coralita

Dutch below

Coralita is an ornamental plant that was introduced to several Caribbean islands but has quickly found its way to the top of the invasive species lists for the Dutch Caribbean.  Its fast-growing vines smother and outcompetes native vegetation, changing the landscape of the islands. Conservations efforts include manual removal, herbicides and awareness campaigns. 

Coralita vine flowering. Photo credit: Marjolijn Lopes Cardozo

It is easy to fall in love with coralita. This ornamental plant, also known as the coral vine (Antigonon leptopus) was introduced to a number of Caribbean islands as a garden accessory in the 1940s.  Its brightly colored flowers and quickly growing vines make quite the statement piece in any garden. In its native territory, growth of this plant is limited by droughts, however in the Dutch Caribbean this plant has been flourishing. Within the Dutch Caribbean, coralita has been able to spread quickly, year round, due to it’s ability to grow near water collection points such as drainage channels. 

Consequences 

Coralita can spread very quickly. Its vines can reach up to 15 meters in length and rapidly cover entire areas of land. This vine is able spread both horizontally (across fields) or vertically (up trees and buildings), smothering native vegetation beneath it. In addition, this decrease in native flora is also impacting local insect and spider communities.  In fact, researchers from the Vrije Universiteit Amsterdam were able to demonstrate that on St. Eustatius, in areas of dense coralita, there was a decrease in native insects and spiders. Although often thought of as pests, these creatures play a critical role in the local ecosystem by serving as pollinators, aiding in decomposition and nutrient cycling as well as serving as a food source for native reptiles and birds.  Decrease in native vegetation and thus a decrease in insects and spiders will have a cascading effect in limiting the biodiversity of these islands in the future. 

Coralita smothering local vegetation. Photo credit: Achsah Mitchell

Innovative Ideas 

Luckily, islands have some creative ways of combating this issue. In 2018, individuals from the St. John’s community on Saba planted five lemon trees to bring attention to and work towards the eradication of the invasive vine.  Land was selected and cleared, to be used as a fruit orchard, both working to eliminate coralita and provide a source of fresh fruit for the island. Overall, this project served to encourage community action (planting lemon trees) to achieve a common goal (removing coralita). 

On St. Eustatius, researchers have found a novel way to use a classification map to help managers quickly identify dense areas of coralita.  In fact, using this method, they showed that coralita is not randomly spread across the island, but typically found along roads and drainage channels.  Overall, the vine was found more commonly in grasslands, disturbed natural areas and urban sites and rarely in undisturbed natural forest. This information will be key in constructing an invasive species management for the island.

Future work 

Photo credit: Jasper Molleman

The impact of coralita on the Dutch Caribbean is significant. It not only threatens the biodiversity of the islands, but it also has economic consequences, such as reduced tourism appeal and increased costs of removal efforts. Education is an important first step to getting involved in local conservation efforts. Current efforts include manual removal by trained volunteers and the use of herbicides to control the plant’s growth. In addition, awareness campaigns are being conducted to educate residents and visitors on the importance of protecting native vegetation and preventing the spread of invasive species.  

DCNA  

The Dutch Caribbean Nature Alliance (DCNA) supports science communication and outreach in the Dutch Caribbean region by making nature related scientific information more widely available through amongst others the Dutch Caribbean Biodiversity Database, DCNA’s news platform BioNews and through the press. This article is part of a series of articles on ‘Invasive Alien Species in the Dutch Caribbean”. This article contains the results from several scientific studies but the studies themselves are not DCNA studies. No rights can be derived from the content. DCNA is not liable for the content and the in(direct) impacts resulting from publishing this article.   

Coralita is een sierplant die op verschillende Caribische eilanden is geïntroduceerd, maar al snel zijn weg naar de top van de invasieve soortenlijsten voor de Nederlandse Cariben heeft gevonden. De snelgroeiende ranken verstikken en verdringen de inheemse vegetatie, waardoor het landschap van de eilanden verandert. Instandhoudingsinspanningen omvatten handmatige verwijdering, herbiciden en bewustmakingscampagnes.

Invasieve Coralita. Foto: Marjolijn Lopes Cardozo

Het is gemakkelijk om verliefd te worden op coralita. Deze sierplant, ook wel bekend als de koraalklimmer (Antigonon leptopus), werd in de jaren 40 op een aantal Caribische eilanden geïntroduceerd als tuinaccessoire. De felgekleurde bloemen en snelgroeiende ranken zijn een blikvanger in elke tuin. In zijn inheemse grondgebied wordt de groei van deze plant beperkt door droogtes, maar in de Nederlandse Cariben woekert deze plant. Binnen het Nederlandse Caribisch gebied kan coralita zich het hele jaar door snel verspreiden omdat het in de buurt van waterverzameling, zoals drainagekanalen, groeit.

