Species diversity and abundance of mobile crustaceans associated with living and dead colonies of the invasive sun coral Tubastraea

The invasive sun corals Tubastraea spp. were introduced to Brazil in the late 1980s. The invasion prompted rapid changes in seascapes and local biological communities by excluding native species, particularly sessile ones. However, little is known about the impact on the mobile invertebrates. Using an experimental approach this study investigated the effects of living and dead sun corals and coral cover (50 vs. 100% covered areas) on the taxonomic composition, diversity (H’) and abundance of reptant and natant macro-crustaceans and tanaids at the species level. Experimental units consisted of 60 tiles measuring 400 cm 2 , half and fully covered with living or dead corals which were deployed between 3 and 5 m for 12 months on concrete blocks. A total of 1346 specimens of decapods were obtained (27 native and 1 invasive species). 1059 specimens of the tanaid Chondrochelia dubia were sampled. The overall taxonomic composition was neither affected by coral condition (live or dead) nor by coral cover area. The diversity of reptant and natant species responded differently to coral condition and coral cover. The combination of dead corals and full cover accounted for the highest abundance of reptants. Natant abundance was influenced by coral cover area, irrespective of coral condition. The positive relationship between body size and abundance was statistically significant. Abundance of the obligate tube builder C. dubia was favoured by the greater availability of space on blocks half covered by corals. No signs were found of invasion meltdown in the mobile crustacean fauna.