Becking, L.E.

The Southern Caribbean forms a separate biogeographic province for marine mollusks and marine fish faunas. The terrestrial desert and xeric shrublands and Venezuelan mangrove ecosystems are not yet represented on the World Heritage List or on any national Tentative List. In addition BNMP is located in the Caribbean Islands Hotspot and two Ramsar sites which are also recognized as Key Biodiversity Areas (Important Bird Areas) are found in the boundaries of BNMP. Any terrestrial extension of the proposed nomination could add additional IBAs and include vegetation ecoregions not represented.

However, there are a large number of natural World Heritage Sites with marine values and the combination of mangrove, seagrass and coral, and even saliñas or hypersalinity, is found in several other marine World Heritage Sites. The comparison analysis highlighted the importance of BNMP to make itself distinctive for criteria vii. For criteria ix the difficulty in finding specific information on parrotfish or herbivore biomass, carbonate production or coral reef growth, % hard coral cover and % algal cover suggests that the chosen attributes will fill a gap in ecological processes.

We identify three action points by which to further increase the Bonaire Marine Park nomination prospects as a World Heritage site: a terrestrial extension, a 12 miles zone extension and a transboundary extension. While the last option is expected to increase prospects most, the first and second option are more feasible to establish. Both of them would increase the integrity of Bonaire Marine Park. A terrestrial extension would include xeric shrubland which is not yet represented in any World Heritage site. The 12 miles zone extension would include endangered species, which demonstrates the global importance, as well as new species, which uniqueness still needs to be demonstrated and requires further research.

This report describes the potential Outstanding Universal Value of the Bonaire National Marine Park from an ecological perspective, that is, according to World Heritage natural criteria vii and ix as defined by the Operational Guidelines for the Implementation of the World Heritage Convention (UNESCO, 2013).

The Bonaire National Marine Park is an outstanding example of a fringing coral reef that has evolved to one of the most diverse reef in the Caribbean.

The Bonaire Marine Park, protected since 1979 and declared a National Park in 1999, includes one of the healthiest coral reef in the Caribbean and two Ramsar sites which include mangrove forests and seagrass meadows, globally important for 4 species of endangered species of marine turtles and at least 29 species of migratory waterbirds and a nursery habitat for many reef fish species. The coral reef is characterized by one of the highest cover of living corals in the Caribbean, large schools of grazing fish for biological control of macroalgae and the reef has an important function as a source of larvae for tropical ecosystems downstream.

The seascape of Bonaire Marine Park offers spectacular seaviews of crystal clear water in different shades of blue, contrasted by green coastal vegetation, white sandy beaches, hypersaline saliñas in different shades of pink in the south and steep limestone cliffs in the north. The high visibility of the crystal clear water and colourful underwater scenery offer spectacular and diverse views of large Montastrea coral mounds in the north, a unique double reef parallel to the fringing reef in the south and waving gorgonian fields on the exposed east coast reef. The fringing reef supports large schools of reef fish and over 500 species, including globally threatened species of sharks and rays and a resident population of impressive tarpons.

The proposed property encompasses all the biophysical and ecological processes that characterise a natural and sustainable ecosystem: the highest carbonate production rate in the Caribbean, large coral colonies and high parrotfish grazing rate. These components of a resilient reef, combined with the location of Bonaire outside of the Caribbean hurricane belt, result in the highest hard coral cover and one of the lowest macro algae cover in the Caribbean.

Well established standards of protection, management and monitoring ensure that the coral reef and associated mangrove and seagrass ecosystems of the Bonaire Marine Park will continue to evolve naturally and to support human uses for the foreseeable future in a sustainable way for generations to come. Bonaire is a volcanic oceanic island with steep reef slopes and lies is a small but unique southern Caribbean arid zone outside the principal hurricane belt. This means that the reefs are relatively little- stressed by sediment, freshwater and hurricane disturbance. The island is structurally fortuitous with conditions essential for the long-term support of healthy coral reefs. As reefs in the region continue to rapidly decline, the arid southern Caribbean represents the last best hope for regional coral reefs and the relative importance of Bonaire’s reefs will continue to increase in the future due to their exceptional resilience. The Bonaire Marine Park is the oldest established marine park in the Caribbean and includes two no-use marine reserves and two no-take fish reserves. Fishing on the ecological important parrotfish is traditionally low on Bonaire and has been banned completely in the entire marine park since 2010.

The global comparative analysis identified opportunities to build the case for BNMP as a distinct and important area potentially worthy of international recognition. The comparisons did not clearly highlight how BNMP is irreplaceable, however the findings do suggest that it is representative of a healthy Caribbean coral reef ecosystem. BNMP fills a gap in the marine biogeography as there is no World Heritage Site in the Southern Caribbean.