Gevolgen

Coralita kan zich zeer snel verspreiden. De ranken kunnen tot 15 meter lang worden en bedekken snel hele stukken land. Deze rank kan zich zowel horizontaal (over velden) als verticaal (op bomen en gebouwen) verspreiden en de inheemse vegetatie eronder verstikken. Bovendien heeft deze afname van de inheemse flora ook gevolgen voor lokale insecten en spinnen. Onderzoekers van de Vrije Universiteit Amsterdam konden zelfs aantonen dat er op St. Eustatius, in gebieden met veel coralita, een afname was van inheemse insecten en spinnen. Hoewel ze vaak als ongedierte worden beschouwd, spelen deze wezens een cruciale rol in het lokale ecosysteem door als bestuivers te dienen, te helpen bij de afbraak en de kringloop van voedingsstoffen en als voedselbron voor inheemse reptielen en vogels. Afname van inheemse vegetatie en dus afname van insecten en spinnen zal een cascade-effect hebben bij het beperken van de biodiversiteit van deze eilanden in de toekomst.

Invasieve Coralita. Foto: Achsah Mitchell

Innovatieve ideeën

Gelukkig hebben eilanden een aantal creatieve manieren om dit probleem te bestrijden. In 2018 hebben individuen uit de St. John’s-gemeenschap op Saba vijf citroenbomen geplant om aandacht te vragen voor en te werken aan de uitroeiing van de invasieve coralita. Er werd land geselecteerd en gekapt om te worden gebruikt als fruitboomgaard, zowel om coralita te elimineren als om een bron van vers fruit voor het eiland te bieden. Over het algemeen diende dit project om gemeenschapsactie aan te moedigen (citroenbomen planten) om een gemeenschappelijk doel te bereiken (coralita verwijderen).

Op St. Eustatius hebben onderzoekers een nieuwe manier gevonden om een classificatiekaart te gebruiken om managers te helpen snel gebieden met veel coralita te identificeren. Met deze methode toonden ze zelfs aan dat coralita niet willekeurig over het eiland wordt verspreid, maar meestal langs wegen en afwateringskanalen wordt aangetroffen. Over het algemeen werd de rank vaker aangetroffen in graslanden, verstoorde natuurgebieden en stedelijke gebieden en zelden in ongestoord natuurlijk bos. Deze informatie zal van cruciaal belang zijn bij het opzetten van een beheer van invasieve soorten voor het eiland.

Toekomstwerk

Foto: Jasper Molleman

Het effect van coralita op Caribisch Nederland is aanzienlijk. Het bedreigt niet alleen de biodiversiteit van de eilanden, maar heeft ook economische gevolgen, zoals verminderde aantrekkingskracht voor het toerisme en hogere kosten voor verwijderingsinspanningen. Onderwijs is een belangrijke eerste stap om betrokken te raken bij lokale inspanningen voor natuurbehoud. Huidige inspanningen omvatten handmatige verwijdering door getrainde vrijwilligers en het gebruik van herbiciden om de groei van de plant te beheersen. Daarnaast worden bewustmakingscampagnes gevoerd om bewoners en bezoekers voor te lichten over het belang van het beschermen van inheemse vegetatie en het voorkomen van de verspreiding van invasieve soorten.

DCNA

De Dutch Caribbean Nature Alliance (DCNA) ondersteunt wetenschapscommunicatie en outreach in de Nederlandse Caribische regio door natuurgerelateerde wetenschappelijke informatie breder beschikbaar te maken via onder meer de Dutch Caribbean Biodiversity Database, DCNA’s nieuwsplatform BioNews en via de pers. Dit artikel maakt deel uit van een serie artikelen over ‘Invasive Alien Species in the Dutch Caribbean’. Dit artikel bevat de resultaten van verschillende wetenschappelijke onderzoeken, maar de onderzoeken zelf zijn geen DCNA-onderzoeken. Aan de inhoud kunnen geen rechten worden ontleend. DCNA is niet aansprakelijk voor de inhoud en de indirecte gevolgen die voortvloeien uit het publiceren van dit artikel.

Published in BioNews 63

Coralita is an invasive plant species, rapidly spreading across St. Eustatius.  A recently published report highlighted the ability to use satellite imagery to systematically map Coralita’s distribution over the island.  The approach could provide key insights into how habitat and vegetation are changing over time to aid in conservationists’ efforts to minimize the negative effects of Coralita and similar invasive species.

Coralita overgrowth (Source: Achsah Mitchell)

Coralita is a fast-growing, climbing vine with beautiful pink or white flowers. Originally from Mexico, Antigonon leptopus started out as a popular garden plant, but has expanded its territory and is now aggressively invading natural areas. Its fast-growing nature means it can outcompete most native species for terrain, quickly making it the dominant species, and reducing overall diversity. This is especially the case on St. Eustatius, where ground surveys indicate the plant already appears on 15-33% of the island.

Mapping Techniques

One of the biggest issues in controlling invasive species is accurately accounting for its presence, particularly if data needs to be collected over a wide area. This is where satellite imagery can help by providing an affordable, high spatial resolution option. A new collaborative study from the Utrecht University, University of Zurich, Wageningen University, and the Technical University of Braunschweig provided key insight by using such satellite imagery to identify Coralita. The method is successful, as areas dominated by Coralita emit a relatively distinct electromagnetic signal that can be detected by satellites. Once the distribution of Coralita has been mapped using this technique, it is possible to identify the environmental conditions associated with Coralita’s presence. This approach provides a relatively low-cost solution that is powerful, accurate and repeatable; key in identifying and monitoring its spread in the future.

