“…On the one hand, the grapsid crab Neohelice granulata is one of the most abundant macroinvertebrates of intertidal areas of the SW Atlantic estuaries where it commonly inhabits the upper vegetated area (marshes) but uses the entire intertidal zone (Alvarez et al, 2013; Angeletti & Cervellini, 2015; Angeletti, Lescano, & Cervellini, 2014; Spivak, Anger, Luppi, Bas, & Ismael, 1994). This burrowing crab could exert a strong pressure on Heleobia australis since it can drastically reduce snail density in vegetated areas due to an intense bioturbation activity (Alvarez et al, 2013; Angeletti & Cervellini, 2015; Angeletti et al, 2014; Spivak et al, 1994) and/or through snail predation (Barutot, D’Incao, & Fonseca, 2011; D’Incao, Silva, Ruffino, & Braga, 1990). On the other hand, parasite pressure also differs along the intertidal zone.…”