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In river ecosystems, spatial complexity as well as anthropogenic factors operating at different temporal and spatial scales are shaping demography, connectivity and population genetic structure of species inhabiting these habitats. Chilina dombeiana is a freshwater gastropod with direct development (absence of a free larval phase) that inhabits the Biobio river basin in Chile (36°S). No studies have yet evaluated the spatial patterns of the genetic diversity of this species and the potential factors that influence these patterns. Consequently, in this study, we analyzed the population genetics of C. dombeiana based on 15 locations along the Biobio river. Eight microsatellite loci were genotyped. Also, at each sampling site, 40 environmental parameters were recorded to characterize them. Results showed that C. dombeiana has low genetic variability with high population structure. In addition, we detected signs of historical decreases in effective population sizes, unidirectional gene flow (upstream to downstream) and contemporary demographic bottleneck. Spatial subdivisions in populations showed a pattern of isolation by distance. The redundancy analysis and variance partitioning showed that spatial components and dissolved oxygen could explain 28% of the interpopulation genetic variation, while the Random Forest analysis identified significant effects of dissolved oxygen, nitrite and total coliforms on the genetic variability of populations (22%). Although C. dombeiana is widely distributed in Chilean rivers, its low dispersal and specific habitat requirements make this species very sensitive to the severe increase in anthropogenic disturbances affecting river ecosystems in recent decades. Long-term monitoring of genetic population conditions and environmental parameters are needed to implement robust management and conservation policies.

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.

Anthropogenic threats and their impacts on aquatic ecosystems have traditionally been evaluated only through literature reviews. Within the last decade, however, expert opinions have become an increasingly popular alternative for gaining complementary information to literature reviews. This study employed a standardized method for collecting bibliographic data combined with synthesize expert opinions to establish a current knowledge baseline on threats to Mediterranean freshwater ecosystems in Chile. We revised 79 scientific articles that included a variety of taxonomic groups containing fish (n = 32); macroinvertebrates (n = 17); amphibians (n = 18); freshwater plants (n = 8); and two taxonomic groups simultaneously (n = 4). From this review, we identified 14 threats, with land-use change, species introductions, and industrial/domestic effluents as salient factors. These findings were in agreement with results from expert opinion surveys (n = 46 researchers). An analysis by taxonomic group indicated freshwater fishes as most threatened by hydropower plants. Aquatic plants were most threatened by mining. Amphibians were most threatened by changes in soil use whereas aquatic macroinvertebrates by industrial/domestic effluents. Remarkably, the magnitude of threats identified in the literature review was of similar order than those catalogued by experts. Moreover, the primary threats identified here align with those reported in other Mediterranean regions of the world. Our combined approach using literature review and expert opinion was useful in determining the consistency of the main threats to each taxonomic group. Our findings can be used as a baseline to further research and in prioritizing management strategies for threatened Mediterranean ecosystems worldwide.

Macroinvertebrates from a small forest stream in central-south Chile were sampled monthly from September 2017 to August 2018 to assess temporal variability in the assemblage and the effects of that variability on ecological indicators. Higher precipitation and flows occurred in winter months, and water quality varied among months. We collected 59 macroinvertebrate taxa, finding higher taxa richness and abundances in summer months than in winter months. Four taxa demonstrated marked seasonality, being abundant in some months and then decreasing in following months (Limnoperla jaffueli (Navas), Nousia maculata (Demoulin), Smicridea sp. (McLachlan), Chironomidae spp.). The scores of the family Hilsenhoff Biotic Index (HBI), Hilsenhoff Species-level Biotic Index (HSBI), Multimetric Macroinvertebrate Index (MMI), and Chilean Biological Monitoring Working Party (ChBMWP) index varied throughout the year reflecting natural variability. However, only HBI and HSBI scores were significantly different among seasons, ranging across three water quality classes (excellent, very good, and good), showing the lowest water classes in spring, coinciding with higher abundances of tolerant species. The MMI and ChBMWP indicated good and very good site conditions throughout the year, respectively. Shannon-Weaver diversity ranged between 2.59 (April) and 1.78 (February); however, Pielou evenness had high values throughout the year (> 0.62), except in February. Changes in macroinvertebrates composition throughout the year were explained primarily by discharge, water temperature, and conductivity. Our findings indicate that natural monthly variability in macroinvertebrate assemblages influences the scores of biological indices throughout the year. Therefore, we recommend that natural stream variability be accounted for in biomonitoring programs. We also emphasize the need to use caution when interpreting biological index scores to avoid misinterpretations in stream quality classification.

