Variação espaço-temporal e caracterização histomorfológica da gônada do gastrópode Tegula viridula (Gmelin, 1791) (Mollusca: Gastropoda)

Abstract

The present work had as objectives to characterize the spatiotemporal variation of Tegula viridula in the intertidal zone, and to characterize histomorphologically the gonad of the gastropod Tegula viridula. The collections were carried out in the intertidal zone of the sandstone reef of Pacheco beach, Caucaia, Ceará. In order to characterize the spatio-temporal variation, five transects were plotted, in order to sample one point in each zone of the mesolitoral, totaling 15 systematic non-random points by collection. The specimens of Tegula viridula were manually collected and quantified and the environment of each zone was characterized using percentage of macroalgal cover and a qualitative evaluation of the predominant substrate. The density of individuals was estimated by counting the number of individuals per collection point. The high-tide zone presented the lowest percentage of coverage by macroalgae and the proportion of algae in the low-tide zone was similar to the average mid-tide zone, but the Mid-tide zone has a more heterogeneous substrate. In general, over the months, the mean density of individuals increased in the middle and low-tide zone and decreased in the high-tide zone. The Mid-tide zone was the zone with the highest average density, differing significantly from the other zones. The total number of individuals per month increased with the onset of the dry period. To make the histomorphological characterization of the gonad, the Tegula viridula specimens were collected through the active search method and submitted to the histological routine for the preparation of permanent slides, which were analyzed in a photomicroscope of light. The ovulogenesis and spermatogenesis in Tegula viridula follow the established pattern for the group, with only subtle changes, such as the size of the cell types.