ABSTRACT The rivers of Patagonia are some of the best conserved aquatic ecosystems in South America; however. However due to the growing economic development in the region, several bodies of water have been threatened by human activities. We analyzed the water quality and structure of macroinvertebrate assemblages at 8 stations along the Palena River; upstream, where there is minimal disturbance, and downstream, at stations perturbed by human activities. Samples were collected over the four seasons of the year (September 2013 to May 2014). Temperature, electrical conductivity, pH, dissolved oxygen, total hardness, silica, aluminum and iron showed significant differences (p < 0.05) between stations located upstream and downstream in the river basin, as well as between seasons of the year. A total of 30 macroinvertebrate families were registered (90% insect larvae), being Díptera the most diverse order (8 families). Leptophlebiidae family (Ephemeroptera) was the most abundant family in the four seasons of the year throughout. Statistically, there were significant differences (p < 0.05) between seasons of the year, which were grouped in two groups: one summer-fall and winter-spring, but not to macroinvertebrate assemblages between stations upstream and downstream. These findings indicate that the seasonal variations have a greater effect on the macroinvertebrates assemblage composition than the spatial differences in the basin. On the other hand, the great diversity of macroinvertebrates registered in the Palena River, in addition to the good water quality, indicate that the activities in the basin are not yet a risk to the aquatic ecosystem.

RESUMEN Los ríos de la Patagonia son uno de los ecosistemas acuáticos mejor conservados en América del Sur. Sin embargo, debido al creciente desarrollo económico en la región, numerosos cuerpos de agua se han visto amenazados por actividades humanas. Analizamos la calidad del agua y la estructura del ensamble de macroinvertebrados en ocho estaciones a lo largo del río Palena, en el sector alto de la cuenca con mínima perturbación y sector bajo para aquellas estaciones perturbadas por actividades humanas. El muestreo abarcó cuatro estaciones del año (septiembre 2013 a mayo 2014). La temperatura, conductividad eléctrica, pH, oxígeno disuelto, dureza total, sílice, aluminio y fierro mostraron diferencias significativas (p < 0,05) entre la parte alta y baja de la cuenca y entre estaciones del año. Se registraron 30 familias de macroinvertebrados (90% larvas de insectos), siendo el Orden Diptera el más diverso (8 familias). La familia Leptophlebiidae (Ephemeroptera) fue la más abundante en las cuatro estaciones del año. Diferencias significativas en el ensamble de macroinvertebrados se registraron entre estaciones del año, agrupándose en dos grupos: verano-otoño y invierno-primavera, pero no entre la estructura del ensamble entre la zona alta y baja de la cuenca. Estos resultados indican que la estacionalidad tiene un efecto sobre la composición del ensamble de macroinvertebrados por sobre diferencias espaciales en la cuenca. Por otro lado, la alta diversidad de macroinvertebrados registradas en el río Palena, y buena calidad del agua, indican que las actividades antrópicas aún no son un riesgo para el ecosistema acuático.

ABSTRACT: Chile is the second-largest producer of Atlantic salmon in the world, and the Chilean salmon production accounts for 27% of the world’s production. One important step of the productive cycle in freshwater is the smoltification process that prepares the fish for the marine life stage. This review describes the biological basis of smoltification in Atlantic salmon, with particular attention on branchial osmoregulatory adaptations. We also discuss some of the infectious diseases and problems in smoltification (two of the main causes of losses in Chilean aquaculture) that could be related from a physiological point of view.

ABSTRACT: With the aim to characterise the biological impact of anthropogenic discharge in a river, gene expression in fish was evaluated as a biomarker for mixture effects of potential toxic compounds in the aquatic environment. Adult male rainbow trout (Oncorhynchus mykiss) were used as monitoring organisms. Within the German experimental set up, trout were exposed actively for 28 days in biologically purified sewage as well as in river water up- and downstream of the sewage treatment plant (STP) effluent. In a different approach, wild trout were captured in southern Chile near anthropogenic discharges. Fish were taken from river Maullin receiving sewage from a settlement and from river Pescado influenced by effluents from a fish farm. In vivo effects were assessed by RT-qPCR analyses of biomarker gene expression, vitellogenin (vg), metallothionein (mí) and cytochrome 1A (cyplA) in liver samples with primers amplifying specific sequences previously confirmed by cloning and sequencing. The modulation of expression of marker genes involved in metal stress, reproduction and detoxifying systems in the liver of male rainbow trout revealed organismal response to anthropogenic contamination in two different study areas, such as Chile and Germany, thereby indicating a potential risk on the aquatic ecosystems.

