Invasive species

The orange cup coral, Tubastraea coccinea, was introduced into the Caribbean in the 1930s from the Indo-Pacific. Since then, it has spread throughout the Caribbean and into the near-shore reefs of Bonaire. In this study, I assessed the interaction of this exotic coral with the native reef community. I hypothesized that the three-dimensional structure of T. coccinea facilitates native species among which it successfully grows by providing habitat and food. To investigate this, colonies of T. coccinea were visually monitored in the field over several the morning (8:00), noon (12:00) and evening (18:00) sessions to capture how native species interact with and use the coral in a natural setting. Colonies of T. coccinea were also collected, defaunated, and experimentally caged-off so that consumers would not be able to graze the biofilm and/or algae growth on the colonies. Percent cover of cyanobacteria and macroalga growing on the corals was monitored over the duration of the study. Species richness within open and closed cages was also measured to assess which native species utilized the habitat as well as biofilm and algae. Cyanobacterial percent cover changed significantly over the duration on the study (increasing to 18% and decreasing to 3% in closed and increasing to 10% and decreasing to 1% in open cages ) as well as differed between closed and open cages (18% versus 9% at highest percent cover, respectively). The percent cover of macroalgae in closed cages was significantly higher than in partially closed cages (45% versus 25%, respectively) from day ten to the completion of the study. This was likely due to the exclusion of herbivorous fishes in the closed cages. Native species richness within both cage treatments increased throughout the duration of the experiment, but showed a fourfold increase between day 5 and10 within closed cages versus a leveling-out in open cages. Native fishes and annelids were observed in both the natural and experimental settings utilizing T. coccinea as both a habitat and a food source. These interactions of native species with T. coccinea suggest that the coral is positively interacting with the ecosystem in which it has successfully invade settled in and has become a facilitator of native species.

This student research was retrieved from Physis: Journal of Marine Science IV (Fall 2008)19: 13-18 from CIEE Bonaire.

Tubastrea coccinea is an invasive coral species found on the reefs of Bonaire. These corals are typically seen at various densities (up to 80% m-2) on hard, vertical substrata suggesting that biotic resistance could be one possible biological factor preventing settlement of T. coccinea elsewhere (e.g.,,, horizontal substrata). The impact potential competitors have on the successful invasion, recruitment and growth of T. coccinea was experimentally assessed by establishing replicated 15 x 15 cm plots of substrata already inhabited by single species or combinations of native species (0-3 and 3 seeded with adult T. coccinea) at the Harbor Village jetty, Kralendijk, Bonaire, which had the necessary vertical substrata. Monitoring occurred over a period of three weeks to assess percent cover change of the studied organisms. Additionally 15 vertical, 5 m transects were run to evaluate mean percent cover of all sessile species that inhabited the surveyed locations for a general representation of species diversity at the jetty. T. coccinea was not observed to settle in any of the experimental plots nor did the seeded adult conspecifics show any evidence of growth or recruitment. Observational data indicated that an algal turf had the highest mean percent cover, but in areas around T. coccinea, algal turf percent cover decreased by almost 20%, suggesting competition between the two organisms. No firm conclusions could be drawn about T. coccinea recruitment or growth, but results suggested that the presence of an invasive species may negatively affect the growth of native species when they are found in close proximity to it.

This student research was retrieved from Physis: Journal of Marine Science IV (Fall 2008)19: 2-6 from CIEE Bonaire.

The orange cup coral Tubastraea coccinea has expanded its range from the Indo-Pacific into the western Atlantic region. It grows on a wide variety of natural and man-made substrates, including rock ledges, docks, and shipwrecks. Its early reproductive age, fast growth rate, and ability to thrive where other species cannot could potentially make T. coccinea a valid threat to native species. The goal of this study is to provide baseline data on the size, depth, and range of T. coccinea on the island of Bonaire in the Dutch Caribbean. Substrate and light intensity preferences were also investigated by estimating percent cover on a variety of substrates and light conditions. A clear preference was observed for concrete substrates and low light conditions. Interactions between T. coccinea and a variety of other coral and sponge species were also investigated for potential harmful effects, but despite documentation of harmful coral-coral interactions in Brazil, no evidence of T. coccinea exhibiting harmful effects on native coral species was found in the study area of Bonaire. While T. coccinea does not currently appear to exhibit negative effects on native species in Bonaire, it may simply be in the early stages of expansion and this expansion needs to be monitored for future development of harmful effects on native species.

This student research was retrieved from Physis: Journal of Marine Science IX (Spring 2011)19: 70-78 from CIEE Bonaire.

