Debrot, A.O.

The lands of the former Bolivia Plantation amount to about three-thousand three-hundred (3,300) hectares of wildlands and basically constitute the eastern quadrant of the island of Bonaire, stretching along the central east coast from Lagun  to Boka Olivia. A brief biological inventory of Bolivia was conducted  3-6 November 1997, in which semiquantitative data was collected on the terrestrial flora and fauna at 34 different sites and/or transects. With exception of most of the lower limestone terrace, Bolivia was found to be well vegetated in terms of overall vegetation cover, and to possess much in the way of of scenic landscapes.

Whereas Stoffers (1956) indicated most of the Middle (limestone) Terrace areas as constituting dry evergreen vegetation, at present most dry evergreen species are virtually absent. One consequence of this finding is that the (likely) better developed dry evergreen formations on Bonaire (e.g. Colombia, Karpata, Tolo) must now be accorded a much higher conservation priority than could heretofore be realised. 

Bolivia shows extensive signs of past agricultural use and strip-mining for coral rubble. At present feral livestock (goats and donkeys) are at clearly detrimental densities, and mining activities form an immediate threat to some very rare coastal rubble vegetation.

Based on this initial assessment, several principal conservation priorities for Bolivia can be identified. These are:

1. Nesting habitat for the Bonaire Lora, along the coastal terrace edge
2. Ecologically important food sources, especially candelabra cacti concentrated in various areas
3. The cave systems of Roshikiri and Spelonk
4. Terrace edge area along the length of the coastline
5. Coastal rubble vegetation between Spelonk and Boven Bolivia
6. Brasía terrace woodland of Beneden Bolivia
7. Washikemba woodland in the souther parts of Bolivia.

On the basis of these principal conservation values and the area's greater role as ecological corridor beween the northern and souther halves of the island, an initial scetch of recommended conservation areas is presented. The results indicate that any potential development  should be concentrated in the central section of Bolivia.

Based on four years of butterfly monitoring in four contrasting natural habitats on St. Eustatius, we document large and consistent differences in the butterfly species assemblages in the different habitats and compare the butterfly assemblages of the three windward Dutch islands to those of other islands of the Lesser Antilles. Seven new species records were established for St. Eustatius, thereby updating the butterfly list to a total of 32 species. Pieridae were the most numerically abundant group of butterflies (48%), followed by Lycaenidae (26%), Hesperiidae (12%), and smaller numbers of both Heliconiinae (6%) and Charaxinae (5%). Heliconiinae and Charaxinae both showed a significant dependence on the moister, wind-sheltered habitats of the volcanic slopes and crater of the Quill, but this dependence was particularly strong for Heliconiinae. The butterfly faunas of the windward Dutch islands numbered a total of 44 species. The presence of larval host plants needed for local reproduction was confirmed for all but two species. Cluster analysis separated the butterfly faunas of these and the surrounding islands into two groups. The more speciose butterfly assemblages of Saba, St. Eustatius, and St. Martin clustered together with the those of the surrounding higher islands of Antigua, Montserrat, Nevis, and St. Kitts, while the poorer faunas of the low-lying islands of Anguilla, St. Bartholomew, and Barbuda formed a separate cluster and had a lower species richness particularly in the Heliconiinae and Charaxinae. Based on consistent effects of elevation on butterfly faunas, at both geographic scales (between areas on St. Eustatius and between islands), our results suggest that island maximum elevation is the overriding factor explaining the distribution of butterfly faunal richness in the northern Lesser Antillean islands studied.

Aruba, Bonaire, and Curaçao (ABC Islands) are located at the southern margin of the Caribbean Plate, just north of South America. Little is known of the arachnid fauna of these islands, and the only work on spiders was published over a century ago. Here we provide a list of arachnids opportunistically collected from the islands, including Klein Bonaire and Klein Curaçao, over approximately 2 months. More than 750 specimens from 4 arachnid orders, (Amblypygi, Pseudoscorpiones, Scorpiones, Araneae) were collected and identified. We recovered 1 species of amblypygid, 2 species of pseudoscorpions, 1 species of scorpion, and 76 species of spiders. Additionally, we compared species diversity between urban and natural areas. The number of species is relatively low given the proximity to South America, but this likely reflects that collecting only took place for a short time and was opportunistic as opposed to systematic. Nevertheless, we found 25 new records and >20 likely undescribed species for the islands, providing insights into the spider fauna of northern South America and indicating that additional surveys of the area are warranted.

