Coral community response to bleaching on a highly disturbed reef.

J R Guest,T C Toh,D Mcdougald,J Low,P D Steinberg,K Tun,C Ng,P A Todd,D Raingeard,K E Ulstrup,L M Chou,J T I Tanzil,B Wilson

doi:10.1038/srep20717

Abstract

While many studies of coral bleaching report on broad, regional scale responses, fewer examine variation in susceptibility among coral taxa and changes in community structure, before, during and after bleaching on individual reefs. Here we report in detail on the response to bleaching by a coral community on a highly disturbed reef site south of mainland Singapore before, during and after a major thermal anomaly in 2010. To estimate the capacity for resistance to thermal stress, we report on: a) overall bleaching severity during and after the event, b) differences in bleaching susceptibility among taxa during the event, and c) changes in coral community structure one year before and after bleaching. Approximately two thirds of colonies bleached, however, post-bleaching recovery was quite rapid and, importantly, coral taxa that are usually highly susceptible were relatively unaffected. Although total coral cover declined, there was no significant change in coral taxonomic community structure before and after bleaching. Several factors may have contributed to the overall high resistance of corals at this site including Symbiodinium affiliation, turbidity and heterotrophy. Our results suggest that, despite experiencing chronic anthropogenic disturbances, turbid shallow reef communities may be remarkably resilient to acute thermal stress.

Highlights

While many studies of coral bleaching report on broad, regional scale responses, fewer examine variation in susceptibility among coral taxa and changes in community structure, before, during and after bleaching on individual reefs
Coral bleaching refers to the paling or whitening of shallow water reef corals that results from the loss of symbiotic dinoflagellate algae or their algal pigments[1]
To further examine the capacity for resistance of Singaporean reefs, here we report on the bleaching responses of corals at a reef site south of mainland Singapore during (June, July) and immediately after (October) the 2010 bleaching event

Summary

Introduction

While many studies of coral bleaching report on broad, regional scale responses, fewer examine variation in susceptibility among coral taxa and changes in community structure, before, during and after bleaching on individual reefs. At the level of the coral assemblage, varies substantially as a consequence of the severity of thermal stress[4], the thermal history of the site e.g.5, local environmental factors that affect irradiance (such as cloud cover and turbidity)6,7,the type and diversity of symbiotic algae present in the coral host tissue[8,9] and the taxonomic community structure of the coral assemblage[10] Of these factors, the role of the symbiont is probably one of the most intensively researched areas in climate change studies of corals, because certain zooxanthellae types are associated with greater thermal tolerance[9]. The taxonomic composition of the coral assemblage is another strong driver of variation in bleaching at a reef scale[10]

Objectives

Methods

Results

Conclusion