Increased anthropogenic disturbances affecting streams worldwide have resulted in declines of freshwater biodiversity. Mediterranean ecoregions are very sensitive to such disturbances because of their high levels of natural hydrological variability and increasing trends in human population growth. The use of aquatic macroinvertebrate assemblages as bioindicators is a commonly applied approach for evaluating water body condition. However, extensive use of macroinvertebrates across similar ecoregions may be limited because of natural local differences in biodiversity and differing anthropogenic disturbances. Here, we present a multi-metric index (MMI) based on macroinvertebrate assemblages from Chilean Mediterranean streams. To evaluate the relative level of disturbance among sampling sites with respect to multiple anthropogenic perturbations, we used an integrated disturbance index based on catchment and local scale disturbances. We sampled 95 sites from streams and rivers during the 2016 austral summer including 26 least-disturbed reference sites, 13 highly disturbed sites, and 56 intermediately disturbed sites. In addition, we re-sampled 14 sites during winter and spring to validate our findings. Using a set of screening criteria, we evaluated 74 candidate macroinvertebrate metrics, representing diversity, composition, trophic structure, and tolerance to pollution. The resulting MMI included Diptera taxa richness, total macroinvertebrate density, number of Ephemeroptera-Plecoptera-Trichoptera individuals, and predator taxa richness. The final MMI scores classified the 95 sampling sites into three categories of biotic condition, including good (n = 46), fair (n = 18), and poor (n = 31). Our approach is transferable to other rivers in the region and is a sufficient tool to evaluate the condition of sites affected by several human perturbations at both local and catchment scales in Chilean Mediterranean streams.

Traditionally, South American aquatic insects have been divided into cold and warm adapted forms. Cold-adapted forms inhabit freshwater systems from higher latitudes, or higher altitudes even around the Equator. Warm-adapted groups are defined as those found in lower latitudes and altitudes. This work aims to answer the questions: Are mayfly assemblages geographically segregated according to geographical (latitude) and topographical (altitude) surrogates of temperature? If so, where is this transition located? Location: South America. Methods: We compiled a data set about the relative incidence of 52 mayfly genera in 326 sampled communities. They span from 0 to 4,320 m and from 47.77° S to 5.74° N latitude. By virtue of the compositional nature of the data set, we applied the statistical procedures behind the Aitchison compositional data analysis. We delimited groups of assemblages based on their Aitchison distances and projected the data points onto a biplot obtained through Principal Component Analysis adjusted to compositions (Aitchison PCA). Results: A strong correspondence among biological and geographical information was detected, with mayfly assemblages clearly segregated in space. Andesiops and Meridialaris are typical cold-adapted forms; Baetodes, Leptohyphes and Thraulodes represent the warm group. Thermal groups can be separated by a curved line of altitude in function of latitude expressed in terms of a superellipse arc. Main conclusions: The classical ecological bipartition of mayflies into warm and cold freshwater groups is formalized quantitatively. The dividing line between warm and cold assemblages levels off at high altitudes (c. 3,300 m) around the Equator and falls to sea level at southern latitudes. The community bipartition line is useful for tracking global change through records of altitudinal displacement below and above of the warm/cold line of involved ecological groups. Fil: Dos Santos, Daniel A.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Biodiversidad Neotropical. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo. Instituto de Biodiversidad Neotropical. Instituto de Biodiversidad Neotropical; Argentina Fil: Molineri, Carlos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Biodiversidad Neotropical. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo. Instituto de Biodiversidad Neotropical. Instituto de Biodiversidad Neotropical; Argentina Fil: Nieto Peñalver, María Carolina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Biodiversidad Neotropical. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo. Instituto de Biodiversidad Neotropical. Instituto de Biodiversidad Neotropical; Argentina Fil: Zúñiga, María Angélica. Universidad del Valle; Colombia Fil: Emmerich, Daniel Enrique. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Biodiversidad Neotropical. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo. Instituto de Biodiversidad Neotropical. Instituto de Biodiversidad Neotropical; Argentina Fil: Fierro, Pablo. Universidad de Concepción; Chile Fil: Pessacq, Pablo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Centro de Investigación Esquel de Montaña y Estepa Patagóica. Universidad Nacional de la Patagonia "San Juan Bosco". Facultad de Ciencias Naturales - Sede Esquel. Centro de Investigación Esquel de Montaña y Estepa Patagónica; Argentina. Centro de Investigaciones Esquel de Montaña y Estepa Patagónicas (ciemep) Esquel; Argentina Fil: Rios-Touma, Blanca. Universidad de Las Americas; Ecuador Fil: Márquez, Javier Andrés. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; Argentina Fil: Gomez, Graciela Cecilia. Universidad Nacional de Jujuy. Instituto de Biología de la Altura; Argentina. Universidad Nacional de Jujuy. Instituto de Ecorregiones Andinas. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Ecorregiones Andinas; Argentina Fil: Salles, Frederico F.. Universidade Federal do Espírito Santo; Brasil Fil: Encalada, Andrea C.. Universidad San Francisco de Quito; Ecuador Fil: Principe, Romina Elizabeth. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; Argentina. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales; Argentina Fil: Gomez, Graciela Cecilia. Universidad Nacional de Jujuy. Instituto de Ecorregiones Andinas. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Ecorregiones Andinas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro de Investigaciones y Transferencia de Jujuy. Universidad Nacional de Jujuy. Centro de Investigaciones y Transferencia de Jujuy; Argentina Fil: Valdovinos Zarges, Claudio. Department Of Aquatic Systems, Faculty Of Environmental; Chile Fil: Dominguez, Eduardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Biodiversidad Neotropical. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo. Instituto de Biodiversidad Neotropical. Instituto de Biodiversidad Neotropical; Argentina