ABSTRACT. This study describes the cephalic sensory canal pores of the Patagonian toothfish's juvenile and adult specimens (Dissostichus eleginoides) from southern Chile. Specimens exhibited four supraorbital, eight infraorbital, and five mandibular pores, followed by six preoperculars, one coronal pore, one supratemporal pore, and four temporal pores. Juveniles exhibited circular pores in the mandibular, infraorbital, and preopercular region. The first two supraorbital pores are circular, the third is rectangular, and the fourth triangular. The coronal pore is circular with a bifurcation; the supratemporal pore is rectangular. In adults, the first mandibular canal pore is circular, and the last four are elongated. The preopercular canal pores are elongated. The two first supraorbital canal pores are circular, unlike the third and fourth, which are rectangular. The coronal pore is rectangular without bifurcation, and the supratemporal pore has a T-shape. The jaw of juveniles does not present all mandibular canal pores; in the infraorbital region, the first five pores extend as a thin canaliculus, while the adjacent pores appear as longer canaliculi in adults. The differences could be related to changes in spatial distribution during larval, juvenile, and adult stages. Adult cephalic sensory canal pores may have an important role in detecting vibratory waves allowing them to capture their prey and perceive potential predators. Our results provide information regarding the cephalic sensory canal pores of the Patagonian toothfish that may stimulate future studies of this species' mechanosensory system.

Resumo O objetivo do presente estudo foi investigar a relação sazonal entre macrobentos e características do sedimento, tais como textura e material orgânico, na lagoa costeira Budi Lagoon, sul do Chile. Medidas físico-químicas e amostragem do macrobentos foram realizadas durante um ano em nove localidades. Sedimento arenoso-lodoso foi o mais comum na lagoa, e percentagens elevadas de material orgânico foram registradas, variando significativamente entre as estações e locais de coleta. Em relação a fauna, foram identificados 28 taxas bentônicos e 7092 indivíduos, que apresentaram variação temporal e espacial. As espécies mais abundantes durante todo o ano foram os moluscos Littoridina cumingii e Kingiella chilenica, e o poliqueta Prionospio patagonica. Os resultados obtidos evidenciaram o importante impacto da matéria orgânica sobre o macrobentos, com riqueza e abundância da fauna diminuindo em presença de alto teor de matéria. As variações encontradas para os diferentes taxons indicaram resposta da fauna ao uso da terra ao redor de Budi Lagoon, que intensamente utilizada para agricultura e atividades turísticas.

Abstract The purpose of the present study was to investigate the seasonal relationship of macrobenthos richness and abundance with sediment characteristics (i.e. texture and organic material) for the coastal Budi Lagoon in southern Chile. Physicochemical measurements and macrobenthos samples were taken over the course of a year at nine sampling stations. Sandy-muddy sediment was the most common, and high percentages of organic material were registered, varying significantly between seasons and stations. The recorded organic material was related to natural (resident wild birds) and anthropogenic (agriculture) sources. Regarding fauna, 28 benthonic taxa and 7092 individuals were identified, with temporal and spatial variations. The most abundant taxa year-round were the molluscs Littoridina cumingii and Kingiella chilenica and the bristle worm Prionospio patagonica. Together, the obtained results evidence the important impact of organic material on the macrobenthos, with macrobenthic richness and abundance decreasing in conditions of high organic material content. The recorded variations for different taxa may indicate a response to the land use around the Budi Lagoon, which is intensely subjected to agricultural and tourist activities.

