Low calcification rate, structural complexity, and calcium carbonate production of Pocillopora corals in a biosphere reserve of the central Mexican Pacific

Abstract

AbstractThe capacity of coral reefs to provide ecosystem services is widely recognized, but this ability depends on continued carbonate production within the coral community. The Islas Marías archipelago (21° 29.5′ N–106° 15′ W) is subject to minimal anthropic pressures. This archipelago serves as a model to study the influence of environmental variables [e.g., sea surface temperature (SST), upwelling periods, El Niño‐Southern Oscillation (ENSO) events, and pH] on the structure of the coral community. The aim of this study was to evaluate the growth parameters, ecological volume, and CaCO3 production of Pocillopora corals, which comprise the dominant genus in the Eastern Tropical Pacific (ETP). During an annual period (2016–2017), 10 colonies were stained with alizarin red and height, major diameter, and minor diameter measurements were recorded. Live coral cover, the annual extension rate (cm/year), skeletal density (g/cm3), the calcification rate (g/cm2 year−1), ecological volume (cm−3), and carbonate production (kg m−2 year−1) were also calculated. The average extension rate (± SD), skeletal density, and the calcification rate were 1.86 ± 0.31 cm/year, 2.28 ± 0.34 g CaCO3 cm−3, and 4.34 ± 1.28 g CaCO3 cm−2 year−1, respectively. The average live coral coverage was 3.19 ± 3.17%, and the relative cover of Pocillopora corals was 65%. Ecological volume increased 140.6 ± 84.28% with respect to the initial volume, and the average production of CaCO3 was 0.46 ± 0.41 kg CaCO3 m−2 year−1. This study shows evidence of low growth rates, low generation of three‐dimensionality, and low CaCO3 production in the study area when compared to other sites in the ETP. These results are relevant because they indicate compromised long‐term maintenance and reef development in Islas Marías, which may result in low reef functionality and compromise the stability of reef‐associated biodiversity and ecosystem services.