This chapter reviews the current state of knowledge of invertebrates of rivers, lakes, and wetlands in western South America, from southern Peru to the Strait of Magellan in southern Chile. A characterization of the diverse groups of insects, mollusk crustaceans, and other smaller groups is presented, and a biogeographic analysis of them is made with emphasis on their main forcing factors, ecology, and threats in the Anthropocene. This fauna presents Gondwanic characteristics, with clear North–South latitudinal patterns, covering from the Desert of Atacama in the North, one of the most arid deserts of the world, to the rainy and cold regions of the southern end of South America. The central zone of this territory includes one of the global biodiversity “hot spots,” which currently presents serious threats associated with changes in habitat, introduction of invasive species, climate change, and overexploitation of aquatic resources.

Changes in land-uses and cover are strong drivers of stream degradation worldwide. In Mediterranean ecoregions, land conversion from forest with native species to tree plantations, agricultural, and urban areas have drastically increased in recent years. Here, we examined the influence of land-use types on water quality (physical and chemical variables) and biota (benthic algae, macroinvertebrates, and fishes). We conducted field surveys between December-March 2016 (dry season) in 24 sites located across four land-use types including native vegetation (NV), tree plantation (TP), agriculture (Ag), and urban (Ur) within the Chilean Mediterranean ecoregion. We calculated metrics and multivariate statistics to assess correlations between biological and environmental variables. Significant differences between land-uses were found for environmental/physicochemical variables and the three biotic groups (i.e., benthic algae, macroinvertebrates, and fishes). We found higher chlorophyll-a biomass for TP, Ag, and Ur compared to NV streams. The macroinvertebrate diversity of sensitive taxa (i.e., Ephemeroptera, Plecoptera, and Trichoptera) and water quality were lower in land draining streams with human uses, other than NV, with the most evident impact found in Ag and Ur streams. NV and TP streams had a lower Diptera density and lower percentage of non-insect taxa. Fish richness and diversity were not affected by land-use. However, cold-water fishes (both native and introduced) were closely associated with NV and TP streams whereas warm-water fishes (mostly introduced) were closely associated with Ag and Ur streams. Multivariate analysis revealed that both local habitat and catchment-scale variables influenced each biological assemblage. Our findings suggest that benthic algae, macroinvertebrates, and fish populations are good indicators of human land-use disturbances, with Ag and Ur areas being the most detrimental for freshwater biota.

