In the 1970s, black band disease (BBD) emerged as a mass coral killer and caught the attention of scientists. Although BBD has been studied for more than thirty years, it continues to confound scientists due to the complexity and composition of the bacterial mat which varies among BBD cases. In previous studies, BBD was found in correlation with small environmental changes. Because the distribution of BBD has not been previously documented for Bonaire, I studied its distribution and measured environmental parameters (depth, temperature, pH, phosphate and nitrogen) at six sites. I also recorded the number of BBD incidents on 3 replicate transects, each 10 m 2 in area and 10 m apart at both 15 and 30 feet. BBD was found at Andrea II (both depths), Angel City (both depths) and Jeannie’s Glory (15 ft), but not at Karpata, Captain Don’s, or Yellow Submarine. Informal surveys at other dive sites on Bonaire and Klein Bonaire showed BBD cases at Monk’s Haven, Monte’s Divi, and Handsoff reef, but it was not present at Boca Bartol or Nukove. Most BBD cases were found shallower than 20 feet. I found no statistically significant differences between environmental parameters and observed BBD cases.
The use of biological entities as indicators of environmental stress can provide links between changes in ecological conditions and ecosystem productivity. Historically, bioindicators have been used as a rapid-assessment tool of areas declining in sustainability for the inhabiting organisms. This study investigated the utility of sessile, filter feeding Christmas tree worms (Spirobranchus giganteus) as bioindicators of the presence of potential coral reef stressors. Christmas tree worm density was compared at low impact sites (> 200 m from a commercial establishment) and high impact sites (< 200 m from a commercial establishment). For each site, four quadrats were randomly placed along a 10 m transect at 6, 12 and 18 m depths to assess percent live coral cover and Christmas tree worm density. These data were compared with potential environmental stressors such as excess nutrients (nitrite, nitrate, ammonia and phosphate), human gut (Enterococcus) bacteria, sedimentation rates, and sediment particle size distributions between high and low impacted sites and among depths. Approximately 97% of the worms inhabited live coral. Live coral cover was similar for 12 and 18 m at both high and low impacted sites (~ 17 % - 20 %) but significantly lower at 6 m depth (~ 2 % - 8 %). Despite the similarity in live coral cover at depth, there were significantly more Christmas tree worms at 12 m of high impact sites. At all other sites and depths, the worms never exceeded ~ 1.5 worms m-2. At 12 m, water chemistry analyses did not show any differences between site impact except for phosphate, with significantly greater concentrations at high impact sites. Bacterial loads, sedimentation rate and particle size distributions did not show any differences between site impact although there were finer sediments at high impact sites and coarser sediments at low impact sites. S. giganteus may be found at high densities at high impact sites due to a greater availability of food acquired through filter-feeding biota. Therefore, they may be used as novel indicators of the presence of environmental stressors, such as excess nutrients and finer sediments, in Caribbean coral reef systems.
The lunar cycle is a key environmental factor influencing the feeding, reproduction, and migration of many marine organisms, including fish, invertebrates, and zooplankton. To investigate the influence of lunar stage on zooplankton density and diversity in Bonaire, Netherlands Antilles, samples of zooplankton were collected from surface waters at midday and at night at each stage of a complete lunar cycle. The purpose of this research was to determine 1) whether zooplankton in surface waters are more abundant during the night or day, 2) during which stage in the lunar cycle zooplankton densities are the highest, 3) whether diel period has an effect on the biodiversity of plankton, and 4) whether lunar stage has a effect on biodiversity of zooplankton. It was found that microzooplankton and macrozooplankton occurred in higher densities at night. The highest microzooplankton density occurred during the waning gibbous phase and the highest macrozooplankton density occurred during the first quarter (289.7 individuals m-3, 28.4 individuals m-3, respectively). Organisms from the classes maxillopoda, malacostraca, and chaetognatha were most prevalent in all samples. The full moon showed both the greatest and least taxonomic diversity among samples with 19 different classes (avg. 13.4) found during the nighttime sample and 7 appearing during the midday sample. Due to an abundance of eggs during the waning gibbous lunar stage it is suggested that lunar spawning has an impact on plankton density and composition.