The Antillean manatee (Trichechus manatus manatus) is a subspecies of the West Indian manatee and is found from Mexico and the Bahamas south to Brazil. It is listed as Endangered by the IUCN (Self-Sullivan & Mignucci-Giannoni, 2008). Population estimation is very difficult in this species but more recently Castelblanco-Martínez, Nourisson, Quintana-Rizzo, Padilla-Saldivar & Schmitter-Soto, 2012) compiled expert estimates to suggest a total metapopulation size of 6,700 animals. There is a Venezuelan regional population stretching from the Orinoco to the Guajira peninsula that was estimated to be about 400 animals (Castelblanco-Martínez et al., 2012). This population is precariously hanging on to existence along the northern Caribbean coast of South America and the species is listed as critically endangered according to the IUCN in Venezuela and locally endangered in Colombia (Boede et al., 2015; Caicedo-Herrera, Trujillo, Rodríguez & Rivera, 2004). In recent decades, very few sightings of manatees along the coast of Venezuela have been recorded.

The most recent population assessment (O'Shea, Correa-Viana, Ludlow & Robinson, 1988) and archaeological review (McKillop, 1985) of manatee occurrence along the central Venezuelan mainland coast are quite dated. Furthermore, neither produced any records for this area, suggesting that the central Caribbean coast of Venezuela (Paria Peninsula to Paraguaná Peninsula) and adjacent islands have long been practically devoid of manatees. However, since then, eight sightings and other records were compiled by Debrot, van Buurt, Caballero and Antczak (2006). Among these were three sightings of manatees reported for the island of Curaçao, dating from the late 1970s, 2001, and 2005 (Figure 1a and b) and a place name (not an actual sighting) “Manparía Kutu” from Bonaire suggesting the former occurrence of this species in Bonaire (Debrot et al., 2006). In this study our first purpose was to report the first-known manatee sighting record for Bonaire, which dates from July 2018 (Figure 1c), and an early colonial reference to this species for Curaçao. The second objective was to update manatee records for the adjacent central coast of Venezuela. For this, we conducted an Internet search of manatee mention in published and online sources for all cities and rivers of the central Venezuelan coast, in both Spanish and English. This literature search allowed us to add five previously unrecorded manatee records for the central coast of Venezuela. The third objective was to combine all manatee records for the areas considered (Table 1) and assess the Dutch Leeward records in the context of what is known about manatee occurrence along the central Venezuelan coast.

Shallow marine macrophyte communities serve key roles in the tropical coastal ecosystem but are undergoing large and rapid deterioration worldwide, as is also the case in the non-estuarine mangrove lagoon of Lac Bay, Bonaire, in the Southern Caribbean. To help better understand both the drivers of assemblage structure and potential consequences of the changes taking place in the bay, we here quantify and describe the distribution of algal and seagrass assemblages along the environmental gradient from the turbid, inner mangrove pools to the clear, open bay conditions, based on 98 randomly-chosen, 4 m2 survey plots. Seven assemblages were described along this land-to-sea gradient, five of which were dominated by marine macrophytes, one by sponges and one by a polychaete. With exception of the hypersaline backwaters which were devoid of benthic macrophyte vegetation, isolated mangrove pools showed the lowest total benthic cover, species richness and biodiversity of all habitats. Salinity and substrate particle-size composition accounted for most variation between the different assemblages and appear to be the key known determinants of assemblage composition. We developed a conceptual model to help disentangle the relationship between and the relative roles of the two principal drivers, as part of a cascade of effects which ultimately result from terrestrial run-off into the bay as mediated by mangrove encroachment into the bay. The model links spatial patterns to ongoing processes and implies that the assemblage patterns described are not only a reflection of, but also allow prediction of how the assemblages develop through time.

The recent status and trends in the Saba Bank fisheries up to and including 2015 port sampling data have been previously reported by de Graaf et al. (2017) and a policy brief has also been written based on those results (Debrot and de Graaf (2018). The purpose of this report is to update recent catch trends in the Saba Bank fisheries with the data from 2016 and 2017.