Changes in land use which directly or indirectly affect freshwater fauna constitute one of the principal anthropic factors which have caused world biological diversity to disappear rapidly during recent decades. This fauna includes aquatic benthic macroinvertebrates, organisms presenting temporal and spatial variation due to a variety of factors, one of which is the diverse food resources available in the rivers. To assess the effect of anthropic activities on this fauna, the distribution, abundance and characterisation of the functional feeding groups of aquatic macroinvertebrates were analysed, together with the physical and chemical variables in the environments of four coastal river basins of southern south-central Chile. A total of 104 taxa of macroinvertebrates were recorded, the principal component of the community being the Diptera (26 taxa). The abundance and richness of taxa were greater in summer and lower in winter. The most abundant species belong to the order Ephemeroptera and Plecoptera. Macroinvertebrates were affected by different land use: stations with less anthropic activity and greater altitude had higher macroinvertebrates abundance, while the lowest abundance was found at the lowest stations. The functional feeding groups which were most abundant spatially and temporally were the collector-gatherers and the shredders. The physical and chemical water quality variables proved to be of exceptional quality in all the stations. These results suggest that policies governing changes in land use in central and southern Chile should take into account the dramatic alterations that these changes impose on the macroinvertebrates community. Policies for biodiversity conservation should therefore focus on these small but important organisms in the north Patagonian region of South America, which is a hotspot of world diversity.

Los cambios en el uso de suelo que afectan directa o indirectamente la fauna dulceacuícola, son uno de los principales factores antropogénicos por los cuales la diversidad biológica mundial está desapareciendo a elevadas tasas durante las últimas décadas. Dentro de esta fauna se encuentran los macroinvertebrados bentónicos acuáticos, organismos que varían temporal y espacialmente debido a diversos factores, uno de los cuales son los diversos recursos alimentarios disponibles en los ríos. Para esto, se analizó la distribución, abundancia, y caracterización de los grupos funcionales alimentarios de macroinvertebrados, y las variables físicas y químicas de cuatro cuencas costeras del centro-sur de Chile. Un total de 104 taxa de macroinvertebrados fueron registrados, siendo los dípteros (26 taxa) el componente principal de la comunidad. La abundancia y riqueza de taxa fue más conspicua en verano y menor en invierno. Las especies más abundantes correspondieron al orden Ephemeroptera y Plecoptera. Los macroinvertebrados fueron afectados por los diferentes usos de suelo: estaciones con menor actividad antropogénica y mayor altura tuvieron la mayor abundancia de macroinvertebrados, mientras que lo contrario ocurrió para la estación de menor altura. Los grupos funcionales alimentarios de recolectores y fragmentadores fueron los más abundantes espacial y temporalmente. Las variables físicas y químicas del agua, presentaron una calidad excepcional en todas las estaciones. Estos resultados sugieren que las políticas de cambio de uso de suelo en la zona centro-sur de Chile, deberían considerar los cambios dramáticos que causan sobre la comunidad de macroinvertebrados. Las políticas de conservación de biodiversidad, deberían enfocarse a estos pequeños pero importantes organismos en una zona hotspot de diversidad mundial como es la región norpatagónica de Sudamérica.

Pinguipes chilensis, Cheilodactylus variegatus and Aplodactylus punctatus are common species in Chilean coastal, but currently information on dietary composition in south of Chile is scarce. Therefore was analyzed the dietary composition and diet overlap of theses species in the coast of Valdivia. The results indicated in spring 2010 that for P. chilensis (n=41) 20 preys were identified, all characterized as being oversized invertebrates, mainly crustaceans (55%) and molluscs (40%), being the Homalaspis plana the most representative specie (70% IRI value). In Ch. variegatus (n=38) 37 preys were identified, mostly small invertebrates, mainly crustaceans (49%), molluscs (31%) and annelids (10%). In the polychaetes of Nereidae Family was most common (23.2% IRI value). In A. punctatus (n=32) red algae predominated (50%) over the brown (41%) and green algae (9%), in total 34 prey species were identified, where Colpomenia sp. (Phaeophyta) was the most common prey (32.4% IRI). Analysis of diet overlap among the three species showed a low similarity between diets. The three species in this study are characterized by sharing the same habitat. P. chilensis and Ch. variegatus shown both as generalist carnivores, since both species have a wide food spectrum, however the morphology and size of your mouth influence the size of the prey they consume. Instead, A. punctatus was confirmed as a specialist herbivore species, consuming preferably red algae.

