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Stream-lake networks include multiple transition zones between lake-like and river-like conditions. This study analysed environmental features, macroinvertebrate assemblages (MIB) and functional feeding groups in outlet, inlet and tributary streams (i.e. streams other than the main stem) of a stream-lake network in Chilean Andean lakes, to verify if lake outlets reflect an ecotone condition. Permutational analysis of variance and canonical analysis of principal coordinates based on environmental features and MIB revealed a significant difference between stream types. Higher taxa richness was found in tributaries, whereas population densities, equitability and diversity indices varied between stream types. Eighty-five taxa were identified, with 7% of taxa found exclusively in outlets, 5% in inlets, and 22% in tributaries. Collector-gatherers were dominant in all stream types and there was no statistical differences among feeding groups and stream types. The distance-based linear model identified water temperature, % rock, % sand, and % FPOM coverage as having significant influence on richness and density of MIB in summer, while water temperature and %FPOM coverage were significant in spring. Our results suggest that lake outlets house MIB different than lake inlets and tributaries, as well as environmental variables, supporting the idea that Andean lake outlets reflect an ecotone condition.

The gross internal anatomy of the cephalocarid crustacean Sandersiella chilenicaStuardo & Vega, 2011 is described based on light microscopy of histological sections of three specimens of the type series, all collected in coastal soft bottoms off central Chile. Observations mainly concern the nervous, digestive, and reproductive systems, heart, haemocoel, and skeleto-musculature. The main organ systems and musculature are similar to those previously described for Hutchinsoniella macracanthaSanders, 1955, Lightiella magdaleninaCarcupino, Floris, Addis, Castelli & Curini-Galletti, 2006, and Sandersiella sp.

This study assessed natural variation in the macroinvertebrate assemblages (MIB) and water quality in one of the main basins with the largest agricultural activities in Chile (Aconcagua River Basin). We sampled throughout the annual cycle, nine sampling sites were established along the basin, classifying according to agricultural area coverage as least-disturbed, intermediate, and most-disturbed. We collected 56 macroinvertebrate taxa throughout the entire study area. Multivariate analysis shows significant differences among the three disturbance categories in different seasons, both water quality variables and the MIB structure. Distance-based linear model (DistLM) analysis for all seasons explained more than 95.9% of the macroinvertebrate assemblages, being significantly explained by chemical oxygen demand, pH, total coliforms, nitrites, elevation, and water temperature. ANOVA test revealed significant differences in the proportion of noninsect individuals, macroinvertebrates density, and the number of taxa among the three disturbance categories (p &lt, 0.05). In general, water temperature, conductivity, chemical oxygen demand, ammonium, nitrites, and nitrates increased their values downstream in the basin. Our results indicate that the elevation gradient and increment in agricultural land use in the basin had a strong influence on water quality and MIB. A better understanding of these ecosystems could help conservation and integrated watershed management.

The subduction earthquake Mw = 8.8 on February 27th, 2010 which affected Chile's south-central coast (37°S) produced a co-seismic uplift of ~1.4 m in coastal Tubul-Raqui wetland area, with abrupt morphological changes. In order to determine the magnitude of the changes, in this area of high conservation value, salt marsh morphological features were identified and quantified by mapping the changing extent of the coverage of morphological features before (2009) and after (2011–2012) the tectonic disturbance. Rectified satellite images of seven study sites were created for the three years using Google Earth images and processed in ArcGIS. The results indicate a total decline of 31.7% in the area of the morphological features and the emergence of 1.25 km2 of dried area; salt pans and tidal creeks were severely affected, with more than 90% loss. In contrast, there was a slight recovery of the Tubul and Raqui main river channel (12%) and the tidal channels (8.5%) between 2011 and 2012, mainly in the area near the river mouth. The salt marsh (cover by Spartina densiflora) showed slight variation after the co-seismic uplift (14.6%), demonstrating high tolerance in the face of high-impact natural disturbances. The changes and later evolution may be explained mostly by the action of the seismic cycle in subduction zones. Continuing to monitor state of the recovery of the salt marsh and other similar environments may help to understand the true role that the seismic cycle plays in the dynamics of coastal ecosystems, as well as its incidence in the recovery process.