Invasive species have a history of damaging their invaded ecosystems and in the case of the Pterois volitans invasion to the waters of many Caribbean Island nations, there has been no exception. Pterois volitans has caused negative impacts to the coal reef ecosystems such as reduced juvenile coral reef fish recruitment and, consequently damage to the associated fisheries. Management strategies of multiple nations are currently centered upon the reduction of populations via hunting. This strategy requires substantial effort and thus long term management solutions may include biotic controls. Parasitism is an important facet of population dynamics and could be important to the population dynamics for Pterois volitans around Bonaire. Pterois volitans is rarely a victim of parasitism in its native range and has similarly low rates of parasitism reported in its invasive range. The prevalence or lack of parasitic interactions between Pterois volitans and native parasites could be important in planning management strategies and controlling populations in the future. This study examined 200 Pterois volitans captured in the coastal waters of Bonaire for parasites in the mouth and gill structure, as well as over the entirety of the skin, to investigate possible interactions occurring between local parasites and Pterois volitans. Only one of the 200 investigated specimens was found to have an isopod attached to its gill structure.

This student research was retrieved from Physis: Journal of Marine Science IX (Spring 2011)19: 44-49 from CIEE Bonaire.

Invasive species are often a detriment to the environment due to the lack of parasites, disease and natural predators in the invaded environment, which allows the population to explode. Pterois volitans were introduced into the eastern part of the Atlantic in 1980’s, and migrated to the southern Caribbean and in October 2009, lionfish were first documented on the island of Bonaire, Dutch Caribbean. The purpose of this study was to document the feeding ecology of lionfish by identifying and quantifying stomach contents of different size classes of lionfish found on the island using four different metrics- frequency of occurrence, percent by volume, percent by number and Index of Relative Importance (IRI). Of the 70 lionfish stomachs analyzed, there was a positive correlation between lionfish size and amount of fish consumed. Similarly, there was a negative trend seen with size class and the amount of shrimp found in the stomach contents. When IRI was used to compare feeding ecology of Bonaire lionfish to a Bahamas study, the top five ranked families of preyed differed. This study identifies major dietary trends of lionfish on Bonaire, and can be used to better understand the feeding ecology and diet habits.

This student research was retrieved from Physis: Journal of Marine Science IX (Spring 2011)19: 38-43 from CIEE Bonaire.

Indo-Pacific lionfish (Pterois spp.) have spread to and established sufficient numbers throughout the Caribbean. They are extreme generalists that feed on ecologically and economically important species, they can reduce recruitment of native fishes by up to 79%, and can occur in densities in orders of magnitude greater than in their home range. Because prey do not recognize lionfish as predators (prey naiveté), lionfish prey on fish and invertebrates using little energy. The purpose of this study was to test if lionfish in Bonaire were obese and if obesity was more pronounced in males over females. Because of limited research on invasive species obesity, the presence of interstitial fat and fat in the liver was used to determine if a lionfish was obese or not. A total of 161 lionfish for interstitial fat and 74 lionfish for liver fat were analyzed. All males in this study were obese (they all had both interstitial and liver fat) however, not all females had interstitial and liver fat. Females also possessed interstitial and liver fat in lesser quantities than males probably because of allocation of energy towards reproduction. This study highlights the importance of studying obesity on invasive species, an open topic in marine science that has not been addressed thoroughly.

This student research was retrieved from Physis: Journal of Marine Science XIV (Fall 2013)19: 89-95 from CIEE Bonaire.

ABSTRACT

We used nightly surveys to monitor the status of building-dwelling gecko species on the southern Caribbean island, Curac ̧ ao. Two gecko species were detected in 10 counts across five nights from 18 sites. We recorded the nonnative Wood Slave, Hemidactylus mabouia (81%, 369/455 observations), native Dutch Leaf-Toed Gecko, Phyllodactylus martini (11%, 50/455 observations), and unidentified geckos (8%, 36/455 observations) on the island. The Dutch Leaf-Toed Gecko was most common near the forest and rare elsewhere. Wood Slave abundance was not influenced by forest proximity. Wood Slaves commonly perched near lights that provided heat and attracted insect prey. In contrast, the Dutch Leaf-Toed Gecko perched away from lights. Similar to gecko species in Florida, Wood Slaves displaced Dutch Leaf-Toed Geckos. The Dutch Leaf-Toed Gecko was syntopic with the Wood Slave on buildings near the forest when resources were not limiting or if other gecko populations were not self-sustaining. As Wood Slave populations grew, they excluded Dutch Leaf-Toed Geckos, and possibly Antilles Geckos, Gonatodes antillensis, from these buildings. This exclusion adds novel obstacles to the continued survival of the Dutch Leaf-Toed Gecko on Curac ̧ ao. A similar situation may be present on Bonaire, and for a congeneric species on Aruba, where the Wood Slave is a more-recent colonist. 