Pinguipes chilensis, Cheilodactylus variegatus y Aplodactylus punctatus son especies comunes de ser registradas a lo largo de la costa chilena, no obstante información sobre su alimentación es escasa para la zona sur de nuestro país. Por ello, se analizó la composición y sobreposición dietaria de estas especies para la costa Valdiviana. Los resultados señalan que para el periodo primaveral del año 2010, en P. chilensis (n=41) se identificaron 20 presas, todas caracterizadas por ser invertebrados de gran tamaño, principalmente crustáceos (55%) y moluscos (40%), siendo la especie Homalaspis plana la más representativa (IRI 70%). En Ch. variegatus (n=38) se identificaron 37 presas, mayoritariamente pequeños invertebrados, principalmente crustáceos (49%), moluscos (31%) y anélidos (10%). Dentro de estos últimos dominaron los poliquetos de la Familia Nereidae (IRI 23,2%). En A. punctatus (n=32) la diversidad de algas rojas (50%) predominó sobre las pardas (41%) y verdes (9%), siendo identificadas 34 especies presa, donde Colpomenia sp. (Phaeophyta) fue la más representativa (IRI 32,4%). El análisis de sobreposición de dieta entre las tres especies mostró una baja similitud entre las dietas. Las tres especies analizadas en este estudio, se caracterizan por compartir un mismo hábitat. P. chilensis y Ch. variegatus se muestran ambas como depredadores carnívoros generalistas, ya que las dos especies presentan un amplio espectro alimentario sin embargo la morfología y el tamaño de su boca influirían en el tamaño de la presa que consumen. En cambio, A. punctatus se confirma como una especie herbívora especialista, ya que consume preferentemente algas rojas.

This paper describes the geomorphology of the coast of La Araucania, using methods proposed by Tricart (1985) Endlicher (1985) and the classification methods of Francke et al. (2004). Based on morphological, morphometric, morphogenetic and land use patterns, the most representative geomorphic units were the mountain range of metamorphic rock, cord metamorphic rock mountain with granite intrusions, both Paleozoic, the metamorphic rock platform and the fluvial-marine plain represented by wetlands of high ecological value. Water erosion was low to moderate in much of the study area and is mainly associated with human factors, such as the historic reduction and change in vegetation cover, poor agricultural practices and almost no application of soil conservation practices.

Se analizó la dinámica geomorfológica de la franja costera de La Araucanía mediante el método propuesto por Tricart (1985), Endlicher (1985) y la clasificación de Francke et al. (2004). En base a patrones morfológicos, morfométricos, mor-fogenéticos y de uso de suelo, las unidades geomorfológicas más representativas fueron el cordón montañoso en roca metamórfica y el cordón montañoso en roca metamórfica con intrusiones graníticas, ambas del Paleozoico, las plataformas en roca metamórfica y la llanura fluviomarina representada por humedales de alto valor ecológico. La erosión hídrica muestra un estado erosivo ligero-moderado en gran parte del área de estudio, asociado principalmente a factores antrópicos como la histórica disminución y cambio de cobertura vegetal, malas prácticas agrícolas y la casi nula aplicación de prácticas de conservación de suelos.

