Traditional datu cactus (Ritterocereus griseus) fences reduce run-off rates and transport of sediment and nutrients on hillsides in Bonaire, Dutch Caribbean
Most reef building corals require seawater with low nutrients and sediment loads to thrive. On coral reefs around the world, increases in run-off and its constituent pollutants are damaging and killing reef building corals due to poor coastal zone management practices. In the marine environment, mangroves provide protection for coral reefs by filtering sediments and absorbing nutrients from run-off. On Bonaire, Ritterocereus griseus, a common cactus species, has the potential to act as a natural filter, analogous to mangroves in the marine environment, on hillsides where run-off is problematic. This research sought to determine the amounts of run-off, phosphate and sediment transported down-slope of plots with cactus fences and plots without fences. Experimental plots with cactus fence were compared to plots without cacti by utilizing simulated rainfall and catching the run-off to measure the difference in volume, phosphate and sediment loads between plots. This study determined that R. griseus reduces the volume of run-off and the amount of sediment and nutrients transported down-slope. The use of cactus fences could increase the resilience on Bonaire's reefs by decreasing sediment and nutrient inputs to near shore waters and are a sustainable resource on the small island.