Population structure of the invasive bivalve isognomon bicolor (C.B. Adams, 1845) on rocky beaches in northeastern Brazil
Estrutura populacional da bivalve invasora isognomon bicolor (C.B. Adams, 1845) nas praias rochosas do nordeste do Brasil
Keywords:marine bioinvasion, population structure, rocky shores
The invasive bivalve Isognomon bicolor is native to the Caribbean and had its first record for the Brazilian coast published in 2002. The objective of this study was to compare the population structure of I. bicolor in two rocky beaches of the coast of Paraíba and verify its temporal variation. Six samples (20 x 20 square cm) were collected on each beach, three in the dry season and three in the rainy season and at two levels of the mid-coastal zone (Bottom and High). Nine samples were obtained for each beach per month, totaling 108 samples. 2,196 specimens of I. bicolor were collected and measured. The highest densities occurred at Carapibus beach. Considering the size structure, there was a significant difference in the length of the nacreous layer between beaches, mid-littoral zones and seasons, with most recruits and smaller individuals occurring on Jacumã beach.