Eleven years of range expansion of two invasive corals (Tubastraea coccinea and Tubastraea tagusensis) through the southwest Atlantic (Brazil)

We report on the temporal and spatial changes in populations of the invasive corals Tubastraea coccinea and Tubastraea tagusensis over an eleven year period at the Ilha Grande Bay, tropical southwest Atlantic. A semi-quantitative method was used to investigate the geographical distribution of the two congeners on subtidal rocky reefs along 350 km of coastline by applying a relative abundance index (RAI) to quantify change. Data were compared among 2000, 2004, 2010 and 2011. The indices showed a transition from rarity to dominance throughout the region as well as range expansion; in contrast at one site, where a pilot management initiative of manual control has been carried out, there was a reduction in abundance over time. Abundance values were compared to distance from possible points of introduction to pinpoint where the initial introduction occurred. The observed relationship between the possible points of entry and abundance of the two Tubastraea species was highly significant for the achorage and oil terminal whereas somewhat less so for the shipyard and port. The data obtained in this study are being used to plan further urgent management actions to control the biological invasion of the two Tubastraea species throughout the region, as well as being applied in modeling the range expansion into other regions.