean is patchy, suggestive of jumps involving long-range ship dispersal, followed by larval dispersal over shorter distances. In 1974, Rapana venosa was first collected in the Adriatic Sea, where it was probably transported by ship, reaching Venice by 1983 (Cesari and Pellizzato 1985). It is now established and abundant in the northern Adriatic Sea (Savini et al. 2002). In 1986, it was found in the Aegean Sea, closer to the Black Sea (Koutsoubas and Voultsiadou-Koukoura 1991). This whelk is established on the Aegean coasts of Greece and Turkey (Cinar et al. 2005; Zenetos et al. 2005). It was collected off Elba Island, in the Tyrrhenian Sea in 1980 (Zenetos et al. 2003). Crocetta (2012) reports living animals found on the Ionian, Tyrrhenian, and Ligurian Sea coasts of Italy.

Rapana venosa has had scattered occurrences on the Atlantic coast of Europe and has at least one established population. A single specimen of R. venosa was collected from England in 1992 (Eno et al. 1997; Mann and Harding 2000). One specimen was found in the Gulf of Morbihan, Brittany in 1998, and a small but stable population is established in Quiberon Bay, Brittany (Goulletquer et al. 2002; Kerckhof et al. 2006; Chandler et al. 2008). A single specimen was collected in the Ría de Arousa, Galicia, Spain in 2007 (Rolan and Banon-Diaz 2007; Banon et al. 2008). Two specimens were collected in the North Sea in offshore waters of the UK and the Netherlands in 2005 (Kerckhof et al. 2006).

In 1999, an adult R. venosa and egg capsules were collected at the mouth of La Plata estuary in Argentina. This whelk is established and abundant on this part of the South American coast (Pastorino et al. 2000; Giberto et al. 2006; Lanfranconi et al. 2009; Carranza et al. 2010). The range of R. venosa has now extended north to the southernmost coast of Brazil, nporth to Brazil, reaching jetties at the mouth of the Patos Lagoon estuary. One specimen was attached to a dead Green Sea Turtle, Chelonias mydas (Spotorno-Oliveira et al. 2020).

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Description

Rapana venosa has a heavy, dextrally coiled shell with a large body whorl and short spire, with 6-7 whorls altogether. The columella is broad and somewhat concave. There is a deep umbilicus. The aperture is oval and lined on its outer edge with fine teeth. The exterior of the shell is heavily sculptured with longitudinal ribs, forming blunt knobs at the shoulder of the body whorl, but continuing to the boundary of the previous whorl. There are also finer growth lines, which are crossed by numerous spiral ribs, which terminate as the teeth on the lip of the aperture. Older specimens are often eroded and the color is variable. The external part of the shell is gray to brown, with dark-brown dashes on the spiral ribs. The interior of the shell ranges from off-white to yellow or orange, and has a smooth, pearly texture. Shells of the Veined Rapa Whelk reach 168.5 mm or more in size. Description from: Golikov et al.1976; Mann and Harding 2000.

Egg capsules of R. venosa are about 9-40 mm tall, 3 mm wide, and taper to a wider, leaf-shaped tip, ending in a pore through which the larvae exit. The egg cases are yellow when laid, but change to gray, and then black when the larvae are ready for release (Harding and Mann 1999). Egg cases are laid in masses or mats of many capsules (ranging from 3-599; average for Black Sea = 84) attached to firm substrates, sometimes over other organisms such as hydroids (Harding and Mann 1999; Saglam et al. 2009). The capsules hatch out as planktonic larvae, which are illustrated by Harding (2006) and Saglam et al. (2009).

