Eduardo Quiroga

Organic enrichment and structure of macrobenthic communities in the glacial Baker Fjord, Northern Patagonia, Chile

In this study we describe community parameters such as densities, biomasses, species composition, feeding modes and normalized biomass size-spectra (NBSS) of macrobenthic invertebrate communities from three stations located in the Baker Fjord obtained on four seasonal campaigns in 2008 and 2009. The macrobenthic communities were dominated by small-bodied polychaetes (Paraonidae, Capitellidae and Cirratulidae) characterized by continuous year-round breeding, short life-spans, and fast turnover rates, which in turn regulated the standing stock in the communities. Principal component analysis and multiple-regression analysis demonstrate the distribution of macrobenthic communities in the study area to be mainly controlled by few local environmental conditions. Macrofaunal densities, diversity and feeding modes were significantly correlated with the total organic carbon (TOC; R 2 = 0 . 74 ; P < 0.001) and chlorophyll-a (Chl-a; R 2 = 0 . 55 ; P < 0.05) content in the sediments. This study also suggests that feeding modes and NBSS can be used to detect and follow possible changes caused by natural perturbations such as glacial lake outburst floods or anthropogenic stressors associated with ecological impacts generated by the construction and operation of hydroelectric power stations in the Baker River.

Classification of the ecological quality of the Aysen and Baker Fjords (Patagonia, Chile) using biotic indices.

The AZTIs marine biotic index (AMBI), an ecological indicator for managing estuarine and coastal waters worldwide, was tested in two fjords in Chilean Patagonia. The Aysen Fjord (42° Lat. S) supports intensive salmon farming in coastal ecosystems, while the Baker Fjord (48° Lat. S) is currently just beyond the limit of the southern expansion of salmon concessions. The ecological status of the Aysen Fjord was classified as good, while the status of the Baker Fjord was classified as high and unbalanced. These differences were consistent with our expectations, illustrating the effect of local environmental conditions and human activities, combined with river inputs into semi-confined fjords. This method is appropriate for the evaluation of the ecological status of the fjords, but requires a sufficient amount of data for the robust environmental assessment as proposed by the Water Framework Directive (WFD).

ESTIMACIÓN DE PRODUCCIÓN SECUNDARIA Y PRODUCTIVIDAD PARA UNA POBLACIÓN INTERMAREAL DE TROPHON GEVERSIANUS (BAHÍA LAREDO, ESTRECHO DE MAGALLANES)

RESUMENEl gastropodo carnivoro Trophon geversianus (Pallas, 1774) es una de las especies bentonicas explotadas comercialmente en la region de Magallanes, de la cual no existe informacion relacionada a su productividad biologica. En este trabajo, se estimo la produccion secundaria y productividad de una poblacion intermareal de T. geversianus a traves del modelo de redes neurales. Los muestreos se realizaron estacionalmente en Bahia Laredo, estrecho de Magallanes entre los meses de agosto 2007 y abril 2008. La longitud de los ejemplares de T. geversianus fluctuo de 12,4 a 55,4 mm (28,4 ± 7,4). La poblacion presento una distribucion unimodal. Las densidades medias estacionales oscilaron entre 0,23 ind m -2 y 0,97 ind m -2 , mientras que la biomasa media vario entre 0,041 g PSLC m -2 y 0,194 g PSLC m -2 . La produccion secundaria anual promedio estimada para T. geversianus vario entre 0,03 y 0,16 g PSLC m -2 ano -1 y la productividad estimada fue de 0,7 ano. En la razon P/B se observo una correlacion significativa con el peso corporal de T. geversianus. La productividad estimada para T. geversianus es consistente con los valores reportados en la literatura para otras especies de moluscos marinos de las areas Antartica, Subantartica y Chilenas.Palabras clave: Gastropoda, Muricidae, razon P/B.

