Bioerosion of Rocky Carbonate Coastlines on Andros Island, Bahamas

Thomas F. Donn, Mark R. Boardman

Abstract


Erosion of rocky carbonate coastlines has been measured and described at intertidal and supratidal locations on Andros Island, Bahamas. Rates of intertidal erosion vary from 1.8 to 2.6 m/1000 years. Supratidal erosion is measured at 0.4 m/1000 years. Intertidal erosion creates terraces and nips which lie near low-tide level. The width of the terraces, combined with the erosion rates, suggests that sea level has been within 0.5 meters of present level for the past 1400 to 3700 years. Degradation of this coastline results in coastal retreat and an annual sediment production of 2.98 kg/m2 which accounts for less than 1 percent of the nearby lagoon sediment. Erosion occurs in an irregular pattern with no preferential lowering of pinnacles or pits. The activity of organisms (endolithic algae, chitons, snails, limpets, barnacles and sponges) is sufficient to account for the majority of the erosion.


Keywords


Bioerosion; sea level; karst; limestone weathering; coastal erosion; Andros Island; Bahamas

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