Ecological and zoogeographical study of some mediterranean associations of brackish water harpacticoids

Abundance data of harpacticoid species collected during meio- faunistic surveys in five Italian brackish environments have been analyzed. Comparisons among lagoon species assemblages were subjected to classification and ordination procedures. Additional lists of harpacticoid species from Mediterranean and Pontic brackish lagoons were assembled from the literature and further comparisons were made among the ten harpacticoid associations on the basis of binary presence-absence data. On a limited distance scale, e.g. the case of the five Italian lagoons, ecological factors, such as the sheltering degree and the extension of the phytal habitat, probably play a predominant role in structuring faunistic associations. On a larger distance scale, e.g. the case of the ten Mediterranean and Pontic lagoons, distributional patterns seem to be more related to zoogeographical factors. Late Quaternary eustatic events are invoked to explain the zoogeographical affinities among Pontic and Adriatic brac...