Dictyota defense: Developing effective chemical protection against intense fish predation for outplanted massive corals.

The incorporation of coral species with massive (., boulder, brain) morphologies into reef restoration is critical to sustain biodiversity and increase coral cover on degraded reef ecosystems. However, fragments and colonies of massive corals outplanted in Miami-Dade County, Florida, US, can experience intense predation by fish within the first week of outplanting, resulting in >70% mortality. Here, we tested for the first time the potential benefit of feeding corals powdered , a brown reef alga that is chemically defended against grazing, to determine if exposure to can confer chemical protection to coral fragments and reduce the impacts of fish predation after outplanting. We found that feeding corals every 2 to 3 days for 2 months with dried and powdered prior to outplanting significantly reduced predation levels on and fragments (with less than 20% of the fragments experiencing predation up to 1-month post-outplanting). We also found that a single exposure to at a high concentration 1 to 2 days prior to outplanting significantly reduced predation for six coral species within the first 24 h following outplanting. Thus, feeding corals dry prior to outplanting appears to confer protection from fish predation during the critical first days to weeks after outplanting when predation impacts are commonly high. This simple and cheap method can be easily scaled up for corals kept prior to outplanting, resulting in an increase in restoration efficiency for massive corals in areas with high fish predation.