Effects of a small harbour on nutrient levels and coral reef health in Bonaire, Dutch Caribbean
The creation of harbours through dredging combined with boat maintenance and waste is known to increase nutrients and sedimentation within coastal waters causing the degradation of nearby coral reefs. Winds and currents play a large role in the transportation of nutrients and sediments. This study investigated the distribution of nutrients in water surrounding Harbour Village Marina in Bonaire, Dutch Caribbean, as well as the extent to which the harbour affects adjacent coral reefs. Water samples were collected at increasing distances from the entrance to the harbour and were tested for nutrients. Percent coral cover was estimated using 10 m line-intercept transects. By noting the wind direction and currents when collecting data, it was determined that both the surface and bottom currents flow predominantly north. Results show that current plays a large role in nutrient distribution, but the effects on coral cover are unknown. Coral cover was also much lower north of the harbour in the direction of current flow compared to the south. This study increases the knowledge on nutrient distribution and coral cover as well as the impact harbours have on surrounding reefs. The results can be used for management efforts to help maintain coral reef health, and to keep nutrient levels low during the creation and upkeep of small harbours.