Pagurized gastropod shells in a northeast brazilian coastal lagoon at the sea-estuary interface

Gastropods are known for the presence of calcareous shells, even after their death. The diversity of this resource can be reflected in the local diversity of living gastropods. These shells are used by hermit crabs as protection and against desiccation. Coastal lagoons are biodiversity hotspots and the site of recruitment of continent-sea connectivity, and their diversity is sometimes altered by connectivity events with adjacent areas. Therefore, we sought to make a list that evaluates the seasonal variation of diversity and demonstrates the pattern of shell use by hermit crab species. The samplings were standardized in six monthly repeated transects from February 2013 to January 2014, using a fishing net trawl. The shells were identified to species level and quantified. Diversity indexes were calculated, seasonally, for the assemblage of used shells. Hermit crabs used 14 species of gastropod shells, of which Vitta virginea and Phrontis vibex were the most abundant and frequent. The diversity indexes indicated a temporal variation of the shells, with April the month showing the highest difference in diversity. A reflection of the change in surface geomorphology, caused by the King Tide, it’s discharge and carrying of empty gastropod shells to the open sea. The usage patterns of these biogenic remains can reveal strategies of decreased intra/interspecific competition. Furthermore, we described the first record in the Brazilian Northeast of the hermit crab C. symmetricus, after its taxonomic resurgence.