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MEPS prepress abstract   -  DOI: https://doi.org/10.3354/meps13643

Gross calcium carbonate production in Eastern Tropical Pacific coral reefs (Gorgona Island, Colombia)

Eliana C. Céspedes-Rodríguez, Edgardo Londoño-Cruz*

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ABSTRACT: The production and accumulation of reef framework carbonate is the positive component of reef development. The main organisms participating in this process are corals and crustose coralline algae (CCA) because their calcareous skeletons combined construct and help to consolidate reef frameworks. We assessed the contribution (i.e., gross production) of corals and CCA to the calcium carbonate budget of the two largest and most developed reefs of Gorgona Island (Pacific coast of Colombia). On each reef zone (back-reef [BR], reef-flat [RP], reef-front [RF], and reef-slope [RS]) of these reefs, we measured substrate rugosity, coral (Pocillopora spp.) and CCA cover, colony density for corals, skeletal density for CCA, and growth rates for the estimation of calcium carbonate (CaCO3) production rates. Pocillopora spp. corals contributed 93.1% of the total carbonate production, while CCA supplied the remaining 6.9%. CaCO3 production was higher at Playa Blanca reef regardless of higher production in the RF of La Azufrada (12.31 kg m-2 yr-1) in comparison to the same zone in Playa Blanca (8.45 kg m-2 yr-1). The reason for this was that the CaCO3 production was higher in all other reef zones of Playa Blanca, although only at the BR these differences were statistically significantly higher (2.25 against 0.29 kg m-2 yr-1 at La Azufrada). The RF contributes the most CaCO3 mainly due to having a high live coral cover and rapid coral growth. Although the contribution of CCA is low, they are key for reef stability. Calcium carbonate production rates reported here (2.86 and 3.80 kg m-2 yr-1 in La Azufrada and Playa Blanca respectively) are within the limits reported for Eastern Tropical Pacific (ETP) reefs and raise hope for the continued existence of coral reefs in an era of increasing threats to this ecosystem.