Koraalriffen zijn de belangrijkste economische hulpbron voor de eilanden van Caribisch Nederland. Zij verkeren in een slechte toestand en zonder actief ingrijpen zullen zij binnen afzienbare tijd verdwijnen. Het is meer dan ooit duidelijk dat de gevolgen van klimaatverandering onafwendbaar op ons afkomen. Dit zal leiden tot meer stress voor de omgeving waarin mensen leven en waarvan ze afhankelijk zijn. Voor de toekomst van Bonaire, Saba en St. Eustatius is het noodzakelijk om een gemeenschappelijke milieu- en natuurvisie te ontwikkelen, daadkrachtig besluiten te nemen en op korte termijn te beginnen met de uitvoering zodat de veerkracht van de natuur van Caribisch Nederland weer omhoog gaat en beter bestand zal zijn tegen de gevolgen van klimaatverandering. De komende 10 jaar zijn cruciaal wil men het tij nog keren. Door nieuw beleid kan de economie omgebogen worden in de richting van een duurzame toekomst waarbij banen behouden worden en negatieve effecten van globale en regionale veranderingen zoveel mogelijk kunnen worden opgevangen door veerkrachtige ecosystemen te realiseren. Dit kan door lokale stressfactoren zoveel mogelijk te minimaliseren. In dit rapport proberen we handvatten aan te reiken voor de ontwikkeling van deze visie en geven we mogelijke oplossingsrichtingen aan gebaseerd op de huidige stand van de wetenschap ten aanzien van duurzaam beheer van koraalrifecosystemen.

In this report we examined the proximate response of fish assemblages, queen conch, and sea turtles onH. stipulacea meadows in Lac Bay, Bonaire, Caribbean Netherlands. Here we primarily focused on the differences between the invasive species H. stipulacea and the principal species of native sea grass in Lac Bay, namely turtle grass Thalassia testudinum .

We addressed the following questions:

• Has H. stipulacea expanded in area since 2011 and what effect is observed on T. testudinum cover?
• How does the structural complexity, in terms of average height and density of vegetation, differ between meadows dominated by T. testudinum and those by H. stipulacea?
• Do monospecific fields of H. stipulacea differ from monospecific fields of native T. testudinum in terms of fish assemblages and abundances?
• Does the queen conch avoid H. stipulacea meadows?
• Will green sea turtles in Lac Bay graze on H. stipulacea?

  In 2011 H. stipulacea was present in 7 of the 45 stations across the bay where the seagrass cover was recorded, while this increased to presence in 12 quadrats in the year 2013. From 2011 compared to 2013 the cover of H. stipulacea had generally increased, while the cover of the native T. testudinum had generally decreased in these quadrats. These results indicate that the invasive species is expanding in area in Lac Bay. It is unclear whether H. stipulacea is actively pushing out the native seagrass species, or whether the native seagrass cover is declining due to other causes and H. stipulacea is rapidly taking over areas that are left open.

  The two species of seagrass differed significantly in habitat complexity, reflected by a difference in the number of shoots and the length of shoots. H. stipulacea had significantly shorter shoots compared to T. testudinum. Higher habitat complexity due to the seagrass canopy (i.e. higher seagrass density, leaf surface or aboveground biomass) is assumed to result in higher faunal abundance due to reduced predation risk and enhanced food supply. Invasive macrophytes can impose changes on native communities via mechanisms that modify the habitat and cause variation in indigenous faunal composition.

  There was a large and significant difference in fish abundance between meadows dominated by T. testudiunum and those dominated by H. stipulacea; the abundance of fish was almost half in the H. stipulacea meadows. This result may be due to the reduced complexity of the invasive seagrass meadows, but also be due to underlying factors that were not measured. There was also a significant difference in the composition of fish species assemblage between T. testudiunum and H. stipulaceameadows. No Pomacentridae, Mullidae, and Sphyraenidae were recorded in the transects placed in H. stipulacea meadows, while these were present in T. testudinum meadows. If this is a long-term trend, the expansion in H. stipulacea may possibly result in a diminished nursery function of certain fish species in Lac Bay.

  Queen conch was equally present on H. stipulacea, native seagrass meadows, and sandy patches. Hence, in the area of observation of the present study, it did not appear to avoid the invasive seagrass. These results only refer to part of Lac Bay, therefore we are cautious with making general conclusions.

