Apple snails

Habitat

• A genus of freshwater snail inhabiting marshes, swamps, ditches, irrigation canals, ponds, and lakes
• Prefers water bodies lined with vegetation and with muddy bottoms
• It can tolerate polluted waters with low oxygen levels

Description

• Pomacea canaliculata and Pomacea maculata are the most documented Pomacea species
• It is difficult to differentiate between Pomacea species without DNA analysis
• Apple snails have a thin, smooth, globose shell, growing 3-8cm in diameter
• Shell colour varies from yellow-brown to dark chestnut with some having dark spiral bands
• Shell whorls are rounded, with deep channels between them
• The snail has four tentacles with only two long and one short tentacle visible
• It has a long extendable siphon on the left side for surface breathing
• Fully grown females are larger than males
• Egg masses are laid just above the waterline on plant material, logs, walls, or rocks
• Masses can contain more than 1000 brightly coloured eggs that get lighter as they are about to hatch
• Eggs hatch after 2 weeks, with hatchling shells around 2mm in diameter
• After 45 days, juveniles become fully grown and can reproduce
• During dry periods it can survive in the soil for more than 5 months, until water is present

Origin and Worldwide Distribution

• Native to South and Central America, including the Caribbean
• One species is native to Florida, USA
• Introduced across Southeast and east Asia, the USA, and the Ebro Delta in Spain
• Sold as pets through the aquarium trade in Northern Ireland, Great Britain and Ireland.

Potential or Known Impacts

• Considered one of the most invasive invertebrates of waterways and irrigation systems
• They have a broad diet, consuming large amounts of aquatic vegetation, altering ecosystems
• Loss of vegetation increases water nutrient concentrations, phytoplankton biomass and water turbidity
• They can reduce native snail biodiversity through predation and competition
• Act as a vector for parasites that can cause human diseases

Is it found in Northern Ireland?

• It is not currently present in Northern Ireland

How could it get here?

• Introductions would most likely be a result of the deliberate or accidental release of individuals kept illegally in aquariums

Management/Methods for Prevention

• Prevention via enforcing the Plant Health (Official Controls and Miscellaneous Provisions) Regulations (Northern Ireland) 2020 ensuring that the genus Pomacea is not introduced to Northern Ireland
• Reporting any sightings so that Rapid Response can be instigated

Current Legislative Position

• The genus Pomacea is listed on the list of Union quarantine pests
• It is illegal to have them on sale in Northern Ireland, whereas they are not illegal to sell in Great Britain
• This requires extra vigilance on aquarium products being shipped from G.B. to N.I.
• Under the Plant Health (Official Controls and Miscellaneous Provisions) Regulations (Northern Ireland) 2020 it is an offence to introduce or cause the spread of the genus Pomacea