Spatio-temporal biodiversity of soft bottom macrofaunal assemblages in shallow coastal waters exposed to episodic hypoxic events.

The Humboldt Current System (HCS) has one of the three most important oxygen minimum zones (OMZ) of the global ocean. Several studies have looked at the macrofaunal benthic assemblages inhabiting the continental shelf and shallow bays off central-southern Chile associated with low oxygen areas, but little is known about open coast macrofaunal communities within this zone, which are frequently subjected to the low oxygen conditions of Equatorial Subsurface Waters (ESSW). In order to assess local and mesoscale coastal macrofauna dynamics, the sampling area (ca. 40 linear km) was divided into seven local zones (Cobquecura, southern Cobquecura, northern Itata, Itata River mouth, external, southern Itata, and Coliumo). Eight oceanographic cruises were carried out between May 2006 and February 2008 covering 16 coastal sampling sites, between 36°07'S and 36°30'S. The macrofaunal assemblage was dominated by polychaetes, crustaceans, and mollusks. Our results suggest a high degree of temporal faunal stability on the mesoscale in soft bottom communities along the open coast, given the persistence of a faunal assemblage dominated by organisms tolerant of low oxygen conditions. While there is some local variability in community attributes, the main structuring factor for soft bottom communities in the shallow coastal area off central-southern Chile is the seasonal intrusion of low oxygen ESSW.

Pectinaria chilensis NILSSON, 1928 (POLYCHAETA: PECTINARIIDAE): taxonomic characterization, new distributional records and ecological notes from the chilean coast

Se revisa Pectinaria chilensis de la costa de Chile a partir de ejemplares recolectados en fondos blandos sublitorales, entre 45 y 93m de profundidad, en cuatro localidades del norte de Chile. Estos especímenes fueron comparados con ejemplares recolectados a 17m de profundidad en Coronel, Golfo de Arauco, Chile, localidad tipo de la especie. Se incluye una caracterización taxonómica, ilustraciones, y nuevas localidades en la distribución geográfica de la especie. Se provee información del hábitat (batimetría, tipo de sedimento, contenido de materia orgánica total y O2 disuelto de fondo) y se incluye una clave para diferenciar las dos especies de Pectinariidae registradas en Chile.

The taxonomy, geographical distribution, and ecological aspects of Pectinaria chilensis are reviewed. Specimens were collected in sublittoral soft bottoms, between 45 and 93m depth, at four localities in northern Chile. These specimens are compared with individuals collected from 17m depth at Coronel, Gulf of Arauco, Chile, the type locality of the species. A taxonomic characterization, illustrations and a list of new localities in the geographical distribution of this species are presented. Ecological information (bathymetry, sediment type, total organic matter content and dissolved O2 concentration of sea water above the bottom) is included, as well as a key for differentiating the two Pectinariidae species registered in Chile to date.

Revisa-se Pectinaria chilensis da costa do Chile a partir de exemplares recolhidos em fundos brandos sub-litorais, entre 45 e 93m de profundidade, em quatro localidades ao norte do Chile. Estes espécimes foram comparados com exemplares recolhidos a 17m de profundidade em Coronel, Golfo de Arauco, Chile, localidade padrão da espécie. Se inclui uma caracterização taxonômica, ilustrações, e novas localidades na distribuição geográfica da espécie. Se fornece informação do hábitat (batimetria, tipo de sedimento, conteúdo de matéria orgânica total e O2 dissolvido de fundo) e se inclui uma clave para diferenciar as duas espécies de Pectinariidae registradas no Chile.