2017 Guest blog: Virgin Islands

During Invasive Species Week 2017 we heard lots about how invasive non-native species (INNS) are having an impact in Great Britain, but further afield they are also an important issue.

The UK has 14 Overseas Territories (OTs), all of which are islands except for the British Antarctic and Gibraltar. Biodiversity in the OTs is globally significant, supporting unique species and ecosystems and a large number of rare and threatened species.

The impacts of invasive non-native species on small islands is often much worse than elsewhere because the native flora and fauna have evolved in isolation from predators, competitors and diseases. As a result native species are less able to compete and defend themselves in the face of new threats.

Read on for a guest blog from one of the UK OTs.

Invasive Species in the Virgin Islands

The three main invasive species on the conservation radar in the Virgin Islands (UK) include the Green iguana (Iguana iguana), the Indo Pacific Lionfish (Pterois volitans) and the Agave Snout Weevil (Scyphophorus acupunctatus). Whilst feral goats and rats are also very high on the agenda and are actively being addressed within protected areas, these three invasive species are so prolific and potentially threatening they warrant a special mention

The green iguana (Iguana iguana) is an introduced species that reproduces rapidly and can outcompete native iguanas. At present it has been reported on at least three to four islands in the Virgin Islands, including the largest island of Tortola and Jost Van Dyke. In 2015 two green iguanas were reported by residents on Anegada, which is home to the critically endangered Anegada Rock Iguana (Cyclura pinguis) and so they were immediately destroyed by National Parks Trust of the Virgin Islands (NPTVI) Park Wardens. It is essential that green iguanas are not allowed to become established in Anegada, and more public awareness is required to ensure that the local community and visitors recognise the difference between the two iguana species.

Monitoring of the movement of items between Anegada and other islands through shipping needs to be monitored for the presence of such invasives. This is part of a larger biosecurity protocol that must be developed for Anegada, but increased capacity and training is required for NPTVI staff and the relevant Government Departments who supervise ports of entry.

The most voracious invasive species in the marine environment is the Indo Pacific lionfish (Pterois volitans). The first lionfish was confirmed to be present in the Virgin Islands in March 2015 at Ginger Island, as divers were on the lookout as it was spreading rapidly throughout the Caribbean.

The Conservation and Fisheries Department collaborated with other UKOTs to develop a response to the invasion which included working with local dive operators to mark the location of lionfish sightings so that trained divers could return and spearfish them. As lionfish are very territorial and stay in the same location, this methodology can be very effective, but can only make a small dent in the overall lionfish numbers. More education is needed to demonstrate that catching lionfish as a food source would greatly assist in reducing overall numbers, but safe.

Finally, the Agave Snout Weevil (Scyphophorus acupunctatus) poses the greatest potential environmental risk to plant species in the Virgin Islands. It is a boring weevil that attacks the Puerto Rico Bank native Agave missionum, which is known locally as the Century Plant. NPTVI is collaborating with the Royal Botanic Gardens Kew and Fera Science Ltd. to conduct more research on the extent of this pest across the Virgin Islands. This invasive pest was first reported in the late 1990s, early 2000s by scientists conducting research on Guana Island, a private island that hosted visiting scientists for an annual research expedition. Since then observations by Kew and Fera suggest that the weevil has led to a Territory wide collapse in the Agave missionum population. This plant species is of cultural importance as the dried inflorescence was formerly used as a Christmas tree, but this is no longer possible due to the high mortality rate of this Agave species. There is no response at present, other than to continue researching its spread and the creation of ex-situ collections at the JR O’Neal Botanic Gardens.

Article written by Nancy Woodfield Pascoe, Deputy Director National Parks Trust of the Virgin Islands

Images (top - bottom):

  • A native Anegada Rock Iguana (Cyclura pinguis) eating a fruit from the Pilosocereus royenii, a Caribbean wide cactus - showing how it is disperses this species. Photo by Sara Barrios, Kew.
  • The invasive Lionfish (Pterois volitans). Photo by Pharaoh Hound.
  • Agave missionum under attack from the Agave Snout Weevil (Scyphophorus acupunctatus). Photo by Nancy Woodfield Pascoe, National Parks Trust of the Virgin Islands.

    More information on the UK OTs can be found here

Thin strip of image show tree trunk and bark