Experimental evaluation of the effects of management of invasive corals on native communities.
The corals Tubastraea coccinea Lesson, 1829 and T. tagusensis Wells, 1982 have invaded coral reefs and tropical rocky shores in the Southwest Atlantic. In Brazil, they cause change in native populations, communities and ecosystem functions. The aims of this study were to (1) examine community-level change on shallow subtidal tropical rocky shore benthic communities due to the invasion, (2) test how the native community responded to different frequencies of experimental removal, and (3) provide information useful for setting control targets and validating ongoing management for recovery. Communities in invaded areas were experimentally manipulated (treatments: single removal of invasives, multiple removal of invasives, single removal of the entire benthic community) and community cover, as well as invader density, were compared to control areas without removal during 1 yr. Settlement/recruitment of Tubastraea spp. occurred throughout the year in removal areas and was much higher than in controls. Manual removal was highly effective in reducing coral cover and enhanced the cover of native species, especially macroalgae cover, which increased about 83%. The biological invasion of Tubastraea spp. creates an alternative stable community state but the manual removal of Tubastraea spp. provides significant long term (>1 yr) recovery in native community structure and the return of some impacted functions (e.g. primary productivity) to levels similar to pre-invasion. Single or repeated manual removal had the advantage of maintaining native species intact and enhanced biotic resistance compared to total community removal. These conclusions support the ongoing programs of manual removal of invasive Tubastraea spp. as a control and ecosystem recovery strategy.