Invasion HistoryFirst Non-native North American Tidal Record: 2017
First Non-native West Coast Tidal Record: 2017
First Non-native East/Gulf Coast Tidal Record:
General Invasion History:
Pomacea canaliculata (Channeled Applesnail) is restricted to the Lower Paraná, Uruguay, and La Plata basins of south-central Brazil, Uruguay, and northern Argentina, a much narrower latitudinal range than that of the very similar P. maculata (Spotted Applesnail), formerly known as P. insularum. The two species are very similar, and were once treated as synonyms, and are still frquently misidentified. Genetic methods are useful in separating the two species (Hayes et al. 2012; Burks et al. 2017). Both snails have been widely introduced around the world, sometimes as food, but more frequently as aquarium animals, or with aquatic plants (Cowie et al. 2017; Hayes et al. 2012). In the United States, P. canaliculata has been found in inland Florida, Georgia, and California, and now the San Francisco estuary.
North American Invasion History:
Invasion History on the West Coast:
The first definite record of Pomacea canaliculata was in Lake Miramar, in San Diego County, California, and a pond in Pasadena (Los Angeles County) in 1997. A population in Fremont (Alameda County) was eradicated in 1998. In 2007, it was found in canals running into the Salton Sea, in Riverside County, California, and in tributaries of the Colorado River, near Yuma, Arizona (Howells et al. 2006; Rawlings et al. 2007; USGS Nonindigenous Aquatic Species 2017). Snails and egg masses were found in the upper San Joaquin Valley, in Fresno County in August 2017. The first estuarine record occurred in the freshwater Dutch Slough-Big Break region of the Sacramento-San Joaquin Delta. Adults and egg masses were found, and this appears to be an established population (USGS Nonindigenous Aquatic Species 2017).
Invasion History on the East Coast:
Pomacea canaliculata (Channeled Apple Snail) is widely distributed in Florida and the Gulf Coast, while the range of P. canaliculata in Eastern North America is restricted to lakes and ponds in the vicinity of Jacksonville, Florida (Jacksonville Shell Club 2017; USGS Nonindigenous Aquatic Species 2017). We have not yet found estuarine records from Florida (USGS Nonindigenous Aquatic Species 2017).
Invasion History in Hawaii:
Pomacea canaliculata was first reported from the Hawaiian Islands on Maui in 1989 (Lach and Cowie 1999), and is now known from Oahu, Hawaii, Maui, Kauai, and Lanai. It was found in 28 low elevation streams in Oahu (Lach and Cowie 1999), but was not found in a survey of fresh-brackish estuaries on Oahu (Englund et al. 2000).
Invasion History Elsewhere in the World:
Pomacea canaliculata (Channeled Apple Snail) has been introduced to 23 countries, mostly in Asia, but also in New Guinea, several Caribbean Islands, Egypt, South Africa, and Spain (Cowie et al. 2017). Pomacea canaliculata, together with P. maculata, were introduced from Argentina to Taiwan around 1979, illegally as a food animal, with multiple introductions from 1980 to 2008, and became widespread in Asia, from southern China, Korea, and Japan to Indonesia as a food item, but increasingly an aquarium pet (Hayes et al. 2008; Cowie and Hays 2012). Most of the populations of Apple Snails in Asia were P. canaliculata (Cowie et al. 2017). Its wider distribution may reflect greater tolerance of exposure to low temperatures (0–5 °C) and desiccation, although tolerance varies among populations of each species (Yoshida et al. 2014; Matsukura et al. 2017).