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Taxonomy

Ecology

General:

Rapana venosa is a large predatory marine gastropod. Sexes are separate and fertilization is internal. Females begin laying egg capsules at 35-50 mm shell length, at 1 year of age. The egg capsules are long and thin, 9-40 mm long, and contain 50-3800 eggs. Size of the capsules and number of eggs increases with size of the females, as does overall annual fecundity, from ~2 X 100,000 at 35 mm length to 4 X 1,000,000 at 160 mm shell length. The Veined Rapa Whelk can live for up to 15 years, so the lifetime reproductive output is very large. The egg capsules are attached in dense clusters of 3-599 capsules, and attached to firm surfaces, such as rocks, shells, pilings, crab pots, and often to fouling organisms attached to these surfaces (Harding et al. 2007; Saglam et al. 2007; Harding et al. 2008). Eggs develop inside the capsule and take 15-28 days to hatch at 22-27°C (Harding 2006; Saglam et al. 2007). The larvae, about 300 to 400 µm in diameter, swim with a bilobed velum and escape through a pore at the tip of the egg capsule to enter the plankton. The larvae feed on phytoplankton and grow to about 1.3 mm before settling in about 24-42 days at 25-29°C (Harding 2006).

Rapana venosa is known from a wide range of habitats, including rocky shores, mussel beds, oyster reefs, sand, silt, eelgrass beds, and pilings, at depths from 0.5 to 25 m (Golikov et al. 1976; Harding and Mann 1999; Giberto et al. 2006; Culha et al. 2009; Carranza et al. 2010; Snigirov et al. 2013). On soft sediments, Veined Rapa Whelks are active burrowers and remain buried in sand, with only their siphons showing, for long periods of time (Harding and Mann 1999). These snails have been found attached to the shells of sea turtles (Harding and Mann 2009; Lezama et al. 2012). They are known from waters with a temperature range of 4-35°C. At the northern part of its native range, near Vladivostok, ice cover occurs in winter (Mann and Harding 2000). The Veined Rapa Whelk is unusual among large marine gastropods for its tolerance of low salinities, which has enabled it to colonize the Black Sea (~18 PSU) and the southern portion of the Sea of Azov (~12 PSU). It can survive for a few days at 9 PSU, but ceases to feed (Chukhchin 1988; Mann and Harding 2000). Veligers show good survival at 18-32 PSU (Mann and Harding 2003), and maintains populations in the Mediterranean Sea at 38-39 PSU (Savini et al. 2002). Rapana venosa is tolerant of hypoxia and continues to feed at 1.4 mg/L, a level which incapacitates some of its bivalve prey species (Munari and Mistri 2011).

The Veined Rapa Whelk is a predatory snail. Younger whelks (<34 mm) feed on bivalves by rasping a hole in their shells using their radulas, but mature snails force the valves apart, relaxing the adductor muscles with the aid of a toxin and do not leave a distinctive 'signature' hole on the prey's shell (Harding and Mann 1999; Harding et al. 2007). Shells of prey bivalves in the Black Sea showed varying degrees of abrasion depending on the size and speceis of prey (Kosyan 201). Prey include cockles, clams, oysters, mussels, and other bivalves of many species, varying with the region invaded (Harding and Mann 1999; Savini and Occhipinti-Ambrogi 2006; Chukhchin 1984; Munari and Mistri 2011; Giberto et al. 2012; Lanfranconi et al. 2013). In Chesapeake Bay experiments, the whelks preferred Hard Clams (Mercenaria mercenaria) to Eastern Oysters (Crassostrea virginica), Softshell Clams (Mya arenaria), or Blue Mussels (Mya arenaria) (Harding and Mann 1999). Rapana venosa also scavenges on carrion, such as dead fish, and some of its occurrences on sea turtles involved feeding on wounded or dying animals (Harding et al. 2009; Lezama et al. 2012).

With the exception of the Black Sea (because of its low salinity), in the regions that it has invaded, R. venosa co-occurs with other predatory gastropods, which are potential competitors, but the Veined Rapa Whelk's large size, high fecundity, and planktonic dispersal may give it an advantage over other species. Potential competitors in Chesapeake Bay are the Knobbed Whelk (Busycon carica), Channeled Whelk (Busycotypus caniculatus), Atlantic Oyster Drill (Urosalpinx cinereus), and Thick-Lipped Drill (Eupleura caudata) (Lippson and Lippson 1997). In Chesapeake Bay, R. venosa tends to occur in lower salinity habitats with smaller drills (Urosalpinx and Eupleura), and less frequently with larger Whelks (Busycon and Busycotypus) (Mann and Harding 2017). Potential predators include Blue Crabs (Callinectes sapidus), which can crush and eat small (< 35 mm) whelks (Harding 2003), and Loggerhead Sea Turtles (Lezama et al. 2012). Other adverse factors affecting this snail, are mortality due to toxic dinoflagellate blooms (Harding et al. 2009), and reproductive limitations due to female reproductive deformities (imposex) caused by the pollutant tributyltin (TBT) (Mann et al. 2006; Harding et al. 2017).