For the lobster fishery (Panulirus argus), the number of fishing trips (and number of traps set) gradually grew from 2012 to 2015 but has since leveled off. The resulting landings of lobster have shown a similar pattern of increase up to 2015 but have now leveled off at around 70 tons annually. Increasing landings per unit effort indicate that the formerly reduced lobster abundance, which had been declining since 2000 and which had reached its lowest level in 2011, has subsequently increased relatively steadily all through 2017, and now has increased back to levels close to those of 2007. The average size of lobsters taken, continues to be large, which is favourable to gradual stock recovery.

Mixed landings of reef fish in the lobster fishery have fluctuated between 10 and 20 tons annually. The LPUE abundance index in bycatch species also shows a decrease of about 35% from high levels in 2000 and 2007 to lowest levels in 2011, followed by an increase up to 2013, after which landings have levelled off.

In the redfish trap fishery (Lutjanus spp.), the number of trips in the redfish trap fisheries had grown significantly during the period 2012 to 2015. In 2016 effort increased again to 625 trips. In 2017 the exerted fishing effort dropped down to about 350 trips, a level seen last in 2012. The landings of redfish have fluctuated over this period, with lower values in 2012 and 2017 and higher values in 2014 and 2016. The LPUE abundance index shows a decrease by 50% between 2007 and 2011, followed by an increase to slightly higher and constant values between 2012 and 2016, while in 2017 the LPUE abundance index continued increasing. The only snapper for which sufficient data was available, was the silk snapper, Lutjanus vivanus. Average size of the silk snappers landed continued its increasing trend, indicative of gradual stock recovery. The drop in snapper landings, despite the higher LPUE in 2017, can especially be ascribed to the 6-month closed season implemented that year (Graaf et al. 2017).

The overall conclusion is that for both the lobster and redfish stocks, stock status, based on the LPUE index and size-structure trends have continued in developing favorably. Bottom drop longline, pelagic and bycatch landings have remained much less important and have shown no significant new developments.

There are two matters of concern that require follow up. Firstly, the positive prognosis for the snapper “stock” status may partly be based on targeting geographically different stocks as well as different species. Hence the data as collected and analyzed may actually be presenting a too optimistic assessment. To evaluate whether this is actually the case will require more detailed analysis based on individual species, as well as more accurate geographical recording of catches than as currently practiced. The second matter of concern regards the fate of the traps that were in the water on the Bank when the hurricanes Irma and Maria struck the area in September 2017. If trap loss was large, this may lead to higher detrimental impacts of ghost fishing in the coming years.

Keywords: endemic species, Caribbean, Saba, Saint Eustatius, Saint Marten, Saba Bank

Endemic species and subspecies (or “taxa” for short) having restricted geographic distributions are an extremely important feature of biodiversity and a key criterion to conservation valuation and nature management goal-setting. Saba, St. Eustatius and St. Martin (the Dutch SSS islands) form part of the Caribbean biodiversity hotspot region but up to now no systematic assessment was available on the occurrence of endemic animals and plants on these islands and in the surrounding marine areas (incl. Saba Bank). We here provide such a preliminary assessment as an aid to conservation and nature management, and to help in prioritizing future research. Our assessment shows that the SSS islands and Saba Bank together possess 223 endemic animals and plants (32 subspecies, 191 species), of which 35 are endemic to the SSS islands or Saba Bank, 15 are endemic to the Northern Lesser Antilles (Virgin Islands southwards up to and including Montserrat, including St Kitts Bank and Anguilla Bank endemics), 110 to the Lesser Antilles (Virgin Islands southwards up to and including Grenada) and 58 to the joint Antilles (Lesser and Greater Antilles). Of the 35 island endemics, 8 are marine, 26 are terrestrial and 1 is from brackish water.

