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The study of fatty acid biomarkers in trophic structures at sub-polar latitudes is fundamental in describing energy fluxes across ecosystems characterized by complex inter-specific interactions. Due to the presence of certain essential fatty acids obtained exclusively from predator–prey interactions, fatty acid biomarkers are widely used to identify trophic interactions. This study analyzed fatty acid compositions in three species inhabiting a relatively pristine Patagonian fjord. This fjord is geographically difficult to access, so there are very little sampling opportunities, biological and oceanographic information. In the three species collected (Ctenodiscus australis (Loven in Lutken 1871) (Echinodermata, Asteroidea, Ctenodiscidae); Munida gregaria (Fabricius 1793) (Arthropoda, Malacostraca, Munididae); Eleginops maclovinus (Cuvier 1830) (Chordata, Actinopterygii, Eleginopsidae)) along this remote area were evaluated their fatty acid trophic markers as a tool to differentiate dietary components and dietary habits. The study reported significant differences in the amount of saturated fatty acids (SFA), monounsaturated fatty acids (MUFA), and polyunsaturated fatty acids (PUFA), with the highest concentrations of all fatty acids in M. gregaria. The last suggests that M. gregaria is considered as a good quality food source or biological component that might support the fjord trophic web in the Southern Hemisphere. The results describe diet compositions in sampled species, and differences among species for fatty acid compositions and proportions. This provides an initial basis for future modeling or projecting how benthic ecosystems of fjords and Patagonian channels respond to food intake, particularly in environments associated with glacial systems characterized by a low phytoplankton biomass and greater sensitivity to climate variability.

The Baker-Martinez fjord system (Chile, 48°S) is a transitional environment between the terrestrial ecosystems of Patagonia and the SE Pacific Ocean. This unique setting makes it an ideal system to evaluate land-ocean gradients in sediment composition and in a range of biogeochemical variables. Here, we studied the composition and organic geochemistry of surface sediments deposited in the Baker-Martinez fjord system to assess spatial changes in sediment properties and identify the best tracers of terrestrial input. We determined concentrations in biogenic opal, organic carbon, calcium carbonate, and lithogenic particles, and we measured diatom abundance, bulk elemental and isotopic organic geochemistry, and n-alkanes distribution, on a series of surface sediment samples distributed along two proximal-to-distal transects (one in the Martinez Channel and a second one in the Baker Channel). Results reveal clear proximal-to-distal trends in the proportion of freshwater diatoms and in the fraction of organic carbon of terrestrial origin calculated from the bulk organic δ13C measurements. Diatoms are particularly sensitive to freshwater input in proximal environments, whereas bulk organic geochemistry better reflects terrestrial input over long distances across the fjord system. Other terrestrial proxies frequently used in the literature, such as the N/C ratio and the n-alkane-based terrestrial/aquatic ratio, did not show clear variations with distance from the fjord head. Our results suggest that the isotopic composition of bulk organic matter (δ13Corg) and the relative proportion of diatoms of freshwater origin are the best-suited proxies to estimate past changes in terrestrial input from fjord sediment archives, irrespective of the glacial status of the fjord and its watershed.

Stable isotopes and geochemical proxies (TOC/TN and Chla/TOC) in sediments can be used to distinguish organic matter sources (anthropogenic, terrestrial, or marine). This study aims to characterize organic matter (OM) in superficial sediments from three sectors of central Chile (33°S) that are highly influenced by urban and industrial development. Our results show that a substantial fraction of these OM in Quintero Bay is anthropogenic, from industrial and domestic wastewater sources. In contrast, a mixture of terrestrial and anthropogenic OM dominates the isotopic signal of surface sediments from Concón, derived from non-point industrial and agriculture sources associated with the Aconcagua River basin, while Ritoque exhibited a mixture of different OM sources. However, deposition of allochthonous OM in our study area depends on coastal topography, which influences the local currents and well-ventilated waters, promoting the dispersion and assimilation of OM and thus providing an environment with a high capacity for natural remediation.

Benthic marine food webs, which recycle organic matter and sustain unique biodiversity, are an important component of estuarine Patagonian fjords; however, these may be heavily influenced by salmon farming activities. Under the above conditions, this study collected several food sources (sediment organic matter, suspended particulate organic matter, macroalgae) and 26 benthic invertebrate species, and analyzed them using a Bayesian mixing model. Briefly, carbon and nitrogen stable isotopes analyses revealed that the highly variable isotopic niche widths respond to food supplies from marine and terrestrial organic matter. In addition, particulate and dissolved waste from salmon farming activities were found to modify isotopic composition ratios in many suspension feeders. Particularly, our results indicate high δ15N values in the sponge Cliona chilensis and the encrusting coral Incrustatus comauensis, which appear to be potential ecological indicators for evaluating stoichiometry imbalances and trace organic pollution sources in fjord environments.