Food:

Bivalve Mollusks

Consumers:

Blue Crabs (Callinectes sapdius)

Trophic Status:

Carnivore

Carn

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Habitats

General Habitat	Unstructured Bottom	None
General Habitat	Oyster Reef	None
General Habitat	Rocky	None
General Habitat	Marinas & Docks	None
General Habitat	Grass Bed	None
Salinity Range	Mesohaline	5-18 PSU
Salinity Range	Polyhaline	18-30 PSU
Salinity Range	Euhaline	30-40 PSU
Tidal Range	Subtidal	None
Vertical Habitat	Endobenthic	None
Vertical Habitat	Epibenthic	None

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Tolerances and Life History Parameters

Minimum Temperature (ºC)	4	Field data for native range, cited by Mann and Harding (2000)
Maximum Temperature (ºC)	35	Field data for native range, cited by Mann and Harding (2000)
Minimum Salinity (‰)	12	Experimental (Chukchin 1984)
Maximum Salinity (‰)	39	Field data, Mediterranean Sea
Minimum Dissolved Oxygen (mg/l)	1.4	Lowest tested, Munari & Misri 2001. Rapana venosa continued to feed on bivalves at this level.
Minimum Reproductive Temperature	15	Temperature at the start of egg-laying season (early May) (Harding et al. 2006).
Maximum Reproductive Temperature	30	Experimental, egg capsule production (Harding et al. 2008)
Minimum Reproductive Salinity	13	>50% 48 h survival of veligers raised at 18-21 PSU and transferred (Mann and Harding 2003)
Maximum Reproductive Salinity	38	Based on established populations in Mediterranean Sea (Zenetos et al. 2005; Savini et al. 2007))
Minimum Duration	24	Harding (2006) reports a minimum development time of 24 days.
Maximum Duration	42	Larval period, 24-26 C (Mann and Harding 2000; Harding 2006). Larvae from eggs spawned in August developed more slowly than those spawned in June, at similar temperatures (Harding 2006).
Minimum Length (mm)	35	Females begin laying egg-masses at 35-50 mm size (Harding et al. 2007).
Maximum Length (mm)	168.5	Mann and Harding 2000
Broad Temperature Range	None	Cold temperate-Warm Temperate
Broad Salinity Range	None	Mesohaline-Euhaline

General Impacts

Rapana venosa is a very large snail which preys on economically and ecologically important bivalves, such as clams, mussels, oysters, and scallops. Its impacts can be especially significant because it can survive and reproduce in salinities too low for other predatory gastropods, and other important shellfish predators, such as starfish (Chukhchin 1984; Zolotarev 1996; Harding and Mann 2005; Mann and Harding 2000). It has had major economic and ecological impacts in the Black Sea (Chukhchin 1984; Zolotarev 1996) and impacts are anticipated in other estuaries, such as the northern Adriatic Sea (Savini et al. 2006), Chesapeake Bay (Savini et al. 2002), and the La Plata estuary (Lanfranconi et al. 2013). On the positive economic side, R. venosa is a popular food item in Asian countries and an export fishery has developed for them in the Black Sea (Alpbaz and Temelli 1997; Staykov 1997).

Economic Impacts

The invasion of R. venosa severely affected shellfisheries in the Black Sea, reducing populations of oysters (Ostrea edulis), scallops (Pecten ponticus), mussels (Mytilus galloprovincialis), and clams (Chamelea gallina) (Chukhchin 1984; Zolotarev 1996). Attempts to eradicate R. venosa on the Bulgarian Coast were unsuccessful (Staykov 1997). In the Black Sea (e.g. Bulgaria, Turkey), commercial fisheries have developed for R. venosa, in which the snails are shipped to Japan and Korea. In Turkey, size limits have been imposed to conserve stocks (Alpbaz and Temelli 1997; Staykov 1997).

