Coral Disease Time Series Highlight Size-Dependent Risk and Other Drivers of White Syndrome in a Multi-Species Model

Austin Greene,Scott F Heron,Megan J Donahue,Erick Geiger,Laurie J Raymundo,Jamie M Caldwell

doi:10.3389/fmars.2020.601469

Abstract

Coral diseases contribute to the decline of reef communities, but factors that lead to disease are difficult to detect. In the present study, we develop a multi-species model of colony-scale risk for the class of coral diseases referred to as White Syndromes, investigating the role of current or past conditions, including both environmental stressors and biological drivers at the colony and community scales. Investigating 7 years of coral survey data at five sites in Guam we identify multiple environmental and ecological associations with White Syndrome, including a negative relationship between short-term heat stress and White Syndrome occurrence, and strong evidence of increasing size-dependent White Syndrome risk across coral species. Our findings result in a generalized model used to predict colony-scale White Syndrome risk for multiple species, highlighting the value of long-term monitoring efforts to detect drivers of coral disease.

Highlights

Diseases naturally persist at low prevalence in coral communities, but may emerge into highprevalence, destructive outbreaks over short time periods under conducive conditions
Current understanding of conditions associated with coral disease is largely based on stratified random surveys, which do not track coral communities affected by disease through time, and are unable to observe local stress accumulation in situ (Winston et al, 2019)
Stratified random strategies are useful for the detection of coral disease or host stress responses such as bleaching over large areas but inferences from stratified random surveys are limited by the lack of colonyand transect- scale prior observations that can identify critical drivers that precede disease onset

Summary

Introduction

Diseases naturally persist at low prevalence in coral communities, but may emerge into highprevalence, destructive outbreaks over short time periods under conducive conditions. The history of thermal stress at a site has found widespread use as an indicator of disease risk, but its effect is variable, due in part to the varied response of coral species to heat stress (Heron et al, 2010; Randall et al, 2014; McClanahan et al, 2015). At the colony- or community-scale, fragmentation and sediment stress ( terrigenous sediments) impacting corals both increase prevalence of tissue loss diseases when combined with thermal stress (Brandt et al, 2013)

Methods

Results

Conclusion