Aspects of the population dynamics of the gastropod Neritina virginea in estuarine region of Rio Grande do Norte, Brazil

Abstract

The gastropod Neritina virginea (Linnaeus, 1758) is abundant in the northeastern coast of Brazil, and despite its high frequency there are few studies on its population ecology. In this context, the objectives of this paper were to determine the distribution pattern, density and age structure of this species, relating them to the salinity and water temperature, sediment grain size and biomass of Ruppia maritima. Monthly for 13 months (May/2007 to May/2008) in the estuary of the River Apodi/Mossoró (RN), transects of 180 m perpendicular to the beach were carried out, and collected shellfish, plant biomass and sediment. Monthly values of temperature, salinity and rainfall were measured. Neritina virginea showed an aggregated pattern of spatial distribution and a high density compared to other species that inhabit the region, such as shellfish Anomalocardia brasiliana. The highest mean density of N. virginea was 7,310 individuals m^-2 in May/2008. The lowest density was observed in December 2007 (765 individuals m^-2). The density values of N. virginea and salinity were negatively correlated. However, no correlation was observed between density of N. virginea and temperature and grain size of the sediment. The density of N. virginea was positively correlated with biomass of R. maritima, being more abundant in areas with the presence of this plant. In the months from February to June, the smaller individuals were more frequent. This period can be considered the main recruitment season of N. virginea in the region.