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.
• Assess sponge and coral cover
• Quantify the diversity and health of the sponge assemblages on Saba Bank
Saba Bank, a submerged atoll in the Caribbean Sea with an area of 2,200 km2, has attained international conservation status due to the rich diversity of species that reside on the bank. In order to assess the role of Saba Bank as a potential reservoir of diversity for the surrounding reefs, we examined the population genetic structure, abundance and health status of two prominent benthic species, the coral Montastraea cavernosa and the sponge Xestospongia muta. Sequence data were collected from 34 colonies of M. cavernosa (nDNA ITS1-5.8S-ITS2; 892 bp) and 68 X. muta sponges (mtDNA I3-M11 partition of COI; 544 bp) on Saba Bank and around Saba Island, and compared with published data across the wider Caribbean. Our data indicate that there is genetic connectivity between populations on Saba Bank and the nearby Saba Island as well as multiple locations in the wider Caribbean, ranging in distance from 100s–1000s km. The genetic diversity of Saba Bank populations of M. cavernosa (π = 0.055) and X. muta (π = 0.0010) was comparable to those in other regions in the western Atlantic. Densities and health status were determined along 11 transects of 50 m2 along the south-eastern rim of Saba Bank. The densities of M. cavernosa (0.27 ind. m-2, 95% CI: 0.12–0.52) were average, while the densities of X. muta (0.09 ind. m-2, 95% CI: 0.02–0.32) were generally higher with respect to other Caribbean locations. No disease or bleaching was present in any of the specimens of the coral M. cavernosa, however, we did observe partial tissue loss (77.9% of samples) as well as overgrowth (48.1%), predominantly by cyanobacteria. In contrast, the majority of observed X. muta (83.5%) showed signs of presumed bleaching. The combined results of apparent gene flow among populations on Saba Bank and surrounding reefs, the high abundance and unique genetic diversity, indicate that Saba Bank could function as an important buffer for the region. Either as a natural source of larvae to replenish genetic diversity or as a storehouse of diversity that can be utilized if needed for restoration practices.
The deep reef of Bonaire, Caribbean Netherlands, was explored with the aid of the “Curasub” submarine of Substation Curaçao. The shallow reefs of the Caribbean are considered a biodiversity hotspot, an area with exceptional diversity of plants, animals and ecosystems, yet surprisingly little is known about the flora and fauna of the deeper reefs.
Dives were made to depths of 140-250m.at three locations on the Southern coast of Bonaire: Kralendijk,Cargill, and Statoil. Distinct depth zonations in substrate features were visible. Coral reef was observed until approximately 45m, then followed a zone of sand mixed with varying amounts of stones. At each site a wide layer of cyanobacteria mats covering sand were found spanning the depths of 45m.to 90m.
The depth from 90-100m was typically dominated by sand with occasional small rocks on which fan corals and sponges resided. From 100-
150m depth fossil barrier reef and rodolith beds were observed, either in long stretches or in patches within a barren sandscape. By providing hard substrate, these fossil reefs displayed heightened biodiversity in a desert landscape of sand. Below 150m the substrate was generally dominated by fine sand. The cause of the cyanobacterial mats remains unclear. These mats are generally believed to indicate nutrient enriched (disturbed) environmental conditions, and should therefore be further studied to elucidate the cause. Trash was observed at all depths. High biodiversity was observed on the sporadic hard substrate below 100m, presumably fossil reef. In total 72 species were recorded, of which at least 15 species are new to science (shrimp, sponges, fish). The major focus was on sponges due to their importance in the deep reef in terms of diversity, filtering activities, biomass, and source of pharmaceutical compounds. A species list and picture gallery are provided in this report. This is just of subset of the true biodiversity of Bonaire’s deep reef. With the description of new species also comes a better understanding of ecosystems.
The aim of this study was to draft a generic ecological assessment framework for coastal systems in Caribbean Netherlands (CN) that offers guidance in the process of license-applications of planned activities that could impact coastal systems, as well as a general guidance towards environmental and ecological monitoring related to proposed projects and existing activities. The study was limited to the review of (inter)national ecological assessment frameworks and monitoring initiatives; peer-reviewed academic literature was not consulted. Though this draft framework provides guidance, it limits itself to standard practice and general regulations. Further fine-tuning of the framework is required to be applicable to the specific situation in CN. Furthermore, it is the responsibility of the individual initiators to customize an adequate and comprehensive ecological impact assessment and monitoring-plan adjusted to the spatial and temporal scale relevant of the type of activities and possible impact resulting from the project.
Fundamental to the draft framework is a network approach in which the impact chain between the activity and ecosystem components is specified by a suit of pressures. The broad strategy of the ecological assessment framework consists of three major phases:
- Establishing the context in which the project will take place.
- Scoping of the project activities, their pressures and the environmental descriptors relevant to the projected area.
- Assessment and evaluation of the pressures on the environmental descriptors.
For each phase practical guidance is provided in the form of questions. While answering these questions an overview is established of all relevant activities, pressures, and environmental descriptors. Each phase is further elaborated upon in the report. An adaptive and interactive management approach is required for the processes of the three phases. Informative environmental descriptors groups were identified based on international monitoring initiatives (Benthic diversity, Coral health, Species requiring special attention, Fish diversity, Chemical water quality, Physical structure) and for each descriptor indicators are proposed. Further study is required into which indicators are most appropriate for CN.
Threshold levels are not commonly available for each of the environmental descriptors. Significance testing in the absence of threshold levels is discussed in de report. A practical guidance is proposed to evaluate and categorize the significance of an impact by listing questions related to the nature, magnitude and intensity of the (expected) impacts. Reference is made to relevant (inter) national treaties or ordinances in which qualitative goals are reported.
This report provides practical guidance and considerations on how to establish appropriate reference situations in a changing environment. The reference situations must be chosen using best available information about the physical and biological characteristics of the environment to ensure that they represent suitable reference conditions. Important factors to consider are summed up in this report. A well set-up monitoring design should include multiple reference sites (spread across space and time) to allow the authorities and the initiator to tease apart natural variability and general trends in decline (e.g. due to climate change) from changes caused by the initiated project.
The proposed framework has not yet been tested with pilot situations or cross-referenced with the legal framework in CN, nor has it been evaluated with stakeholders. It is highly recommended to evaluate this framework by applying it to pilot or actual cases, and to adapt were necessary.