The coastal area of the Araucanía Region stands out for the presence of wooded wetlands of Temu and Pitra (Blepharocalyo-Myrceugenietum exsuccae), from the association Blepharocalyo-Myrceugenietum exsuccae. These are nowadays affected by antropic activities. We evaluated the vascular flora, the degradation level and the condition of conservation of these forests, working in six basins of the coastal border (Imperial, Comúe, Chelle, Boroa, Boldo and Toltén) of the Araucanía Region. For determining the condition of conservation, different methods of evaluation were applied, using both floristic as well as territorial variables. Among these, the valuation of the influence of the adjacent ecosystems on the forest, the human intervention degree, and the relation between the surface of the forest and its basin. We used cartographic information about the distribution and surface of the swampy forest, setting this way the vegetation mosaic and the diversity of the main uses of the soils. The results show that the main uses of the area are agricultural, cattle and forestry activities. The vascular flora of the area consists of 94 species, 14.9% of them are introduced and the major percentage corresponds to natives from Chile and Argentina (64.9%) and endemics of the country (20.2%). Eleven species have conservation problems. At the same time, all the stands show some deterioration degree, being the stands with the highest level of deterioration those located in the basin of the Imperial river, unlike those located in the basin of the Boldo river, that have not been so damaged. We conclude that the average conservation condition of the stands of the whole studied area corresponds to "degraded", due to the effect of the different human activities carried out in these forests and on the periphery of them as well.

El área costera de la Región de La Araucanía destaca por la presencia de humedales con vegetación boscosa de temu y pitra, de la asociación Blepharocalyo-Myrceugenietum exsuccae. Actualmente estas formaciones se encuentran afectadas por actividades antrópicas. En este estudio se determinó la flora vascular y se evaluó el nivel de degradación y estado de conservación de estos bosques en seis cuencas hidrográficas del borde costero (Imperial, Comúe, Chelle, Boroa, Boldo y Toltén) de la Región de La Araucanía. Para determinar el estado de conservación se emplearon variables florísticas y territoriales, como la valoración de la influencia de los ecosistemas adyacentes sobre el bosque, la relación superficie/ cuenca y el grado de intervención antrópica. Se utilizó información cartográfica sobre la distribución y superficie de los bosques pantanosos, estableciéndose de esta forma el mosaico vegetacional y la diversidad de los principales usos de los suelos. Los resultados muestran que los principales uso del área son agrícola, ganadero y silvícola. La flora vascular de los bosques la componen 94 especies, de las cuales el 14,9% son introducidas, y el mayor porcentaje corresponde a nativas (64,9%) y endémicas del país (20,2%). Once especies se encuentran con problemas de conservación. Asimismo, todos los rodales presentan algún grado de degradación, siendo los ubicados en el curso inferior de la cuenca del río Imperial los que poseen el nivel más alto de degradación, y los menos intervenidos se encuentran en la cuenca del río Boldo. Se concluye que el estado de conservación promedio de los rodales en toda el área corresponde a "degradado". Como principal causa del deterioro están las actividades humanas realizadas tanto al interior como en la periferia de estos bosques.

Riparian vegetation comprises the ecotonal zone in the transition between a water body and the adjacent terrestrial environment and it plays an elemental role in the functioning of aquatic ecosystems. Coverage, structure, and composition of vegetation have a fundamental influence in controlling the energetic input in the aquatic ecosystem. The multiple environmental functions performed by riparian ecosystems and the flow of ecosystem services, influencing in a direct or indirect way the well-being of society, makes knowledge of ecological quality of these areas to be considered as a good environmental indicator. It is useful in territory management and planning, particularly in coastal ecosystems. By applying the QBR index, it was possible to determine the quality of riparian vegetation in Chaihuín and Lingue rivers, both coastal basins in southern Chile. The results indicate that the Chaihuín river has a better quality of vegetation on its banks, compared with Lingue river, where low QBR values are product of the replacement of natural riparian vegetation due to establishment of agricultural land and forest plantations. The application of this index and the overall experience of its use, indicate it to be an economic and quick-use tool that provides reliable and useful results for decision-making in territorial diagnosis, considering the multiple roles and values that makes riparian vegetation good environmental indicators and diagnosing main impacts and problems to propose restoration and/or mitigation measures.