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.

Given the great extent of the Tubul-Raqui marshland, in addition to its high biodiversity and biological productivity, combined with a low degree of human disturbance, this wetland corresponds to one of the most important ones in Chile. This chapter describes its main features and effects caused by the February 2010 earthquake. The wetland continues to provide nesting and shelter sites for numerous resident and migratory bird species, many of which have conservation problems. The major anthropogenic threats to the conservation of the wetland and its different habitats have historically been bird hunting and deforestation of river shores that affect the sedimentation of the rivers that feed it. As for the structure of the physical habitat, water quality and aquatic biota of the wetland, since the earthquake of 2010 a series of relevant environmental changes have occurred. Some of them were expressed immediately during the earthquake, while others still continue to manifest themselves. The main changes resulting from the earthquake have resulted from its uprising of about 1.6 m above sea level, which has led to the total drying of the network of internal channels that irrigate the wetland, and partial one of the main channels of the rivers Tubul and Raqui. This has also limited the exchange with the sea, generating a decrease in the salinity of the waters to the interior of the wetland. The two most important benthic species for the artisanal fishery, the “Pelillo” seaweed (Gracilaria sp.), and the “navajuela” bivalve (Ensis macha), were severely affected and there is still no evidence of any degree of recolonization. Although the ecosystem was severely affected by the earthquake, it retains properties that allow it to remain within the country’s most important coastal wetlands.

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.

Many researchers have shown the importance of water chemistry and benthic habitat characteristics for the conservation of the freshwater macroinvertebrate biodiversity. However, few authors have examined the physical effect of extreme water-level fluctuations in lakes. The present study set out to determine, through a comparative study between a regulated lake (Laja Lake, LL) and an unregulated lake (Icalma Lake, IL) of the Andean zone of southern Chile, how man-made disturbances of the natural hydrological regime affect the structure of the benthic macroinvertebrate community. The results showed LL had very low values for species richness, density and biomass in comparison with IL, and the community was composed mainly of few individuals belonging to opportunistic taxa such as Chironomidae and Naididae. We suggest that the low values in the regulated lake are potentially explained by littoral zone factors driven by the water-level fluctuations such as: desiccation, freezing of the biota, removal of organic particles from the sediment and absence of aquatic macrophytes.

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

Knowledge of species richness centers is necessary for the design of conservation areas. In this study, we present a GIS analysis of two years of field data on animal and plant diversity distributions in evergreen, coastal rain forests of southern Chile (39°30′–41°25′ S). Despite their high endemism, these forests have remained largely unprotected. Field records were complemented with data from museum collections and scientific literature. We used selected environmental variables (evapotranspiration, altitude) and, in some cases, forest types as predictors of species distributions. Our study focused on the distribution of forest bryophytes, vascular plants, soil invertebrates, amphibians and birds. We generated distributional maps for each taxa based on their field records in the study area, complemented by natural history information, except in the case of bryophytes and soil invertebrates. In general, species richness was lower at 600 m elevation or above for all the taxa studied. Species richness tends to increase in the northern sector of the study area. We observed a greater richness of vascular plants near rivers and streams, and noted important floristic differences between west and east-facing slopes of the Coastal Range, with more species in the oriental side. Because species in high altitude forests are not a subset of those found at lower elevations, we propose that conservation strategies should prioritize the protection of the entire altitudinal gradient of the southern Coastal Range, especially in the more diverse oriental and northern sectors.

