In a healthy reef ecosystem, accretion rates are higher than erosion rates. When organisms that maintain the reef as primary eroders spike in population, such as urchins, they can have a negative effect on the health of the reef. For this project, Taryn examined the bioerosion effects and excrement matter of two urchin species, Tripneustes gratilla (collector urchin) and Echinometra mathaei (burrowing urchin), to discover how much these species are consuming from and affecting the reefs in the Hawaiian Islands.