Recurrent Disturbances and the Degradation of Hard Coral Communities in Taiwan

Chao-Yang Kuo,Yang-Chi Chang,Yeong Shyan Yuen,Pi-Jen Liu,Ping-Ho Ho,Chaolun Allen Chen,Tung-Yung Fan,Chang-Feng Dai,Hsing-Juh Lin,Jih-Terng Wang,Andrew Hamilton Baird,Pei-Jie Meng

doi:10.1371/journal.pone.0044364

Abstract

Recurrent disturbances can have a critical effect on the structure and function of coral reef communities. In this study, long-term changes were examined in the hard coral community at Wanlitung, in southern Taiwan, between 1985 and 2010. In this 26 year interval, the reef has experienced repeated disturbances that include six typhoons and two coral-bleaching events. The frequency of disturbance has meant that species susceptible to disturbance, such as those in the genus Acropora and Montipora have almost disappeared from the reef. Indeed, almost all hard coral species have declined in abundance, with the result that total hard coral cover in 2010 (17.7%) was less than half what it was in 1985 (47.5%). In addition, macro-algal cover has increased from 11.3% in 2003 to 28.5% in 2010. The frequency of disturbance combined with possible chronic influence of a growing human population mean that a diverse reef assemblage is unlikely to persist on this reef into the future.

Highlights

Coral reefs are declining rapidly on a global scale due to natural and anthropogenic disturbances [1,2,3,4,5]
Recurrent disturbances to the coral reef at Wanlitung have resulted in a degraded coral community in which most taxa, in particular, the structurally important Acropora, are less abundant than in 1987
The reefs of Wanlitung are not resilient, the recent trajectory suggests a phase shift towards a depauperate coral assemblage dominated by macroalgae

Summary

Introduction

Coral reefs are declining rapidly on a global scale due to natural and anthropogenic disturbances [1,2,3,4,5]. Repeated disturbances to reefs in Tahiti have caused a dramatic change in assemblage structure with many species that dominated the reefs in the 1970 s, such as the Acropora, rare or absent despite coral cover remaining relatively constant [15,16]. Multiple disturbances can cause a phase shift [sensu 17] from corals towards a degraded state often dominated by macroalgae [6,11,18,19]. A transect tape was placed perpendicular Species for Corals Total algae to the coast and extended seaward from 3 m depth to the reef edge at 25 m depth. We were interested in whether recurrent disturbance would cause a phase-shift from a coral dominated assemblage to alternative state or whether these reefs might prove resilient

Materials and Methods

Results

Findings

Discussion