Differences in nematode descriptors and functional attributes among typologies (fixed factor: closed, ICOLL and open), lagoon (random factor: 5 closed, 5 open and 5 ICOLL, nested in typology) and location (random factor: inner and outer, nested in lagoons and nested in typology) were tested with a permutational analysis of variance (PERMANOVA) run on Euclidean distance matrices with 9999 permutations, and the residuals were permuted under a reduced model . To visualize the similarity of the meiofauna composition among different lagoon typologies and location within lagoons, similarity matrices were constructed based on the Bray-Curtis similarity measure. Ordination was done by nMDS, and significance tests for differences in the multivariate structure of nematode assemblages performed using PERMANOVA . The variation in species composition of nematode assemblages (beta diversity) was decomposed into replacement and richness difference using abundance data dissimilarities and the Sorensen index . These analyses were performed using the R software . Total β-diversity and decomposed replacement and richness differences were analyzed using PERMANOVA tests with the same design described above. The decomposition of beta diversity can be done by two methods, the “POD” and “BAS” . Although both indices may not show congruent patterns , in the present study they showed agreement for total dissimilarity and replacement. For richness, the BAS method returned negative sums of squares for the factor typology, while the POD did not (see Results).