Queule River Research Articles

Erratum to: Ephemeral Aquatic Bird Assemblages in Estuarine Wetlands from South-Central Chile: Using an Intertidal Flat Habitat During the Austral Summer

The use of intertidal environments by aquatic birds is an important topic of study in the northern hemisphere, grouping baseline distributional descriptions to assess human–bird interactions during shellfish harvesting in soft substrates. However, patterns of tidal regime plus human and natural disturbances may differ in areas in the southern hemisphere. We studied the use of an intertidal flat by a temporary (i.e., ephemeral) assemblage of migratory and resident shorebirds and waterbirds in the Queule River Estuary (39° S), in south-central Chile, during the summers of 2003 and 2008. Migrant species such as Whimbrel Numenius phaeopus and resident Southern Lapwing Vanellus chinesis positively selected sandy substrates when feeding during both spring (periods with stronger tidal range) and neap tides (periods with weaker tides). The resident Yellow-billed Pintail Anas georgica only positively selected the muddy–sandy bottom during spring tides. The predominant activity of resident species was feeding during both tides, except for the Yellow-billed Pintail which rested during neap tides. We highlight the importance of microhabitats such as the intertidal flats system as feeding and resting areas for migratory and resident species. We also comment on their conservation and natural modification by mega-earthquake and tsunami effects that may result in the future destruction or generation of these key environments.

A study of the geographic distribution of swamp forest in the coastal zone of the Araucanía Region, Chile

A study was made of the geographic distribution of swamp forest in the coastal territory of the Araucanía Region, Chile. An analysis of maps, aerial photographs, and satellite images was carried out, together with field work, to determine the location, degree of fragmentation, shape of fragments and habitat use of the forest. The results showed a total area of 7675 ha of forest (in a region of 165,168 ha) divided into 427 fragments of highly irregular shapes, set in a farming matrix. This forest type was located principally on alluvial (37%) and fluvial-marine (33%) plains associated with the Toltén and Queule river basins. Land unsuitable for agriculture accounted for 50% of the area of forest (CIREN Classes VII and VIII), while land with a superficial phreatic water table (0–20 cm depth) and poorly drained soils concentrated 47% and 66% of the forest respectively. The majority of the forested area stands on soils with poor drainage (available habitat), as a response to the greater biophysical restrictions which such areas represent for agriculture. Of the forested area, 59% was located on 859 properties belonging to small-holders with up to 200 ha, while 39% was located on 58 medium to large properties (over 200 ha and over 1000 ha respectively). Forty percent of the forest is within 300 m of a road and only 8% is more than 1000 m away. It is concluded that the forest is under severe pressure from human activity (by clearing for agricultural land, grazing and firewood extraction) and that there is an urgent need for a plan giving priority to conservation.

Habitat use and spatial behaviour of the endangered Southern river otter ( Lontra provocax) in riparian habitats of Chile: Conservation implications

The spatial behaviour of 10 Southern river otters Lontra provocax was analysed using radio-tracking data collected in the Queule River, Southern Chile. The estimated otter density was 0.25 individuals km −1. Females with cubs and adult otters displaying mating behaviours were the only social group recorded. Studied otters were solitary and observed behaviour patterns suggest an intrasexual territoriality. No home range overlap among males existed while an average of 33% and 87% home range overlapped among females and between sexes, respectively. In the situation of core areas, only one case of overlapping between an adult male and an adult female was observed. Average home range and core area lengths were 11.3 km and 0.9 km, respectively. Otters used rivers more frequently than expected, whereas they avoided small streams. Low intensity livestock farming, without canalization of watercourses and riparian vegetation extraction practices, seems compatible with the presence of Southern river otter populations since the spatial behaviour of the studied otters was not affected under these circumstances. Based on the present official reserve sizes and distribution within the country, and also the increase of variant anthropogenic land uses outside these areas that result with consequent habitat loss and deterioration, we strongly recommend considering the importance of spatial dimension in quantity and quality habitats in further conservation planning for the Southern river otter using an integrated catchment management.

