Document Type

Technical Report

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Publication Source

Marine Ecology Progress Series



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Competition between corals and benthic algae is prevalent on coral reefs worldwide and has the potential to influence the structure of the reef benthos. Human activities may influence the outcome of these interactions by favoring algae to become the superior competitor, and this type of change in competitive dynamics is a potential mechanism driving coral-algal phase shifts. Here we surveyed the types and outcomes of coral-algal interactions varied across reefs on the different islands. On reefs surrounding inhabited islands, however, turf algae were generally the superior competitors. When corals were broken down by size class, we found that the smallest and the largest coral colonies were the best competitors against algae; the former successfully fought off algae while being completely surrounded, and the latter generally avoided algal overgrowth by growing up above the benthos. Our data suggest that human disruption of the reef ecosystem may lead to a building pattern of competitive disadvantage for corals against encroaching algae, potentially initiating a transition towards algal dominance.

Copyright/Permission Statement

This article is a Feature Article in the publication Marine Ecology Progress Series, meaning that it is published under a Creative Commons Attribution license (CC BY).


At the time of this publication, Dr. Barott was affiliated with San Diego State University, but she is now affiliated with the University of Pennsylvania.


crustose coralline algae, turf algae, macroalgae, coral reef, interaction, Line Islands



Date Posted: 04 October 2017

This document has been peer reviewed.