“In creating this map,” said Elizabeth Haber, first author of this study, “it was my hope to produce something that could be useful for those who are caring for and protecting the incredibly special nature on Statia.”

Results

Using this method, researchers sampled 162 locations across St. Eustatius and estimated that Coralita was the dominant canopy cover (>50%) on over 3% of the island (64 ha). Perhaps more importantly, this map also showed that Coralita was not randomly distributed but generally found, for example, in areas of water accumulation, near roads or near drainage channels. Furthermore, Coralita was often found in grasslands and areas of development and is relatively rare in natural forests, highlighting how human disturbances can promote the spread of Coralita. It is important to note that data filtering and physical limitations of using satellite imagery means that Coralita growing under trees or shrubs or in smaller patches is likely underrepresented in this study.

Map of the distribution of Coralita on St. Eustatius (Haber et al., 2021)

Conservation Implications

Even with the physical limitations, the fact that this study is cost effective and repeatable means that consistent comparisons of Coralita’s distribution can be made over time. These comparisons are vital in understanding how populations and habitats are shifting, granting conservationists a fantastic tool in forecasting the spread of invasive species. Arguably the greatest asset of the Caribbean is its vast biodiversity. Already threats of climate change, habitat loss, invasive species and urban development are upsetting this fragile balance. St. Eustatius, although small, is home to several endemic plant species, two of which are the Statia morning glory and Statia milkweed, along with the critically endangered Lesser Antillean Iguana which could all be threatened by the habitat alterations of Coralita growth.

To read more, please find the full report on the Dutch Caribbean Biodiversity Database using the link below.

https://www.dcbd.nl/document/high-spatial-resolution-mapping-identifies-...

Article published in BioNews 48

Abstract
Invasive species are a worldwide threat to biodiversity, especially on Caribbean islands.
Through their impact on the structure and functioning of ecosystems, they also affect
ecosystem services. Therefore, invasive species can have profound socio-economic
effects. On the Dutch Caribbean Island of St. Eustatius, the invasive perennial vine Coralita
is present on roughly 33% of the Island. While ecological damage is evident, effective
management strategies are still lacking. This study links the ecological, cultural and
societal effects of the invasion to the economy of the Island by estimating the ecosystem
service losses due to Coralita in monetary value. We have spatially assessed the
economic value of five main ecosystem services (tourism, non-use value, carbon
sequestration, archaeology and local cultural and recreational value) to the different
habitats on the Island and estimated the loss of these values under three scenarios of
Coralita cover: 0%, 3% and 36% dominant cover. The baseline scenario of 0%
demonstrated a total ecosystem service value of $2.7 million per year, concentrated on the Quill volcano. The 3% and 36% scenario showed a yearly loss of $39,804 and $576,704, respectively, with the largest losses located on the northern and eastern slopes of the Quill.
These areas should be prioritised for management and the known potential gain per area
enables choice of strategy, based on cost-benefit considerations. To reduce further
economic loss by Coralita, we urgently advise an immediate management strategy and
ongoing research into eradication and restoration methods.

Keywords
BES Islands, Coralita, economic value, invasive species, spatial assessment, scenario
mapping

This one-year pilot project aims to provide an insight in the ecology of Antigonon leptopus (Corallita) an invasive vine, which is overgrowing the native vegetation (Photo 1). This pilot project is just a first step in controlling the Antigonon leptopus. This research was done on a small scale and under controlled circumstances. Our ideas are just for small scale use in town but also to eradicate ‘hotspots’ to prevent further spreading especially near the National Parks. The government with STENAPA as a consultant should take further actions to continue this project and put it as a high priority. The first step was made and we hope this will contribute in containing the species and monitoring the species closely. More research on the life circle and possible natural enemies and its sensitivity for herbicides should be done in order to start a larger scale eradication campaign. The project does not stand on its own, the vine contributes in the prevention of soil erosion on the island. A full size project including replanting/reforestation with native species and renewed agricultural activities should be set up for the long term.

Objectives

• The primary research aim is to reduce and control the growth of Corallita on St. Eustatius and to prevent the species from invading the national parks. In order to achieve this, it is necessary.
• To gather information about the ecology of the species, such as its life cycle, dispersal, germination capacity, use of the species by animals etc. • To gather information about how the species will react on different potential control methods.
• Inform the local community about control methods if usable results are obtained.

Discussion and conclusion

Three weeks after the first treatment at Gallow Bay no regrowth was observed, this means the herbicide does work with smaller concentration (12.5% and 25%) on short term. After six weeks the first regrowth was observed. The tubers are still intact after the first treatment. It is not known how many times the treatment with these concentrations is needed.

In both plots of Sandy Road the plants have regrowth after 7½ weeks. Our observation on 13th January 2007 showed that a lot of Corallita was growing from the border into the plots covering the soil. The treatment did work but probably needed a second treatment if there is regrowth of 30-40cm. Further monitoring of large plots (during one year) is needed to make sure smaller concentrations will kill the plants. Tubers should de dug up and checked on viability. New plots should be selected.