De tropische landslak Helicina fasciata

Disappearance of Sint Maarten’s snails

Dutch Caribbean Nature Alliance (DCNA)
30-MAR-2022 - Over the course of three visits in 2015, 2020 and 2021 on Sint Maarten land and freshwater mollusks were surveyed. Snails are important for a healthy soil and are an important food source for many species. Alarmingly, it has become clear that a number of land snail species are declining. In fact, it is suspected that a number of species will disappear completely if no action is taken soon.
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About 49 species of mollusks (namely clams and snails) have been documented on Sint Maarten. Depending on which list you use, 15 or 16 are endangered, representing about a third of the island’s mollusk populations. Unfortunately, too little research has been done on these mollusks to make definitive conclusions, but it appears that four species may have already been lost, including the Apple Snail (Pomacea glauca), Marbled Physa (Aplexa marmorata), Glabrous Ramshorn (Biomphalaria glabatra) and Mottled Fingernail Clam (Eupera viridans). The terrestrial snails Pupiform Mountain Snail (Chondropoma pupiforme), Striped Helicinid (Helicina fasciata), Transparant Bulimulus (Bulimulus diaphanous fraterculus) and some more species are endangered on Sint Maarten.

Critical Habitats

The main causes of the decline in populations include habitat loss due to hurricanes, pollution and construction. In fact, the island has almost no primary (or original) forest left. Secondary forest is restored forest where, in addition to indigenous species of plants and animals, there are often many introduced exotic species which can bring about a number of other issues for the island.

One particularly vulnerable habitat is forest with calcareous moist soil. On the Dutch side of the island, this habitat is mainly found at Billy Folly, where only a limited piece of original habitat is still present. Nearly the entire 'mountain' has now been built up with houses. During the 2021 visit, a road was built right through the primary forest. This road will likely lead to new construction projects, which could result in the disappearance of the last remnant of forest causing the loss of any snail species bound to this area.

Sint Peter Hill

Another disappearing habitat is moist secondary forest on neutral soil. This habitat is mainly found on the French part around Paradise Peak. This habitat is scarce but not threatened because there are no building plans on and around Paradise Peak. On the Dutch side it is found on Sentry Hill and Sint Peter Hill.

Importance of snails

These snails represent an important part of the natural balance for the island. They consume rotting leaf litter and fungi and can help recycle nutrients in the soil. In addition, they provide food source to a number of mammals, birds, reptiles and even insects, helping convert nutrients found in the soil to a digestible food source for larger predators. A healthy environment for Sint Maarten starts in the soil, so understanding and preserving these tiny island inhabitants will be critical in protecting the island’s delicate ecological balance. 

Report your sightings

Pleurodonte guadeloupensis martinensisHave you observed snails? Report your nature sightings and photos on the website Observation.org or download the free apps for iPhone (iObs) & Android (ObsMapp).

Species reports by local communities and tourists are invaluable for nature conservation efforts to help increase public awareness and overall species protection. Besides, DCNA, Observation International and Naturalis Biodiversity Center are working together to develop on automated species identification app for your phone. Your uploaded photos are of great value to make this possible. For questions, please contact research@DCNAnature.org.

More information

Text: Tineke van Bussel, Dutch Caribbean Nature Alliance (DCNA)
Photos: Christian König, SHAPE/DCNA (lead photo: Striped Helicinid (Helicina fasciata)); Tello Neckheim