Traditional datu cactus (Ritterocereus griseus) fences reduce runoff rates and transport of sediment and nutrients on hillsides in Bonaire, N.A.

Most hard corals require seawater with low nutrients and sediment loads to thrive. Unfortunately, on a global scale, increases in both are currently occurring due to poor coastal zone management practices. This causes damage that is often fatal to reef building corals. Plants living in near shore areas provide natural filters for sediments and nutrients, and recently managers have been harnessing the filtering capabilities of plants to protect aquatic ecosystems. In the marine environment, mangroves provide protection by filtering sediments and absorbing nutrients from runoff before it reaches coral reefs. Ritterocereus griseus, a common cactus species on Bonaire, N.A., has similar capabilities in the terrestrial realm. The following hypotheses were tested regarding cactus fences in Bonaire: smaller amounts of phosphate and sediments would be transported, and lower amounts of runoff would be collected down-slope of plots with cactus fences than plots without cactus fences. Experimental plots with cactus fences were compared to control plots without cacti. To construct plots, steel guides were used to direct simulated rainfall across plots with and without cactus fences into a collection cup at the base of the set-up. This study determined that R. griseus reduces the volumes of runoff 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.

This student research was retrieved from Physis: Journal of Marine Science VI (Fall 2009)19: 20-26 from CIEE Bonaire.

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