Saba

The Saba black iguana, Iguana (guana/melanoderma) is a Lesser Antillean endemic variety of the green iguana that is (likely) only found on Saba and Montserrat. The species is the largest native land vertebrate of Saba. Hybridization with the introduced Green Iguana is now an imminent threat to this unique black island variety of iguana.

During fieldwork in 2021 non-native Green Iguanas were seen, captured, culled and genetically confirmed for Saba. If more animals remain on the island or have hybridized with the native Saban black iguana, there is an imminent threat that the latter will be displaced and disappear. A “Rapid Resonse Removal Campaign” is urgently needed to quickly and hopefully completely remove the invasive Green iguana. This Kennisdeskvraag therefore is aimed to swiftly design and rigorously execute such a campaign in close cooperation with local stakeholders. The project will be modelled after a similar successfully-executed campaign for Statia (Debrot et al. 2022).

As the number of Green iguanas is likely still very small, a Rapid Response Action is feasible and called for. The Ministry Agriculture Nature and Food Quality of the Netherlands carries ultimate responsibility for endangered species in the Caribbean Netherlands. In light of the local lack of capacity and expertise the ministry decided to commission the execution of a removal campaign by WMR. 

Together with local and Dutch expert iguana spotters two thorough surveys will be conducted this year in key risk areas to eliminate all iguanas that have Green Iguana or hybrid characteristics. The project will provide practical experience and lessons learnt that will be of great value to the further implementation of the Invasive Alien Species Joint Action Plan as previously also commissioned by the same ministry.

A B S T R A C T

Fish assemblages of different types of artificial reefs can differ greatly in abundance, biomass and composition, with some reef types harboring over five times more herbivores than others. It is assumed that higher herbivorous fish abundance results in a higher grazing intensity, affecting the benthic community by means of enhanced coral recruitment, survival and growth. Territorial fish species might affect this process by chasing away other fish, especially herbivores. In this study we compared the fish assemblage, territorial behavior and grazing intensity by fish on two artificial reef types: reef balls and layered cakes, differing greatly in their fish assemblage during early colonization. In addition, the effect of artificial reef type on benthic development and coral recruitment, survival and growth, was investigated. Although layered cakes initially harbored higher herbivorous fish biomass, this effect was lost during consecutive monitoring events. This seems to be the result of the higher territorial fish abundance around the layered cakes where almost four times more chasing behavior was recorded compared to the reef balls. This resulted in a more than five times lower fish grazing intensity compared to the reef-ball plots. Although macroalgae were effectively controlled at both reefs, the grazing intensity did not differ enough to cause large enough structural changes in benthic cover for higher coral recruitment, survival or growth. The high turf algae cover, combined with increasing crustose coralline algae and sponge cover likely explained reduced coral development. We recommend further research on how to achieve higher grazing rates for improved coral development on artificial reefs, for example by facilitating invertebrate herbivore. 

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

On January 17th, 2022, Mark Zagers, Managing Director of the Saba Electric Company (SEC), officially handed over the keys to Peter Johnson, President of the Saba Conservation Foundation (SCF), the new tenant of the old power plant at the Fort Bay harbor. Also present were commissioner, Bruce Zagers, other SCF board members, resident researchers, and staff. After the handover, the group toured and inspected the newly renovated facility.

Due to climate change, overfishing, coastal development and other stresses, coral reefs worldwide are drastically in decline and scientists are racing to save the “rainforest of the sea” from extinction. The facility will provide novel opportunities to conduct coral reef research at an ideal location, adjacent to the Saba Marine Park and near the Saba Bank. The project was initiated in collaboration and with support of the island government.

Kai Wulf, managing director of the SCF, explained: “Our plans are to enhance the building to provide a controlled environment, so called mesocosms, to grow and study reef organisms, to better understand and control factors that impact and promote their wellbeing, with the aim to develop practical solutions to restore marine ecosystems.”

Official key handover; from left to right: Ayumi Kuramae Izioka, Saba Bank Science Coordinator, Lynn Costenaro, Board Member, Saba Conservation Foundation Mark Zagers, Managing Director, Saba Electric Company Peter Johnson, President, Saba Conservation Foundation Alwin Hylkema, Resident Researcher, Van Hall Larenstein University, Bruce Zagers, Commissioner, Saba Island Government. Credit: Kai Wulf

Services provided by Saba’s marine and terrestrial ecosystems are vitally important to the island’s fisheries and tourism industries, with an estimated total economic value of US $29 million per year (TEEB Study, Wolf’s Company 2014).

For example, by cultivating and restocking Diadema sea urchins, important herbivores decimated in the Caribbean by a viral disease during the early 1980s, algae growth that is now smothering and choking corals, could be vastly reduced. Scientists may also be able to develop new techniques to propagate stony coral that is more resilient to rising ocean temperatures and C02 induced acidification.

Successful research and coral restoration practices could bring much publicity and elevate Saba’s visibility internationally. Additionally, the research facility will create a new form of sustainable tourism for Saba, attracting scientists, students and coral reef restoration practitioners to the island. These visitors usually stay for longer periods and often bring family and friends, contributing substantially to the economy to the island. Further benefits will not just include guided tours, but could also provide career options for local students interested in marine biology and engage interested residents in meaningful citizen science.

The finalization of the building modifications approved by SEC and full operational capacity depend on the ability of the SCF and its partners to raise the necessary funding.

