Is #2 the number one problem in Bonaire? An examination of fecal contamination and sedimentation from runoff
In this study I assessed the extent of sedimentation and contamination by human enteric bacteria Enterococci on the reefs of Bonaire, Netherlands Antilles as well as the relationship of these factors to the prevalence of coral disease and bleaching. Largely the effects of sedimentation and enteric bacteria from wastewater run-off in Bonaire have been relatively unknown. Because of the lack of wastewater treatment in Bonaire, runoff contamination by sewage and nutrient fluxes is common. Assessment sites for this study were chosen based on the intensity of nearby anthropogenic activity. These sites were defined as “More Impacted” (MI, n=2) and “Less Impacted” (LI, n=2). Water and sediment samples were acquired at 12 m on a weekly basis for the assessment of enterococcal concentration using the Enterolert™ fluorescing substrate system and determination of sediment particle size distributions. In addition, the frequency of coral disease and extent of coral bleaching were assessed using Coral Point Count software on data acquired along two 10 m video transect lines laid at 12m for each site over 4 weeks. Overall sediment particle size analysis yielded statistically significant differences between LI and MI particle size distributions, with more fine grained sediments at MI sites and more coarse grained sediments at LI sites. Finer grains suggest greater human impact. Enteric bacteria were found at several sites over time and their concentrations show a positive correlation between human presence and higher bacteria counts. Bleaching and disease did not show any correlation with sediment particle sizes or presence of enteric bacteria.