Rapana venosa's invasion is expected to have economic impacts on shellfisheries in Chesapeake Bay because of its role as an efficient predator of bivalves. Populations of Mercenaria mercenaria (Hard Clams) are expected to be most affected. This fishery has annual landings of about 1.1 million pounds, with a dockside value of $6 million (Harding and Mann 1999). The harvest is currently declining, due in part to overfishing, pollution, and disease (Savini et al. 2002). Consequently, the addition of a new predator is viewed with alarm. In laboratory experiments, small R. venosa (60-100 mm) consumed ~3.6% of their body weight in M. mercenaria per day, while large specimens (>101 mm) ate ~0.8% of their body weight per day (Savini et al. 2002). Savini et al. (2002) estimate that a population of 1,000 R. venosa could reduce the annual Hard Clam harvest by 0.3-0.9% per year. Thus, it appears likely that the present small population of R. venosa is having at least a small impact on the Hard Clam harvest. Predation on Crassostrea virginica (Eastern Oyster) is expected to be less significant, because most remaining beds are in low-salinity waters, near the tolerance limits of R. venosa (Mann and Harding 2000). In the Rio de La Plata estuary (Argentina-Uruguay), its predominant prey are several species of mussels

Ecological Impacts

Predation: In the Black Sea, R. venosa feeds primarily on bivalve mollusks. In aquariums, it feeds on mussels, oysters, clams, scallops, cockles, and limpets. It shows a preference for mussels over oysters, probably because of the thinner shell. Young-of-the year whelks eat Bay barnacles (Amphibalanus improvisus). It may also feed on carrion, including the meat of mussels, oysters, dead fish and crabs (Chukhchin 1984). In Chesapeake Bay, Hard Clams (Mercenaria mercenaria) were preferred over Eastern Oysters (Crassostrea virginica), but this may reflect the present occurrence of this snail in soft-bottom habitats in Chesapeake Bay, where mussels and oysters are scarce (Harding and Mann 1999; Mann and Harding 2000). In the Adriatic Sea, R. venosa preys on the abundant small Indo-Pacific ark shell Anadara inaequivalvis, in preference to the larger Venerupis philippinarum (Japanese Littleneck) (Savini 2006). In the Rio de la Plata estuary, predation by R. venosa is affecting several species of clams (Erodona mactroides and Mactra isabelleana) and mussels (Mytilus edulis platensis; Brachidontes rodriguezii; Mytella charruana) (Carranza et al. 2010; Lercari and Bergamino 2011; Lanfranconi et al. 2013). Overall, R. venosa seems to be a flexible and opportunistic predator.

The predatory impacts of R. venosa in the Black Sea were especially large, because prior to the invasion, large predatory gastropods and other invertebrate predators, such as starfish, were absent. Chukhchin (1984) describes the changes as: ‘Before its establishment in the Black Sea, predatory gastropods played an insignificant role in shellfish populations. The Black Sea lacked predatory marine organisms, including predatory gastropod mollusks which could feed on bivalves. The establishment of Rapana created a new ecological niche. This brought about substantial changes in Black Sea shellfish beds – one dominant species essentially replaced all others. In the Gudaytskii oyster bank, before the establishment of Rapana, four species of lamellibranch bivalves predominated, Ostrea taurica, Mytilus galloprovincialis, Pecten ponticus, and Modiola adriatica (Nikitin 1934). Our studies on the Gudaytskii oyster bank showed that in 1958, after the full destruction of large mollusks by Rapana, the dominant role went to the small mollusk Gouldia minima'.

In the Chesapeake Bay, Rapana venosa in aquaria consumed Mercenaria mercenaria (Hard Clams), but are likely to feed on other bivalves in the wild. The extent of predation in the field is difficult to determine, because R. venosa does not leave a clear signature, such as boring or rasping marks on bivalve shells (Harding and Mann 1999; Mann and Harding 2000). Nearly all collections have been from soft sediments, in the lower Bay, where the dominant large bivalve is M. mercenaria. Impacts on Crassostrea virginica (Eastern Oysters) are expected to be small, because diseases have confined substantial oyster populations to low salinities (Mann and Harding 2000).

