Caribbean

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 internship report

The project Restoration of resilience of nature and society in the Caribbean Netherlands aims to improve the resilience of the coral reefs in the BES (Bonaire, Sint Eustatius, Saba) islands, by mitigating the local stressors. One of the methodologies used is water quality monitoring. For this research, the focus was on chlorophyll a and turbidity temporal and spatial variability in Saba, and on how this could be related to anthropogenic and natural land-based local stressors. Chlorophyll a is a key water quality parameter which can give an insight on the eutrophic state of an area, while turbidity can be used as an indicator for coastal erosion and run-offs. These parameters were measured in 13 sampling sites, bi-weekly from May to August 2022, using two CTDs, a sensitive sensor technology. The land-based stressors were mapped as a result of qualitative analysis. Chlorophyll a values were highly variable, and often exceeded the safety threshold (0.2 μg/L) previously chosen, suggesting that the area was in a chronic state of eutrophication. Turbidity instead remained more stable and nearly always below the 3 NTU threshold. On one hand, spatial variability was not always directly linked to land-based stressors, and might be better interpreted including the action of sea currents. Temporal fluctuations, on the other hand, can be only partly explained by the amount of rainfall increasing run-offs from land to sea. Moreover, further research is needed to quantify local stressors, and long-term monitoring is necessary to fully understand the amplitude and nature of their influence on water quality.

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

The 1983-1984 die-off of the long-spined sea urchin Diadema antillarum stands out as a catastrophic marine event because of its detrimental effectson Caribbean coral reefs. Without the grazing activities of this key herbivore, turf and macroalgae became the dominant benthic group, inhibiting coral recruitment and compromising coral reef recovery from other disturbances. In the decades that followed, recovery of D. antillarum populations was slow to non-existent. In late January 2022, a new mass mortality of D. antillarum was first observed in the U.S. Virgin Islands. We documented the spread and extent of this new die-off using an online survey. Infected individuals were closely monitored in the lab to record signs of illness, while a large population on Saba, Dutch Caribbean, was surveyed weekly before and during mortality to determine the lethality of this event. Within four months the die-off was distributed over 1,300 km from north to south and 2,500 km east to west. Whereas the 1983-1984 die-off advanced mostly with the currents, the 2022 event has appeared far more quickly in geographically distant areas. First die-off observations in each jurisdiction were often close to harbor areas, which, together with their rapid appearance, suggests that anthropogenic factors may have contributed to the spread of the causative agent. The signs of illness in sick D. antillarum were very similar to those recorded during the 1983-1984 die-off: lack of tube feet control, slow spine reaction followed by their loss, and necrosis of the epidermis were observed in both lab and wild urchins. Affected populations succumbed fast; within a month of the first signs of illness, a closely monitored population at Saba, Dutch Caribbean, had decreased from 4.05 individuals per m2 to 0.05 individuals per m2. Lethality can therefore be as high as 99%. The full extent of the 2022 D. antillarum die-off event is not currently known. The slower spread in the summer of 2022 might indicate that the die-off is coming to a (temporary) standstill. If this is the case, some populations will remain unaffected and potentially supply larvae to downstream areas and augment natural recovery processes. In addition, several D. antillarum rehabilitation approaches have been developed in the past decade and some are ready for large scale implementation. However, active conservation and restoration should not distract from the primary goal of identifying a cause and, if possible, implementing actions to decrease the likelihood of future D. antillarum die-off events.

