Smith, S.R.

In this review the following three reef restoration techniques are discussed: 1. Coral gardening, 2. Larval seeding, and 3. Reef balls. These techniques are commonly used in the Caribbean and have widely different approaches. Coral gardening utilize the natural process of asexual reproduction through fragmentation to provide new coral clones for population growth. Healthy wild colonies are once clipped/fragmented and further grown (and cloned multiple times) in an underwater nursery and ultimately transplanted to the reef.
In contrast, larval seeding is based on the sexual reproduction of corals, where large amounts of coral eggs and sperm are collected in the field with subsequent fertilization in the lab. The coral recruits are then made to settle and grown in aquaria until a certain size, after which they are transplanted to the reef. Reef balls are artificial concrete structures designed to provide shoreline protection and sometimes shelter for fish, while at the same time providing substrate for natural recruitment and attachment of benthic organisms such as corals.
A general introduction to coral reproduction is provided to show how life history characteristics are used in restoration efforts and how these can affect the genetic variation within coral populations. The three approaches are compared based on:
1. Survival of fragments and larvae before transplantation to the reef.
2. Survival of transplants at the restoration site.
3. Introduction of exogenous material.
4. Indirect effects of coral restoration on the reef.
5. Genetic diversity.
6. Feasibility and effectiveness.
The main advantages of the production of colonies from fragments are that it bypasses the early larval stages where mortality is high and that new colonies can be grown completely in the field. Generally, the asexual reproduction technique demands less advanced expertise and the public outreach of this method is high because volunteers can easily be incorporated into the program. Furthermore, results become apparent relatively soon since the used species are relatively fast growing. However, there is the risk of creating populations with little genetic variability and the method is only applicable to branching coral species. Presently the method is mainly used for one single species, namely staghorn coral (Acropora cervicornis).
Larval seeding (sexual reproduction) is arguably the best method since it ensures natural genetic diversity and can be used with many species. The disadvantage with this method is that it demands a reasonably high level of expertise and takes more time than the asexual production of new colonies by fragmentation. Also a high percentage of new colonies is lost during the early stages. It is still mostly in the development phase.
Reef balls may increase fish biomass and protect shorelines, but their potential for coral reef restoration is judged to be limited due to the generally low levels of natural recruitment to these structures.
The restoration techniques suffer presently from a lack of independent scientific publications with good data to validate survival, regeneration, and growth rates of colonies in the different phases of the restoration program.
Different populations of the branching Acropora species can differ fundamentally in reproductive characteristics and may respond differently to environmental change. Their difference in strategy may also be a result of adaptation to local environmental factors. All studies and protocols thus stress the necessity to adapt methods to specific locations and environments.
Consideration of genetic factors is essential because the long-term success of restoration efforts (depending on resilience of the populations) may be influenced by genetic diversity of restored coral populations. The use of molecular tools may aid managers in the selection of appropriate propagule sources, guide spatial arrangement of transplants, and help in assessing the success of coral restoration projects by tracking the performance of transplants, thereby generating important data for future coral reef conservation and restoration projects.
It is proposed to study genetic variation in the natural populations around the islands of the Dutch Caribbean and within the various restoration projects in progress. Additionally, it is recommended to assess survival, growth and regeneration of fragments ánd mother colonies in the field. We recommend to combine characteristics of the two main coral restoration techniques (fragmentation and larval rearing) to create a new hybrid approach to increase survival of sexually derived colonies and genetic diversity. In addition, the cost-effectiveness of the larval seeding method should be ascertained and compared with the fragmentation method.
We conclude by pointing out that reef restoration can only be successful if environmental conditions are adequate for survival and growth of coral colonies. This will mean that presently the selection of restoration sites with good environmental conditions is crucial. Thus, active management of anthropogenic stressors is a prerequisite for reef restoration — if a reef is not effectively managed and chronic stressors persist or develop, restoration will ultimately fail. Reef restoration must only be considered as complementary to management tools that address the wider causes of reef degradation.

The land cover map of Saba gives a coarse representation of the distribution of forest, shrub, pasture and artificial surface. Invasive species (like Corallita) are included where technically possible. See this report for more information

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. 

