With the objective of characterizing the subtidal benthic malacofauna in Laguna Grande del Obispo, monthly samplings were carried out during a year, in 4 stations. For the collection of living biological material, a 0.015m² corer was used at a depth of 1m, while temperature and salinity data were taken. The molluscs were quantified and identified for the determination of the ecological parameters and the Permanova analysis to verify spatial changes in the malacofauna, in addition to a Simper to determine species that characterize seasons and a Cluster to observe group formations. The temperature presented the maximum value during the calm period, and an inverse behavior to salinity. 789 molluscs were collected, the Bivalvia class (19 sp and 461 organisms) and the Gastropoda (18 sp and 462 organisms). Monthly abundance varied between 87 (November) and 12 (September), richness between 11 (December) and 7 sp (July), while E2 presented the maximum value (348 organisms and 20 sp) and the minimum in the E4 (102 organisms and 13 sp), confirming significant differences in the malacofauna between stations (F=2.4071; p=0.0266). Diversity and equity presented similar behaviors, with maximum values in
September (3.01 bits/ind and 0.95) and minimum values in November (1.4 bits/ind and 0.44). Cerithium lutosum,
Chione cancellata and Lampanella minima were the dominant and constant species, evident in the Simper, while 8
groups were formed, according to the characteristics of the species at the end, according to the Cluster. The results
show that the spatial changes could be due to the dynamics of this group and the proximity between the different
environments (Thalassia, corals, mangroves) that could contribute positively in terms of richness and diversity to the
structure of the malacological community.
