Dutch Caribbean

Dutch below

Two researchers from Wageningen University and Research surveyed the steep inner slopes of the Quill Volcano. The field work is part of a long running study of the flora and vegetation of the Dutch Caribbean islands. The steepness of these slopes and presence of loose rocks makes the inner slopes argely inaccessible. Consequently, little is known on the species that live there. By using remote techniques, the researchers tried to identify the plant species growing on the slopes and describe the vegetation.  John Janssen and André van Proosdij worked in close cooperation with STENAPA during this and previous visits to Statia.

Studying the flora and vegetation

Vegetation on the South-facing, sunny slope showing yellow blossom (Tecoma stans), monkey tail (Anthurium cordatum), eyelash orchid (Epidendrum ciliare), columnar cactus (Pilosocereus royenii), and tillandsia’s.

The team was able to identify most species found on the slopes. Not surprisingly, the slope vegetation clearly differs from any other vegetation type on the island. The sun-facing slopes harbor a sparse vegetation with yellow blossom (Tecoma stans), Monkey tail (Anthurium cordatum), Eyelash orchid (Epidendrum ciliare), Columnar cactus (Pilosocereus royenii), White cedar (Tabebuia heterophylla), Pudding white (Cissus verticillata), and Tillandsia’s. The North-facing slopes are more densely covered, due to the shade and lower drought-stress and show large clumps of Monkey tail (Anthurium cordatum), Clapper (Pitcairnia angustifolia), Wild balsam tree (Clusia major), Strangler figs (Ficuscitrifolia), and several species of ferns. Particularly the large numbers of orchids and ferns are important, as on rocks accessible to goats these are eaten.

Spectacular discovery

West Indian Tree Fern Cyathea arborea rediscovered after 138 years on the steep inner slope of the Quill.

By far the most spectacular discovery were five individuals of West Indian Tree Fern (Cyathea arborea). Tree ferns originate from the Carboniferous era, a geological period dating back 360-300 million years ago. This species was first recorded for Statia in 1885 but was never seen again. There were found growing on the lower part of steep, north-facing slopes, where the microclimate is cool and moist.  For 138 years, this ancient plant species survived, in places truly inaccessible for humans and not visible from the main viewpoints. The presence of these rare tree ferns illustrates the high biodiversity in the Quill National Park and the importance of safeguarding the natural vegetation.

More to be discovered

Janssen and Van Proosdij state, “This discovery points out that on these most inaccessible steep slopes and the crater rim, more rare and critically endangered species are yet to be discovered.” STENAPA and the WUR researchers intend to continue the exploration of these areas.

Twee onderzoekers van Wageningen University and Research hebben de steile binnenwanden van de Quill vulkaan op Sint Eustatius onderzocht. Het veldwerk is onderdeel van een langlopend onderzoek naar de flora en vegetatie van de Nederlands Caribische eilanden. De steilheid van de hellingen en de losliggende rotsblokken maken deze hellingen ontoegankelijk voor mensen. Als gevolg daarvan is er weinig bekend over de soorten die op deze hellingen leven. Door gebruik te maken van remote technieken probeerden de onderzoekers de planten te identificeren die op de hellingen groeien en de vegetatie te beschrijven. John Janssen en André van Proosdij werkten nauw samen met STENAPA tijdens dit en eerder veldonderzoek op Statia.

Het team kon de meeste van de aangetroffen plantensoorten identificeren. Zoals verwacht, is de vegetatie duidelijk anders dan elke andere vegetatie op het eiland. De op de zon gerichte hellingen herbergen een ijle vegetatie met o.a. Tecoma stans, Anthurium cordatum, de orchidee Epidendrum ciliare, de zuilcactus Pilosocereus royenii, Tabebuia heterophylla, Cissus verticillate en Tillandsia’s. De naar het noorden gerichte hellingen zijn dichter begroeid, als gevolg van de schaduw en lagere droogte-stress. Hier groeien grote groepen Anthurium cordatum, Pitcairnia angustifolia, Clusia major, de vijg Ficus citrifolia en meerdere soorten varens. Met name de grote aantallen orchideeën en varens zijn belangrijk, aangezien deze op andere rotsachtige plaatsen die wel voor geiten toegankelijk zijn, worden opgegeten.