Abstract

Invasive alien species (IAS) are species that have been introduced to locations outside of their distributional range via human transport. In their novel exotic range, these species reach quickly reproduce and/or spread, hence the connotation “invasive”. Examples of well-known problematic IAS include tropical mosquitos bearing diseases such as Zika virus, predatory animals such as the lionfish or black rats, and plants blanketing anything they encounter. IAS are considered to be a major threat to biodiversity with extensive societal and economic consequences. However, invasive species do not become invasive overnight; invasion is the final and most detrimental stage of a much longer process. The aim of this thesis was to disentangle the natural and anthropogenic causes and consequences of species invasion by following exotic species from their origin to their impact. This thesis is structured along the different stages of species invasion and answers three overall research questions: Where do exotic species come from?; Where do exotic species end up?; What are the consequences of exotic species invasion?. The first question Where do exotic species come from? is answered in Chapter 2 that showed that exotic species and species endangered with extinction inhabit the same locations but contrast each other in terms of their traits. Both groups are overrepresented on human-impacted oceanic islands. The question: Where do exotic species end up? is answered by Chapters 3-5. In this section I conclude that within islands invaded by several exotic reptiles, these species are found almost exclusively in human-impacted environments with open or shrubby vegetation. Conversely, native species reach highest abundances in forest sites (Chapter 3). Hurricanes severely alter available habitats for reptiles (Chapter 4). Native species abundances of the lizard genus Anolis decreased with increasing levels of hurricane-induced habitat change, especially on St. Martin that was severely hit by the hurricanes Irma and Maria. Exotic species varied in their response, but we detected exotic species in previously uninvaded forests. That species from small, less populated islands also get introduced was demonstrated by the first published record of an exotic Saban anole (A. sabanus) found in the harbor of St. Eustatius (Chapter 5). This chapter serves as proof of concept that shipping is an important vector for exotic reptiles. The question What are the consequences of species invasion? is answered in Chapters 6-8, featuring the extensive invasion of the Coralita vine (A. leptopus) on St. Eustatius, impacting approximately one-third of this island. Coralita significantly alters the species composition of arthropod communities on St. Eustatius. After invasion the unique communities in urban and natural sites become homogenized to the point where they become undistinguishable (Chapter 6). The plant also has societal consequences through the reduced availability of ecosystem services (ES) (Chapter 7-8). Through a novel methodology we were able to provide estimates of ES value loss to the economy of St. Eustatius (Chapter 7-8), amounting to 42.000 dollar per year in case 3% of the island would be dominantly covered by the plant, rising to 640.000 dollar per year in case the entire range of Coralita would reach dominant coverage. We estimate that it requires a total investment of 12,7 million dollars (12% of GDP) to revert back from the worst case scenario to a Coralita-free situation. In general based on the work in this thesis I can conclude that the process of species invasion is 1) to some extent predictable at its various stages; 2) an important, independent driver of change augmented by several natural and anthropogenic factors; and 3) has major consequences for biological systems as well as human welfare and wellbeing through invasion-induced changes in ecosystem services.

https://research.vu.nl/en/publications/biodiversity-in-a-globalized-worl...

Abstract

The economies of small tropical islands often benefit from large-scale tourism, attracted by the guarantee of beach facilities, sun and warmth, landscape beauty, and cultural and underwater life. While these are highly valued assets, it is unclear how local communities benefit from tourism, or how they perceive their natural environment, which has been the basis for their rich cultural history. Against this background, the main aim of this article is to investigate inhabitants’ perceptions about locals’ inclusiveness in tourism and recreation on a small island called Bonaire. A total of 400 households were interviewed during the period November 2021–February 2022. Inclusiveness in tourism and the welfare it brings are judged as low, based on the findings in this study. With a share of around 40% of the population of Dutch Caribbean islanders living in poverty, the challenge of inequality is urgent. While environmental degradation contributes to inequality, inequality can also contribute to environmental degradation. To reduce inequalities, while ensuring life below water and life on land, the handling of poverty is one of the most critical bottlenecks in this society.