Coseismic uplift, as caused by high-magnitude earthquakes, can modify shoreline morphologies and the functioning of coastal wetlands. This phenomenon occurred with the 8.8-Richter scale earthquake that affected central-south Chile in 2010. The recorded coseismic uplift was 1.6 m.a.s.l. significantly changed the Tubul-Raqui Saltmarsh. The most important impact of this event was decreased marine intrusion, which, in turn, led to desiccation within the saltmarsh and, consequently, the death of aquatic organisms. This study recorded the effects that physical/chemical changes in water quality and the sedimentary environment had on the macrobenthic community (>500 μm) 2, 6, and 10 months after the uplift event, with data compared against historical records. Non-metric multidimensional scaling evaluated changes in the biological community, while principal components analysis was used to assess environmental changes. Both matrices were adjusted through correlation. Significant pre-versus post-earthquake modifications were found at sites closest to the estuary inlet. The most significantly affected macroinvertebrate was Paracorophium hartmannorum. The most tolerant taxa to environmental perturbations (i.e., Diptera, Annelid, and Polychaeta) surpassed pre-earthquake abundance records after just ten months, whereas the most sensitive taxa were not found after the earthquake. Most (81.8%) variables of water quality (i.e., total suspended/inorganic/organic solids and chlorophyll-a), as well as the sedimentary environment (i.e., sediment redox potential, fine fraction, and area of emerged bed), were significantly correlated with the macrobenthic community. The results of this study show the resilience capacity of important components of a saltmarsh after a major natural disturbance.

Los ecotonos transicionales entre lagos y rios han recibido menor atencion que aquellos de ecosistemas terrestres, y pueden reunir caracteristicas particulares de gran importancia para la conservacion de la biodiversidad dulceacuicola. Con el objeto de evaluar lo anterior, se estudio la dinamica espacio-temporal de las abundancias y tallas, de poblaciones de 13 especies de peces nativos chilenos, presentes en la zona ecotonal Lago Rinihue - Rio San Pedro, ubicada en la cuenca hidrografica del rio Valdivia (Chile). Se muestrearon mensualmente 35 sitios localizados en tres zonas hidromorfologicas del area de estudio (numero de sitios por zona: Ml = 9, M2= 17, M3= 9). Los muestreos se llevaron a cabo el ano 2006. De manera complementaria, se realizaron muestreos en todos los sitios los anos 2007 (enero - febrero, junio - agosto y diciembre) y 2008 (enero - marzo). Los resultados de este estudio muestran la presencia de un ecotono muy dinamico tanto espacial como temporalmente, apoyando la hipotesis que estas zonas transicionales poseen caracteristicas especiales que deben ser tomadas en consideracion para la conservacion de la biodiversidad.

The Chilean lake district includes diverse lentic ecosystems along ca. 700km of the country (36°–43°S), including the “Nahuelbutan lakes”, “Araucanian lakes” and “Chiloe lakes”. This area is recognized as an important “hot spot” of benthic freshwater biodiversity in Southern South America. In Chilean temperate lakes, increased nutrient loads of P and N caused eutrophication, particularly in the Nahuelbutan Lakes. The freshwater Hyriidae mussel Diplodon chilensis (Gray, 1828) which is one of the most abundant species in Chilean temperate lakes, is known to be very susceptible to eutrophication. This species presents a clear reduction in its geographic ranges and is considered to be a threatened species in many Chilean lakes. In this study, we used a correlative approach to determine how eutrophication-driven changes in the food supply and in geographical parameters of different Chilean lakes affected the shell growth rates of D. chilensis. The results obtained from sclerochronological analyses of the mussel shells suggest an association with a group of environmental variables, including geographical types (negative), such as latitude and altitude, and limnological types (positive), especially phosphorous and turbidity. However, the D. chilensis populations under extreme conditions of turbidity in eutrophic and hypertrophic lakes are extinct or nearly so. The high positive correlation of the mean D. chilensis growth rates with orthophosphate (R=0.76; P

Oxygen uptake rates of undisturbed sediment columns have been used as an integrative measure of the metabolic activities of benthic communities. Since the intensity of metabolic processes of profundal lake is dependent on the production of organic matter in the pelagic zone, oxygen uptake rates reflect the trophic condition of the whole lake. Four small lakes of central Chile, differing strongly in trophic conditions, provided a possibility to compare benthic oxygen uptake rates, under different oxygen conditions (Quinenco, Grande, Chica and Lleulleu). Our objective was to establish the relationship between the oxygen uptake rates and bottom characteristics of lakes with different trophic conditions. At 8 mg O2 l-1 in the overlying water of the cores studied, the oxygen uptake rates of the sediment were: Quinenco 51.2–56.0 mg O2 m2 h-1 (eutrophic), Grande 41.2–46.4 mg O2 m2 h-1 (mesotrophic), Chica 23.2–18.1 mg O2 m2 h-1 (mesotrophic) and Lleulleu 11.7–16.0 mg O2 m2 h-1 (oligotrophic). By exposing the sediments to different oxygen levels in the laboratory, it was found that benthic community metabolism decreased with oxygen concentrations. The slope of regression lines, relating oxygen uptake rates to oxygen concentrations, differed for the different sites investigated, closely related with the trophic conditions of the lakes. It was positively correlated with the organic matter content of the sediment of the cores (r2= 0.78, p

