Puerto Rico’s 1,200 kilometers of coastline is disappearing. Since 2017, there has been an increase in sea levels of 1.65 millimeters in northern regions and 1.35 millimeters in southern regions, averaging around 3 millimeters of annual increments in sea levels. Leaving two thirds of the island’s 3.2 million inhabitants at risk of losing their homes, businesses, and schools. Climate organizations have begun to use Rhizophora mangle as a natural barrier, unfortunately the growth has drastically dropped because of surrounding pollution. To combat this growth stunt, I propose “Nature’s Fertilizer: Sargassum” a natural and sustainable fertilizer initiative to promote the re-population of the species. In collaboration with local climate conservation agencies and volunteers, sargassum will be collected around the coastline, and analyzed, using ICP-MS, for heavy metals that may further stunt the growth of the species. Then they will be sun dried, pulverized, and distributed into 1.5 grams biodegradable bags. Finally, with the help of botanists, they will be dispersed while planting the species along the coastline of Puerto Rico. “Nature’s Fertilizer: Sargassum” is a long-lasting alternative to conserve the Rhizophora mangle that is used to mitigate the effects of erosion in the puertorican coastline.