West-Indische Boomvaren Cyathea arborea na 138 jaar herontdekt op de steile binnenhelling van de Quill. Credit: John Janssen.

De meest opzienbarende vondst is die van vijf exemplaren van de West-Indische boomvaren (Cyathea arborea). Boomvarens ontstonden in het Carboon, een geologisch tijdperk 360-300 miljoen jaar geleden. De aanwezigheid van deze soort is voor het eerst op Statia gedocumenteerd in 1885, maar is sindsdien nooit meer waargenomen. De vijf aangetroffen exemplaren groeien op het lagere deel van de noord-georiënteerde helling, waar het microklimaat koel en vochtig is. Gedurende 138 jaar kon deze soort voortbestaan op plekken die niet voor mensen toegankelijk zijn en die niet zichtbaar zijn vanaf de uitzichtpunten op de wandelpaden. De aanwezigheid van deze zeldzame boomvarens illustreert de hoge biodiversiteit van het Quill nationaal park en onderstreept het belang van bescherming van de natuurlijke vegetatie.

Janssen en Van Proosdij spreken zich uit: “De vondst van deze boomvarens wijst erop dat op deze uiterst steile hellingen en op de kraterrand nog meer zeldzame en ernstig bedreigde soorten voorkomen die nog niet ontdekt zijn.” STENAPA en de WUR zetten het onderzoek naar deze gebieden graag voort.

Published in BioNews 71

Summary
The health of coral reefs is threatened by anthropogenic land-based input, which is a global problem. High nutrient conditions make corals less resilient to environmental stresses like climate change and intense weather. Poor water quality is likely for the island of St. Eustatius due to the lack of sewage treatment and its erodible coastline. However, there are no data on this island’s long-term water quality monitoring. Chlorophyll-a concentrations, used to indicate water quality, were monitored at 13 locations around St. Eustatius twice a month from May to November 2022 (n=13). Additionally, images of the ocean floor at 10m were made using a remotely operated vehicle (ROV) to monitor benthic species communities and their habitat. The main conclusion of this research shows that the reefs are primarily in an algal-dominant state. This may be explained by the frequent, chronic exceedances of the 0.2 g/l chlorophyll-a threshold. Chlorophyll -a thresholds were surpassed more frequently and with higher amounts on the sites with a larger anthropogenic influence. The lower threshold for chlorophyll-a was surpassed at 5 out of the 11 sites by more than 30% of the measurements. This would point to a more pervasive low-level eutrophic condition at all sites. On many of the sand-based substrate areas, seagrass has covered it.

For full report or more information,  please contact erik.meesters@wur.nl or gulsah.dogruer@wur.nl

MSc internship report

The health of coral reefs is threatened by anthropogenic land-based input, which is a global problem. High nutrient conditions make corals less resilient to environmental stresses like climate change and intense weather. Poor water quality is likely for the island of St. Eustatius due to the lack of sewage treatment and its erodible coastline. However, there are no data on this island’s long-term water quality monitoring. Chlorophyll-a concentrations, used to indicate water quality, were monitored at 13 locations around St. Eustatius twice a month from May to November 2022 (n=13). Additionally, images of the ocean floor at 10m were made using a remotely operated vehicle (ROV) to monitor benthic species communities and their habitat. The main conclusion of this research shows that the reefs are primarily in an algal-dominant state. This may be explained by the frequent, chronic exceedances of the 0.2 g/l chlorophyll-a threshold. Chlorophyll -a thresholds were surpassed more frequently and with higher amounts on the sites with a larger anthropogenic influence. The lower threshold for chlorophyll-a was surpassed at 5 out of the 11 sites by more than 30% of the measurements. This would point to a more pervasive low-level eutrophic condition at all sites. On many of the sand-based substrate areas, seagrass has covered it.

For full report or more information,  please contact erik.meesters@wur.nl or gulsah.dogruer@wur.nl

MSc intership report

Coral reef systems have been declining all over the world. The project “Restoration of resilience of nature and society in the Caribbean Netherlands” focuses on mitigating further decline by improving the resilience of the coral reef. This is done, among other things, through water quality monitoring. In this report, we focussed on the quality of the coastal waters of Saba.

