Erosive activities of chitons at Aldabra Atoll

Chitons, common on tropical limestone shores, use magnetite-capped radula teeth to scrape algae from upon and within the substrate, and at the same time remove quantities of rock debris. A quantitative estimate of the erosive activities of intertidal chitons at Aldabra Atoll shows that 0.023 g/day of rock debris are defecated by each chiton, which amounts to 40.20 g/m ² /yr/chiton. This accounts for a 0.017 mm/m ² /yr rate oF erosion of the rock surface, which is about 3.4% of the total erosion. Chitons, although effective agents at rock removal, are insufficiently abundant to be a major cause of intertidal erosion at Aldabra.