The breakdown of the 223 endemic species and subspecies according to larger taxonomic groupings is as follows: Worms (Polychaeta): 1; Spiders, scorpions and pseudoscorpions (Arachnida): 23; Copepods (Hexanauplia): 2; Beetles (Coleoptera): 33; Flies (Diptera): 4; True bugs (Hemiptera):3 ; Sawflies, wasps, bees, and ants (Hymenoptera): 3; Butterflies and moths (Lipidoptera): 12; Dragonflies and damselflies (Odonata): 1; Grasshoppers, locusts and crickets (Orthoptera): 22; Amphipods: 1; Crabs, lobsters and shrimps (Decapoda): 1; Isopoda: 1; Pycnogonida: 1; Bony fish (Actinopterygii): 4; Sharks and rays (Chondrichthyes): 1; Birds: 23; Amphibians: 1; Mammals (bats): 5; Reptiles: 16; Cnidarians: 5; Bivalves: 5; Gastropods: 28; Flatworms (Platyhelminthes) 1; Red Algae: 3; Spermatophyta (Vascular plants): 22.

The breakdown of the 35 taxa that are endemic to the SSS islands or Saba Bank is as follows: Polychaeta: 1; Arachnida: 4; Hexanauplia: 2; Coleoptera: 3; Diptera: 1; Hemiptera: 1; Orthoptera: 10; Bony fish: 2; Reptiles: 3; Bivalves: 1; Gastropods: 3; Red Algae 1; Vascular plants: 3.

 The breakdown in numbers of island endemics for the SSS islands and Saba Bank is:

· St. Martin: 12 island endemics (10 animal species and 2 plant species)

· St. Eustatius: 10 island endemics: (8 animals species and 2 plant species)

· Saba: 10 island endemics: (10 animals species, 0 plant species).

· Saba Bank: 3 endemics (3 animal species, 0 plant species)

The number of endemics is probably larger than reported here. Very little marine taxonomic research has been conducted in the SSS islands and many species probably remain to be described. In the past decade many new and potentially endemic species (of algae, fish, corals, sponges, etc.) have been discovered, mainly on the Saba Bank. Furthermore, additional research on specific species groups (e.g. beetles) could result in the discovery of yet more new endemic species. The IUCN assesses the conservation status of plant and animal species worldwide. Most rare and endangered island endemics are not included in the assessments due to lack of information or perceived priority. Therefore, most IUCN-listed threatened species for the SSS islands are species with much wider distributions. Assessments are only available for 42 of the endemic (sub)species of the SSS islands. The only recent endemic ground-dwelling mammal, the Nevis rice rat, is extinct. The endemic bats and bird subspecies have wider dispersal capabilities and currently carry no IUCN threatened listing, eventhough several only survive in tiny, scattered and vulnerable populations. Only

the following six endemic terrestrial reptiles currently carry a IUCN threatened status:

· Critically Endangered: Lesser Antillean Iguana (Iguana delicatissima).

· Endangered: Anguilla Bank Racer (Alsophis rijgersmaei); Spondylurus powelli.

· Vulnerable: Saba Racer (Alsophis rufiventris) and Anguilla Bank Bush Anole (Anolis pogus).

· Near threatened: St. Christopher Ameiva (Pholidoscelis erythrocephalus).

Many of the 223 endemic taxa listed here are restricted to very small populations on one or only a few small islands. This makes them very vulnerable to extinction. Indeed, in the recent past, some species may already have become extinct (e.g. two endemic plants known only from St. Martin). Therefore, assessments of the conservation status of each of the identified endemic taxa are urgently needed for the SSS islands and Saba Bank. In addition, conservation strategies need to be developed to minimize extinction risk for the most endangered endemics.