Abstract

Invasive alien species are among the main drivers of the ongoing sixth mass extinction wave, especially affecting island populations. Although the Caribbean is well-known for its high species richness and endemism, also for reptiles, equally important is the regional contribution of non-native species to island biodiversity. The Lesser Antilles encompass high genetic diversity in Iguana, though most native populations either have gone extinct or are declining following competitive hybridization with invasive non-native iguanas. Here we assessed non-native presence in two poorly-studied native melanistic Iguana iguana populations using available genetic tools, and explored utilizing size-dependent body measurements to discriminate between native and non-native iguanas. Genetic samples from Saba and Montserrat were genotyped across 17 microsatellite loci with STRUCTURE and multivariate analyses indicating non-native iguanas presence only on Saba. This was corroborated by mtDNA and nDNA sequences, highlighting a non-native origin in Central America and the ABC islands. We identied preliminary evidence suggestive of hybridization. Morphological variation among size-dependent characteristics showed that non-native iguanas have signicantly larger subtympanic plates than native iguanas. Non-native individuals also differed in scalation and coloration patterns. Overall, our ndings demonstrate the need for continuous monitoring for non-native iguanas within remaining native Iguana populations in the Lesser Antilles, with those not directly threatened by non-native iguanas restricted to only 8.7% of the historic range. Although genetic data allows for identication of non-native or hybrid iguana presence, this eld-to-lab workow is time consuming. Rapid in-situ identication of non-native individuals is crucial for conservation management, and besides scale and coloration patterns, we have highlighted the utility of size-dependent variables for rapid diagnosis. We urge regional partners to build morphometric databases for native Iguana populations that will help to quickly detect future incursions of non-native iguanas and allow the rapid implementation of effective countermeasures during the early phase of invasion.

A B S T R A C T
The long spined sea urchin Diadema antillarum was an abundant grazer on Caribbean coral reefs, until
1983–1984, when densities were reduced by ~98% during a region wide die-off. Since then, there has been very
little natural recovery of the species and interest is growing in applying aquaculture as a tool for population
enhancement. In this study we optimized a new shaker bottle cultivation method for D. antillarum. The method
was tested in a series of experiments by culturing D. antillarum from egg to juvenile in the Netherlands as well as
the USA. Larvae were cultured in standard 1-L glass reagent bottles, suspended by gentle constant movement on
an orbital shaking table and fed with either the microalgae Rhodomonas lens or Rhodomonas salina. Effects on
larval growth and survival were evaluated for different microalgal feeding concentrations, larval densities, and
culture temperatures. Larval density and growth were measured twice a week over a period of up to 56 days.
Larvae grew significantly faster on a higher feeding concentration up to 90,000 Rhodomonas sp. cells mL

Abstract

Small Island Developing States (SIDS) have a high dependency on fossil fuels for energy, water, and food production. This has negative implications on the carbon footprint and resilience of the SIDS. Wind power is one of the most promising options for renewable energy in the coastal areas of the SIDS. To account for the seasonal intermittent nature of wind energy, ammonia can be used for energy storage. In this paper, ammonia as an energy vector, is examined to reduce the costs and carbon footprint of energy on the island of Curaçao as a showcase for Caribbean SIDS. The levelized cost of electricity (LCOE) for the combined wind and ammonia energy storage system is 0.13 USD/kWh at a discount rate of 5%. This is cost competitive with the LCOE of 0.15–0.17 USD/kWh from heavy fuel oil, which is the main electricity source in the Caribbean SIDS. In Curaçao, the LCOE from LNG and coal without carbon capture and storage (CCS) is 0.07–0.10 USD/kWh and 0.09–0.14 USD/kWh, respectively. When CCS is applied, the LCOE from LNG and coal is 0.10–0.13 USD/kWh and
0.14–0.21 USD/kWh, respectively. This suggests that the LCOE of the combined wind and ammonia energy storage system can be competitive with fossil-based alternatives with carbon capture and storage (CCS) in a decarbonized energy landscape. The CO2-footprint of the combined wind energy and ammonia energy storage system is 0.03 kg CO2/kWh, compared to 0.04 kg CO2/kWh and 0.12 kg CO2/kWh for LNG-/coal-based energy generation with CCS, respectively.

