Factors affecting the distribution and abundance of Tripneustes ventricosus on Kralendijk’s waterfront
Coral reefs are being threatened by both anthropogenic and environmental factors. One prominent factor is the loss of herbivores on coral reefs due to overfishing and disease. Herbivores play a key role in coral reef ecosystems by grazing away competing algae that threaten coral survivorship and recruitment. The loss of Diadema antillarum in the Caribbean due to an unknown pathogen has been detrimental; however, there is another species of sea urchin emerging in the reef environment: Tripneustes ventricosus. Little is known about the environmental factors that influence the abundance and distribution of T. ventricosus in the reef environment. This study seeks to quantify the distribution and abundance of a particular population of T. ventricosus on the back reef found along the waterfront of Kralendijk, Bonaire, Dutch Caribbean. It also examines the effects of benthic composition and competition on the distribution of T. ventricosus. In order to examine these factors, 30-m transects were laid at three different distances from the waterfront wall at five sites. Quadrats were placed at 5-m intervals along each transect. Within each quadrat, algal, benthic, and sea urchin composition was observed and recorded. Water samples were taken from each site to test nitrogen concentration. The diversity and abundance of algae and substrate type appear to be factors influencing T. ventricosus’ distribution and abundance; competition did not appear to be a factor. The area of the abundance of T. ventricosus seems to have ideal conditions for T. ventricosus, and many other urchins, including D. antillarum, that were observed at this site indicating that it may be an ideal place for sea urchins in general.