Boa constrictor was first documented on the Caribbean island of Aruba in 1999. Despite intensive efforts to eradicate the snake from the island, B. constrictor has established a stable, reproductively successful population on Aruba. We generated mitochondrial sequence and multilocus microsatellite data for individuals from this population to characterize the origins and means of introduction to the island. Phylogenetic analyses and measures of genetic diversity for this population were compared with those for invasive B. constrictor imperator from Cozumel and B. constrictor constrictor from Puerto Rico. Cozumel populations of B. c. imperator had significantly higher number of alleles and significantly higher values for FIS than the Puerto Rico and Aruba populations. Observed, expected, and Nei's unbiased heterozygosities, as well as effective number of alleles, were not significantly different. The effective population sizes from Aruba and Puerto Rico were generally lower than those for either of the Cozumel populations; however, there were broad confidence intervals associated with published estimates. We conclude that the present B. constrictor population on Aruba probably was not established from the introduction of a single gravid or parthenogenic female but instead most likely resulted from the release or escape of a small number of unrelated captive snakes. This study adds to the growing body of evidence suggesting the ease with which a small number of relatively slow-maturing B. constrictor can quickly invade, become established, and avoid eradication efforts in a new location with suitable habitat.

Summary:

Lionfishes are venomous species of scorpionfishes which are native to Indo-Pacific coral reef ecosystems and adjacent habitats. Because of their colorful and dramatic appearance, they are prized by aquarists around the world. Through accidental and/or purposeful release into warm Atlantic waters, they have become established as a highly problematic alien species that poses a serious threat to coral reefs in Bermuda, Florida, the Gulf of Mexico, the Caribbean islands, Central America, and northern South America. Invasive lionfish populations can reach high densities and cause extreme disruption to native fish communities; they have been shown to reduce biodiversity, are responsible for the decline of ecologically important species, and hinder stock-rebuilding efforts for economically important species.

In January 2010, in recognition of the severity of the lionfish invasion and its impact on coral reefs and local communities, the 24th General Meeting of the International Coral Reef Initiative (ICRI) agreed to set up an Ad Hoc Committee to develop a strategic plan for the control of lionfish in the Wider Caribbean. The Strategy described in this document is one of the actions implemented by the Ad Hoc Committee, known as the Regional Lionfish Committee (RLC). It seeks to build on the existing programs and efforts aimed at minimizing the impacts of the lionfish in the region, and to provide a framework for action to provide a regionally coordinated response to the lionfish threat. The Strategy is based on the following objectives:

1. i)  Facilitate collaboration among governments, reef-reliant industries, civil society, and academia by providing mechanisms for coordination of efforts across political and geographical boundaries,
2. ii)  Encourage a coordinated research and monitoring agenda,
3. iii)  Encourage governments to review and amend relevant legislation and, if necessary, develop new regulations and policies to control lionfish,
4. iv)  Control invasive lionfish populations using regionally coordinated, effective methods, and
5. v)  Provide education, information and outreach mechanisms to generate public support and foster stewardship in invasive lionfish programs.

Each of the objectives is supported by strategies and actions with specific stakeholders identified as possible implementers. It is expected that this Strategy will be used by governments and other stakeholders to create plans to implement many of the actions identified in this strategy. The action plans would include timelines and indicators to measure effectiveness in achieving the objectives of this Strategy. Local government, coastal communities, non-governmental organizations (NGOs), and marine industries will play an important role in implementing on-ground actions to reduce lionfish impacts and enhance the resilience of reefs in the Wider Caribbean region. 

Summary:

Recent inventories have documented no less than 211 exotic alien species in the wild for the Dutch Caribbean. These amount to no less than 27 introduced marine species, 65 introduced terrestrial plants, 72 introduced terrestrial and freshwater animals and 47 introduced agricultural pests and diseases. A list of these species, pests and diseases are found in resp. Debrot et al. (2011), Van der Burg et al. 2012, and Van Buurt and Debrot (2012, 2011). The rate of introductions and establishment of invasive alien species (IAS) worldwide has grown rapidly as a result of increasing globalisation. Invasive species cause major ecological effects (decimating native flora or fauna populations) as well as economic losses to these islands, across sectors such as agriculture (diseases, weeds and vectors), fisheries (fish diseases and the lionfish), industry (rodents and termites), tourism (roadside weedy species) and public health (mosquitos). Recently in Curaçao the kissing bug Triatoma infestans was found; this is a vector for Chagas disease. It almost certainly came in with palm leaves imported from South America to be used as roof covering for recreational beach “palapa’s”.