The spatial and temporal variation of chlorophyll a, salinity and temperature was assessed and connected to possible land-based activities and anthropogenic stressors.

The local stressors were assessed through informal interviews. The water quality indicators were measured with sensitive sensor technology. This was done by boat, every two weeks, on 13 locations around Saba, at a depth of 1.5-10 meters.

Both a temporal and spatial variation in chlorophyll a, temperature and salinity have been found. The chlorophyll a values seem concerting when looking at the coral reef threshold. Temperature and salinity are not yet troubling within he period of this research. However, if their temporal trend persists, there would be cause for concern. A baseline for potential local stressors has been identified but more extensive research is needed. Prolonged monitoring of the water quality indicators and more research into local stressors and how these affect one another is needed to fully understand what is going on.
For full report or more information,  please contact erik.meesters@wur.nl or gulsah.dogruer@wur.nl

ABSTRACT There is a lack of information on presence of vibrios in the marine environment in the Caribbean. The aim of this study was to determine the occurrence of Vibrios in the coastal waters of Bonaire. Fifty samples of marine water collected at different depths from various sources around Bonaire were examined for the presence of vibrios. Species identification was confirmed by KB007 HiVibrioTM, Identification Kit and TOFEL-MALDI. Forty of the samples contained Vibrio alginolyticus, 33 yielded V. parahaemolyticus and 29 showed presence of V. vulnificus / V. cholerae. Regarding total colony counts in the sample, 47.4% of the colonies were V. alginolyticus, 35.2% were V. parahaemolyticus, and 17.4% represented V. vulnificus /V. cholerae. Further, of the 25 surface samples from various sites, 14 had a colony count percentage of 50% or greater number of V. alginolyticus. Another 10 sites had a colony count percentage of 50% or greater for V. parahaemolyticus; three of them had a colony count percentage of 50% or greater for V. vulnificus / V. cholerae. The present study constitutes the first study of its kind providing evidence of the prevalence of pathogenic Vibrio species, viz. V. alginolyticus, V. parahaemolyticus, and V. vulnificus / V. cholerae in marine water from the Dutch Caribbean.

Abstract

Red-billed Tropicbirds have historically been considered rare visitors to the waters around the islands of Aruba, Curaçao, and Bonaire in the southern Caribbean. However, in recent years there has been an increase in documented records. We summarize all known Red-billed Tropicbird records for the region and review broader regional population and movement data to place this increase in records in context. We recommend continued careful documentation of Red-billed Tropicbird records on and around the islands of Aruba, Curaçao, and Bonaire and the implementation of a standardized monitoring pro-gram across the Caribbean range for the species to better understand the species' population status, trends, and breeding and at-sea distribution

The unique natural world of the Caribbean part of the Kingdom plays the leading role in a special cinema film entitled WOW!. This was announced during the SMILE event at the University of Sint Maarten at a press conference by 360º of Innovation from Aruba and M&N Media Group from the Netherlands. The production of the film about Aruba, Bonaire, Curaçao, Saba, Sint Eustatius and Sint Maarten has begun and the film will launch in cinemas in 2025 both in the Netherlands and on the islands.

from left to right you see Wyb Meijer from SHTA, Melanie Meijer zu Schlochtern from the Nature Foundation Sint Maarten, Ignas van Schaick from EMS films from the Netherlands, Bianca Peters from 360º of Innovation of Aruba, Elton Arends of 360º of Innovation of Aruba and Tadzio Bervoets of DCNA

Bianca Peters, co-founder and director of 360º of Innovation, is delighted: “For us, WOW! Is a dream come true. The film will not only portray the beauty, diversity and resilience of nature on the islands in a special way but also the vulnerability and importance of a healthy balance between people and nature. Audiences on both sides of the Atlantic are sure to be amazed and filled with pride. Viewers will not have realized before how special nature is in the Caribbean part of the Kingdom.”