In augustus 2011 is er op Bonaire onderzoek gedaan naar de manier waarop de exploitatie van een rioolstelsel en een rioolwaterzuiveringsinstallatie op een verantwoorde manier kan plaatsvinden. Dit onderzoek is door de Stichting ABC Advies uitgevoerd op verzoek van USONA, die ter plaatse dit project begeleidt en de financiering ervan bewaakt namens de EU. Het onderzoek is uitgevoerd door lezing van een groot aantal publicaties van verschillende aard. Voor zover deze van belang zijn, zijn deze genoemd in dit rapport. Naast lezing van documenten is het bezoek ter plaatse en de diverse gesprekken met direct verantwoordelijken zoals bestuurders, medewerkers van USONA en anderen betrokkenen van grote waarde voor de beeldvorming van de onderzoeker geweest. In de bijlagen bij dit rapport is een lijst van gevoerde gesprekken opgenomen1 . De kern van de onderzoeksuitkomst is dat het hebben van een rioolstelsel en een zuivering voor Bonaire van onschatbare waarde is, maar dat door het Openbaar Lichaam Bonaire nog veel keuzes moeten worden gemaakt alvorens een heffingenstelsel operationeel is. In het rapport worden daarvoor enkele richtinggevende mogelijkheden geschetst. De bijkomende problematiek van een tijdelijke afvalwaterzuivering die een nogal permanent karakter heeft gekregen is complicerend, ook voor de dekking van de exploitatielasten, maar maakt geen onderdeel uit van de onderzoeksvraag. Dit geldt eveneens voor het vraagstuk van het beheer van de zuivering. Ook dat onderwerp, hoewel het zeker raakvlakken heeft met de exploitatiekosten en dus ook het tarief, kan –vanwege de onzekerheid over de uitkomst van dit vraagstuk- geen onderdeel uitmaken van dit rapport. Bij dit rapport is een opzet gemaakt voor een kostenoverzicht van de jaarlijkse exploitatielasten van het ‘Bonaire Sewerage and Sanitation Project’. De onderzoeksperiode van ruim 1 week is niet voldoende om deze cijfers ook zonder nader onderzoek en overleg met (technisch en financieel) ter plaatse deskundigen over te nemen. De opzet biedt naar de mening van onderzoeker wel een aanzienlijk beter inzicht dan tot nu voorhanden was. Vanaf het moment dat het Bestuurscollege en de Eilandraad enkele, in deze rapportage genoemde, keuzes hebben gemaakt is het (nog) verder uitwerken van de exploitatiebegroting en het tarievenstelsel aan de orde. Ook kan dan de benodigde regelgeving worden opgesteld. Het zou, vanwege het grote belang dat met het slagen van dit project is gemoeid, naar de mening van onderzoeker een goede vervolgstap zijn dat de uitkomsten van deze rapportage met direct betrokkenen op het Bonaire worden besproken. Daarbij wordt gedacht aan de DROB, het hoofd financiën en andere betrokkenen. Indien nodig kan dan verfijning plaatsvinden.
The endangered Lesser Antillean Iguana, Iguana delicatissima, is an emblematic species for the island of St. Eustatius and in Caribbean Netherlands it is only found on St. Eustatius. In this study we conducted an extensive population survey for the iguana and compared densities in different areas to densities documented most recently in 2004. We conducted 39 field surveys and spent a total of 80 hours and 21 minutes searching for iguanas. We covered 63,672 m of trails and tracks and found only 22 iguanas. An overall average of 3.70 hours were searched for each iguana found. Due to the low encounter rates, detailed estimation and comparison of population densities remain problematic. Overall population density was 0.35 iguanas per hectare which represents 0.5-1% of densities documented elsewhere in healthy populations. Current population densities have declined across all habitats since the 2004 survey. Iguana encounter rates and densities in natural habitat were highest for the region where the northern hills abut onto the central plain. Island-wide, those areas provide the best combination of sun, shelter, food and potential for nesting sites. The population of the Lower Town sector, indicated in 2004 as the most dense and promising subpopulation, has all but disappeared. Island-wide, the residential estate subdivisions remains the second-most important area for the iguana.
We conclude that even though several valuable conservation measures are in place (e.g. establishment of legally protected parks, designation as a legally protected species and a successfully-run awareness campaign), the status of the iguana has not improved significantly in the last 8 years. Our results show that compared to 2004 when the population was estimated to number 425 (275-650) animals, current population size certainly lies on the low side of this range. This is far below the required minimum viable population size of 5000 animals and means that the iguana is critically endangered on St. Eustatius. It is readily vulnerable to extirpation on the island. Human hunting is likely a minor problem, shelter and food availability on the island are abundant, and invasive predator densities in the wild are relatively low. Of the 28 documented instances of death or endangerment of iguanas during the study period, most were attributable to anthropogenic causes. Suitable nesting sites for the iguana appear very limited, especially due to a combination of geology and vegetation. Therefore, lack of nesting sites and high iguana mortalities due to anthropogenic causes are suggested as the two core factors limiting recovery of the iguana on St. Eustatius .