Pomacea canaliculata (Channeled Apple Snail) has a relatively thick, dextrally coiled and globose shell with a low spire. The shell is smooth, with fine axial growth lines and occasional growth arrests. The adult shell has 5–6 whorls, separated by a deep suture. The shell opening is large and oval to round, with a reflected edge. The upper shoulder of the aperture is curved, and projects out at an angle of less than 90 degrees, in contrast to a right angle in P. diffusa. The umbilicus is narrow, but deep. The operculum is corneous (horn-like) in texture and completely seals the aperture. The operculum is sexually dimorphic, concave in females, and convex in males. Adult shells range from 35 to 165 mm, and are highly variable in color, ranging from yellow-green to greenish brown, or dark chestnut, frequently with a dark banding pattern. The body is grey-brownish with dark spots. The egg masses are reddish to orange-pink, whitening as they develop, and deposited up to 2 m above water level on hard surfaces or vegetation. The egg masses average about 300 eggs, but can contain up to 1000 eggs, smaller than those of P. maculata. The eggs are ~3 mm in diameter. Description from: Thompson 2004, Howells et al. 2006, Rawlings et al. 2007, Hayes et al. 2012, and Ghesquiere 2013.
Pomacea maculata (=P. insularum) and the unidentified species formerly known as P. haustrum and P. canaliculata belong to a species complex of South American apple snails, which have been widely introduced in warmer parts of North America and Asia. The three species have only small differences in shell morphology, but their egg masses are more distinct in color and shape. Molecular identification has been important in clarifying the identity and origin of these snails (Rawlings et al. 2007; Hayes et al. 2008; Hayes et al. 2012; Cowie and Hayes 2012).
Ampullaria australis (d'Orbigny, 1835)
Ampullaria dorbignyana (Philippi, 1852)
Pomacea canaliculata chaquensis (Hylton Scott, 1948)
Potentially Misidentified Species
Pomacea diffusa (Spike-Topped Apple Snail), native to South America, is established in lakes and canals in northern and southern Florida.
Pomacea haustrum (Titan Apple Snail), native to South America, has a limited range in lakes and canals in southern Florida.
Pomacea maculata (Spotted Applesnail) is native to South America, and widely established in freshwater on the Gulf Coast and Florida.
Pomacea paludosa is native to Florida.
Pomacea canaliculata is limited to fresh and oligohaline waters in warm-temperate to tropical climates. The lower temperature limit for long-term survival is 15°C, but it can tolerate lower temperatures for shorter time periods, eg., 93% survival at 5 days at 5°C (Matsukura et al. 2016). The upper experimental salinity limit was is ~8 PSU (Bernatis et al. 2016), but we have not found records from saline waters so far. Apple Snails are obligate air-breathers and have a pulmonary sac as well as a gill, and are amphibious in their habits (Cowie and Hayes 2012). The Channeled Apple Snail can tolerate 38–33 days of air exposure, depending on temperature and humidity (Glasheen et al. 2017). This could facilitate overland transport with crops or other cargo.
Pomacea canaliculata grazes on emergent aquatic plants, terrestrial plants adjacent to the water, and submerged plants. Pomacea maculata and P. canaliculata are believed to have similar diets and are documented to feed on more than 80 species of plants (Carlsson et al. 2004; Howells et al. 2006). These include exotic aquatic plants from South America and elsewhere (e.g. Alligatorweed- Alternanthera philoxeroides; Water Hyacinth- Eichhornia crassipes), and also crops such as Rice (Oryza sativa), Taro (Colcasia esculenta) and Lettuce ((Lactuca sativa) (Howells et al. 2006). Populations in Florida fed most heavily on native Utricularia spp. (Bladderworts) and Bacopa caroliniana (Blue Water-Hyssop) (Morrison and Hay 2010).
Submerged vegetation, emergent vegetation
birds, fishes, mammals, humans
Other Ampullarid snails
|General Habitat||Nontidal Freshwater||None|
|General Habitat||Fresh (nontidal) Marsh||None|
|General Habitat||Tidal Fresh Marsh||None|
|Salinity Range||Limnetic||0-0.5 PSU|
|Tidal Range||Low Intertidal||None|
|Tidal Range||Mid Intertidal||None|
|Tidal Range||High Intertidal||None|
Pomacea canaliculata has separate sexes and females tend to be larger than males. Fertilization is internal and eggs are laid in masses, out of the water, up to 2 m above the water line on rocks or vegetation. The egg masses are bright pink and are easily visible (Cowie and Hayes 2012). Eggs numbers per clutch averaged 150–300, occasionally reaching 1000 (Kyle et al. 2012; Cowie and Hayes 2012). Eggs take about 2 weeks to hatch, varying with temperature, with the young snails falling into the water. Out-of-water egg deposition is probably an adaptation to stagnant tropical waters (Cowie and Hayes 2012).
