Abstract:

In a recent dissertation (Vermeij, 2002) it is stated that with no action by the Curaçao government, the coral reefs will have disappeared in 30 years. To answer the question "What can be done?", this document focuses on the following causes of coral decline:

• Sedimentation
• Inorganic and organic pollution
• Overfishing
• Oil pollution
• Heavy metals and pesticides

A dead dolphin found on Bonaire in August 2011 is identified as adult Fraser’s dolphin Lagenodelphis hosei, a new species for the Dutch Caribbean. A first closer examination showed a collapsed lung, stomach parasite infection and abundant mouth ulceration as indications of its health status. The animal was relatively fresh and did not die very long before it was found. Like more often with stranded deep diving cetacean species within the area, remnants of crustacean were found in its beak indicating recent foraging. 

A review of the introduced agricultural pests and animal and plant diseases and vectors for the Dutch Caribbean in which a total of 47 exotic pests, diseases, parasites and pathogens established on one or more of the Dutch Caribbean islands are listed and discussed. These include 2 species of voracious herbivorous snails, 7 species of millipedes, 8 species of invasive ants, and some 16 species of insects that infest plants. Most agricultural pests are not strongly host-specific and will typically also affect native plants and/or animals. This makes it very difficult to eradicate or control these species once established. Therefore, prevention and early eradication is key.

The most information on invasive alien pests is available for the leeward Dutch islands while the least is known for the windward Dutch islands. The principal means of entry is the importation of unsterilized soil and plant material through container shipment, import of ornamental plants and air traffic. The economic costs, both in terms of damages and control measures, as well as missed opportunities that these species cause, has not been estimated but certainly runs in the millions of dollars annually. By far the most economically costly invasive species is the yellow fever mosquito Aedes aegypti, a pest and disease vector closely associated with man. In a few cases, biological control and eradication has been successful.

Introduction of invasive pest species continues at a high rate in the Dutch Caribbean and preventive measures are urgently needed to limit future costs and risks in terms of economy and health.

Key recommendations are: a) to strongly restrict and control importation of ornamental plants, most of which can be propagated locally without risk of new introductions, b) restrict importation of unsterilized foodstuffs, c) practice tighter control and prophylactic fumigation of container shipments, d) continue strict veterinary controls on animal importations. To effectively implement such measures, will require greater awareness, supporting legislation, cooperation of customs agents and shippers and the presence of a biosecurity unit authorized and equipped to act on short notice.

Based on experiences in other Caribbean countries and existing trade patterns and taking into account which species could survive in an arid climate, it is possible to draw up a preliminary listing of “Alert” species for the Dutch Caribbean. Such a listing is a critical tool for effective prevention. The preliminary Alert list discusses 21 species to be on the look-out for, most of which are insects and most of which can be expected to cause important damage to crops and/or nature, or both, if introduced.

The marine exotic species of the Dutch Caribbean are less well-known than its terrestrial exotics. So far, only 27 known or suspected marine exotic species, some of which are also invasive are documented for one or more islands of the Dutch Caribbean. Four of these were documented only once or were only present for a certain period of time and are no longer present. Six of the species are marine epidemic diseases. As very little is known about these diseases, they might actually be native, but based on the literature and their ecological signature we regard them as special cases of invasive species.

In addition to these documented species, 76 other exotic species that have already been observed elsewhere in the Caribbean may already be present or can be expected to arrive in the Dutch Caribbean in the near future. The marine communities of the Dutch Caribbean have suffered major changes based on a handful of marine exotic and/or invasive species, particularly in the special case of (opportunistic) pathogens. In certain cases experience shows that after decades, the affected systems/species may show slow signs of recovery from initial impacts (e.g. the green turtle fibropapillomas), while in other cases the impact may be long-lasting and recovery doubtful (e.g. sea fan mortality).

Compared to terrestrial exotic species, eradication and control have been proven difficult or impossible for marine exotics. Therefore, management practices aimed at controlling unwanted species introductions should focus on preventing the arrival of such species by ships-- that transport exotics in their ballast water or as fouling communities on their hulls-- and (accidental) introductions from aquaculture or the aquarium trade. Busy harbors can be expected to be the areas where most marine exotics likely establish first.

Because of dispersal of marine exotics is facilitated by ocean currents, local approaches to prevent their arrival or reduce their numbers will be less effective compared to similar efforts for terrestrial species. In the case of marine exotics and invasives, it is paramount that prevention, control and management efforts should be regionally integrated. We conclude this report by listing a number recommendations on how to develop effective management approaches with which to address the impacts and risks associated with marine exotic species.

This research is part of the Wageningen University BO research program (BO-11-011.05-004) and has been financed by the Ministry of Economic Affairs, Agriculture and Innovation (EL&I) under project number 4308202004.

We here provide an overview of 72 invasive animals of the terrestrial and freshwater environments of the Dutch Caribbean, eleven of which are no longer present. All invasive animals that are principally agricultural pests and or animal and plant diseases (46 species) are excluded as these are discussed separately elsewhere. The 61 species documented and discussed here as presently living in the wild or semi-wild state on one or more of the Dutch Caribbean islands, amount to 12 exotic mammals, 16 birds, 13 reptiles, 5 amphibians, 2 freshwater fishes, 3 insects, 2 mollusks and 8 exotic earthworms. For most species, the ecology, distribution, status and current impact remains poorly known as few invasive species have been object of directed studies. Some of the most deleterious animal introductions have been mammals, particularly the grazers and the predators, most of which have been introduced in the historical past. Among these, the four key species are grazing goats, the mongoose the cat and the black rat. In most cases, such species cannot be eradicated because they are widespread and firmly established or even kept as livestock. Nevertheless, these species must urgently be controlled in sensitive areas where possible. Our review also shows that many introduced mammals and reptiles are still present in relatively small populations, making eradication still very feasible. Seven species have the status of being native in parts of the Dutch Caribbean but introduced to other parts where they are not native. The most threatening of this last category is the green iguana, as introduced to St. Maarten where it outcompetes and hybridizes with the weaker Lesser Antillean iguana.

The key priorities for successful action against invasive exotic animals are:

• the control of goats;
• control of introduced predators (rats and cats) near seabird breeding colonies;
• eradication of several small populations of exotic mammal predators and reptiles as long as this is possible before the get a strong foothold and spread; 
• eradication of introduced species from small satellite islands which serve (or served) as seabird breeding habitat.

In addition to such on-island action against species already present, it is critical to prevent further introductions. The most important pathways to focus control on are the container transport of goods, the international trade in pets and the trade in ornamental plants. Two key action points are urgently needed: a) develop the existing legislation and b) invasive species management teams (ISMTs) empowered for action. It is essential that these initiatives be firmly imbedded in a policy framework. The first step ahead in these respects should be to outline an Invasive Species Strategy and Action Plan (ISSAP). However, in the interim, the lack of an ISSAP should not hinder directed critical action at the local level (eg. against goats in the national parks and cats at seabird breeding sites).

This research is part of the Wageningen University BO research program (BO-11-011.05-004) and has been financed by the Ministry of Economic Affairs, Agriculture and Innovation (EL&I) under project number 4308202004.