Sinds de staatkundige herstructurering van het Koninkrijk in 2010, maken de Caribische eilanden van Bonaire, Saba en St. Eustatius als speciale gemeenten formeel deel uit van Nederland. Het Ministerie van Economische Zaken (sinds eind 2017: Ministerie van Landbouw, Natuur en Voedselkwaliteit) heeft daarmee de eindverantwoordelijkheid voor de uitvoering en implementatie van een zevental internationale natuurbeschermingsverdragen voor de eilanden. Deze verantwoordelijkheden houden verplichtingen in en leiden tot verschillende beleidsvragen. Om hieraan invulling te geven wordt eens in de vijf jaar een natuurbeleidsplan opgesteld en wordt er gerapporteerd in het kader van de Convention on Biodiversity (CBD) en het Specially Protected Areas and Wildlife (SPAW) protocol van het Cartagena Verdrag maar er wordt niet gerapporteerd door middel van een “natuurbalans” zoals in Europees Nederland. Voor de evaluatie van het gevoerde natuurbeleid en het opstellen van nieuwe natuurbeleidsplannen is echter rapportage over de staat van de natuur essentieel. Als maat voor de “staat van de natuur” hebben we een methodiek gebruikt die zoveel mogelijk aansluit op de staat van instandhouding (SvI) conform de Habitatrichtlijn (HR).
Caribisch Nederland maakt onderdeel uit van de Caribische “biodiversity hotspot” met een zeer hoge biodiversiteit en hoge menselijke druk. De hoge biodiversiteit uit zich in het voorkomen van zeer veel endemische soorten (soorten met een zeer klein verspreidingsgebied) en de hoge menselijke druk uit zich in veel bedreigde soorten. Caribisch Nederland telt ongeveer 130 endemische soorten en 143 internationaal bedreigde soorten van beleidsrelevantie (bijlage 1).
In deze opdracht wordt door 33 deskundigen en natuurbeheerders gerapporteerd over de SvI van een selecte groep habitats en soorten of soortgroepen (bedreigde, sleutel- en indicator-soorten) waarvoor over voldoende kennis wordt beschikt. Als maat voor de SvI van de natuur hebben we een methodiek gebruikt die zo nauw mogelijk aansluit op de methodiek voor de bepaling van de SvI zoals gehanteerd
in de HR. Daarnaast wordt ook een probleemanalyse gegeven van mogelijke oorzaken en aanbevelingen gedaan voor managementoplossingen. Vanwege de structurele achterstand in kennis en monitoring van het grootste deel van de Caribisch Nederlandse biodiversiteit was een kwantitatieve rapportage voor de meeste soorten en soortgroepen niet mogelijk.
Voor Caribisch Nederland onderscheiden wij (van hoog- naar laag gelegen) de volgende habitats: nevelwoud, regenwoud, droge tropische bossen, grotten, stranden, zoutpannen en zoutmeren, mangrove bossen, zeegrasvelden en wiervelden, koraalriffen, open zee en diepzee. Deze habitats zijn niet alleen van belang voor het voortbestaan van de vele soorten die ervan afhankelijk zijn, maar ook voor de mens vanwege de vele ecosysteemdiensten die zij vervullen. In 2013 vertegenwoordigde de economische waarde van ecosysteemdiensten voor Bonaire, Saba en St. Eustatius, respectievelijk 31%, 63% en 24% van het Bruto Binnenlands Product (BBP) van de eilanden. Er is geen rapportage
gemaakt over het zoetwaterhabitat daar dit zeer klein is en er zeer weinig over bekend is.
Er wordt ook gerapporteerd over negen geselecteerde soorten (de Antillenleguaan, de Geelvleugelamazone, de Flamingo, vijf sternsoorten en de Kroonslak) en vier soortgroepen (beschermde planten van Bonaire, zeezoogdieren, zeeschildpadden en visbestanden).
Ook rapporteren we over drie van de belangrijkste bedreigingen die brede consequenties hebben voor de natuur. De staat van bepaalde bedreigingen bepaalt in grote mate de staat van de natuur en vertegenwoordigt een ecosysteembenadering in plaats van een individuele “soort-” of “habitatbenadering”. Het betreft vaak ook vraagstukken die een unieke managementbenadering nodig hebben. Deze onderwerpen zoals “invasieve soorten”, “loslopend vee” en “klimaatverandering” worden als zodanig besproken in dit rapport. “Overbevissing” is een soortgelijk vraagstuk met consequenties voor de natuur, maar is niet apart opgenomen in deze rapportage maar wordt deels wel besproken in
onze hoofdstuk over de visstand (3.10).
Op basis van onze analyses concluderen wij dat zonder uitzondering de huidige SvI van de biodiversiteit in Caribisch Nederland beoordeeld moet worden als matig tot zeer ongunstig. Dit geldt zowel voor de habitats als voor de hiervan afhankelijke soorten en/of soortgroepen. Dit contrasteert sterk met het beeld voor de Europese Unie en Europees Nederland, waar de overheden al decennia structureel investeren in natuurbeleid en beheer. Zo vertoonde 16% van de habitattypen en 23% van  | 6 van 214 | Wageningen Marine Research rapport C086/17 de soorten in de EU een gunstige SvI. Van de habitattypen met een ongunstige SvI, vertoonde in de EU in 2013, 33% geen trend en 4% een verbetering (EEA 2015). Vooral Europees Nederland scoort hoog voor het herstel van habitattypen. Daar vertoonden 41% van de habitattypen die ongunstig beoordeeld werden een positieve trend in de rapportageperiode 2007-2012.
De beschikbare data maken voor 2017 een voldoende goede inschatting voor de SvI van de gekozen habitats en soort(groep)en voor Caribisch Nederland mogelijk. Het gaat voornamelijk om data in opeenvolgende jaren waarmee een trend kan worden gevolgd, zoals bijvoorbeeld voor Caribische flamingo’s, zeeschildpadden, Geelvleugelamazones en zeegrassen op Bonaire. Ongeveer een kwart van de data is van matige kwaliteit en voor ruim tweederde zijn de data zeer matig. Voor statistische trendanalyses, zoals in Europees Nederland, zijn de meeste data dus ontoereikend. Om voor de meeste habitats en soorten beter te kunnen begrijpen wat er gaande is en om de managementimplementatie te evalueren zijn goede monitoringsmechanismen nodig, zodat er meer en betere data verzameld kan worden.
Uit onze evaluatie wordt duidelijk dat de huidige aanpak van bedreigingen niet voortvarend genoeg is, waardoor de overwegend negatieve trends zich naar verwachting zullen voortzetten. Er is geen aanleiding om te veronderstellen dat de snelheid van het biodiversiteitsverlies zal verminderen of stoppen. Hieraan liggen vele bedreigingen ten grondslag, maar de belangrijkste bedreigingen
betreffen loslopend vee, invasieve exoten, klimaatverandering en overbevissing. Daarnaast mogen kustontwikkeling, erosie en eutrofiëring door afvalwater niet vergeten worden. De eerste drie (loslopend vee, invasieve exoten en klimaatverandering) zijn in grote mate bepalend voor het feit dat de kwaliteit van ruim 80% van de habitats wordt beoordeeld als matig tot zeer ongunstig. Omdat te weinig tegen de bedreigingen wordt ondernomen is dit ook in grote mate bepalend voor de 100% matig tot zeer ongunstige score op het toekomstperspectief. Habitats met een ongunstige kwaliteit, zijn daardoor onvoldoende veerkrachtig om de effecten van klimaatverandering nu en in de toekomst
op te vangen.