La vegetación ribereña comprende la zona ecotonal en la transición entre un cuerpo de agua y el ambiente terrestre contiguo, desempeñando un rol elemental en el funcionamiento de los ecosistemas acuáticos. La cobertura, estructura, y composición de la vegetación influyen de manera fundamental en el control de la entrada de energía al ecosistema acuático. Las múltiples funciones ambientales que cumplen los ecosistemas ribereños, y el flujo de servicios ecosistémicos que directa o indirectamente influyen en el bienestar de la sociedad, hacen que el conocimiento de la calidad ecológica de estas áreas sea considerado como un buen indicador ambiental, útil en la planificación y gestión del territorio, especialmente en ecosistemas costeros. Mediante la aplicación del índice QBR se determinó la calidad de la vegetación ribereña en los ríos Lingue y Chaihuín, ambas cuencas costeras del sur de Chile. Los resultados obtenidos indican que el río Chaihuín presenta una vegetación de mejor calidad en sus riberas, en comparación con el río Lingue, donde los bajos valores de QBR son producto de la sustitución de la vegetación ribereña natural para el establecimiento de terrenos agrícolas y plantaciones forestales. La aplicación de este índice y la experiencia global de su utilización indican que resulta ser un instrumento económico y de rápida aplicación, que entrega resultados confiables y útiles para la toma de decisiones en el diagnóstico territorial, considerando las múltiples funciones y valores que hacen de los ecosistemas ribereños buenos indicadores ambientales, diagnosticando los principales impactos y problemas para proponer medidas de restauración y/o mitigación.

The aim of this study was to determine the feeding of Micropogonias furnieri (n= 256 of commercial size over 25 cm) during austral summer and winter 2004. During the summer period anchoveta Engraulis ringens was the main prey item in terms of percentage of frequency (%F), percentage of weight (%P) and percentage of Index Relative Prey Importance (%IRI); on the other hand, during winter aquatic plants (i.e. undigested remnants of Myriophyllum aquaticum) were the main prey. Therefore, M. furnieri may act like an opportunistic omnivorous fish similar to that described for population from Río de la Plata (Argentina).

The water quality in a Southern Chile river was characterized using the Biotic Index in a spatio-seasonal context, to analyze the composition and distribution of benthic macroinvertebrates and their correlation with 14 physico-chemical parameters. Sampling was done over a year at 5 sampling stations in the basin of the Boroa River. A total of 77 taxa were recorded, with the most represented orders being the Ephemeroptera (43.30%), Diptera (24.16%) and Plecoptera (18.03%). The most abundant species were Meridialaris diguillina, Nousia maculata (Ephemeroptera) and Limnoperla jaffueli (Plecoptera). According to the modified FBI (Family Biotic Index), the findings indicated excellent, very good and good water quality, the latter quality being registered principally in winter. Likewise, the physico-chemical parameters indicated exceptional water quality. These results suggested a low level of anthropogenic impact in the basin. Applying the modified Hilsenhoff Biotic Index based on macroinvertebrates, the influence of seasonality on water quality was evident.

Se caracterizó la calidad del agua en un río del sur de Chile a través de un Índice Biótico, en un contexto espacio-temporal y además se analizó la composición y distribución de macroinvertebrados bentónicos y su correlación con 14 parámetros físico-químicos. La toma de muestras ocurrió durante un año en 5 estaciones de muestreo en la cuenca del río Boroa. Se registró un total de 77 taxa, los órdenes más representativos fueron Ephemeroptera (43,30%), Diptera (24,16%) y Plecoptera (18,03%). Las especies más abundantes fueron Meridialaris diguillina, Nousia maculata (Ephemeroptera) y Limnoperla jaffueli (Plecoptera). Acordando al IBF modificado (Índice Biótico de Familias) los resultados indicaron excelente, muy buena y buena calidad de agua, la última calidad fue registrada principalmente en invierno. Los parámetros fisicoquímicos así mismo indicaron calidad de agua excepcional. Estos resultados indican un bajo nivel de impacto antropogénico en la cuenca. Al aplicar el Índice Biótico de Hilsenhoff modificado basado en macroinvertebrados, la influencia de la estacionalidad sobre la calidad del agua fue evidente.

