Macroalgae Has No Effect on the Severity and Dynamics of Caribbean Yellow Band Disease

Ivana Vu,Robert F Whitehead,Gillian Smelick,Sam Harris,Sarah C Lee,John F Bruno,Ernesto Weil,Steve Vollmer

doi:10.1371/journal.pone.0004514

Abstract

By removing herbivores and promoting increases in macroalgae, overfishing is thought to indirectly cause coral disease and mortality. We performed three field manipulations to test the general hypothesis that overfishing and the subsequent alteration of coral reef trophic dynamics are a cause of coral epizootics. Specifically, we asked whether the presence of macroalgae can influence within- and among-colony spread rates of Caribbean Yellow Band Disease in Montastraea faveolata. Macroalgae were placed next to infected and healthy, adult and small coral colonies to measure effects on disease spread rate, coral growth and coral survival. Surprisingly, the addition of macroalgae did not affect disease severity or coral fitness. Our results indicate that macroalgae have no effect on the severity and dynamics of Caribbean Yellow Band Disease and that fisheries management alone will not mitigate the effects of this important epizootic.

Highlights

Infectious disease outbreaks are a major cause of coral loss and reef degradation
The removal of herbivores has led to substantial increases in benthic macroalgae on some reefs [20], which could facilitate disease outbreaks either by acting as pathogen reservoirs or vectors [21] or by increasing the concentration of Dissolved Organic Carbon (DOC)[22]
The purpose of this study was to test the hypothesis that changes in coral reef trophic dynamics and benthic community structure are a cause of increased coral disease severity

Summary

Introduction

Infectious disease outbreaks are a major cause of coral loss and reef degradation. In the Caribbean, outbreaks of white band disease in the early 1980s nearly extirpated the dominant species Acropora cervicornis and Acropora palmata [1]. There is evidence that nutrient pollution [7,8,9] and anomalously high ocean temperature [10,11,12] can increase within- and amongcolony spread rates of several coral diseases. These and other environmental stressors could increase pathogen virulence and decrease host resistance [13,14,15]. The removal of herbivores has led to substantial increases in benthic macroalgae on some reefs [20], which could facilitate disease outbreaks either by acting as pathogen reservoirs or vectors [21] or by increasing the concentration of Dissolved Organic Carbon (DOC)[22]

Objectives

Methods

Results

Discussion

Conclusion