Concept drawing of future research station. Credit: Kai Wulf

Published in BioNews 51

Abstract.– Intraspecific diversity is among the most important biological variables, although still poorly understood for most species. Iguana iguana is a Neotropical lizard known from Central and South America, including from numerous Caribbean islands. Despite the presence of native melanistic I. iguana populations in the Lesser Antilles, these have received surprisingly little research attention. Here we assessed population size, distribution, degree of melanism, and additional morphological and natural history characteristics for the melanistic iguanas of Saba, Caribbean Netherlands based on a one-month fieldwork visit. Using Distance sampling from a 38- transect dataset we estimate the population size at 8233 ±2205 iguanas. Iguanas mainly occurred on the southern and eastern sides of the island, between 180-390 m (max altitude 530 m), with highest densities both in residential and certain natural areas. Historically, iguanas were relatively more common at higher altitudes, probably due to more extensive forest clearing for agricultural reasons. No relationship was found between the degree of melanism and elevation, and few animals were completely melanistic. Furthermore, we found that body-ratio data collection through photographs is biased and requires physical measuring instead. Although the population size appears larger than previously surmised, the limited nesting sites and extremely low presence of juvenile and hatchling iguanas (2.4%), is similarly worrying as the situation for I. delicatissima on neighboring St. Eustatius. The island’s feral cat and large goat population are suspected to impact nest site quality, nest success, and hatchling survival. These aspects require urgent future research to guide necessary conservation management.

The massive die-off of the herbivorous sea urchin Diadema antillarum in 1983 and 1984 resulted in phase shifts on Caribbean coral reefs, where macroalgae replaced coral as the most dominant benthic group. Since then, D. antillarum recovery has been slow to non-existent on most reefs. Studying settlement rates can provide insight into the mechanisms constraining the recovery of D. antillarum, while efficient settlement collectors can be used to identify locations with high settlement rates and to collect settlers for restoration practices. The aim of this study was to compare pre and post die-off settlement rates and to determine possible settlement peaks in the Eastern Caribbean island of St. Eustatius. Additionally, we aimed to determine the effectiveness and reproducibility of five different settlement collectors for D. antillarum. D. antillarum settlement around St. Eustatius was highest in May, June and August and low during the rest of the study. Before the die-off, settlement recorded for Curaçao was high throughout the year and was characterized by multiple settlement peaks. Even though peak settlement rates in this study were in the same order of magnitude as in Curaçao before the die-off, overall yearly settlement rates around St. Eustatius were still lower. As no juvenile or adult D. antillarum were observed on the reefs around the settlement collectors, it is likely that other factors are hindering the recovery of the island's D. antillarum populations. Of all five materials tested, bio ball collectors were the most effective and reproducible method to monitor D. antillarum settlement. Panels yielded the least numbers of settlers, which can partly be explained by their position close to the seabed. Settler collection was higher in mid-water layers compared to close to the bottom and maximized when strings of bio balls were used instead of clumps. We recommend research into the feasibility of aiding D. antillarum recovery by providing suitable settlement substrate during the peak of the settlement season and adequate shelter to increase post-settlement survival of settlers. The bio ball collectors could serve as a suitable settlement substrate for this new approach of assisted natural recovery.

Surveying subaqueous beach profiles and features beyond wading depths can be a costly process, requiring use of expensive equipment and boats. This paper describes the materials and methods of a simple, low-cost technique for underwater bathymetric surveying, herein named the diver depth-gauge profiling (DDGP) method. Although accuracy of depth data depends on the quality of the depth gauges used, it is commonly within 0.3 m. Data collection reliability was evaluated by repeated underwater beach profile surveys, and an example of its use in the Caribbean is provided.

Trail maps of Saba 2016 (GIS)

source : Saba Conservation Foundation

Saba is a five square mile island with about 1200 permanent inhabitants located off the coast of St. Maarten in the Netherlands Antilles (go to map from link in banner). English is the official language of the island but Dutch is also taught in schools and is spoken by many Sabans.

In February 2006, Conservation International, in conjunction with the Saba Conservation Foundation, embarked on a project to survey the biodiversity of Saba from beneath the sea to the summit of its highest peak, Mt. Scenery. As part of this effort, the Department of Botany of the Smithsonian Institution surveyed the marine algae.

In 2006 and 2007, The New York Botanical Garden participated in surveying the bryophytes, lichens, and vascular plants of the island. Although small in size, Saba's rugged topography is covered by several vegetation types, ranging from near desert to cloud forest. Our goal is to provide illustrated checklists (a virtual museum) of all of the plants and lichens that grow on Saba and in the surrounding sea. Both native and introduced plants are included.

To find collections representing species of flowering plants, gymnosperms, ferns, bryophytes, marine algae, or lichens, you can access the information available for a given group by clicking on the appropriate image on the left hand side of this page.

It is forbidden to pick plants and to remove plants from the island of Saba. All natural history studies must first be approved by the government of Saba. To find out how to obtain permission to collect herbarium specimens as was done in this study contact the Saba Conservation Foundation.

All photographs are copyrighted by the photographer. Most of the photographs of the flowering plants, gymnosperms, ferns, bryophytes, and lichens were taken by Carol Gracie and most of those of the marine algae were taken by Diane Littler. Harrie Sipman took the photo micrographs of the lichens. For permission to use the images, contact the photographers. Citizens of Saba have permission to download images from the website for personal or educational purposes.

Abstract
Surveying subaqueous beach profiles and features beyond wading depths can be a costly process, requiring use of expensive equipment and boats. This paper describes the materials and methods of a simple, low-cost technique for underwater bathymetric surveying, herein named the diver depth-gauge profiling (DDGP) method. Although accuracy of depth data depends on the quality of the depth gauges used, it is commonly within 0.3 m. Data collection reliability was evaluated by repeated underwater beach profile surveys, and an example of its use in the Caribbean is provided.