Abstract:

On 10 October 2010 Bonaire, Saba and St. Eustatius became ‘special municipalities’ of the Netherlands, making the Dutch government responsible for the implementation and adherence to several international conventions that apply to these islands (e.g. Convention of Biological Diversity, Ramsar convention), including the protection of nature.

Knowledge on the whereabouts of endangered and key species or habitats is essential to ensure their protection against the negative effects of activities such as uncontrolled socio-economic developments (e.g. construction works, harbour expansion, expansion of residential areas) and natural phenomena (e.g. hurricanes, Sea Level Rise). This necessitates early identification of risk locations where future expected activities may collide with species/habitat presence. To determine these whereabouts, monitoring is necessary. Monitoring in the field, however, is often costly and time-consuming. A more effective and quicker approach is desired to obtain a realistic overview of key habitat distributions and associated key species.

At the request of the Dutch Ministry of Economic Affairs the present study examines the possibility to identify the different land cover types (natural and artificial) on Very High Resolution1 satellite images of the Caribbean islands Bonaire, Saba and St. Eustatius, using remote sensing1 analysis. In addition, the possibility to link key species with specific land cover types was assessed by identifying the species’ habitat requirements. Linking species habitat requirements with associated land cover types allows for the identification of their potential occurrence on the islands. It was expected that with niche-modelling potential distribution maps could be developed for different species and habitats. Such maps are valuable to determine risk locations where species/habitat occurrence and planned activities may conflict in the future. This would allow for the proper and early implementation of protective measures.

Worldview-2 satellite images of Saba and St. Eustatius (acquired on 3 December 2010 and 18 February 2011, respectively) were analysed. Analysis of the satellite image of Bonaire was not possible, due to time constraints. From the results of Saba and St. Eustatius it can be concluded that identification of land cover types using satellite images is possible. At present, the results are limited due to a) heterogeneous land cover types and b) the lack of ecological knowledge (e.g. baseline studies).

The identification of artificial features1 (e.g. infrastructure) is not a problem. The challenges encountered are mainly related to the largely mixed heterogeneous vegetation found on Saba and St. Eustatius. Due to the high level of mixing, spectral overlap between different vegetation types is high. Consequently, separating the different vegetation types is difficult. Corrections can be made based on visual interpretation and expertise in the field. This requires time and expert knowledge of the different vegetation types. In addition, both Saba and St. Eustatius exhibit strong differences in altitude, resulting in numerous shadowed areas that impede the identification of the land cover types underneath. Such terrain effect can be corrected using a Digital Elevation Model (DEM). Unfortunately, a sufficiently good DEM (with a high spatial accuracy of around 1 meter) was not yet available2.

Analysis of satellite images resulted in land cover maps with good fit to the distribution of the different land cover types on Saba and St. Eustatius. The produced land cover maps (Figures 4 to 7) give a coarse representation of the distribution of Forest, Shrub, Pasture and Artificial surface on the islands. In addition, it was possible to identify the extent and location of invasive vegetation (e.g. Corallita and other species), although identification to species-level was not possible. At present, these maps provide insufficient detail for biodiversity monitoring, because of the lack of connection with species. They could, however, be used to monitor different land cover development (e.g. forestation, artificial surfaces, shrub and pastures) on the long term (e.g. in years) or to gain a quick overview on the location of invasive vegetation. A distinctive land cover classification based on the available satellite images during the present study, however, was only achieved for the coarser vegetation types.

Ecoprofiles were developed for various species and habitats, describing their habitat requirements. With sufficient detail, these requirements link the species to habitats and thereby allow for the creation of species specific maps. The level of available data on habitat requirements varies per species. Overall knowledge on habitat requirements is generally not sufficient, associating species with multiple habitat types, and making it difficult to pinpoint essential habitat types. The amount of knowledge on habitat requirements has direct influence on the success of niche modelling. This illustrates the necessity of detailed knowledge on species biology, ecology and life history characteristics even when using advanced techniques such as remote sensing.

The production of maps through niche-modelling meant to show the expected geographical distribution of species was not possible due to the limited level of detail within the identified land cover types, and the restricted data on the habitat requirements of the species occurring on Saba and St. Eustatius, in combination with time constraints. Before such maps can be developed several issues need to be solved first. These include specific knowledge on species biology, ecology and life history characteristics of the target species (baseline studies); the collection of more training samples (ground truthing data) in the field; a high quality DEM of Saba and St. Eustatius (and Bonaire as well). This will lead to further adaptation of the chosen classification scheme and aid in separating spectral overlap between the different vegetation types.