The most ubiquitous and well recognized diversity pattern at large spatial scales is the latitudinal increase in species richness near the equator and decline towards the poles. Although several exceptions to this pattern have been documented, shallow water mollusks, the most specious group of marine invertebrates, are the epitome of the monotonic decline in species diversity toward higher latitudes along the Pacific and Atlantic coasts of North America. Here we analyze the geographic diversity of 629 mollusk species along the Pacific South American shelf. Our analyses are based on the most complete database of invertebrates assembled for this region of the world, consisting of latitudinal ranges of over 95% of all described mollusks between 10° and 55°S. Along this coast, mollusk diversity did not follow the typical latitudinal trend. The number of species remained constant and relatively low at intermediate latitudes and sharply increased toward higher latitudes, - south of 42°S. This trend was explained by changes in shelf area, but not by sea surface temperature, unlike the pattern documented for Northern Hemisphere mollusks. Direct sampling of soft bottom communities along the gradient suggests that regional trends in species richness are produced by increased alpha diversity. and not only by artifacts produced by the increase in sampling area. We hypothesize that increased shelf area south of 42°S, geographic isolation produced by divergence of major oceanic currents, and the existence of refugia during glaciations, enabled species diversification. Radiation could have been limited by narrow continental shelves between 10°-42°. Asymmetries in latitudinal diversity trends between hemispheres show that there is not a single general factor determining large-scale diversity patterns.

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.

The consistent decrease in species richness with latitude shows several exceptions among marine organisms. We hypothesize that contrasting latitudinal diversity gradients can be explained by differences in critical life-history attributes, such as mode of larval development (MLD). We deconstructed latitudinal species richness patterns of marine benthic invertebrates according to MLD to elucidate differences in patterns of species richness and to reveal underlying processes. The patterns of species richness were remarkably similar across taxa within MLD but differed between MLD. Species richness decreased polewards in planktotrophic species and increased in direct developers. Temperature explained most of the variation in species richness. Low temperature at high latitudes may generally favour direct developing species, but, together with low chlorophyll-a concentration, limit the distribution of planktotrophic species. The contrasting influence of temperature on different MLDs might be explained by its effect on the length of planktonic life and on brooding costs.

En enero de 2006 se estudiaron los patrones espaciales de distribucion de comunidades de macroinvertebrados bentonicos de la cuenca hidrografica del rio Baker (45°50' O y 47°55' S) y los principales factores controladores, intentando cubrir la mayor variedad de ecosistemas loticos. Para llevar a cabo el estudio se seleccionaron 27 estaciones de muestreo ubicadas en las diferentes subcuencas del rio. En cada estacion se realizo una caracterizacion fisicoquimica del agua (conductividad, oxigeno disuelto, pH, temperatura y turbidez), y se documentaron las caracteristicas del tramo de rio (e.g. ancho del cauce y tipo de sedimento) e informacion cartografica utilizando un sistema de informacion geografica (SIG). Se identificaron un total de 51 taxa que correspondieron en su mayoria a larvas de insectos (80 %). Los grupos con mayor riqueza fueron los ordenes Ephemeroptera (15 taxa), Plecoptera (8 taxa) y Trichoptera (8 taxa). Los analisis de clasificacion y ordenacion realizados con los datos de abundancia, permitieron reconocer siete grupos de estaciones diferentes (A-F) que fueron estadisticamente significativos (P < 0.05). El analisis de regresion multiple, muestra que la variable ambiental que mejor explica los patrones biologicos observados, fue el porcentaje de cobertura de bolones, explicando el 44 % de la varianza de los datos biologicos (r2 = 0.44 P < 0.05).

A new species of Biomphalaria found in Andean swamps close to Isluga, Tarapaca Region, north of Chile, is described. The study of its anatomy, particularly of those structures which have been assigned taxonomic and phylogenetic value, allows both its comparison and evaluation to establish relationships and differences with other species of the High Andes plateau.