Until the early 1990s, information on sea turtle nesting in the Netherlands Antilles amounted to little more than a few anecdotal accounts and sea turtle nesting was considered nothing more than a rare or accidental occurrence. However, several recent studies have found significant levels of sea turtle nesting activity and have served as an important impetus to successful implementation of new conservation measures and initiatives. We pre- sent and discuss new information that documents several additional sea turtle nesting beaches for con- servation on four Caribbean islands, and that can serve as baseline data for future reference. While most studies elsewhere have focused on large sea turtle nesting beaches, our findings support the idea that small, scattered nesting beaches could cumulatively contribute significantly to both reproductive output and recovery potential of several species when examined on a regional scale.

We discuss the significance of two manatee records for the Dutch Windward Islands (Saba, St. Eustatius, St. Maarten) as well as six manatid and one crocodile record for the Dutch Leeward Islands (Aruba, Curaçao, Bonaire). The persistence of the manatee in the Lesser Antilles until the early 17th century suggests that in pre-Columbian times manatees would have also occurred regularly in the Dutch Windward Islands. In pre-Columbian times, suitable habitat for the American crocodile was sufficient in the Dutch Leeward Islands to have supported small resident populations, and habitat for the manatee was possibly also present. Both species have been widely hunted by early humans and we surmise that small, isolated populations of these species could easily have been extirpated in the Dutch Leeward Islands well prior to European colonization. However, two manatee sightings with the last five years, suggest that these islands may somehow still form part of the active range of this rare and elusive species.