Natural Disease Resistance in Threatened Staghorn Corals

Steven V. Vollmer,David I. Kline,John F. Bruno

doi:10.1371/journal.pone.0003718

Steven V. Vollmer, David I. Kline + Show 1 more

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https://doi.org/10.1371/journal.pone.0003718

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Abstract

Disease epidemics have caused extensive damage to tropical coral reefs and to the reef-building corals themselves, yet nothing is known about the abilities of the coral host to resist disease infection. Understanding the potential for natural disease resistance in corals is critically important, especially in the Caribbean where the two ecologically dominant shallow-water corals, Acropora cervicornis and A. palmata, have suffered an unprecedented mass die-off due to White Band Disease (WBD), and are now listed as threatened under the US Threatened Species Act and as critically endangered under the IUCN Red List criteria. Here we examine the potential for natural resistance to WBD in the staghorn coral Acropora cervicornis by combining microsatellite genotype information with in situ transmission assays and field monitoring of WBD on tagged genotypes. We show that six percent of staghorn coral genotypes (3 out of 49) are resistant to WBD. This natural resistance to WBD in staghorn corals represents the first evidence of host disease resistance in scleractinian corals and demonstrates that staghorn corals have an innate ability to resist WBD infection. These resistant staghorn coral genotypes may explain why pockets of Acropora have been able to survive the WBD epidemic. Understanding disease resistance in these corals may be the critical link to restoring populations of these once dominant corals throughout their range.

Highlights

Disease epidemics have radically altered tropical coral reefs and are becoming more frequent and extensive because of climate change [1,2,3]
White Band Disease (WBD) transmission was achieved by grafting active fragments of WBD to replicate fragments of each staghorn coral genotype placed on clips in cinderblock common gardens (Fig. 1A)
Data from our in situ transmission experiments and field surveys indicate that roughly six percent of staghorn genotypes (3 out of 49) from Bocas del Toro, Panama are resistant to WBD infection

Summary

Introduction

Disease epidemics have radically altered tropical coral reefs and are becoming more frequent and extensive because of climate change [1,2,3]. Since it was first observed in the late 1970s [8], WBD has caused unprecedented Caribbean-wide declines in its hosts A. cervicornis and A. palmata [7,13,14], with losses of up to 95% of living acroporid cover common across the greater Caribbean [13,15,16] Recovery of these formerly dominant shallow-water corals has been slow [7,17], due in large part to poor larval recruitment [18,19,20], highly restricted larval dispersal [21,22] and a heavy reliance on asexual (i.e. vegetative) propagation [23,24,25]. Both species have recently been listed as threatened on the US Endangered Species Act [26,27] and listed as critically endangered under the International Union for the Conservation of Nature (IUCN) Red List criteria [28]

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