This research is part of the Wageningen University BO research program (BO-11-011.05-019) and was financed by the Dutch Ministry of Economic Affairs (EZ) under project number 4308701012. 

Abstract

On the island Bonaire, eutrophication is a point of serious concern, affecting the coral reefs in the marine park. Eutrophication can cause altered balance of the reef ecosystem because algae shall outcompete corals, eventually leading to a disturbed composition of the reef.
The reef of Bonaire faces nutrient input by various sources, of which enriched groundwater outflow from land to the reef is considered to be a substantial source. Groundwater is enriched with nutrients due to the e.g. leaking septic tanks.

In order to reduce the input of nutrients on the reef via sewage water, a water treatment plant is being built on Bonaire. The treatment of sewage water will be extended in 2012 with a sewage system covering the so called sensitive zone, the urbanised area from Hato to Punt Vierkant. Based on the dimensions of the treatment plant and estimated connections to the plant, it can be assumed that a total of 17520- 35040 kg of Nitrogen a year will be removed from the sensitive zone, and will not leach out to the sea at the western coast of Bonaire.

At the moment limited information is available about the total amount of nutrients in the marine environment. Therefore, Rijkswaterstaat Waterdienst asked IMARES to conduct a monitoring study.The goal of this coastal monitoring study was to collect baseline water quality data to be able to study the effectiveness of the water treatment facility in coming years. No estimates are known of the contribution of other sources to the total nitrogen load.

The study consisted of two phases and resulted in two reports:

1. recommendations for baseline monitoring in 2011,
2. monitoring, data evaluation, and recommendations

The aim of this first report was to define recommendations for the baseline monitoring the, expected positive, impact of the new sewage treatment system on the marine environment of Bonaire, with special emphasis on baseline monitoring. For this an evaluation was made of:

• Parameters/indicators to analyse, including argumentation, critical conditions
• Methods for sampling and critical conditions, including costs
• Potential sampling locations

Abstract:

A preliminary inventory is given of key terrestrial nature values of Bonaire in order to determine their occurrence in relation to areas designated as “nature” and “open landscape”, according to the Spatial development plan of Bonaire. This was based on a literature study and supplemented by expert advice.

In 2010 a spatial development plan was written in order to determine the spatial policy and regulation for the future development of Bonaire. The island was partitioned into areas for different uses such as agriculture and recreation. Two specific designations are “nature” and “open landscape”. The occurrence of nature values within these areas remained unclear. This makes implementation of protective measures based on international treaties and island legislation problematic. An inventory of the occurrence of these values should help facilitate more effective implementation of these protective measures. In the present study key nature values are determined, both in terms of protected species and essential habitat (e.g. caves). 

From the literature study it became apparent that data on the occurrence of most of the priority species of flora and fauna, is limited and scattered, especially with respect to “open landscape” and “nature” outside parks. Therefore, only a preliminary inventory is provided showing the general distribution of nature values across the entire island, as linked to various habitat types. An exact distribution of the different nature values was not possible at this time, but extrapolation from areas of known occurrence into other areas of similar habitat type was used to show the occurrence of overlapping distributions of nature values within the designated areas of “nature” and “open landscape”. The number of overlapping distributions of nature values may contribute to setting conservation priorities.

From the results it can be concluded that the areas of “open landscape” and “nature” (outside the national parks) seem to harbour unique and critical nature values. These areas are not actively managed or protected as national parks. The “open landscape” of Bolivia possibly harbours a few rare plant species (unique), an important population of critical key columnar cacti and at least two columnar cactus-pollinating bat species. The “open landscape” of Washikemba/Bakuna harbours key mangrove species that only have another main location at Lac Bay (national park). The “nature” area of Terrace Landscape Middle Bonaire seems to harbour a concentration of unique (e.g. Tillandsia balbisiana) and rare plant species (e.g. Krugiodendron ferreum etc.) and four bat species. The same is the case for Lima (e.g. Sabal palm, Maytenus versluysii and three bat species) while in Southern Bonaire key mangrove species also still occur. Table 1 shows which nature values are found or expected to occur within each “open landscape” and “nature” (outside national parks) area.

