Diversity, distribution and ecology of the family Syllidae (Annelida) in the Portuguese coast (Western Iberian Peninsula)

Abstract

The diversity, distribution and ecology of the family Syllidae along the Western Iberian coast was studied, based on 145 sediment samples covering the whole Portuguese coastal shelf and 30 Saccorhiza polyschides holdfasts sampled in the north of Portugal. A total of 55 species were identified in 2,306 specimens. A total of 33 species were recorded in the holdfasts and 36 in the shelf samples spanning a wide range of sediments, bathymetry and latitude. A total of 14 species were shared between both substrates. A total of 26 species were here firstly recorded, increasing to 80 the number of species known in Portugal, and new insights were added to the ecology and geographic distribution of several species. A multivariate analysis identified three assemblages, characterized by the species (a) Sphaerosyllis bulbosa and Syllis pontxioi in the western shelf coarse sediments, (b) Parapionosyllis brevicirra and Syllis mercedesae in the southern shelf muddy sands and (c) Brania pusilla and Myrianida brachycephala in the kelp holdfasts. The type of substrate (kelp holdfast vs. soft-bottom sediments) and the sediment grain size (coarser vs. finer) were the descriptors best related to the Syllid assemblages.