Seasonal and interannual variability in population abundances of the intertidal macroinfauna of Queule river estuary, south-central Chile

Durante octubre de 1990 a abril de 1992 y entre septiembre de 1995 a noviembre de 1997 se recolectaron muestras mensuales de sedimento en el estuario del rio Queule (ca. 39° S), centro sur de Chile, con el objetivo de estudiar la variabilidad temporal en las abundancias poblacionales de la macroinfauna que habita los sustratos arenosos y areno-fangosos del intermareal. Los sedimentos arenosos tuvieron mayores porcentajes de particulas de arena y porcentajes mas bajos de particulas de fango, agregados biogenicos y materia organica total en relacion a los sedimentos areno-fangosos. Se encontraron las mismas especies de macroinfauna en ambos sitios. La macroinfauna total estuvo dominada por poliquetos: Prionospio (Minuspio) patagonica Augener 1923, Capitella sp. y Perinereis gualpensis Jeldes 1963. Otros organismos comunes fueron el anfipodo Paracorophium hartamannorum Andres 1975 y el pequeno bivalvo Kingiella chilenica Soot-Ryen 1959. Las abundancias mas altas de la macroinfauna total ocurrieron usualmente durante los meses de verano (enero-febrero). La especie mas abundante fue P. (M.) patagonica (hasta 130-140.000 ind m-2 en los sedimentos areno-fangosos). Durante algunos meses, esta especie tuvo abundancias significativamente mas altas en esos sedimentos. Tendencia similar es la mostrada por P. hartmannorum; i.e., abundancias significativamente mas altas en los sedimentos areno-fangosos (hasta 75.000 ind m-2). Durante muchos meses las abundancias poblacionales de Capitella sp. y K. chilenica fueron significativamente mas altas en el sitio arenoso. Las abundancias mas altas de Capitella sp. estuvieron proximas a 37.800 ind m-2 (febrero de 1991 y febrero de 1996), mientras que los valores maximos para K. chilenica estuvieron en el rango de 13.000-14.000 ind m-2 (febrero de 1991 y noviembre de 1995, respectivamente). Las abundancias poblacionales de P. gualpensis (con la excepcion del periodo octubre de 1995 a enero 1996) fueron similares en ambos sitios. Comparaciones interanuales de las abundancias de la macroinfauna del sitio arenoso no mostraron diferencias para la macroinfauna total y todas las especies con excepcion de P. gualpensis. No se encontraron diferencias interanuales significativas para la macroinfauna total y las abundancias de P. (M.) patagonica, P. gualpensis y P. hartmannorum en el sitio areno-fangoso. Por otra parte, las abundancias de Capitella sp. y K. chilenica mostraron diferencias significativas entre anos. Se encontraron diferencias significativas entre meses dentro del mismo periodo anual, tanto para la macroinfauna total como para las abundancias especificas en el sitio arenoso y areno-fangoso. La variabilidad temporal de la macroinfauna no tuvo ninguna relacion significativa con la variabilidad temporal de las caracteristicas del sedimento

Population Biology of the Intertidal Snail Chilina ovalis Sowerby (Pulmonata) in the Queule River Estuary, South-Central Chile

The temporal variability in abundance and population structure of the gastropodChilina ovalis Sowerby was studied in the upper intertidal zone of Queule River estuary, south-central Chile (c. 40°S). Snails were collected monthly (September 1995–December 1997) from haphazardly-located quadrats (50×50 cm, n=5 each time), and counted and measured (shell height) in the laboratory. Water and sediment samples were collected at the same time to study the snail's habitat characteristics. Overall mean abundance was 115 individuals m−2 (SD=55). Monthly abundance estimates indicated a clear decrease during 1997. This decrease appeared to be related to the annual recruitment success of the species and at least partially to water temperature and sedimentological variability. Overall size range ofC. ovalis was 1.5–27.5 mm shell height. Growth varied seasonally with highest growth rates observed after recruitment (November–February). Slower growth continued throughout the austral winter months. Despite changes in abundance between 1996 and 1997, no differences were detected when population growth estimates were compared between years. A maximum longevity of approximately 4 yr was estimated from the growth curves of the cohorts, and a life cycle with more than one reproductive period is suggested.

