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The commensals on Chilean Decapoda of inland waters are characterized by a marked microendemism. The aim of the present study was to do an exhaustive review on the ectocommensals on Chilean inland-water decapods. The literature revealed the presence of species of Protozoa, viz., eight known only from Parastacus pugnax (Lagenophrys andos, Operculigera insolita, O. parastacis, O. seticola, O. striata, O. taura, Chilenophrys allendei, and Circolagenophrys shiftus), one for both P. pugnax and P. nicoletti (L. anticthos), one for Parastacus pugnax and Samastacus spinifrons (O. asymmetrica), and one reported for Aegla laevis (O. velata). In addition, the presence of flatworms was described, specifically Temnocephala chilensis, associated with A. laevis, P. pugnax, and S. spinifrons, and species of Polychaeta, i.e., Stratiodrilus platensis associated with A. abtao and A. bahamondei, S. aeglaphilus for A. laevis, and S. pugnaxi for P. nicoletti. Biogeographical, ecological and taxonomic implications are discussed.

The distributional patterns of the species of the South American freshwater crayfishes of the family Parastacidae were analysed using panbiogeographical track analyses to identify targeted regions of crayfish biodiversity for understanding biogeographical patterns. Two generalized tracks were identified using the track analysis approach: (1) Uruguay and Brazil (Parastacus brasiliensis, P. brasiliensis promatensis, P. buckupi, P. caeruleodactylus, P. defossus, P. fluviatilis, P. gomesae, P. guapo, P. macanudo, P. pilimanus, P. pilicarpus, P. saffordi, P. tuerkayi, P. varicosus); and (2) Central-southern Chile (P. nicoleti, P. pugnax, Samastacus spinifrons, Virilastacus araucanius, V. jarai, V. retamali and V. rucapihuelensis). These areas were exclusive, with no overlap between them. The results indicate the presence of South American Parastacidae crayfish in Atlantic coastal sub-tropical and Pacific coastal temperate wet climate regions with biogeographic similarities to other South American inland water decapods.

The crayfishes of Chile are endemic species and have been poorly studied with respect to their biology. The available literature is restricted to species descriptions, whereas there is no information about other biological topics such as ectocommensals and parasites, which can affect crayfishes. The aim of the present study was to do a literature review and update the information about ectocommensals and parasites that have been reported from Chilean crayfishes. The literature mentioned the presence of Temnocephala chilensis (Platyhelminthes), Stratiodrilus pugnaxi (Polychaeta) and Protozoa such as species of the genera Operculigera and Lagenophrys as ectocommensals for Parastacus pugnax and Samastacus spinifrons. As an endoparasite, Psorospermium haeckelii was reported, a unicellular eukaryotic organism that was found in P. pugnax ovaria. An additional analysis of collected specimens of P. pugnax and S. spinifrons revealed the presence of T. chilensis, albeit at a low incidence. Ecological, biogeographical and evolutionary topics are discussed considering the case of a marked microendemism of an organism associated with Chilean crayfishes.

The Chilean north Patagonian lakes are characterized by their marked oligotrophic or oligomesotrophic status and low abundance of zooplankton species; many of the lakes with oligomesotrophic status are associated with human intervention due to towns on their shores. The aim of the present study was to determine the relations between spectral properties (LANDSAT OLI), chlorophyll and plankton abundances in two north Patagonian lakes: Villarrica, which has two towns on its shores, and Lake Caburgua, which has native forest on its shores. The results revealed that Lake Villarrica has high reflectance in the near infrared, red and green bands, high concentrations of chlorophyll a, the absence of mixotrophic protozoa, and a high abundance of bacterial and plankton, mainly phytoplankton (Chlophyceae and diatoms) and zooplankton. Lake Caburgua, on the other hand, has low reflectance in the same bands, and low chlorophyll concentrations, low bacterial and zooplankton abundances, with the exception of high mixotrophic ciliates and small phytoplankton, and Volvox colonies. The obtained results agree with limnological observations on both lakes, and observations agrees with similar observations of the spectral properties of glacial north Patagonian lakes and of the zooplankton community, and in this scenario, the use of remote-sensing techniques would be a good tool to predict the plankton community in Patagonian lakes.

