Chaetozone gibber Woodham and Chambers, 1994 is recorded for the first time on the coasts of the Iberian Peninsula. This species is characterized by a dorsal thickening in the anterior segments and three types of setae. It is distinguished from C. setosa Malmgren, 1867 by the incomplete ring of acicular setae in the posterior segments and from Caulleriella zetlandica (Mc Intosh, 1911) by the absence of bidentate acicular setae. In the La Coruña estuary, C. gibber is found in muddy and sandy sediments, with the highest abundance in muddy bottoms. The species is also present in other Galician estuaries and the continental shelf of Galicia.

A review of the genus Glycera in the Iberian Peninsula, including recent additions of Glycera dayi O'Connor, 1987 and Glycera oxycephala Ehlers, 1887. The article provides a description of Glycera oxycephala based on specimens collected from the coasts of Huelva and Galicia, and includes a taxonomic key for this genus in the Iberian Peninsula.

Benthic samples were collected at 21 stations in the Vigo estuary to describe macroinfaunal communities, sediment microbiology, and the sedimentary environment. Two main communities were identified: the Amphiura filiformis community in sandy mud sediments of the outer estuary and the Spiochaetopterus costarum community in fluid, organic-rich muds of the inner estuary. Bacterial abundance and production positively correlate with organic content but negatively with macroinfauna abundance and species number. The sediments in the Vigo estuary are less altered by human activities compared to other Rías Bajas, such as Pontevedra and Arosa.

The species Aonidella dayi Maciolek 1983 is recorded for the first time in the Iberian Peninsula, marking the first record of the genus Aonidella in this area. The article provides a redescription of the species and includes some ecological data.

Samples were taken at 19 points in the Ría de Pontevedra to study the infaunal benthic community in relation to sediment parameters. Organic waste from the Marín cellulose factory significantly increases the organic content of the sediment in the middle and inner zones of the Ría, altering the benthic community, which is almost exclusively reduced to the tubicolous polychaete Telepsavus costarum. Diversity is nearly zero, although biomass can be high in some areas. A moderately contaminated zone with slightly lower organic matter values also predominantly features T. costarum but includes other organisms. The least affected areas are the outer part of the Ría and some points on the southern shore, where diversity is higher, and dominant organisms include Lumbriconereis paradoxa, Amphiura chiajei, Venus striatula, and Dentalium novemcostatum. The use of the polychaete T. costarum as an indicator of sediment contamination by excess organic matter is proposed.