Temporal and spatial variability in the sediments of a tidal flat, Queule River Estuary, south-central Chile

Los estuarios micromareales de planicie fluvial estan numerosamente representados a lo largo de la costa de Chile centro-sur (ca. 3541°S). El estuario Queule (39°23'S, 73°12'W) presenta una planicie mareal, originada despues del sismo y tsunami de mayo de 1960, y esta compuesta por areas arenosas y fangosas. Los estudios anteriores en esta planicie fueron el resultado de muestreos de corto plazo; por esta razon los objetivos de este estudio incluyeron la evaluacion de los cambios texturales estacionales, la interpretacion del posible sincronismo de tales cambios en ambas areas, y la determinacion de la eventual relacion entre las caracteristicas sedimentologicas y la variabilidad de la descarga del rio y la altura de la onda de marea. Ambas areas se muestrearon 27 veces desde noviembre de 1995 a diciembre de 1997. Se aplicaron procedimientos estandar de laboratorio para determinar la textura de las muestras. Tambien, se obtuvo informacion meteorologica desde una estacion cercana, y ademas datos de proyecciones de marea de tablas nacionales. Esta informacion se uso para explorar la variabilidad temporal de las caracteristicas sedimentologicas y las relaciones con las variables ambientales por medio de modelos estadisticos de analisis de varianza de una via, regresion multiple y analisis canonico. Dos variables, tamano medio de la arena y el porcentaje relativo de la fraccion organica del fango no presentaron diferencias entre ambas areas. La mayoria de los parametros sedimentologicos, i.e., porcentajes de arena organica, fango organico e inorganico, y tamano medio de la arena variaron simultaneamente en ambas areas, pero la variacion fue mas importante en la zona fangosa. Se detectaron relaciones significativas entre la variabilidad de algunas caracteristicas de los sedimentos y la altura de la marea y la precipitacion. Los cambios mas conspicuos estuvieron relacionados con la temporada lluviosa del evento El Nino de 1997.

Seasonal Vertical Distribution of the Intertidal Macroinfauna in an Estuary of South-central Chile

Seasonal sampling of sediments (May 1988–May 1989), carried out at two intertidal areas of the Queule River Estuary, was used to analyse the vertical distribution of the macroinfauna and sedimentological characteristics. In all seasons, the substratum characteristics of both areas showed small differences between 0 and 12 cm depth. The macroinfauna of both areas showed a clear stratification with the highest abundances at the superficial layer of sediment (0–3 cm). No spatial partitioning among the species was evident. It was concluded that the substratum characteristics were not a primary factor in determining the stratification of the macroinfauna. However, some physical factors may well limit the burrowing capabilities of the species (e.g. the discontinuity between the oxidized and reduced sediments), as well as biological factors such as body size (particularly that of the juveniles) and responses against epibenthic predation by burrowing to deeper sediments. Some of these factors would probably better explain the vertical distribution of the intertidal macroinfauna in the Queule River Estuary.

Macroinfaunal Assemblages Associated with Mussel and Clam Beds in an Estuary of Southern Chile