Aegla alacalufi and A. neuquensis are exclusively found in freshwater systems of Patagonia. The geographic distribution range of A. alacalufi is vast and fragmented, covering continental and insular rivers. A new record of this species on Duque de York Island (50°34′S-75°20′W) defines the southernmost limit for the distribution of freshwater anomuran crustaceans. Aegla neuquensis is only found in Extra-Andean Patagonian rivers. The current geographic distribution patterns of these species can be explained by the existence of multiple island glacial refuges during the Last Glacial Maximum and by the hydrographic captures that occurred during the Late Glacial.

Se estudiaron las comunidades de macroinvertebrados bentonicos de la cuenca hidrografica del rio Aysen (44°45' -46°15'S; 71°00' - 73°00'W). Semuestreo en 14 estaciones que se distribuyeron en las diferentes subcuencas intentado cubrir la mayor variabilidad del paisaje fluvial. Los muestreos de macroinvertebrados se realizaron empleando una red Surber. En cada sitio se cuantificaron parametros fisico-quimicos de la columna de agua (pH, conductividad electrica, solidos disueltos, temperatura y oxigeno disuelto), ademas de parametros fisicos del rio (orden del rio, pendiente, ancho, profundidad media, velocidad media, tipologia de la vegetacion riberena y substrato). Se identifico un total de 59 taxa, la mayor parte de los cuales correspondio a estados inmaduros de insectos (83%). Dentro de estos, los grupos mas diversos fueron los ordenes Plecoptera (19 taxa), Ephemeroptera (14 taxa) y Trichoptera (10 taxa). Los analisis de clasificacion y ordenacion de estaciones realizados con los datos de abundancia, permitieron reconocer cinco grupos de estaciones estadisticamente diferenciados (P

El extremo sur de Sudamerica representa una de las areas subantarticas mas interesantes desde un punto de vista ecologico y biogeogranco. A pesar de ello, el conocimiento que se tiene sobre la biodiversidad del area, y en particular de los habitats marinos submareales, es relativamente pobre. En el ano 2004 se realizo un proyecto de investigacion sobre biodiversidad como parte del crucero Fiordos Cimar-10, organizado y financiado por el Comite Oceanografico Nacional de Chile (CONA). En este articulo se describen los resultados obtenidos sobre de los moluscos submareales. Las muestras fueron obtenidas en el invierno del 2004, a bordo del buque Agor 60 "Vidal Gormaz". El area de estudio se localizo en el extremo norte de la Patagonia chilena, desde el Seno de Relocanvi (41 °31' S) hasta la Boca del Guafo (43°49'S), en la plataforma continental comprendida entre 22 y 353 m de profundidad. Los moluscos fueron recolectados en 23 estaciones de muestreo empleando una rastra Agassiz. Se registro un total de 67 especies, consistentes en 4% Polyplacophora (Leptochitonidae, Ischnochitonidae), 58% Gastropoda (Lepetidae, Fissurellidae, Trochidae, Turbinidae, Calyptraeidae, Capulidae, Naticidae, Ranellidae, Cerithiopsidae, Epitoniidae, Muricidae, Buccinidae, Columbellidae, Nassariidae, Volutidae, Cancellariidae, Turridae, Pyramidellidae, Acteonidae, Chilinidae), 36% Bivalvia (Nuculidae, Yoldiidae, Malletiidae, Tindariidae, Limopsidae, Phylobryidae, Mytilidae, Pectinidae, Propeamussidae, Lucinidae, Thyasiridae, Neoleptonidae, Carditidae, Condylocardiidae, Veneridae, Tellinidae, Lyonsiidae, Pandoridae, Cuspidariidae) y 1% Scaphopoda (Rhabdidae). Nuestros resultados muestran que las especies submareales presentan una elevada proporcion con caracter austral (magallamco). Del total de 67 taxa registrados, 45 especies son estrictamente magallamcas o antarticas (67%) y 16 presentan una amplia area de distribucion que se extiende al sur del area de estudio (24%). Solo seis de las especies (9%) son estrictamente de la provincia biogeografica peruana.

