Statian invasions

This news-item was published in the Caribbean Netherlands Science Institute Annual Report 2017

Introduced predators such as cats, dogs, and rats are found all over St. Eustatius and are a primary threat to the island's biodiversity. Rats, which are not limited to urban areas and can be found all the way up the Quill, have become an especially challenging issue as they not only threaten the survival of native plant and animal species but also pose a potential health risk to the island’s inhabitants.


Islands like St. Eustatius are particularly vulnerable to invasive species due to their relatively small size and isolated location, together covering just 5% of the Earth’s land mass. Yet, islands represent the greatest concentration of biodiversity and species extinctions (40% of fauna at risk of extinction; 80% known extinctions since 1500).

Once an invasive species arrives on an island, early detection is crucial to avoid excessive eradication costs and negative side-effects once it becomes established. Actions that can be implemented includespecies alert lists, action plans, effective border controls, public awareness, invasive species management teams, government policy (and enforcement), and quarantine import documents.

Invasive fauna species can impact human health, native wildlife and ecosystems, and the local economy. The green iguana (Iguana iguana) is a perfect example of an invasive species that has spiraled out of control on many Caribbean islands. The potential severity of this situation on Statia was addressed in November through an invasive species workshop tailored specifically for relevant port of entry staff, civil servants, and public health and park management staff. CNSI hosted the workshop under the Nature Awareness project, which is funded by the Ministry of Economic Affairs.

The workshop was facilitated by three marine and terrestrial biologists from Naturalis Biodiversity Center in the Netherlands (Dr. Bert Hoeksema, Dr. André van Proosdij, and MSc. Niels Schrieken).

The arrival of the green iguana is terrible news for islands that house the regionally endemic lesser Antillean iguana (Iguana delicatissima), and unfortunately, Statia has recently fallen victim to this. Following the discovery of an adult female green iguana in 2016, six hybrids were captured during intensive search efforts. This is an ongoing cause for concern on the island.

In 2000, the first lionfish were spotted in Bermuda and have since spread across the Caribbean Region. With their voracious appetites and rapid reproductive rates, lionfish pose a severe threat to native fish species. On Statia they are harpooned and brought back to shore where their stomach contents are analyzed, and the flesh can safely be eaten once the poisonous spines are cut off.

Invasive plants like Corallita, which covers around 30% of the island’s surface, grow quickly and aggressively, spreading and displacing other plant species.


The SETL-project is a community study which monitors the diversity of species living on a hard surface. This project was launched in 2006 in the Netherlands by GiMaRIS, in close collaboration with the Smithsonian Marine Invasions Laboratory, and is still run by them. The SETL-project is also run locally in the USA by the Salem Sound Coastwatch and is project-based in other European countries and throughout the Ponto-Caspian region (see figure).

The plate design has been deployed along both coastlines of northern America and in Hawaii to facilitate comprehensive comparisons. Within the Caribbean Basin, there are sites in Central America but none on the Atlantic side. Thus in November, St. Eustatius became the first SETL-location for the Caribbean Basin on the Atlantic side. 

A SETL-plate consists of a 14x14x0.5 cm PVC plate, hanging from a plastic line with a metal core in the water column and deployed under the water line. Monitoring the plates is best done repetitively. Pictures taken of the plates are divided on an overview photo into 25 grids, and the presence of species is scored for each grid. Six SETL plates have been installed on St. Eustatius, and if data is collected quarterly for ten years, the presence/absence of some 450,000 records of species can be documented.


The invasive species workshop encompassed interactive sessions and discussions that led to extensive knowledge sharing and development at all levels. A recommendation/discussion document was created based on particular issues flagged for importance, including inspections/border control, customs, and capacity-building.

CNSI will organize a follow-up session to promote further discussion and to formalize specific action points between key island stakeholders. It will encourage those who could not attend the workshop to become involved, and will focus on the creation of a task force and/or training if necessary. The responsibility of various stakeholders for e.g. detection of invasive species will also be discussed.

A booklet highlighting the threat of existing and potential invasive species on St. Eustatius was given to all participants of the workshop.

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