Competition: Other predatory gastropods, in Chesapeake Bay and the northwest Atlantic, with similar feeding habits are Busycotypus caniculatus (Channeled Whelk), Busycon carica (Knobbed Whelk), and Neverita duplicata (Shark Eye Snail). Competition between these species and Rapana venosa has not been studied. In the La Plata Estuary, Argentina, modeling suggests that R. venosa could compete with molluscivorous fishes, such as a croaker (Micropogonias furnieri) and rays, as well as native predatory gastropods (Lercari and Bergamino 2011).

Habitat Change: One effect that R. venosa's invasion may have had in Chesapeake Bay, involves changing the shell resources for hermit crabs, possibly favoring the now-rare Clibanarius vittatus (Striped Hermit Crab) over the dominant Pagurus pollicaris (Flat-Clawed Hermit Crab). Rapana venosa's morphology appears better suited to the former crab (Harding and Mann 1999).

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Regional Impacts

M130	Chesapeake Bay		Ecological Impact	Predation
In laboratory experiments, small R. venosa (60-100 mm) consumed ~3.6% of their body weight in Mercenaria mercenaria (Hard Clams) per day, while large specimens (>101 mm) ate ~0.8% of their body weight per day (Savini et al. 2002). Savini et al. (2012) estimate that a population of 1,000 R. venosa could reduce the annual Hard Clam harvest by 0.3-0.9% per year. Thus, it appears likely that the present population of R. venosa is having at least a small impact on the Hard Clam harvest. Predation on Crassostrea virginica (Eastern Oyster) is expected to be less significant, because most remaining beds are in low-salinity waters, near the tolerance limits of R. venosa (Harding and Mann 1999; Mann and Harding 2000).
NA-ET3	Cape Cod to Cape Hatteras		Ecological Impact	Predation
In laboratory experiments, small R. venosa (60-100 mm) consumed ~3.6% of their body weight in Mercenaria mercenaria (Hard Clams) per day, while large specimens (>101 mm) ate ~0.8% of their body weight per day (Savini et al. 2002). Savini et al. (2002) estimate that a population of 1,000 R. venosa could reduce the annual Hard Clam harvest by 0.3-0.9% per year. Thus, it appears likely that the present  opulation of R. venosa is having at least a small impact on the Hard Clam harvest. Predation on Crassostrea virginica (Eastern Oyster) is expected to be less significant, because most remaining beds are in low-salinity waters, near the tolerance limits of R. venosa (Harding and Mann 1999; Mann and Harding 2000).
MED-IX	None		Ecological Impact	Predation
In the Black Sea, this mollusk: 'Feeds primarily on bivalve mollusks, paralyzing them with toxins and eating them with the aid of its soft proboscis. In aquariums, R. venosa eats Mytilus galloprovincialis (Mediterranean Mussels), Ostrea edulis (European Oysters), Tapes (=Venerupis decussatus, a clam), Chamelea gallina (gallina clams), Pecten (Flexopecten glaber ponticus, scallops), Cardium spp. (=Cerastoderma spp., cockles), and the gastropod mollusk Patella (spp., limpets). When Rapana is offered mussels and oysters simultaneously, it clearly prefers the former. This is explained, probably, by the thinner shell of the mussels which Rapana can more easily penetrate. Young-of-the year Rapana venosa eat Amphibalanus improvisus. Rapana venosa may also feed on carrion. In the aquarium, they eat the meat of mussels, oysters, dead fish and crabs.' (Chukhchin 1984, PF transl.). A recent increase (2004 -2012) in the abundance of this whelk around Zmiinyi Island (Ukraine), off the Danube delta, led to a sharp decline in the abundance of mussels, and a decline in demersal fishes that feed on mussels (Snigirov et al. 2013).
MED-IX	None		Economic Impact	Fisheries