In close collaboration with the Dutch Caribbean Nature Alliance (DCNA), the WOW! production team has started visiting possible film locations. Discussions are also currently taking place with stakeholders to gain a good insight into all the ins and outs of the local nature and the stories and developments on the islands.

“Unfortunately, the islands are often negatively in the news in the Netherlands. With this film, we want to build a bridge based on the connecting power of nature to help improve cooperation between the Netherlands and the islands. Diversity and inclusivity in the film and the production team is an important starting point. After all, we are one Kingdom!”, says Peters.

In addition to the film, the makers are also working on a television series that sheds light on the individual islands from the perspective of the relationship between people and nature. What challenges will there be for the inhabitants of the islands in the coming years in their route to a sustainable relationship with nature? But also which solutions have already been created. Various educational and musical programs are also being developed in which local talents are involved.

“I am extremely proud that we as a distributor are so closely involved in the realization of this special film project. It is obvious that we will use music from the islands as a soundtrack for this,” says Jeffrey de Graaff, co-owner of M&N Media Group.

“It is a great honor to be able to make this film about the six Caribbean islands of the Kingdom. We have already made many worldwide successful films about Dutch nature, such as De Nieuwe Wildernis and De Wilde Stad, but this is the first time that we will be filming on this side of the ocean. Collaboration with local parties is extremely important in this regard. We look forward to visiting all six islands in the upcoming period and exploring what we want to film together with a team of talented makers from diverse backgrounds,” said Ignas van Schaick, EMS FILMS.

The production team of WOW! consists of 360º of Innovation, EMS FILMS and associate producer AM Pictures. M&N Media Group is responsible for worldwide distribution.

The film will be shot over the next two years and is expected to be shown in cinemas in the Netherlands and on the islands in 2025. To learn more about WOW! Visit www.wowthenaturefilm.com or visit the Facebook page @wowthenaturefilm.

Published in BioNews 52

Abstract

The island of Bonaire is a nesting location for at least four tern species: a subspecies of the Least Tern (Sternula antillarum
antillarum), the Common Tern (Sterna hirundo), the Royal Tern (Thalasseus maximus), and a subspecies of the Sandwich
Tern (Thalasseus sandvicensis eurygnathus). The island is also a significant nesting site for the Caribbean Least Tern (Sternula
antillarum) population. Our main objectives were to: a) measure and compare breeding success at five known nesting sites on
northern Bonaire, b) document and compare the impact of natural and introduced predators on each site, and c) give management
recommendations for increasing breeding success based on our results. Our nest counts from 2014 indicate a significant
decline in nest abundance compared to historical observations from the 1950s, matching previous studies and observations
from the last two decades. Among the five nesting sites in our study, terns at the two island sites had the largest number of
breeding pairs and achieved the greatest success, fledging a maximum of ~0.8 chicks per nest, compared to all other sites which
were connected to the shoreline. We recorded rats and cats as predators at the peninsula site and field observations suggested
that predation by Laughing Gulls (Leucophaeus atricilla) might also be occurring at two sites. Both natural and artificial islands
on hypersaline lagoons provide good nesting sites for terns on Bonaire as they are protected from mammalian predators. However,
recreational disturbance remains the single most serious and pervasive threat to the future of seabird nesting on Bonaire
and requires concerted action. We propose a list of management actions to increase the numbers of nesting terns throughout
the sites studied. Increasing protection from predators and human disturbance by making artificial nesting islands will provide
the potential for Bonaire, and its sister islands, to become major refuges for southern Caribbean metapopulations of these four
tern species.

Large marine apex predators have become exceedlingly rare in shallow neritic waters around most Caribbean islands, including the ABC-island (Aruba, Bonaire, Curacao) of the Leeward Dutch Caribbean. This is especially the case for several species of sharks. In May 2000, 24 2-hr long deepwater submersible dives were conducted off the isaldns of Aruba, Bonaire and Curacao, at depths ranging between 80-900m.  Eight shark sightings were recorded, amounting to 6 different species, among which the endnagered Hexanchus griseus. These observations suggest a surprising diversity and density of deepwater sharks aroudn the steep island slopes of leeward Dutch islands.

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.