Influence of the invasive bivalve Isognomon bicolor on the native community found in northeast Brazilian coast

The Caribbean bivalve Isognomon bicolor (C. B. Adams, 1845) is currently among the main invasive species along the Brazilian coast. The present study evaluated the co-occurrence, influence, and relationship of the native macrobenthic community with I. bicolor. The study was performed on samples collected from two sandstone reefs located in Northeast Brazil. We observed that the macrobenthic community differed significantly across reefs, zones, and seasons. The higher density of I. bicolor in the lower intertidal zone (347.7 ind/m² ± 800.8) was one of the main differentiation factors of zonation. The results indicated that the evenness of the community and some gastropods had a negative effect on I. bicolor. We found a negative correlation between the co-occurrence of I. bicolor with the macroalgae Hypnea sp. and Gracilaria caudata J. Agardh 1852 and the microgastropod Eulithidium affine (C. B. Adams, 1850). This study provides data on the relationship between I. bicolor and the native community of sandstone reefs, which could be applied to monitor the expansion of I. bicolor to the Northeast region of Brazil.