It can be concluded that outside the current parks, the main regions that harbour a concentration of key nature values are Terrace Landscape Middle Bonaire/Sta. Barbara, Bolivia, Washikemba/Bakuna and Lima. Terrace Landscape Middle Bonaire is designated as “nature” area, while Washikemba/Bakuna and Bolivia are in part designated as “open landscape”. Lima has both “nature” and “open landscape” designations. Sta. Barbara is designated for other uses, but the present review shows that the occurrence of several significant nature values is likely within this area.

Additionally, based on the preliminary inventory, the combination of apparent concentrations of rare plants, occurrence of critical bat species and the high probability of corridor values show that the areas of Terrace Landscape Middle Bonaire/Sta. Barbara and Lima are important areas concerning conservation and further research. The areas of Bolivia and Washikemba/Bakuna follow closely.

To be able to implement the necessary protective measures within these areas, it is recommended that more extensive research through fieldwork is done, in order to obtain a complete inventory of the different nature values found on Bonaire, not only in the areas of “nature” and “open landscape” but also in areas with other designations. Additionally, it is recommended to assess the list of vulnerable and endangered species (‘Informatieblad beschermde dier- en plantensoorten Bonaire’) as certain species that may be of importance to Bonaire are not included.

When executing a complete and extensive inventory of Bonaire it would be of value to also determine the ecological conditions needed for the different species to survive. Based on the ecological conditions necessary for their life functions, it may be possible to pinpoint those areas of main ecological importance per species. A complete inventory of the nature values on the island can contribute to better management of nature values (e.g. determining the distribution of caves and the distribution, health status and diversity of keystone cacti species for better management of bat populations). It is also recommended to determine areas with high potential for the occurrence of rare or relict species and which areas harbour high corridor values.

Management Recommendations:

For future research it is recommended to execute a complete and extensive inventory of Bonaire, through fieldwork, in order to implement the necessary protective measures to ensure the conservation of these nature values. The present study shows that the areas of WNSP/Brasil, Terrace Landscape Middle Bonaire, Lima and Bolivia may be of priority as these areas seem to harbour a concentration of unique and critical plants.

Present studies shows that key nature values may occur in areas with a different designation than “nature” or “open landscape”. For future research it is recommended not to limit inventory research to the areas of “nature” and “open landscape”, but to include other areas with different designations.

In the present study the nature values chosen were based on the list of vulnerable and endangered species (Informatieblad beschermde dier- en plantensoorten Bonaire). During the study several species were added based on expert knowledge. The list used therefore seems to be limited. For future research it is recommended to assess if there are other nature values that are important to Bonaire that should be included on the list (e.g. Clusia sp, Ammodramus savannarum).

A complete inventory of the nature values on the island can contribute to the better management of nature values. A good example is the management of Bonaire’s bat population. In order to define the priority areas to maintain for the management of the different bats on Bonaire it is essential to obtain a detailed inventory of the different caves that these species use as habitat.

Additionally for the nectar-feeding bats it is crucial to map the occurrence of the different candle cacti on which they feed. The nectar-feeding bats are the critical pollinators of the three candle cacti (Petit, 2001). As already mentioned these cacti are key species on the island as they provide food for several species of animals during the dry season, when many other plant species are non-productive (Petit, 2001). Research on the distribution, health status and diversity of candle cacti on Bonaire is recommended in order to pinpoint priority areas for nectar- feeding bats. The cactus populations are threatened severely by feral livestock (goats, donkeys) which remove the bark of the mature trees, thereby threatening the food supply for frugivores and nectarivores. From our analysis open land areas of Bolivia would seem to possess large cactus populations of vital interest to conservation of endangered bird species on an island-wide scale.

When executing a complete and extensive inventory of Bonaire it would be of value to determine the ecological conditions and various habitats needed for the different species to survive. Based on the ecological conditions necessary for their life functions it may be possible to pinpoint those areas of principal ecological importance per species.

It is necessary to identify those areas with a high potential for the concentration of nature values rare species or relict vegetation species in order to secure the survival of these species and to be able to implement the necessary protective measurements. Such areas for instance are the open land and nature sections of Lima, Terrace Landscape Middle Bonaire (nature) and Bolivia (open). For future research it is recommended to determine those areas with high corridor values for the implementation of ecological corridors and buffer zones on Bonaire.