  We establish that Caribbean green turtles can feed on the invasive H. stipulacea. This was documented using a cafeteria experimental set-up. All three seagrass species were selected at least once.Thus the present study indicates that the green sea turtle does not necessarily avoid H. stipulacea as a food source. While H. stipulacea is new to the Caribbean, H. stipulacea forms an important food species in its native distributional range for the green turtle in the Red Sea. H. stipulacea is increasing in cover in Lac Bay and may become the main food source for green sea turtles. What is more, when sea turtles consume seagrass the associated invertebrates are an important component of the diet. Invertebrates that are associated with seagrass differ per seagrass species (e.g. Willete & Ambrose 2012) and this could result in a different nutritional uptake for the turtles. It is important to understand the nutritional difference this shift in diet may cause, before it can be concluded what the effect of long term consumption of H. stipulacea on green turtle health may be.

From Bonaire, we here provide the first documented case of the green turtle feeding on the invasive seagrass, Halophila stipulacea, in the Caribbean. The seagrass is rapidly invading existing seagrass meadows and altering key foraging habitat of this endangered marine reptile throughout the eastern Caribbean. We expect that more records of green turtles feeding on this invasive species will gradually follow from throughout the region and that the green turtle might alter its foraging behavior in response to the changing species composition of its foraging habitat. 

Introduction:

Since 2010, the Saba Bank falls under the jurisdiction of The Netherlands. Spanning an area of 2000km2, the Saba Bank houses the largest coral reef in the Caribbean Netherlands with a great diversity of species. The past 5 years the Dutch Ministry of Economic Affairs has funded research on the biodiversity, health and ecological functioning of the bank. On 8 December 2016 The Saba Bank Symposium was organised with 11 speakers and a panel discussion on the knowledge gaps and future perspectives of the bank. With this letter we provide an overview of results and future directions for policy and research.

Key message:

We need to improve the resilience of the Saba Bank to cope with the effects of climate change and fisheries. 

From 19-27 October 2013, IMARES (Wageningen UR) organized a research expedition to the Saba Bank, to investigate the ecological functioning of the Bank. The expedition is a follow up of a survey of the bank in 2011 and is part of the “The Saba Bank Research Program 2011-2016” initiated by the Dutch Ministry of Economic Affairs (EZ). The bank is the largest submarine atoll in the Caribbean Sea, spanning an area of 2200km2. It is a Marine Protected Area and is acknowledged by the Convention of Biological Diversity as an Ecologically and Biologically Significant Area. The project is part of the implementation of the Exclusive Economic Zone management plan for the Dutch Caribbean.

If the Saba Bank is to serve as a source of healthy larvae for the neighboring reefs, a key question is how populations of reef organisms on the bank are connected with populations in the region and in the Wider Caribbean. The aim of the current report is to investigate the health status and the population genetic structure of two common native benthic species, Xestospongia muta (giant barrel sponge) and Montastrea cavernosa (great star coral), and an invasive species, Pterois volitans (lionfish). With the aidof molecular techniques and species assessments, we aim to assess:

• the level of genetic diversity within the populations of two common benthic species (X. muta and M. cavernosa) on the Saba Bank;
• the degree of genetic connectivity between populations on Saba Bank and surrounding reefs, based on newly obtain genetic sequences and sequences obtained from GenBank from populations across the Wider Caribbean;
• the current density and health status of the populations of X. muta and M. cavernosa on Saba Bank.
• the genetic connectivity, population size and the dispersal direction of the invasion of the lionfish on the Saba Bank, in relation to the Eastern Caribbean populations. 

The management of small rookeries is key to conserving the regional genetic diversity of marine turtle populations and requires knowledge on population connectivity between breeding and foraging areas. To elucidate the geographic scope of the populations of marine turtles breeding at Bonaire and Klein Bonaire (Caribbean Netherlands) we examined the post-breeding migratory behavior of 5 female loggerheads Caretta caretta, 4 female green turtles Chelonia mydas, and 2 male and 13 female hawksbill turtles Eretmochelys imbricata during the years 2004-2013. After leaving Bonaire, the 24 tracked turtles frequented foraging grounds in 10 countries. The distances swum from Bonaire to the foraging areas ranged from 608 to 1766 km for loggerhead turtles, 198 to 3135 km for green turtles, and 197 to 3135 km for hawksbill turtles, together crossing the waters of 19 countries. Males represented the minority in this study, but we made 2 key observations that require further research: males remained in the vicinity of the breeding area for 3-5 mo, which is 2-5 times longer than females, and males migrated greater distances than previously recorded. Although the turtles dispersed widely across the Caribbean, there appeared to be 2 benthic foraging areas of particular importance to all 3 species of marine turtles breeding at Bonaire, namely the shallow banks east of Nicaragua and Honduras (n = 8 tracked turtles) and Los Roques, Venezuela (n = 3). Marine turtles breeding at Bonaire face threats from legal turtle harvesting, illegal take, and bycatch in the waters that they traverse across the Caribbean.