Antofagasta Bay is characterized by having a high primary productivity due to the presence of the cold Humboldt Stream. However, due to the current global climate change, also the previously generated biodiversity patterns are changing. The aim of the present study was analysing Antofagasta Bay in order to determine the existence of correlations between optical, i.e., spectral, properties recorded through remote sensing on the one hand, and the presence of dinoflagellates and zooplankton, on the other. The studies were done during two periods, i.e., in February 2019 and February 2020. The results revealed the existence of three main groups of sites: a first group comprising sites sampled in February 2019, with high Band 3 and Band 4 reflectance, high chlorophyl values, and high abundances of Dinophysis and copepods; a second group combining four sites visited in February 2019, with high Gymnodinium and Ceratium, high reflectance in Band 1, Band 2, Band 5, Band 6 and Band 7, and low zooplankton abundance; and finally a third group encompassing all sites sampled in 2020, with high Prorocentrum abundance, and low zooplankton abundance, as well as low reflectance. A similar situation with regard to zooplankton and optical properties was earlier reported for Chilean Patagonian lakes.

The Chilean Patagonian lakes are characterized by their marked oligotrophic or oligomesotrophic status and low zooplankton species abundances, many of these lakes with oligomesotrophic status is associated to human intervention due towns in their shores. The aim of the present study was determine the relations between spectral properties (LANDSAT ETM+), chlorophyll and plankton abundances in two north Patagonian lakes, Villarica, that has two towns in its shore, and Caburgua, that has native forest in its shores as basis of environmental pollution monitoring tools. The results revealed that Villarica lake has high reflectances in near infrared, red and green bands, high chlorophyll (a, b and c) concentrations, and high bacterial and plankton abundances, whereas Caburgua lakes has low reflectance in the same bands, and low chlorophyll concentrations, low bacterial and plankton abundances, with exception to high mixotrophic ciliates. The obtained results agree with limnological observations about both lakes, and the comparison with spectral properties agree with similar observations for glacial north Patagonian lakes about spectral properties and zooplankton community.

Antofagasta Bay is characterized by a high primary productivity due to the presence of the cold Humboldt Stream that is associated with a high diversity in flora and fauna in the benthic and pelagial environments of the Chilean west coast. Nevertheless, due to the global climate changes, the existing biodiversity patterns change as well. The aim of the present study was to analyse Antofagasta Bay for determining the existence of patterns between optical properties of the water, and the phytoplankton and zooplankton. The results show that one site had high chlorophyll concentrations, high reflectance, a high abundance of the dinoflagellate genus Dinophysis, and a high abundance of copepodites, whereas five sites had low chlorophyll concentrations, a low reflectance value, low copepodite abundances, and high abundances of dinoflagellates of the genera Ceratium, Gymnodinium and Prorocentrum. These results are similar to earlier observations for the coastal waters along northern Chile.

A database containing data from cytogenetic studies of Chilean fish species is documented for the first time. The cytogenetic data compiled for Chilean fishes include 28 species belonging to 11 families, 9 orders and 16 genera, taking as reference 18 publications since 1972. The application of a variety of cytogenetic methods has provided information on chromosome number, karyotype morphology, genome size, and /or location of different DNA sequences. These data represent only ca. 2.7% of Chile’s fish diversity.

Laboratory experiments were carried out to evaluate juvenile and adult mortality in Musculium argentinum over a given period of time. Specimens of M. argentinum were collected in May 2009 from the evacuation channel of the Lautaro fish farm, Araucania Region, Chile (38°32′ S, 72°27′ W), and a laboratory experiment was carried out consisting of 2 treatments (T1 and T2), with 3 replications of each. In each treatment and replication, a plastic container (15×10×5 cm) was filled with water and dead leaf litter from the channel inhabited by the study species. During T1, the population density of the container was 100 individuals (D100); during T2, the population density was 60 individuals (D60). The individuals were allowed 2 days to adapt to their new environment. Every 7 days during the following 2 mo, the anteroposterior valve length of each specimen in each treatment was measured to an accuracy of 0.1 mm. Adults were measured using digital calipers, and juveniles were measured using a stereomicros...

To evaluate the capacity for movement of freshwater mussels in sandy and sand-gravel substrates and to test their ability to differentiate among types and qualities of substrates, experiments were carried out in the laboratory and in the field, using Diplodon chilensis from Lake Panguipulli, Chile. The movement of mussels was greater in sandy than in sand-gravel substrates. In the absence of food, there was a significant preference for sandy substrate, and when mussels were offered sandy or sandgravel substrates with and without food they chose the substrate with food with no preference to substrate type. Under natural conditions mussel presence and abundance along time is regulated by variables with a synergistic effect, niche of which substratum is not always the major one.

