Debrot A.O.,Institute for Marine Research and Ecosystem Studies |
van Rijn J.,Van Hall Larenstein University of Applied Sciences |
Bron P.S.,Van Hall Larenstein University of Applied Sciences |
de Leon R.,Stinapa Bonaire
Marine Pollution Bulletin | Year: 2013
Data on beach debris and tar contamination is provided for 21 natural beach sites in Bonaire, Southeastern Caribbean. Transects amounting to a combined length of 991m were sampled March-May 2011 and a total of 8960 debris items were collected. Highest debris and tar contamination were found on the beaches of the windward east-coast of the island where geometric mean debris concentrations (± approx. 70% confidence limits) were 115±58itemsm-1 and 3408±1704gm-1 of beach front. These levels are high compared to data collected almost 20years earlier on the nearby island of Curaçao. Tar contamination levels averaged 223gm-1 on windward beaches. Contamination levels for leeward west-coast beaches were generally two orders of magnitude less than windward beaches. © 2013 Elsevier Ltd.
Slijkerman D.M.E.,Wageningen UR IMARES |
Leon R.D.,Stinapa Bonaire |
Vries P.D.,Wageningen UR IMARES
Marine Pollution Bulletin | Year: 2014
Bonaire is considered to harbor some of the best remaining coral reefs of the Caribbean, but faces multiple pressures including eutrophication. We measured multiple water quality indicators twice annually, from November 2011 to May 2013, at 11 locations at the west coast of Bonaire. This study resulted in 834 data points. DIN concentrations ranged from below quantification to 2.69. μmol/l, phosphate from below quantification to 0.16. μmol/l, and chlorophyll-a from 0.02 to 0.42. μg/l. Several indicators showed signs of eutrophication, with spatial and temporal effects. At southern and urban locations threshold levels of nitrogen were exceeded. This can be a result of brine leaching into sea from salt works and outflow of sewage water. Chlorophyll-a showed an increase in time, and phosphorus seemed to show a similar trend. These eutrophication indicators are likely to exceed threshold levels in near future if the observed trend continues. This is a cause for concern and action. © 2014 Elsevier Ltd.
Simal F.,Stinapa Bonaire |
De Lannoy C.,CARMABI |
Garcia-Smith L.,Wild Conscience |
Doest O.,Veterinary Practice Doest |
And 9 more authors.
Journal of Mammalogy | Year: 2015
Of the 3 species comprising the genus Leptonycteris Miller, L. curasoae has been the least studied with respect to its long-distance flights and potential for seasonal migrations. We studied long-distance movements between islands and between islands and the mainland in the Curaçaoan long-nosed bat. We used mark-recapture with periodic sampling and marking of bats in Aruba, Curaçao, Bonaire, and 1 location (Butare) in Falcón State, on the Venezuelan coastline. Between October 2008 and April 2014, we captured a total of 7,518 individuals at 11 sites (Aruba: n = 1,827, Curaçao: 778, Bonaire: 4,128, and Butare: 785). Between 78.3% and 98.0% of the bats captured at each island and mainland were marked, and the overall percentage of recaptured animals across all sampling sites was 8.31% (n = 529). L. curasoae inhabits the 3 islands year-round. On each island, it roosts in several caves, which can be used alternatively by the same individuals. Despite being a resident species, L. curasoae can perform long-distance oversea flights between islands and between islands and the South American mainland. A total of 11 long-distance flights were recorded (2 Bonaire-Aruba, 4 Bonaire-Curaçao, 1 Curaçao-Bonaire, 1 Bonaire-Venezuela, and 3 Aruba-Venezuela). We propose that populations of this species in Aruba, Curaçao, Bonaire, and Falcón State, Venezuela, exchange individuals, and part of the insular populations migrate seasonally southward as a response to cyclical changes in local resource availability and the yearly reproductive regime. © 2015 American Society of Mammalogists.
Rivera-Milan F.F.,U.S. Fish and Wildlife Service |
Bertuol P.,Stinapa Bonaire |
Simal F.,Stinapa Bonaire |
Rusk B.L.,Grenada Dove Conservation Programme
Condor | Year: 2015
The Grenada Dove (Leptotila wellsi) is critically endangered; its abundance, as estimated by territory mapping, ranges from 68 to 91 calling males (or 136-182 individuals, assuming a census of paired males). However, an accurate census is unlikely in dry and moist forests, unpaired males may be more detectable than paired males, and sex ratio may be male biased. Because methodology can limit the value of monitoring, we used a systematic grid of survey points and distance sampling to estimate abundance (density and population size), accounting for covariates that may influence detection. Time of day was the most important covariate (e.g., individuals were detected at larger distances early than late in the morning). Density was negatively influenced by disturbance level (deforestation) and positively influenced by food abundance and vegetation cover (leguminous trees). None of the covariates caused extreme heterogeneity; and conventional and multiple-covariate analyses generated similar detection and density estimates, which suggests that model selection was of secondary importance for abundance inferences. Detection probability (mean ± SE) was 0.166 ± 0.031 (95% confidence interval [CI]: 0.114-0.242) within 340 m, density was 0.021 ± 0.004 individuals ha-1 (95% CI: 0.014-0.030), and population size was 160 ± 30 individuals (95% CI: 107-229) in 7,621 ha. Although spatial distribution was slightly clumped (dispersion parameter: b∼1.31), we recommend surveying 150 points twice between late July and early August for abundance coefficient of variation (CV) ≤0.15, even if spatial distribution becomes more clumped (e.g., b=2.5). More survey data are needed to better understand spatial and temporal density variation, test hypotheses about survey design (e.g., road bias in density estimation) and Grenada Dove ecology (rainfall, food, cover, and density correlations), and evaluate management actions (predator removal in nesting areas). With <250 Grenada Doves in the survey region, our data highlight the precarious conservation status of this island endemic, and the urgent need for effective management and targeted monitoring. © 2015 Cooper Ornithological Society.