Tolerances and Life History Parameters
|Minimum Temperature (ºC)||10||Adults cease feeding and activity at 10 C, but can survive up to 12 days at 0 C (Wada and Matsukura 2017; Matsukura et al. 2015).|
|Maximum Temperature (ºC)||36.2||
Heat coma temperature (Seuffert et al. 2010, cited by Wada and Matsukura 2017)
|Minimum Salinity (‰)||0||This is a freshwater species.|
|Maximum Salinity (‰)||8||Experimental (Bernatis et al. 2016)|
|Minimum pH||5.5||Experimental (Bernatis et al. 2016)|
|Maximum pH||9.5||Experimental (Bernatis et al. 2016)|
|Minimum Reproductive Temperature||20||Seuffert and Martin 2017|
|Maximum Reproductive Temperature||30||Seuffert and Martin 2017|
|Minimum Reproductive Salinity||0||This is a freshwater species. There was 0-7 days survival of hatchlings at 8 PSU, the lowest salinity tested (Bernatis et al. 2016). Intermediate salinities between 0 and 8 PSU were not used in this study.|
|Minimum Length (mm)||35||Hayes et al. 2012|
|Maximum Length (mm)||265||Hayes et al. 2012|
|Broad Temperature Range||None||Subtropical-Tropical|
|Broad Salinity Range||None||Limnetic-Oligohaline|
Pomacea canaliculata (Channelled Applesnail) has had a wide range of ecological and economic impacts. Because of their large size and varied colors and markings, they are widely sold as aquarium pets (Ghesquiere 2013). They were shipped to Asia, in an unsuccessful attempt to introduced them as food, and soon became serious agricultural pests in ricefields (Carlsson et al. 2004; Howells et al. 2006). This snail is on the IUCN (International Union for Conservation of Nature) list of the 100 World's Worst Invasive Species (Invasive Species Specialist Group 2017), because of its damage to crops, native wetland vegetatiom, and competition with native snails. In North America, P. maculata has colonized a greater area, on the Gulf Coast and Florida Peninsula, while populations of P. canaliculata have localized populations in northeast Florida, Arizona, and southern California (Howells et al. 2006; Rawlings et al. 2007; USGS Nonindigenous Aquatic Species 2017). In August, 2017, a population of P. canaliculata was discovered in the Dutch Slough-Big Break region of the Sacramento-San Joaquin Delta, a major agricultural area. Specific impacts of P. canaliculata in North America have not been reported.
Pomacea canaliculata is regarded in Asia as one of the most damaging pests in irrigated rice culture. Pesticides are extensively and often illegally used to control snails in ricefields. It is also a pest of cultivated Taro (Colocasia esculenta) in Hawaii (Cowie and Hays 2011). Pomacea canaliculata feeds on a very wide range of aquatic and riparian plants, including native and introduced, invasive plants. Experiments and field studies in Thailand indicate that Apple Snails at high densities can eliminate aquatic plants, resulting in domination of water by phytoplankton (Carlsson et al. 2004). In experiments in Florida, P. maculata and P. canaliculata both consumed naïve plants (Bladderwort, Utricularia sp. and Blue Waterhyssop, Bacopa caroliniana, at higher rates than the native P. paludosa (Morrison and Hay 2010). Experiments and observations of Apple Snails (P. canaliculata) in Thailand can alter water quality and nutrient cycling in wetlands by eliminating macrophytes, leading to dominance by phytoplankton, increased turbidity, and elevated concentrations of nitrogen and phosphorus (Carlsson et al. 2004).
Regional Distribution Map
|Bioregion||Region Name||Year||Invasion Status||Population Status|
|P090||San Francisco Bay||2017||Def||Estab|
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