NUEVOS REGISTROS Y DISTRIBUCIÓN DE POLIQUETOS BENTÓNICOS SUBMAREALES DE FONDOS BLANDOS EN LA REGIÓN DE AISÉN, CHILE: FAMILIAS PARAONIDAE Y SPIONIDAE (ANNELIDA: POLYCHAETA).

Results from a taxonomic analysis of subtidal benthic polychaetes belonging to the Paraonidae and Spionidae families are present. The samples were taken during benthic research cruises, conducted by the Center for Advance Research in Patagonian Ecosystems (CIEP), at the Aisen region (Northern Patagonia). Benthic samples were collected from the Piti-Palena fjord, Aisen fjord, Estero Elefantes and Baker fjord, between 6 and 126 m water depth. we identified five species of Paraonidae family ( Aricidea antartica Hartmann-Schroder & Rosenfeldt 1988, Aricidea strelzovi Hartmann-Schroder & Rosenfeldt 1990, Aricidea catherinae Laubier 1967, Aricidea albatrossea Pettibone 1957 and Levinsenia antartica (Strelzov 1973)) and nine species of Spionidae family (Spiophanes soederstroemi Hartman 1953, Spiophanes bombyx (Claparede 1870), Scolelepis chilensis Hartmann-Schroder 1962, Rhynchospio glutaea (Ehlers 1897), Prionospio patagonica Augener 1923, Prionospio elhersi Fauvel 1928, Prionospio orensanzi Blake 1983, Laonice weddellia Hartman 1978 and Aonides sp). New records and range extensions of paranoids and spionids polychaetes species in the Aisen region and Chile are reported.

Polychaete diversity in the Scotia Arc benthic realm: Are polychaetes tracers for faunal exchange?

The Scotia Arc is the only shallow-water and island bridge linking nowadays Patagonia and the Antarctic. The Antarctic Circumpolar Current as an oceanographic peculiarity makes this region an interesting biogeographic transition zone, because this frontal system traditionally is said to isolate the Antarctic fauna from that of the adjacent northern ecosystems. Based on benthos samples from three expeditions onboard R/V Polarstern, we studied distribution patterns of 200 polychaete species and 34 major benthic taxa in order to evaluate the role of polychaetes in the benthic realm of this part of the Southern Ocean. ANOSIM test distinguished three station groups: the central eastern Scotia Sea, the continental shelf off South America and stations at the tip of the Antarctic Peninsula. These station groups differed in organism densities and diversities with stations at the tip of the Antarctic Peninsula hosting the most diverse and dense community. The polychaete diversity patterns in the three assemblages evidenced closer connectivity between the tip of the Antarctic Peninsula and the central eastern Scotia Sea than between the continental shelf off South America with either the stations off the tip of the Peninsula or the central eastern Scotia Sea. This is probably supported by the Polar Front, which divides the island chain into two branches. Species distribution and community patterns of polychaetes appear to be associated with oceanographic and sediment conditions in this region. Most of the shared species showed the capability to tolerate differences in hydrostatic pressure. We suggest that the islands of the Scotia Sea may constitute a bridge for exchange of benthic species, particularly for polychaetes with eurybathic distribution and high dispersal capabilities.

Familia Parapaguridae (Anomura, Paguroidea) en Chile: Nuevos registros de cangrejos ermitaños de profundidad

Two new distribution records of hermit crabs of the family Parapaguridae, i.e., Oncopagurus haigae and Sympagurus dimorphus are presented. The material examined was collected by 2 expeditions from the Chilean coast. The PUCK-156 and INSPIRE Expeditions in 2001 and 2010, respectively, at depths ranging from 340 to 1300 m. The present study provides taxonomic and distributional information as well as a key to aid in the identification of the species of Parapaguridae present in waters off Chile. With these results the family in southeast Pacific waters off Chile is represented by 14 species belonging to the genera Oncopagurus (3 species), Paragiopagurus (3 species), Parapagurus (3 species), Sympagurus (3 species), Strobopagurus (one species) and Tylaspis (one species).