A quantitative study of metazoan meiofauna was carried out in Valparaiso Bay (33°S 71°W) which is affected by seasonal hypoxia in central Chile. The contents of bottom water, dissolved oxygen (BWDO), organic carbon, chloroplast pigments and composition of stable carbon isotope (d13C) in the sediment were used as a measure of the contribution of primary production in the water column, which accumulates in the sediment. Meiofauna abundances in the three sampling stations (80-140 m depth) ranged from 2.218 ± 643 to 1.592 ± 148 ind 10 cm-2. Nine upper metazoan meiofauna groups were recorded, with nematodes as the dominant group, contributing with more than 95% of total abundances. The abundance vertical distribution was concentrated in the first layers of sediment in most groups except Acari and nauplii larvae. Canonical correspondence analysis revealed significant correlations (P < 0.05) between the meiofauna abundance and organic content, depth and redox potential from sediments. These results represent a first approach to understanding the ecology of meiofaunal assemblages in the Valparaiso Bay and may be useful as a baseline for future comparisons and descriptions of the ENSO (El Niño Southern Oscillation) and seasonal variations of these unknown benthic communities.

Complex marine-terrestrial interactions characterize Chilean fjords, where benthic communities influence the distribution of organic matter (OM). We examined spatial and seasonal changes in the hydrography, sediment conditions and soft-bottom macrobenthic, meiobenthic, and total microbial biomass in a glacial Patagonian fjord (Martinez Channel, Chile). The transport of a high load of glacial mineral and particulate OM to the fjord in the austral summer coincided with low total live benthic biomass. Multivariate analysis evidenced temporal-related macrofaunal groups influenced by the different environments produced by the advection of sediment transport and terrestrial OM from the Baker River, Chile. The relationships between density/biomass and respiration versus body size varied considerably with distance from major riverine inputs, but the slopes of density size spectra and normalized biomass size spectra were less negative in summer than in winter. Occasional large-scale advective processes in the water column affected sediment conditions and removed surface macrofauna, influencing the slope and intercept of the regression models. In the outer fjord, lateral advection and subsequent sedimentation of terrestrial OM contributed a significant fraction to total OM sediments (

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.

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).

The AZTI's 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).

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; R2 = 0.74; P a (Chl-a; R2 = 0.55; P

El analisis de material obtenido durante la Expedicion INSPIRE 2010 abordo del B/C Melville permitio el registro de una especie de poliqueto Eunice pennata (O.F. Muller 1776). Esta especie fue recolectada con una rastra Agassiz (AGT) en siete estaciones en el centro y sur de Chile (36° - 46°S) en profundidades entre 460 y 906m. Esta especie habita en grietas y tubos asociados a costras car-bonaticas derivado de la actividad antigenica en sitios activos y pasivos de filtracion de metano. Esta especie difiere de las otras especies con que esta relacionada por presentar branquias que se inician en el setigero 3 y por la presencia de una base en forma de anillo en el notopodio posterior. Esta es la primera mencion de la especie en aguas del Pacifico Suroriental, siendo formalmente citado para la costa del Pacifico Sur.

In the present study we review datasets available for the Chilean margin to assess the relationship between environmental (or habitat) heterogeneity and benthic diversity. Several factors, such as the presence of different water masses, including the oxygen-deficient Equatorial Sub-surface Waters (ESSW) at the continental shelf and upper slope, and the Antarctic Intermediate Waters (AIW) at mid slope depths appear to control the bathymetric distribution of benthic communities. The presence of methane seeps and an extended oxygen minimum zone (OMZ) add complexity to the benthic distribution patterns observed. All these factors generate environmental heterogeneity, which is predicted to affect the diversity patterns both along and across the Chilean continental margin. The response to these factors differs among different faunal size groups: meio-, macro-, and megafauna. Physiological adaptations to oxygen deficiency and constraints related to body size of each group seem to explain the larger-scale patterns observed, while sediment ⁄habitat heterogeneity (e.g. at water mass boundaries, hardgrounds, biogeochemical patchiness, sediment organic content, grain size) may influence the local fauna diversity patterns. Marine Ecology. ISSN 0173-9565

