The following dendrogram presents species assemblages based on depth. The cluster analysis shows a series of seven well-structured clusters. The first two clusters, at 0-50 m of depth, occur in the surface layer. The third cluster, at 50-100 m, corresponds fairly closely to the cold intermediate layer. The deep layer contains four clusters: the fourth and fifth (upper and lower slopes respectively), and the fifth and sixth (bathyal clusters). The sixth cluster is found in the maritime estuary and the Gulf, while the seventh is only found in the Gulf. The apparent dissimilarity between the deepest layers (> 500 m) can be attributed to the low sample size at these depths.