Introduction

The Caribbean region is emerging as a hotspot for the spread of non-native reptile species (Powell et al. 2011; Powell and Henderson 2012). Two lizard groups, anoles (species from the genus Anolis) and geckos (species from the infraorder Gekkota), are among the most prominent of introduced reptiles on Caribbean islands (Helmus et al. 2014; Perella and Behm 2020). Anole and gecko species are frequently introduced accidentally through the live plant trade, but may also be introduced intentionally as pets (Kraus 2009). The Caribbean region is also a reptile biodiversity hotspot and most islands have unique endemic anole and gecko species (Myers et al. 2000; Hedges 2011). Therefore, identifying newly introduced gecko and anole species, including their introduction pathways and ecological impacts, is a conservation priority.

Aruba has 10 previously recorded introductions of non-native reptile species, including two anoles, Anolis sagrei (Duméril & Bibron, 1837) and A. porcatus (Gray, 1840), and four geckos, Gonatodes albogularis (Duméril & Bibron, 1836), G. antillensis (Lidth de Jeude, 1887), G. vittatus (Lichtenstein & Martens, 1856), and Hemidactylus mabouia (Moreau de Jonnès 1818), making it one of the most invaded islands in the Caribbean (van Buurt 2005, 2011). Aruba is also one of the most economically connected islands in the region which likely explains the high rate of introductions (Powell et al. 2011; Helmus et al. 2014). Interestingly, unlike most Caribbean islands, the natural habitat in Aruba is quite arid and may be difficult for species to invade if they are not adapted to those conditions. Many of the non-native species may be using anthropogenic habitat that receives irrigation subsidies. Given the high rate of introductions and harsh natural conditions, we searched anthropogenic habitat on Aruba for non-native reptile species. Here, we report the first observations of two new non-native anole and one non-native gecko species on Aruba. In addition, we report a range expansion of a non-native anole species that was previously observed at only one location on Aruba. To better understand the context and potential impacts of the four introduced species we documented on Aruba, we compiled information from the literature regarding the timing, introduction pathway, and ecological impacts of those four species in their introduced ranges within the Caribbean region.

Abstract

Coral reefsare experiencing large scale degradation. Motivated by the need for regular data monitoring and forquantification of the state and change of benthic and pelagic organisms,the Global Coral Reef Monitoring Networkprotocolwas executed on 18 dive sites in fished and unfished areasaround the island of Saba in the Saba National Marine Park (SNMP) in the Dutch Caribbean from March to May 2019. Pictures of the benthos were taken andanalysed with the Coral Point Count Excel extension software and fish biomass was calculated through the Bayesian length-weight-relationship. Although considerablybelow the Caribbean-wide average, coral cover around the island seems to be slowlyrecoveringfrom past diseasesand hurricane events. Coral species richnesspositively correlates with reef fish density and Serranidae species richness. As in other parts of the Caribbean, macroalgae in the SNMP arerapidly spreadingand increasingly competefor space with habitat-providing gorgonians, sponges and other benthic organisms. Incontrast toexpectations, fish density and biomass continue to increase, evenin zones where fishing is allowed. This mightbe explained by the higher availability of macroalgae that serve as food for variousherbivorous fish species, which in turn are, amongst others, the prey of predatory fish and thosehigher up in the trophic cascade. However, with the exception ofthe commercially important fish family Lutjanidae all key fish species have declinedin average size in recent years. Another findingis the increase of coral diseases. The results indicate the need for further species-specific research in order to identify the factorsthat arecausing the degradation ofthe reefs in the SNMP. A better understandingofthe interactions, ecological roles and functions of benthic and fish communities is therefore essential for the protection of reefs, that are of high value to Saba. The results of this study contribute to the adaptive management of the Saba Conservation Foundation that manages the SNMP.

Keywords: GCRMN, Reef Health Index, marine protected area, fish-benthos interaction, macroalgae, herbivory, trophic cascade, fishing, coral disease, Caribbean