Estruturação das comunidades bentônicas, fauna associada e potencial anti-incrustante dos corais invasores Tubastraea spp. (Cnidaria: Dendrophylliidae) em Arraial do Cabo, Brasil

Abstract

Marine bioinvasions are a threat to coastal ecosystems, as invasive species can alter the composition and dynamics of invaded communities. However, interactions between exotic and native species are complex and there is great difficulty in estimating the real impacts of invasive species on native communities. The expansion of areas of occurrence and abundance of invasive corals Tubastraea spp. for the Brazilian coast has caused great concern due to putting marine biodiversity at risk. In the present study, we addressed the interaction of Tubastraea spp. with the invaded communities of Baía do Arraial do Cabo (BAC), Rio de Janeiro, and investigated its antifouling potential. Thus, the colonization of Tubastraea spp. was (1) monitored in the field the its influence on the benthic community over five years in areas with Low (BI) and High (AI) infestation of this invasive coral; (2) characterized the macrobenthics associated with colonies of Tubastraea coccinea and Tubastraea sp. and; (3) evaluated the space-time variation in the antifouling potential of crude extracts of T. coccinea against marine micro and macrofoulings. The abundance of Tubastraea spp. in invaded communities was very low compared to native species and, as well as the composition and abundance of benthic organisms, in general, did not vary significantly over the five years of the experiment or between areas with BI and AI. The indices of richness, diversity and evenness of benthic species or did not show differences between sampling times and between areas with BI and AI, or were higher in the area with AI and over time. Five phyla associated with Tubastraea spp. were recorded: Annelida, Mollusca, Arthopoda, Echinodermata and Platyhelminthes. Tubastraea coccinea showed higher species abundance, richness and diversity compared to Tubastraea sp.. Most associated macrobenthic organisms were endobionts. Overall, a greater abundance and richness of native taxa associated with Tubastraea spp. was recorded. A facilitation process was identified between Tubastraea spp. with the exotic mussel Leiosolenus aristatus. Crude extracts of T. coccinea showed anti-fouling action against micro-fouling, inhibiting the growth of biofilm-forming bacteria, but showed no significant effect against the macro-fouling, the mussel Perna perna. Space-time variation was detected in the antifouling activity of T. coccinea extracts. There was no inhibition pattern in the extracts of T. coccinea colonies collected on four rocky shores. However, in extracts from collections of T. coccinea in three different sampling periods, there was better antifouling activity for April and August, to the detriment of December.