The effect of coral restoration on Caribbean reef fish communities

Abstract

The Caribbean has seen a dramatic loss of coral over the last 30 years due to direct and indirect anthropogenic factors, causing a decrease in reef three-dimensional complexity and fish abundance and diversity. Restoration practices, such as outplanting coral colonies onto degraded reefs, are increasingly used to revive reef ecosystems to preserve fisheries, tourism, and ecosystem functions, which are currently valued at $375 billion globally. However, few studies have examined whether coral restoration and the consequent addition of structural complexity can restore reef ecosystems. Thus, this study aims to better understand early fish community dynamics following restoration using Acropora cervicornis, a major reef building coral and focus species for restoration that has experienced a greater than 80% drop in cover since 1980. To examine fish dynamics after restoration, surveys of fish, environmental conditions, benthic seafloor characteristics, and rugosity were conducted on outplanted plots and control plots without outplants. Surveys were conducted off the north shore of St. Croix, USVI (17°46′15.0″N, 64°49′03.8″W) from May 30, 2016 to August 4, 2016, and on December 28, 2016, and January 4, 2017. Within a week of outplanting, fish abundance was significantly higher in experimental plots compared to controls. After outplanting, there was also an increase in fish species richness and a significant shift in fish community composition over time. These results demonstrate the early stages of fish colonization after outplanting A. cervicornis, providing insight into how restoration can cause rapid change in fish abundance, richness, and community composition.