Benthic megafaunal and demersal fish assemblages were sampled in three areas off Chile during the German-Chilean Expedition PUCK (SO-156) onboard the R/V Sonne from March to May 2001, at depths ranging from 120 to 2201 m. These samples, taken with an Agassiz trawl, are among the deepest ever taken in Chilean waters. A total of 147 species were recorded, mainly decapod crustaceans (Galatheidae, Pandalidae, Crangonidae), gastropods (Trochidae, Muricidae, Volutidae), ophiuroids (Asteronychidae, Gorgonocephalidae, Ophiolepididae, Ophiurinae), asteroids (Pterasteridae, Solasteridae, Goniopectinidae), polychaetes (Onuphidae, Aphroditidae, Maldanidae), and demersal fish (Macrouridae, lpnopidae, Squalidae). Species richness and rarefaction analyses suggest that the fauna was undersampled. From the 147 species identified in this study, 36 species (24.5%) occurred only once and another 24 species occurred only twice (16.3%). Depth and dissolved oxygen levels were found to be the main factors influencing megafaunal changes along the continental shelf and in bathyal areas, as indicated by principal component and Pearson's correlation analyses. Some species appear to be limited to distinct areas in the upper and lower bathyal zones, whereas other species have a wider range, extending from the continental shelf to lower bathyal zones. Biogeographic relations exist with the Pacific, South Atlantic, and Southern Oceans, but the latter seem to be weaker than would be expected considering the connection by Antarctic intermediate water. (C) 2008 Published by Elsevier Ltd.

The course of environmental conditions and shelf macrobenthic communities off Central Chile (∼36°S) during the strong 1997–98 El Nino (EN) event is compared with a subsequent and basically “normal” period (2002–2003). Changes in macrofaunal community, feeding mode structure, and biomass size spectra are contrasted over time with changes in oceanographic and sediment settings, in order to assess intra- and inter-annual changes in faunal composition during both ENSO periods. During EN, there was a decrease in biomass and abundance of species known to be well adapted to organic-rich, oxygen-deficient environments, such as the interface-feeding polychaete Paraprionospio pinnata. On the other hand the abundance of highly mobile, burrowing polychaetes remained unaffected, or even increased in biomass. The decline of P. pinnata lasted several years after the demise of warm conditions, possibly due to negative interactions with those more mobile burrowing polychaetes. The percent contribution of subsurface-deposit feeders to total biomass increased during EN (49.3±12.4% during summer) and declined only in the summer-fall period of 2002–03 (11.1±4.1%). An opposite trend was observed for interface and surface-deposit feeders. From EN to summer-fall 2002–03 (i.e., normal to low oxygen conditions) the size-structure of the macrobenthos switched from a larger to a smaller-sized assemblage. However, biomass was maintained due to successful recruitment and high abundance of both P. pinnata and the squat lobster, Pleuroncodes monodon. Our results suggest that the shelf macrofaunal community structure exhibit fluctuations at various time scales, and that these changes are more pronounced during and after a strong EN event. In such cases, the effects of such an event may be recorded at latitudes as far south as 36°S, with consequences in the biota lasting for many years after the demise of warm conditions.

La subregión del Trópico de Cochabamba forma parte de la Cuenca Amazónica y abarca cinco municipios: Villa Tunari, Chimoré, Puerto Villarroel, Entre Ríos y la agencia cantonal de Shinahota (las cabeceras municipales no forman parte del Trópico). Su superficie alcanza a 37.390 km2 y su población, en 2001, a 145.050 habitantes, de asentamiento relativamente reciente y predominantemente campesina (84 por ciento de población rural). Su situación ha mejorado relativamente en los últimos 30 años pero aún presenta fuertes carencias.

A quantitative study of macrobenthos was carried out on three transects on the shelf and continental slope off Chile (22° to 42°S; from 100 to 2000 m water depth) within and beneath the oxygen minimum zone (OMZ). Macrobenthos mean densities ranged from 104 to 13 808 ind m−2, with highest values off Concepción (∼36°S), where highest chloroplastic pigment equivalents were also measured. Polychaetes were the numerically dominant group in all transects and depths, followed by peracarid crustaceans. Species richness and diversity correlated with observed changes in bottom-water oxygen concentrations and sediment-bound pigments. Our results show that the shelf macrobenthic communities were negatively affected by low oxygen. The non-metric multidimensional scaling (nMDS) analysis evidenced depth-related station groups which may be related to the different environments provided by the water masses involved. Indeed, the depth ranges of stations groups with their specific species inventories coincide quite well with the boundaries of the three important water masses in the region, the Equatorial Subsurface Water (∼50 m to ∼400 m depth), the Antarctic Intermediate Water (∼400 to ∼1200 m depth), and the Pacific Deep Water (>1200 m depth).