Based on literature review and malacological collections, 168 native freshwater bivalve and five invasive species have been recorded for 52 hydrographic regions in South America. The higher species richness has been detected in the South Atlantic, Uruguay, Paraguay, and Amazon Brazilian hydrographic regions. Presence or absence data were analysed by Principal Coordinate for Phylogeny-Weighted. The lineage Veneroida was more representative in hydrographic regions that are poorer in species and located West of South America. The Mycetopodidae and Hyriidae lineages were predominant in regions that are richest in species toward the East of the continent. The distribution of invasive species Limnoperna fortunei is not related to species richness in different hydrographic regions there. The species richness and its distribution patterns are closely associated with the geological history of the continent. The hydrographic regions present distinct phylogenetic and species composition regardless of the level of richness. Therefore, not only should the richness be considered to be a criterion for prioritizing areas for conservation, but also the phylogenetic diversity of communities engaged in services and functional aspects relevant to ecosystem maintenance. A plan to the management of this fauna according to particular ecological characteristics and human uses of hydrographic regions is needed., Facultad de Ciencias Naturales y Museo

Introduced juvenile Chinook salmon (Oncorhynchus tshawytscha) have been found co-occurring with native fishes in the Allipen River, Chile. Due to this co-occ...

El propósito del presente estudio fue comprobar si han ocurrido cambios, después de 16 años, en los patrones de abundancia, distribución espacial y estructura de talla de la almeja de agua dulce Diplodon chilensis en sustratos arenosos y areno-pedregosos del sector Chauquén del Lago Panguipulli. Los resultados indican que las almejas en 1987 y 2003 presentan una distribución espacial agregada en ambos sustratos y con una mayor fuerza de la agregación en los sustratos areno-pedregosos que arenosos. La densidad fue significativamente mayor en sustrato areno-pedregoso, tanto en 1987 (P < 0,001) como en el 2003 (0,001< P < 0,01). No se presentaron diferencias significativas (P > 0,05) en densidad entre los distintos años dentro de un mismo tipo de sustrato. La estructura de talla en ambos sustratos y periodos estudiados no varió mayormente, registrándose sin embargo en 2003 juveniles en ambos sustratos, lo que indicaría que ha ocurrido reclutamiento. Se discuten estos resultados en relación al rol que desempeñan estos bivalvos en el ecosistema y en su potencial uso en la evaluación ecológica de ambientes lacustres.

Con el propósito de conocer cualitativamente la alimentación y la conducta alimentaria de la almeja de agua dulce Diplodon chilensis, se analizó mediante estudios de laboratorio y de campo el comportamiento alimentario y el contenido digestivo de especímenes procedentes de sustratos areno-pedregosos y arenosos del Lago Panguipulli y se relacionó con la oferta ambiental existente en el sustrato (fitobentos) y en el agua (fito-plancton). El análisis del contenido digestivo de los especímenes y los resultados experimentales, indican que Diplodon chilensis tiene una alimentación mixta en base a fitoplancton, fitobentos y materia orgánica existente en el plancton y en el bentos To determine qualitatively, feeding and alimentary behavior of the freshwater mussel, Diplodon chilensis, it was studied by means of field and laboratory studies the alimentary behavior and the digestive content of specimens inhabiting sand-gravel and sandy substrates of Lake Panguipulli; the digestive content of D. chilensis specimens was correlated to the environmental food offer existing in the substrate (phytobenthos) and in the water (phytoplankton). The digestive content analysis of the specimens and the experimental results show that D. chilensis has a mixed feeding based on phytoplankton, phytobenthos and organic matter existent in the plankton and benthos

The karyotype of a freshwater population of Diplodon chilensis located in La Poza area of the Villarrica Lake (39º18'S; 72º05'W), Southern Chile, was studied. The chromosomes were obtained by squash of cleaving embryos, previously treated with colchicine and fixed in ethanol-acetic acid 3:1 at 4ºC and stained using the Feulgen reaction. Diplodon chilensis showed a diploid karyotype of 2n = 34, with metacentric and submetacentric chromosomes. This work is the first approach to cytogenetic characterization of Chilean populations of this species.

Efecto de Azinphos-etil sobre la densidad de microartropodos del suelo en praderas de la IX Region (Chile)