Through an oceanographic cruise carried out between the southern area of Aysén and the northern one of Magallanes, Canal Trinidad to Canal Smyth (50º00'S, 75º00'W to 52º00'S, 73º48'W), 13 collecting stations were made to gather biological material to record and characterizing the intertidal biotopes of this extended area. A total of 19 biotopes were identified, from which 12 of those had been recorded previously at more septentrional areas of Aysén; other 6 represented variations of those previously recorded in other areas and only 1 was described as a new intertidal biotope. Among the former ones are rocky shore biotopes belonging to the dominant species Bostrychia harveyi, Acrosiphonia pacifica, Porphyra sp., Adenocystis utricularis, Iridaea tuberculosa and Mazzaella laminarioides-Nothogenia fastigiata. Among the 6 ones which represent variations of some biotopes before described there are 2 of Porphyra sp., 3 of Bostrychia harveyi and 1 of Mazzaella laminarioides-Nothogenia fastigiata. Just the rocky shore biotope integrated by the macroalgae Caepidium antarcticum and crustose coralline algae was the only new one. This new biotope is distributed in the lower eulitoral subzone of sheltered areas and it is characterized by having a strong subantarctic influence. Coastal biotope biodiversity was high, as a consequence of the multiple geographic, geologic, oceanographic and climatic factors interacting in this extended region. In general, the area was characterized by exhibiting a high biological diversity reflected through the diversity of observed biotopes, which demonstrated the presence of highly productive ecosystem.

The Eastern South Pacific coastal zone is characterized by seasonal and interannual variability, driven by upwelling and El Niño Southern Oscillation (ENSO), respectively. These oceanographical conditions influence microbial communities and their contribution to nutrient and greenhouse gases recycling, especially in bottom waters due to oxygenation. This article addresses the seasonal hydrographic and biogeochemical conditions in the water and sediments during El Niño 2015. Bottom water active microbial communities, including nitrifiers, were studied using amplicon sequencing of 16S rRNA (cDNA) and RT-qPCR, respectively. The results of the hydrographic analysis showed changes in the water column associated with the predominance of sub-Antarctic Waters characterized by warmed and low nutrients in the surface and more oxygenated conditions at the bottom in comparison with El Niño 2014. The organic matter quantity and quality decreased during fall and winter. The bottom water active microbial assemblages were dominated by archaea (Ca. Poseidoniales) and putative ammonia oxidizing archaea. Active bacteria affiliated to SAR11, Marinimicrobia and Nitrospina, and oxygen deficient realms (Desulfobacterales, SUP05 clade and anammox) suffered variations, possibly associated with oxygen and redox conditions in the benthic boundary layer. Nitrifying functional groups contributed significantly more during late fall and winter which was consistent with higher bottom water oxygenation. Relationships between apparent oxygen utilization nitrate and nitrous oxide in the water support the contribution of nitrification to this greenhouse gas distribution in the water. In general, our study suggests that seasonal oceanographic variability during an El Niño year influences the microbial community and thus remineralization potential, which supports the need to carry out longer time series to identify the relevance of seasonality under ENSO in Eastern Boundary Upwelling Systems (EBUS) areas.

The Syllidae subfamilies Eusyllinae, Anoplosyllinae and Autolytinae, as well as the incertae sedis genera (Aguado et al., 2012), were studied from samples collected in shallow water from fjords and channels in Chilean Patagonia. One new species Paraehlersia kawesqar sp. nov. is described. The genus Nudisyllis Knox & Cameron, 1970 is recorded for the first time for Chile, while the species Brachysyllis infuscata (Ehlers, 1901a) and Syllides japonica Imajima, 1966 are recorded for the first time for continental Chile. Finally, Syllides articulosa Ehlers, 1897 and Epigamia sp. are also reported. The majority of the species were found inside tubes of the polychaete worm Chaetopterus cf. variopedatus (Renier, 1804) – a new habitat for syllid polychaetes. This work is an important contribution to the knowledge of syllids in Chile and to the polychaete fauna of the Patagonian region generally.

Durante el Crucero 16 CIMAR Fiordos realizado entre el Estrecho de Magallanes y el Canal Beagle (53º11,16'S; 73º24,06'W-55º09'03,92''S, 68º08'27,9''W) se realizó un muestreo intermareal y submareal de 14 estaciones. Estas muestras se obtuvieron manualmente y por buceo apnea, en transectas perpendiculares a la línea de la costa, con orientación sur-este y en ellas se aplicó la metodología establecida en el Crucero CIMAR 15 para la caracterización de los biotopos costeros. Se determinaron 10 biotopos marinos que corresponden a tres grandes grupos: 1) biotopos con fuerte influencia de agua dulce de deshielos y lluvias, con playas extensas sin pendientes rocosas; son de diversidad baja, con presencia notoria de Porphyra spp. en sectores rocosos planos y con salinidades que varían entre 1 y 20‰; 2) biotopos rocosos con mayor pendiente, comparativamente con mayor influencia de mareas y presencia de algas rodófi tas, feófitas y clorófi tas asociadas a bivalvos, gasterópodos, cirripedios y otros invertebrados, y con salinidad de 24 a 28‰; y 3) submareales someros, desde 1 hasta 16,4 m de profundidad, caracterizados principalmente por la presencia de feóficeas, Macrocystis pyrifera principalmente, asociadas con moluscos, crustáceos, poliquetos y equinodermos, y con salinidades entre 32 y 35‰. Se observaron coincidencias con los biotopos descritos para el sector del Parque Nacional Laguna San Rafael, estero Elefantes, archipiélago de los Chonos, y tres biotopos mencionados para los canales Trinidad y Smyth, al norte del Estrecho de Magallanes.