Se presentan los resultados del análisis taxonómico de poliquetos bentónicos de las familias Parao-nidae y Spionidae en fondos blandos submareales provenientes de diversas campañas de investigación conducidas por el Centro de Investigación en Ecosistemas de la Patagonia (CIEP) en la región de Aisén, Chile. Las muestras fueron recolectadas en el fiordo Piti-Palena, fiordo Aisén, estero Elefantes y fiordo Baker, entre los 6 y 126 m de profundidad. Durante estos estudios se han identificado cinco especies de poliquetos de la familia Paraonidae {Aricidea antartica Hartmann-Schróder & Rosenfeldt, 1988, Aricidea streízovi Hartmann-Schróder & Rosenfeldt, 1990, Aricidea catherinae Laubier, 1967, Aricidea aíbatros-sea Pettibone, 1957 y Levinsenia antartica (Strelzov, 1973)) y nueve especies de la familia Spionidae (Spiophanes soederstroemi Hartman, 1953, Spiophanes bombyx (Claparéde, 1870), Scolelepis chilensis Hartmann-Schróder, 1962, Rhynchospio gíutaea (Ehlers, 1897), Prionospio patagónica Augener, 1923, Prionospio elhersi Fauvel, 1928, Prionospio orensanzi Blake, 1983, Laonice weddellia Hartman, 1978 y Aonides sp). Se reportan nuevos registros y extensión de los rangos de distribución de estas especies de paraonidos y espionidos en la región de Aisén y Chile.

The growth and size-structure of the bathyal ophiuroid brittle star, Stegophiura sp., were analysed from skeletal growth bands and disc diameter frequencies. Specimens were collected in trawl samples taken on the continental slope off central Chile (~36°S) at two sites within the recently discovered Concepción Methane Seep Area (CMSA) and at two control non-seep sites. Growth bands were measured as radii of vertebral ossicles from scanning electron microscope (SEM) micrographs and used to provide size-at-age data. The von Bertalanffy and the Gompertz growth models provided good fit to size-at-age data. The size-structure distributions observed in the study area suggest that small-bodied (Stegophiura sp. are more abundant near seep sites, probably attracted there by the presence of methane-derived authigenic carbonates, which provide a preferred habitat for ophiuroids and benthic fauna in general. Furthermore, size-at-age data from measurements of the ossicle growth bands indicate relatively rapid growth of Stegophiura sp. populations at seep sites. Assuming that the growth rings are annual, the maximum Stegophiura sp. age was estimated to be 15 years. The growth performance of this species falls within the range of values reported for sub-Antarctic and bathyal species.

Se revisan las especies de camarones de aguas profundas, a partir de material bibliografico y especimenes recolectados durante la expedicion PUCK 156 (2001) a bordo del B/C Sonne en tres areas de la costa de Chile: Antofagasta (22° lat. S), Concepcion (36° lat. S) y Chiloe (42° lat. S). 111 especimenes correspondientes a 12 especies fueron reconocidos, incluyendo tres nuevos registros para la carcinofauna chilena; Metacrangon procax, Nematocarcinus productus y Merhyppolite sp. aff. M. americana. La presencia de Nematocarcinus lanceopes, Lebbeus antarcticus, Pandalopsis ampla y Sclerocrangon atrox en el material recolectado permite extender sus rangos de distribucion desde areas sub-Antarticas a temperadas de la costa de Chile

Species of the family Pilargidae are revised based on bibliographic information and on specimens collected in soft bottoms, from 16 to 68 m depth, in three localities of the northern Chilean coast. Five genera and six especies, including a new record for the Chilean fauna, Parandalia fauveli, are recognized. Synonyms, diagnostic features, geographic distribution data and illustrations are provided for each species. Abundance data and biomass, as well as granulometry and organic matter of the sediments where the specimens were collected, are also reported. Presence of Pilargis berkeleyae and Sigambra bassi in the collected material allows extension of their distributional ranges from approximately 35-36ºS to 18º30'S. A taxonomic key to the six species of Pilargidae from the Chilean coast is provided Se revisan las especies de Pilargidae de la costa de Chile a partir de especímenes recolectados en fondos blandos sublitorales, entre 16 y 68 m de profundidad, en tres localidades del extremo norte del país, y se complementa con información bibliográfica. Se reconocen 5 géneros y seis especies incluyendo un nuevo registro para la fauna de Chile, Parandalia fauveli. Se incluye sinonimia, caracteres diagnósticos, distribución geográfica e ilustraciones para cada especie. De las especies recolectadas se entregan, además, valores de abundancia y biomasa así como también valores de granulometría y contenido de materia orgánica de los sedimentos que habitan. La presencia de Pilargis berkeleyae y Sigambra bassi, en el material recolectado, permite extender sus rangos de distribución hacia el norte de Chile desde aproximadamente 35-36ºS hasta 18º30'S. Se incluye una clave taxonómica para las seis especies de pilárgidos de la costa de Chile