Island apple snail
Island apple snail (Pomacea maculata) is a very large invasive freshwater snail, capable of breathing air. A native of South America, this species has been recognised for its damaging potential to agricultural and ecological sites. The island apple snail’s ability to rapidly destroy large plants can lead to reduced water quality by negatively affecting nutrient cycling, increased turbidity, and an increase in the presence of phytoplankton, posing a serious biosecurity threat to Australia’s rice industry and natural wetland habitats. Island apple snails have a high tolerance to temperature variations and can maintain extended durations away from aquatic habitats, and as such can be easily introduced as stow-aways on cargo, crops, and vehicles. While not currently detected in Australia, they have been introduced into Northern America, Spain, and South-east Asia through the aquarium and food trade, where they have inflicted wide-spread economic and environmental damage.
Reporting
If you think you have seen an island apple snail in NSW, please take several clear, high-resolution photos of the shell. For identification, we need to see the:
- Shell size – please include something for reference (e.g. a coin, ruler)
- Shell shape and colour
- Close-up of the shell opening and operculum (lid-like structure)
Please send photos to aquatic.biosecurity@dpird.nsw.gov.au, along with details of when and where the snail was seen.
Identification
Key features
- Smooth and globular with a very large opening.
- Short spire with 5-6 whorls, separated by a deep groove.
- Variations in colour include a combination of yellow, green, and brown, may have a pattern of bands.
- Adult shells may be in excess 100mm in width.
Known locations
- Not in Australia
Habitat
- Rivers, wetlands, rice fields, irrigation canals.
- Tolerates a wide range of temperatures (7-37°C), low salinity, and long term exposure to air.
- Found grazing on aquatic plants and terrestrial plants near water.
Vector
- Illegal release from aquarium or aquatic plant trade.
- Illegal release from live food trade.
- Movement of contaminated vehicles, crops, cargo.
- Running water, irrigation, and drainage channels.
Impacts
- Outcompetes native species for food and space.
- Alters nutrient cycling and water clarity.
- Devastates agricultural crops and native plants
- Significant biosecurity risk to the aquarium and agriculture industries.
Similar native species
These native species may be confused with the island apple snail. These species do not need to be reported to biosecurity.
Billabong banded snail (Notopala kingi suprafasciata) (critically endangered)
Key features
- Outer shell is often polished and spherical, green to brown in colour
- Up to 32mm in size
- Lacks dark lines between the 5 whorls, but has bands diffused along shell circumference
Known locations
- Large ponds and billabongs throughout western New South Wales
Habitat
- Muddy sediment within waterbodies
Hanley’s river snail (Notopala hanleyi) (critically endangered)
Key features
- Outer shell is smooth and spherical, green to brown in colour
- Maximum width of 25mm
- Lacks dark lines between the 5 whorls
Known locations
- Murray River catchment, Lachlan and Murrumbidgee Rivers included
Habitat
- Attached to logs or rocks, or in sediment along riverbanks
- Artificial irrigation pipeline environments
Darling river snail (Notopala sublineata) (critically endangered)
Key features
- Outer shell is smooth and spherical, green to brown in colour
- Maximum width of 25mm
- Lacks dark lines between the 5 whorls
Known locations
- Formerly Darling River and associated tributaries, now restricted to irrigation pipes near Bourke, Brewarrina, and Walgett.
Habitat
- Attached to logs or rocks, or in sediment along riverbanks
- Artificial irrigation pipeline environments