The following management measures are proposed:
1. Protect current populations by:
- Prevention of introduction of invasive species
(Train and equip border officials to prevent potential entry of the mongoose and the Green Iguana from neighbouring islands),
- Enforcement and upgrading of legal protection
(Implement enforcement and upgrade protective legislation),
- Development and protection of additional nesting sites
(Develop and maintain new additional nesting habitat, a measure that is both easy and inexpensive),
- Establishment of an “iguana-friendly yard” programme
(Establish a programme to promote “iguana-friendly” gardens, as the main means of reducing cumulative mortality).
2. Increase the biological knowledge about the iguana by conducting studies for a better knowledge of the critical biological parameters,
3. Create public awareness for the plight of the species,
4. Establish a small, local husbandry project.
(Development of an in situ husbandry and breeding project could serve a pivotal role in bolstering the other core program themes and especially offers a relaxed setting in which islanders can experience the iguana as the gentle and beautiful animal that it is).
This report is part of the Wageningen University BO research program (BO-11-011.05-004) and was financed by the Ministry of Economic Affairs, Agriculture and Innovation (EL&I) under project number 4308701004.
In this report we review and assess possible consequences of climate change for the biodiversity of the Dutch BES islands (Bonaire, Saba and St. Eustatius), and present various options for adaptation. From our review it is quite clear that climate change not only poses a severe threat to the ecosystems of the BES islands, but also to the totality of benefits and services the inhabitants of these islands derive from those ecosystems. Key changes in climate expected this century include increases in air and sea surface temperature, an increase in sea level and ocean acidity, an increase in the frequency and intensity of storms and hurricanes, general aridification and greater overall unpredictability in weather. The consequences for both terrestrial and marine biodiversity are predicted to be far-reaching. The principal effects will likely include further losses to the coral reef systems, erosion of coasts and beaches, salinification of ground water sources, losses in hilltop vegetation and flora, soil humus losses and erosion, increases in various disease vectors, changes in ocean currents, fish recruitment and migration, and a stronger foothold for invasive species.
The main areas of environmental policy involving the management of biodiversity are those of land-use planning and zoning, forestry and terrestrial conservation, and marine conservation. As for land-use planning and zoning, main issues of concern will be the introduction of the 'set back' policy for coastal development, the preservation of the full range of key habitats, and sufficient habitat surface area to sustain minimum viable populations for native species. In addition these habitats must be ecologically connected to allow free movement of animals across the habitats they need throughout the different seasons of the year and phases of their life cycle. In terms of forestry and terrestrial conservation policy, the focus will especially need to be on solving the problem of uncontrolled grazing of livestock, and the implementation of reforestation and groundwater conservation. Key issues in marine conservation policy will be to tackle the technically and financially challenging problem of eutrophication and the socially controversial limits to the harvest of reef organisms.
While it is the large industrialized countries that drive man-induced climate change, it is the small island developing states (SIDS) and small coastal states that will suffer the most from climate change. In this respect it may be especially valuable for the BES islands to develop and participate in larger efforts to convince (pressure, lobby) the large industrialized nations to adopt those changes needed in their industrial and energy policies by which to avert the most disastrous scales of global climate change. As the stakes are obviously very high, the BES islands should seek to actively develop and/or participate in such efforts. However, to do this credibly and convincingly will require the islands to develop their own vision and policy and to implement important measures of their own. While the topic of climate change has recently come to the attention of government, preparation and readiness for climate change lags behind.
The main options for local adaptation measures as outlined all come down to just one principle: to 'manage for resilience' of the ecosystems as much as possible by reducing the stress induced by local anthropogenic pressures. This will require proper data and knowledge as well as a proper monitoring of impacts and results. In this, investment in baseline inventories, dedicated research and a monitoring system is essential.
If international resolve falters and precipitous global climatic change cannot ultimately be avoided, large ecological regime shifts may cause ecosystems and species in any given area to become ecologically untenable, and introduced species to become firmly established and impossible to eradicate. If so, it will be important to make hard choices and not waste valuable time and resources fighting lost causes. Therefore, in the future successful management of natural resources will often require managers and decisions makers to think differently than in the past, to abandon old paradigms and objectives, and to focus more on general ecosystem services than on specific details. Hence our ability and willingness to adaptively 'manage for change' will be critical, as will be the need for effective decision making under conditions of complexity, uncertainty and imperfect knowledge.