Samples were collected from September 1990 to February 1992, at three subtidal sites of the middle reaches of the Queule River estuary, southern Chile, to analyze the spatial and temporal variability of the macroinfauna inhabiting substrata with different abundances of bivalves. In addition, water and sediment samples were obtained to study the relationships between the temporal variability in macroinfaunal abundances, physical factors and chlorophylla content. Temperature, salinity, and chlorophylla showed a rather strong seasonal variability but slight between-site differences. Sediment characteristics and bivalve abundances, by contrast, exhibited little temporal variability but large differences between sites. The macroinfauna was primarily represented by polychaetesPrionospio (Minuspio) patagonica being dominant in the three areas. Most dominant species showed similar trends of temporal variability, with maximum abundances recorded during spring and fall. The appearance of recruits was restricted to the summer with little difference among sites. Multiple regression analyses showed that the temporal variability of macroinfaunal adults and recruits, was primarily associated with variability in salinity and water temperature, respectively. Spatial variability of these organisms was also explained by variations in these factors, together with those of sediment texture and organic matter content. No evidence of interactions (significant relationships) was found between the abundances of bivalves and those of the macroinfauna, nor among macroinfaunal organisms.

Temporal Variability in the Intertidal Macroinfauna in the Queule River Estuary, South-central Chile

The surface sediments (0-3 cm) of two intertidal areas of the Queule River estuary ( c. 39°S) were sampled monthly to study the seasonal variability of the macroinfauna and its relationship with the variability of water and sediment characteristics. One of the areas had sandy sediments; the other had muddy sand. Temperature and water salinity showed a seasonal trend with the lowest values during winter months. No differences were found in the sediment temperatures between areas but the muddy sand area had higher percentages of mud, aggregates, organic matter and water, as well as higher penetrability values. All but one of the macrobenthos species occurred at both areas and the same taxa dominated both assemblages. Population abundances fluctuated seasonally with higher values during summer-autumn and higher variability at the muddy-sand area. Of the variability in the abundances of the most representative species 28-84% was accounted for by the variability in some of the physical variables. Thus, these results show that macrofaunal assemblages occupying different sedimentological facies in the intertidal zone (sand-muddy sand) do not have major differences in their patterns of seasonality, and suggest that sedimentological characteristics have a limited role in determining community structure in the areas studied.

Reproductive habits and life cycle of the small clam Kingiella chilenica (Bivalvia: Cyamiidae) in an estuarine sand flat from the south of Chile

A population of the small clam Kingiella chilenica Soot Ryen 1959 was studied from March 1986 to December 1988 in an intertidal flat at Queule River, in the south of Chile. The life cycle and life history pattern of the bivalve were established contrasting population structure and dynamics to its reproductive habits. Individuals are gonochoristic and semelparous, presenting a typical annual life cycle. The species is a sequential brooder whose embryos undergo direct development. After the brooding season (summer through autumn), the adults disappear gradually (autumn through winter). Recruited juveniles overwinter during a relatively long period, undergoing rapid growth during the spring to attain the adult stage during the summer. The number of brooded embryos increases in proportion to adult length cubed. Life history traits of this bivalve are compared to those reported for other small brooder clams. Some basic tendencies become apparent when traits for semelparous versus iteroparous species are contrasted. As in other semelparous sequential brooders (Transennella tantilla, Gaimardia bahamondei), the relationship between brood size and shell length obseved in K. chilenica does not fit the allometry hypothesis for marine brooding invertebrtes that allometric constraints on the brooding space limit the fecundity of larger individuals. Also contrary to theoretical predictions, small body size does not limit the diversity of a clam's developmental patterns. Possible explanations for this finding are discussed.

Community Structure of the Subtidal Macroinfauna in an Estuarine Mussel Bed in Southern Chile