17 páginas, 5 tablas., [EN] A comprehensive literature review was conducted to determine the species richness of all the possible taxa of free-living benthic marine invertebrates in Chile. In addition, the extent of endemism to the Pacific Islands and deep-sea, the number of non-indigenous species, and the contribution that the Chilean benthic marine invertebrate fauna makes to the world benthic marine invertebrate fauna was examined. A total of 4,553 species were found. The most speciose taxa were the Crustacea, Mollusca and Polychaeta. Species richness data was not available for a number of taxa, despite evidence that these taxa are present in the Chilean benthos. The Chilean marine invertebrate benthic fauna constitutes 2.47 % of the world marine invertebrate benthic fauna. There are 599 species endemic to the Pacific Islands and 205 in the deep-sea. There are 25 invasive or non-indigenous species so far identified in Chile. Though the Chilean fauna is speciose there is still a considerable amount of diversity yet to be described, particularly amongst the small bodied invertebrates and from the less well explored habitats, such as the deep-sea., [ES] Se realizó una revisión exhaustiva de la literatura para determinar la riqueza de especies de todos los taxa de invertebrados bentónicos de vida libre en Chile. Además, se analizó el endemismo de invertebrados marinos bentónicos para las islas chilenas del Pacífico y el mar profundo y el número de especies no indígenas; del mismo modo que la contribución de estos invertebrados a la riqueza mundial de invertebrados bentónicos marinos. Para Chile se acumuló un total de 4.553 especies de invertebrados bentónicos. Los taxa con más especies fueron Crustacea, Mollusca y Polychaeta. En algunos taxa de invertebrados no se encontró información sobre la diversidad de especies presentes en Chile, a pesar de existir evidencia de que éstos están presentes en el bentos marino chileno. Los invertebrados bentónicos marinos chilenos contribuyen con el 2,47 % de la riqueza mundial de dichos invertebrados. Se encontraron 599 especies endémicas de las islas chilenas del Pacífico y 205 especies endémicas para el mar profundo. Hasta ahora en Chile se han identificado sólo 25 especies invasoras de invertebrados bentónicos marinos. Los invertebrados bentónicos marinos chilenos son diversos, pero aún hay especies no descritas, especialmente dentro de los invertebrados bentónicos de pequeño tamaño corporal que se encuentran en hábitat poco explorados, como por ejemplo el mar profundo., We acknowledge FONDAP-FONDECYT grant 1501-0001, Program 6 supporting M.R. Lee post-doctoral training. The Mellon Foundation Grant to J. C. Castilla. and S. Navarrete provided funds for the work of C. Hermosilla. We are grateful to M. Pardo, M. Rivadeneira and N. Ruiz-Tagle for their help compiling the database. We also acknowledge financial support from the FONDAP-FONDECYT grant 1501-0001 to the Center for Advanced Studies in Ecology & Biodiversity (JCC & MF) and a Pew Marine Conservation Fellowship to MF.

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.

Los moluscos del extremo sur de Sudamerica son desde un punto de vista taxonomico moderadamente bien conocidos. Sin embargo, la literatura esta dispersa, hay poca informacion sobre sus habitat y son muy pocos los registros distribucionales, particularmente en el area de los fiordos comprendidos entre la Isla de Chiloe (42° S) y Tierra del Fuego (55° S). Aunque se sabe bastante acerca de la biologia y ecologia de algunas especies de Nacellidae, la taxonomia del grupo ha sido relativamente poco estudiada, particularmente en areas remotas del planeta, como es el caso de los fiordos chilenos. El interes del presente estudio ha sido clarificar el estatus nomenclatural y describir las caracteristicas morfologicas y distribuciones de los Nacellidae chilenos. En particular, se plantearon los siguientes objetivos: (i) clarificar la identidad de las especies descritas, (ii) descripcion de detalles morfologicos, destacando los caracteres diagnosticos de cada especie, y (iii) delimitacion y discusion de sus rangos geograficos. El analisis de los Nacellidae de los fiordos chilenos ha permitido el reconocimiento de una especie de Nacella (Nacella) y siete de N. (Patinigera), cuyas principales diferencias a nivel de especie radican en la concha (forma, espesor y color) y en la morfologia de la denticion radular. El genero Nacella y su subgenero Patinigera son habitantes exclusivos de aguas antarticas y subantarticas. Estos organismos son lapas de aguas frias fundamentalmente subantarticas, pero que tambien se extienden hacia la Antartica por el area del Arco de Escocia, y hacia el norte a lo largo de la costa chilena, hasta el area de Valparaiso a 33° S (N. (P.) clypeater). Aparentemente este genero tiene su centro de distribucion en la Provincia magallanica en el sur de Sudamerica, correspondiendo a un area de elevada diversidad de especies (N. (N.) mytilina, N. (P.) chiloensis, N. (P.) deaurata, N. (P.) delicatissima, N. (P.) flammea, N. (P.) magellanica, N. (P.) venosa), donde las especies tienden a dispersarse hacia el este, con un transporte larval probablemente facilitado por la corriente de deriva del oeste que opera fuertemente en la zona subantartica