Resilience in carbonate production despite three coral bleaching events in 5\xa0years on an inshore patch reef in the Florida Keys

Derek P Manzello,Ian C Enochs,Lauren Valentino,Graham Kolodziej,Renée Carlton

doi:10.1007/s00227-018-3354-7

Abstract

The persistence of coral reef frameworks requires that calcium carbonate (CaCO3) production by corals and other calcifiers outpaces CaCO3 loss via physical, chemical, and biological erosion. Coral bleaching causes declines in CaCO3 production, but this varies with bleaching severity and the species impacted. We conducted census-based CaCO3 budget surveys using the established ReefBudget approach at Cheeca Rocks, an inshore patch reef in the Florida Keys, annually from 2012 to 2016. This site experienced warm-water bleaching in 2011, 2014, and 2015. In 2017, we obtained cores of the dominant calcifying coral at this site, Orbicella faveolata, to understand how calcification rates were impacted by bleaching and how they affected the reef-wide CaCO3 budget. Bleaching depressed O. faveolata growth and the decline of this one species led to an overestimation of mean (± std. error) reef-wide CaCO3 production by + 0.68 (± 0.167) to + 1.11 (± 0.236) kg m−2 year−1 when using the static ReefBudget coral growth inputs. During non-bleaching years, the ReefBudget inputs slightly underestimated gross production by − 0.10 (± 0.022) to − 0.43 (± 0.100) kg m−2 year−1. Carbonate production declined after the first year of back-to-back bleaching in 2014, but then increased after 2015 to values greater than the initial surveys in 2012. Cheeca Rocks is an outlier in the Caribbean and Florida Keys in terms of coral cover, carbonate production, and abundance of O. faveolata, which is threatened under the Endangered Species Act. Given the resilience of this site to repeated bleaching events, it may deserve special management attention.

Highlights

Much of the ecosystem function of coral reefs is directly linked to their three-dimensional structure (Enochs and Manzello 2012; Graham and Nash 2012)
The extension rates of O. faveolata were significantly impacted by warm-water bleaching in 2011, 2014, and 2015 (Fig. 3, Tables 1, 2)
degree heating weeks (DHWs) are a measure of the magnitude and duration of sea temperatures ≥ 1 °C above the maximum monthly mean temperature and are the most often used metric of thermal stress for coral reefs (Liu et al 2006)

Summary

Introduction

Much of the ecosystem function of coral reefs is directly linked to their three-dimensional structure (Enochs and Manzello 2012; Graham and Nash 2012). Calcium carbonate (CaCO3) production by corals and other calcifiers (e.g. crustose coralline algae, Halimeda, bryozoans, etc.) must. Exceed CaCO3 loss due to physical, chemical, and biological erosion for coral reef frameworks to persist (Glynn and Manzello 2015). Climate change and ocean acidification (OA) will reduce the production of C aCO3 by corals via mortality from bleaching, as well as depressed coral calcification from sub-lethal thermal stress and decreasing carbonate saturation state (Glynn 1988; Chan and Connolly 2013; Cantin and Lough 2014; Perry and Morgan 2017). Experimental studies suggest that OA will accelerate coral reef bioerosion and dissolution, possibly leading to net erosion and/or dissolution of reefs globally by the end of the century (Tribollet et al 2009; Wisshak et al 2012; ReyesNivia et al 2013; Silbiger et al 2014; Enochs et al 2015, 2016a; Eyre et al 2018)

Methods

Results

Conclusion