Distribuição espaço-temporal de Turbinella laevigata, Anton, 1839 (Mollusca: Gastropoda: Turbinellidae), no Banco dos Cajuais, Icapuí, Ceara, Brasil

Abstract

The Turbinelidae family is characterized as a group of marine hot water prosobranch gastropods, being represented by five species in Brazil. Turbinella laevigata is endemic to Brazil, from the state of Amapá to Espírito Santo, occurring in areas between tides ranging to 40 m deep in sandy and muddy bottom areas. Marine animals, among them mollusks, mainly gastropods, are used in various fishing communities as natural medicines, aphrodisiacs, for religious purposes, contributing economically with the sale of shells as souvenirs and also have importance in feeding these communities. As these animals inhabit shallow water and intertidal zones, they are susceptible to overexploitation due to the ease of capture, causing population decline. Due to the lack of studies on the distribution of several species of gastropod molluscs, the present work had as objective to determine the spatial and temporal distribution of Turbinella laevigata in an intertidal zone of the Banco dos Cajuais, in Icapuí, Ceará. A pilot collection was performed to determine an area with a good amount of individuals for sampling, forming a quadrilateral. This area was divided into four subareas in the sea-beach axis, being visited in field visits in order to find specimens of T. laevigata, for marking and determination of measures of length and width of the shell. A predominance of individuals with large shells was found in the area compared to medium shells, with area 4 being the most representative of all, with 29 individuals. Variation between length and shell width of the samples, except for the individuals of area 1, presenting a high coefficient of variation. The mean overall length was 113,5 mm (± 16,9 mm) and the overall mean width was 51,3 mm (± 9,1 mm). The spatial distribution showed an aggregate pattern (p = 0.0284), with greater predominance in area 4, from the central portion to the south. No correlation was found between the density of individuals and rainfall, although a higher density was found in the period with higher rainfall (45 individuals) compared to the less rainy period (40 individuals). The dry period presented the specimens with the highest average length (117.8 ± 8.4 mm) and width (53.5 ± 5.8 mm) of shell. The data in the present study are a contribution to ecological data that are still scarce regarding T. laevigata, and can be used to help in the management of the species, avoiding future losses.