The invasion of the Black Sea by Rapana venosa severely affected shellfisheries, severely reducing populations of oysters (Ostrea edulis), scallops (Pecten ponticus), mussels (Mytilus galloprovincialis), and clams (Chamelea gallina) (Chukhchin 1984; Zolotarev 1996). Attempts to eradicate R. venosa on the Bulgarian Coast were unsuccessful (Staykov 1997). However, the fishery for R. venosa for export to Asia, has become economically important in the Black Sea region. Management of the fishery is complex, because of environmental disturbance caused by dredging, the risk of overfishing of Rapana depleting the resource, and damage to other fisheries by Rapana predation. Janssen et al. (2014) describe efforts to develop ecosystem-based management in Bulgaria and Turkey for R. venosa fisheries.
M130	Chesapeake Bay		Economic Impact	Fisheries
Savini et al. (2002) estimate that a population of 1,000 R. venosa is having at least a small impact on the Hard Clam harvest.
NA-ET3	Cape Cod to Cape Hatteras		Economic Impact	Fisheries
Savini et al. (2002) estimate that a population of 1,000 R. venosa is having at least a small impact on the Hard Clam harvest.
SA-II	None		Ecological Impact	Predation
Observations indicate extensive predation by R. venosa on Mytilus edulis platensis and Brachidontes spp., in beds already depleted by pollution and over-harvesting (Carranza et al. 2010). Modelling indicates that predation by R. venosa affects populations of the native bivalves Erodona mactroides and Mactra isabelleana (Lercari and Bergamino 2011). In experiments, R. venosa from the La Plata estuary, fed on Brachidontes rodriguezii and Mytella charruana, at a mean rate of 0.88 mm per snail. Medium-sized (20-30 mm) mussels were consumed at a higher rate than larger or smaller mussels (Lanfranconi et al. 2013).
SA-II	None		Ecological Impact	Competition
Ecopath modelling suggests that predation by R. venosa negatively affects populations of the predatory fish Micropogonias furnieri, rays, and native predatory gastropods (Lercari and Bergamino 2011).
MED-IX	None		Ecological Impact	Trophic Cascade
A recent increase (2004 -2012) in the abundance of this whelk around Zmiinyi Island (Ukraine), off the Danube delta, led to a sharp decline in the abundance of mussels, and a decline in demersal fishes that feed on mussels (Snigirov et al. 2013).
SA-II	None		Ecological Impact	Food/Prey
Rapana venosa constituted a major prey item of Loggerhead Turtles (Caretta caretta) in the Rio de la Plata estuary, constituting up to 100% of the diet (Carranza et al. 2011).
MED-VII	None		Ecological Impact	Predation
In field experiments in the northern Adriatic, Rapana venosa fed heavily on the introduced Indo-Pacific ark shell Anadara inaequivalvis, while feeding less on the introduced Japanese Littleneck Clam (Venerupis philippinarum) and the Mediterranean Mussel (Mytilus galloprovincialis). The observed rate of predation would be sufficient to reduce the population of A. inaequivalvis and affect community composition (Savini and Occhipinti-Ambrogi 2006). Indirect effects on the commercially important V. philippinarum and the Mediterranean Mussel (M. galloprovincialis) are possible, but were not studied in this experiment.
MED-VI	None		Economic Impact	Fisheries
'According to local Fisheries and Aquaculture Associations it has become a considerable nuisance in the oyster and mussel beds in the area' (Thermaikos Gulf) (Zenetos et al. 2005)
MED-VI	None		Ecological Impact	Predation
Heavy predation on oyster and mussel beds (Zenetos et al. 2005)

References

Mrcelic, Jelic Gorana; Nerlovic, Dogan, Vedrana Alper (2023) Sustainable Management of High-Impact Non-Native Molluscs and Their Potential Commercial Importance in the Eastern Adriatic Sea, Sustainabliity 15(1134): <missing location>
https://doi.org/10.3390/ su151411384

Alpbaz, Atilla; Temelli, Belgin (1997) Review of the molluscan fisheries of Turkey, NOAA Technical Report NMFS 129: 227-232

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