Several countries in the Caribbean have developed a strategy to address the invasive species problem already, such as Jamaica (Townsend 2009), the Bahamas (BEST Commission 2003) and St. Lucia (Andrew and John 2010, Chase 2011). Islands are particularly at risk because of a number of factors: their small size, resulting in small vulnerable plant and animal populations, a relatively large border which is difficult to control, a small human population lacking the necessary expertise and resources to take adequate measures. For islands, the sea acts as a strong natural barrier for natural transport of terrestrial flora and fauna, however human activities helped in overcoming this barrier. The issue of feral animals, especially roaming cattle, donkeys, goats create similar problems everywhere: they have a devastating effect on tree and shrub regeneration, which greatly degrades the natural vegetation, with severe soil degradation as a result. This shifts the competitive advantage to hardy exotics and creates runoff of nutrients and silt into the sea, where algal growth and silt deposition are damaging the coral. The new nature policy plan for the Caribbean Netherlands assigns a high priority to the invasive species problem (MinEZ 2013), which worldwide is considered second only to habitat destruction as a long-term threat to biodiversity (Kaiser 1999, Mooney 2001).

While acknowledging a focus on the Caribbean Netherlands in specific (Bonaire, Saba, St. Eustatius) this report sets the first key steps in developing a common frame of reference for the whole of the Dutch Caribbean (i.e. including the islands of Aruba, Curacao and St. Maarten). These islands share historical and cultural ties, partly similar climates, scarce expertise, and experience most IAS as a common problem. The magnitude and severity of the problem is evident and necessitates a joint strategy into which action at insular level can be embedded for maximum efficiency and synergy: a common Invasive Alien Species Strategy (IASS).

Management Recommendations:

The main action points for implementation are:

1. Develop and adopt guiding legal lists for action: Black lists, Alert lists and Watch lists, enumerating the species for which border control is essential or for which control and management actions would be required. A special task group should be made responsible for keeping these lists up to date.

2. Install effective border controls. To prevent is better than to cure: the costs of controlling or eliminating invasives once established can be very costly. For this reason and because of the earlier indicated special vulnerability of the island ecosystems, it is strongly recommended to prevent the entrance of (more) invasives.

3. Establish Invasive Species Management Teams. For the coordination of data collection, evaluation and the initiation of actions, a special team is required. This ISMT team shall have its own facilities and budget.

4. Define responsibilities and mandates. Ultimate responsibility for IAS control lies with the island governments. This means that policies regarding IAS will be determined by the government. However, to be effective and efficient the ISMT (see 9.) needs full mandate to act within the limits of their own budget.

5. Require quarantine documents. Phytosanitary certificates and animal health certificates will be required for all imports.

6. Enforcement. Staff must be trained and instructed how to perform border controls. They must obtain sufficient mandate and means to confiscate and dispose of prohibited goods.

7. Develop action plans. A plan of action needs to be ready, describing the successive steps and decisions that have to be made for key threat species at all stages of the invasion process.

8. Arrange access to properties. When an alien species is invasive and needs to be eliminated, it is important that regulations allow the exterminators access to all properties, private and public alike.

9. Assure public support. Large scale programs for extermination and control, especially of animals, needs extensive public support. Volunteers may prove essential to assure enough ‘eyes’ and manpower.

10. Make rapid surveys. In order to decide whether a complete eradication is needed or that monitoring and restricting the distribution (mitigation) is the best or only option, a survey of the extent of the problem must be assessed by experts.

11. Rapid response. Usually a rapid action can localise the problem to a restricted area or eliminate the first individuals effectively so that no further costs have to be made.

12. Make risk assessments before introducing natural enemies. In case species are already present in vast numbers, biological control is often a last resort. This usually means introducing a natural enemy from the area of origin of the species. This means introducing another alien species, which may become a pest in itself. Expert consultation and small-scale experimenting is usually needed before the potential natural enemies can be safely released.

13. Create an information system. A team of experts managing a computer database is needed. This ISMT team needs to develop a system for easy reporting of new discoveries of alien species, for maintaining and updating information on key threats. The information system supports policy, action and research at all levels of the invasion process.

14. Create a platform for cooperation. In order to develop the system further, a national as well as an island platform is needed for participation of all relevant stakeholders. These platforms will develop recommendations for the ISMT and the island governments, and may also act as support group for the ISMT.