De acuerdo a la literatura, los gastrópodos dulceacuícolas chilenos están compuestos por 73 especies, i.e., 30 spp. de Chilinidae (género Chilina Gray 1828), 4 spp. de Physidae (género Physa Draparnaud 1801), 5 spp. de Lymnaeidae (género Lymnaea Lamarck 1799), 7 spp. de Planorbidae (género Biomphalaria Preston 1910), 5 spp. de Ancylidae (género Anisancylus Pilsbry 1924 y Uncancylus Pilsbry 1913), y 22 spp. de Hydrobiidae (género Potamolithus Pilsbry 1896 y Littoridina Souleyet 1852). La distribución del conjunto de especies de gastrópodos se extiende desde Arica en el norte hasta Magallanes en el sur. Sin embargo, la mayor parte de las especies tiene su rango geográfico restringido a una o unas pocas cuencas hidrográficas contiguas a lo largo del gradiente latitudinal. La mayor concentración de especies de gastrópodos se localiza entre las regiones administrativas VII y X. Actualmente existe una importante falta de conocimiento en relación a la taxonomía, biología, ecología, biogeografía y estado de conservación de prácticamente todas las especies de gastrópodos dulceacuícolas chilenos.

Estudios de la biodiversidad existente en la zona intermareal rocosa del centro-sur de Chile, tanto de carácter local como regional, todavía son limitados. Debido a ello, no permiten el reconocimiento de patrones de diversidad a lo largo de la costa con una gran resolución espacial, lo cual es información básica al momento de priorizar áreas para la conservación de la biodiversidad. En este sentido, el objetivo de la presente contribución es estudiar la malacofauna de la zona intermareal rocosa del centro-sur de Chile, en un tramo de 250 km de costa, comprendida entre Punta Pingueral (36° 31'S) y Cabo Tirúa (38° 25'S). Se estudiaron los moluscos de 23 sitios de muestreo, incluyendo las islas Santa María y Mocha. En cada sitio se caracterizó el hábitat rocoso (morfometría, tipo de roca, grado de exposición al oleaje, abundancia de arena intersticial, y área total de la superficie) y se realizaron muestreos exhaustivos de malacofauna en los niveles del intermareal superior, medio e inferior. Se registró un total de 90 especies de moluscos pertenecientes a 29 familias. Del total, el 61,1% son Gastropoda, el 25,6% Bivalvia y 13,3% Polyplacophora. Se discuten aspectos taxonómicos y se presenta una clave de identificación de las especies

En un sistema léntico los cambios en los niveles de trofía normalmente están acompañados de cambios estructurales en la biota. Una de las formas de establecer estos cambios estructurales en forma simple es a través de una evaluación rápida de la biodiversidad, realizada basándose en la discriminación de morfoespecies, sin tener que profundizar las identificaciones taxonómicas a niveles de género y especie. Se evaluó la biodiversidad de las comunidades de macroinvertebrados bentónicos de cinco lagos de la VIII Región de Chile (Chica y Grande de San Pedro, Lleu-Lleu, Quiñenco y Lanalhue), y se discute su asociación a distintos niveles de trofía. Se registró un total de 44 morfoespecies, la mayoría de los cuales corresponden a larvas de Insecta (39%), Acari (25%) y "otros taxa" (35%), incluyendo Annelida, Mollusca, Crustacea y Platyhelminthes. El número de morfoespecies fue similar a la de otros lagos temperados sudamericanos. Los datos sugieren que la abundancia de Acari se incrementa desde la oligotrofía a la eutrofia, pudiendo ser potenciales bioindicadores en lagos de Chile central In a lentic ecosystem the trophic levels are usually accompanied by structural changes in the biota. One of the ways to establish such changes in a short time is the rapid biodiversity assessment, based on the discrimination of morphospecies instead of the identification of the genera and species levels. We evaluated the biodiversity of the benthic community of five lakes of the VIII Region of Chile (Chica y Grande de San Pedro, Lleu-Lleu, Quiñenco y Lanalhue), and we discuss its association with distinct trophic levels. A total of 44 morphospecies were recorded, and found that the majority of them corresponded to Insecta larvae (39%), Acari (25%), and "other taxa" (35%), including Annelida, Crustacea, Mollusca and Platyhelminthes. The number of morphospecies was similar to other South American temperate lakes. The data suggest that the abundance of Acari is incremented from oligotrophy to eutrophy, suggesting that they are potential bioindicators in lakes of central Chile