Abstract. The mussels Choromytilus chorus and Mytilus chilensis are the most distinctive bivalves of the subtidal soft bottoms of Queule River estuary, southern Chile (ca. 40 °S). In some artificially farmed areas of this estuary, the semi‐buried mussels reach densities as high as 250–300 adult indiv. m‐2. We carried out seasonal (1983) and fortnightly samplings (August 1984 to December 1985) to compare abiotic and biotic characteristics (i. e., macroinfaunal community structure) on bottom areas with and without mussels. Biodeposition within the mussel bed area did not result in organic enrichment of the sediments, a situation which is discussed in relation to the breakdown of mussel biodeposits. During most of this study, organic matter (%) was higher in the sediments of this area versus that without mussels. While the sediments of the mussel and control area were dominated by the same macroinfauna (i.e., polychaetes), that of the mussel area generally had lower abundances, number of species, and diversity indices. Several explanations are presented to account for diminished abundance and diversity values here. These include insufficient substrate for settling larvae, space limitation, and negative effects of sediment characteristics.SummaryMussel biodeposition in a mussel bed area at the Queule River estuary did not result in organic enrichment of the sediments. This may be attributed to the high rate of biodeposit disintegration. During most of the study, the percentage of combustibles (i. e., organic matter) was higher in the mussel bed sediments. This was not necessarily the effect of mussel biodeposit accumulation, since field studies (between‐site comparisons during flood and ebb tides) showed no significant differences between the amount of organic matter in the near fluid, fecal‐rich sediments surface (i. e., 0.5 cm) of the mussel and control area. The macroinfauna of both areas was dominated by the spionid Minuspio chilensis and one capitellid worm. The abundance of the whole macroinfauna and that of the most characteristic taxa peaked during summer‐autumn months. No changes were detected in the community structure of either area (e. g., no changes in the rank of dominant species). The abundances, number of species, and diversity indices were generally lower in the mussel bed area. This condition may be related to negative effects of some sort of mussel‐macroinfauna interaction such as space reduction, adult‐larval interactions, or changes in sediment characteristics.

Annual fluctuations of the subtidal macroinfauna in an Estuary of South of Chile

Monthly samples taken at two separate stations in the Queule River Estuary, between May 1980 and April 1981, were used to study annual fluctuations of the subtidal macroinfauna. In both stations, t...

Subtidal Benthic Macroinfauna in an Estuary of South Chile: Distribution Pattern in Relation to Sediment Types

Abstract. A quantitative survey (18 stations) of the subtidal soft bottom macroinfauna in an estuary of the south Chilean coast was conducted during January, 1980. The map of sedimentological facies elaborated for the Queule River Estuary shows sandy bottoms in the outlet and upper part of the area studied, while the middle part is occupied by muddy sand. The ordination of stations by Principal Component Analysis is fundamentally defined by mud and gravel percentage and is, in general, concordant with the distribution of sediments in the facies map. A total of 17,405 animals was collected (16 taxa), Polychaeta being the dominant group in density (77.47%) and biomass (73.4%). The maximum number of species was obtained outside the mouth of the estuary, while maximum densities and biomass were obtained in the middle of the estuary.The Factor Analysis performed with the abundances data of the most abundant species rendered the ordination of two groups of stations (concordant with a Cluster Analysis) in the Q‐mode and two groups of species in the R‐mode. One group of stations is restricted to sandy habitats of the outlet area and is dominated by suspension feeders. The other, in the middle and upper part of the estuary (muddy sand or sandy bottoms with a higher percentage of organic matter), is dominated by deposit feeders. Between these two groups, significant differences in sedimentological variables (sand, mud, and organic matter percentage) were detected. Each of the two delineated groups of species corresponds to the groups of stations, showing that most of the taxa can be combined in faunal assemblages with preference for different types of substrate.

Estudio estacional de los sedimentos del estuario del Queuele, IX Región

An area between the mouth and 3.5 km upstream was seasonaly sampled, in order to analyze in detail and from a dynamic viewpoint the sedimentary facies spatial distribution and the organic matter content of the present sediments of the Queule River Estuary.Grain size analyses were determined by the combined sieve and pipette method, and the content of carbon organic matter was determined by ignition. Granulometric parameters of mean size, sorting and skewness were calculated by the method of statistical moments.Ten textural facies in summer and nine in winter were distinguished in the estuary. In the time between summer and winter samplings, facies were affected by changes in their spatial distribution, in response to the energy level variations in the estuary. The distribution of carbon organic matter in the sediments correlates closely with the distribution of fine - grained material, and there exists a great correlative coefficient between both components. The contents of totalorganic matter (21% maximum) seem to be higher than would be expected to occur naturally in an estuary of this type.