We describe the benthic macroinvertebrate associations Budi coastal lagoon southern Chile, salt nature. They relate the abundance and biomass species with organic matter levels and types of sediment, 9 stations were chosen for sampling. The muddy bottom is the substrate dominates more than gravel, which is the least represented. Organic matter showed the highest percentages in the mud at stations Allipén and Temo with 87.35 and 84.29% respectively. 8 species were identified, distributed in the Phyla: Annelida (2), Arthropoda (3) and Mollusca (3), being Prionospio patagonica (Polychaeta, Spionidae) and Littoridina cumingi (Mollusca, Cyamiidae) the most abundant species. The highest recorded average abundance per sampling station corresponded to 351 ind. m-2 and the highest average biomass was 1.0132 g m-2 at the station Deume 2. The lowest values of diversity are consistent with the highest values of dominance. ABC curves, indicate that the Budi River, Temo, Allipén, Bolleco, Botapulli, Deume 1 y Deume 3 stations have low disturbance. The results of nonparametric ordination (MDS) indicate that there is a clear segregation into two groups. The main difference between stations is the abundance of the polychaete Spionidae Prionospio patagonica. Different macroinvertebrate communities are closely related to the levels of organic matter and sediment. It states that the macrofauna community comes in two segregations, which are related to coastal features of the lake.

Se describen las diferentes asociaciones de macroinvertebrados bentónicos del lago costero Budi, Sur de Chile, de naturaleza salada. Se relacionan la abundancia y biomasa de especies con los niveles de materia orgánica y tipos de sedimento, para lo cual se eligieron 9 estaciones de muestreo. El fondo fangoso es el sustrato que domina sobre el de grava, que es la menos representada. La materia orgánica presentó sus mayores porcentajes en el fango de las estaciones Allipén y Temo con 87,35 y 84,29% respectivamente. Se determinaron diferencias significativas entre las estaciones tanto para % textural como materia orgánica. Se identificaron 8 especies, distribuidas en los Phyla: Annelida (2), Arthropoda (3) y Mollusca (3), siendo Prionospio patagonica (Polychaeta, Spionidae) y Littoridina cumingi (Mollusca, Cyamiidae) las especies más abundantes. La mayor abundancia promedio registrada por estación de muestreo correspondió a 351 ind. m-2 y la mayor biomasa promedio fue de 1,0132 g m-2 en la estación Deume 2. Los valores más bajos de diversidad concuerdan con los valores más altos de Dominancia. El análisis de curvas ABC, señalan que las estaciones río Budi, Temo, Allipén, Bolleco, Botapulli, Deume 1 y Deume 3 presentan una baja perturbación. Los resultados de la ordenación no paramétrica (MDS), indican que existe una evidente segregación en dos grupos. La principal diferencia entre las estaciones es la abundancia del poliqueto Spionidae Prionospio patagonica. Las diferentes comunidades de macroinvertebrados presentan una estrecha relación con los niveles de materia orgánica y sedimentos. Se establece que la comunidad de la macroinfauna se presenta en dos segregaciones, las que se relacionan con las características ribereñas del lago.

The main aquaculture activities in the Quempillen estuary involve cultures of oysters, Ostrea chilensis and algae Gracilaria chilensis. Anthropogenic intervention inside the estuary generates significant changes in sediments and organic matter content.

Las principales actividades acuícolas en el estuario de Quempillen son la acuicultura de ostras, Ostrea chilensis, y del alga Gracilaria chilensis. La intervención antropogénica al interior del estuario genera cambios significativos a nivel del sedimento y de los contenidos de materia orgánica.

The “robalo” Eleginops maclovinus (Valenciennes 1830) is a common fsh in the littoral, estuaries and rivers (under tidal effects zone) of southern South América, including the Falkland islands. The feeding habits of this species is known mainly in the two frst mentioned habitats, where it consumes mostly animals from marine and estuarine origin. However, little is known about its seasonal feeding habits in limnetic environments. It is only assumed that it has to eat preys from freshwater origin. In the present study, 127 specimens of E. maclovinus were analysed, 119 of which had stomach contents. The zoophagic tendency of the species is corroborated, but also animáis from low salinities and limnetic salinities were found to be consumed inthe freshwater environment. Consequently, E. maclovinus appears as an extraordinarily versatile species, in relation to its feeding capacities, with physiologic characteristics allowing a wide osmoregulatory spectrum at the digestive level, probably one of the most variable within the suborder Notothenioidei, which has strong Antarctic links.