Highly mercury-resistant strains from different Colombian Amazon ecosystems affected by artisanal gold mining activities.

Two sites of the Colombian Amazon region with different levels of human intervention and mercury pollution were selected for the collection of samples of river and lake water, sediments, and associated forest soils. The Tarapacá region, affected mainly by barrage mining, showed low mercury concentrations, whilst in the Taraira region, affected by underground mining, there were several points with high mercury pollution levels. A collection of 72 bacterial and 10 yeast strains with different levels of mercury resistance was isolated and characterized. Most of the highly resistant bacterial strains (MIC > 40 mg L-1 HgCl2) were isolated from soil and sediment samples and belonged to either Pseudomonas (60%) or Bacillus (20%). Most of highly resistant bacterial strains were positive for the presence of the merA gene, suggesting an active mercury resistance mechanism. This was confirmed in the two most resistant strains, Pseudomonas sp. TP30 and Burkholderia contaminans TR100 (MIC = 64 and 71 mg L-1 HgCl2, respectively), which in the presence of increasing mercury concentrations expressed the merA gene at increasing levels, concomitant with a significant mercury reduction activity. Analysis of the MerA sequences present in the different isolates suggested a high gene conservation within the taxonomic groups but also several horizontal gene transfer events between taxonomically distant genera. We also observed a positive correspondence between the presence of the merA gene and the number of antibiotics to which the strains were resistant to. The most resistant strains are good candidates for future applications in the bioremediation of mercury-contaminated sites in the Amazon.Key points• Amazon sediments affected by underground gold mining have higher Hg levels.• Highly Hg-resistant isolates belonged to Pseudomonas and Bacillus genera.• TR100 and TP30 strains showed remediation potential to be used in the Amazon region.

A new species of Metopiellus (Coleoptera, Staphylinidae, Pselaphinae) from the northern Colombian Amazon.

The genus Metopiellus (Staphylinidae, Pselaphinae) is confirmed in Colombia with the description of Metopiellusguanano sp. nov. from the northern Amazon. Major diagnostic characters, a distributional map, and ecological data are given. Finally, a previous taxonomic key to Metopiellus is updated to include the new species.

Pre-Columbian fire management and control of climate-driven floodwaters over 3,500 years in southwestern Amazonia.

In landscapes that support economic and cultural activities, human communities actively manage environments and environmental change at a variety of spatial scales that complicate the effects of continental-scale climate. Here, we demonstrate how hydrological conditions were modified by humans against the backdrop of Holocene climate change in southwestern Amazonia. Paleoecological investigations (phytoliths, charcoal, pollen, diatoms) of two sediment cores extracted from within the same permanent wetland, ∼22 km apart, show a 1,500-y difference in when the intensification of land use and management occurred, including raised field agriculture, fire regime, and agroforestry. Although rising precipitation is well known during the mid to late Holocene, human actions manipulated climate-driven hydrological changes on the landscape, revealing differing histories of human landscape domestication. Environmental factors are unable to account for local differences without the mediation of human communities that transformed the region to its current savanna/forest/wetland mosaic beginning at least 3,500 y ago. Regional environmental variables did not drive the choices made by farmers and fishers, who shaped these local contexts to better manage resource extraction. The savannas we observe today were created in the post-European period, where their fire regime and structural diversity were shaped by cattle ranching.

Re-imagining environmental governance: Gold dredge mining vs Territorial Health in the Colombian Amazon.

This article describes and analyses an encounter in the Colombian Amazon between Indigenous practices and arrangements to manage their environment and the conservation policies of the State. Indigenous peoples understand their world as populated by powerful human and nonhuman beings; for them, the moral duty of achieving happiness and abundance for all implies sustaining reciprocal and respectful relations with these beings (including the State). In contrast Colombian environmental policy distinguishes between nature and culture, seeking to safeguard landscapes from human interference so that natural processes can unfold unhindered. In practice these partially connected, yet incommensurable worldviews make for a 'perfect storm' - opening opportunities for illegal mining. Drawing on recent fieldwork among the Andoke, an ethnic group well acquainted with extractivism in its different historical modalities and presently affronting the fallout of gold dredge mining we narrate how a parallel, non-state governance system makes it difficult for them to care for their land and entertain mutual and respectful relations with human and nonhuman beings (which we translate as 'territorial health'). We conclude by arguing for the need to re-imagine environmental governance in ways that more closely engage with what we call pluriversal governance: a form of (environmental) governance that does ontological justice to those involved in the environmental conflict - including, crucially, Indigenous people.

A new species of Acorhinotermes Emerson, 1949 (Blattodea, Isoptera, Rhinotermitidae) from Colombia, with a key to Neotropical Rhinotermitinae species based on minor soldiers.

Acorhinotermes Emerson, 1949 is the only Neotropical Rhinotermitine genus with no major soldier. Herein Acorhinotermes claritae Castro & Scheffrahn, sp. nov. is described based on minor soldiers and an alate nymph collected in a secondary rain forest in the Colombian Amazon. The minor soldier of A. claritae Castro & Scheffrahn, sp. nov. has longer mandibular points and it is comparatively smaller than A. subfusciceps. An illustrated key to the minor soldiers of the Neotropical species of Rhinotermitinae is presented.

Insects of forensic importance associated to cadaveric decomposition in a rural area of the Andean Amazon, Caquetá, Colombia / Insetos de importância forense associados à decomposição cadavérica em uma área rural na Amazônia Andina, Caquetá, Colômbia

ABSTRACT Forensic entomology is a frequently used tool to estimate the time interval between death and the discovery of the corpse. Succession of arthropods associated with cadaveric decomposition was monitored in a rural area of the Municipality of Florencia, Department of Caquetá, Colombia. Three pigs (Sus scrofa) were used as study models. Insect sampling, and monitoring of carcasses and environmental conditions were carried out every five hours. The total time from death to skeletonization was of 545 hours (22.7 days). A total of 30833 insect individuals were collected. Specimens were distributed in nine orders, 46 families, 95 genera and 106 species. Diptera was the most abundant, with 23215 individuals (75.3%), followed by Coleoptera, with 3711 individuals (12%), and Hymenoptera, with 3154 individuals (10.2%). Immature stages of Cochliomyia macellaria, Chrysomya albiceps, Hemilucilia semidiaphana and Ophyra aenescens were the main species involved in tissue consumption and acceleration of the decomposition process. Due to the presence of ants Cheliomyrmex sp., Camponotus sp. and Dinoponera sp., and coleopterans Hister sp., Acylophorus sp. and Philonthus spp., it was not possible to obtain sufficient Diptera egg masses for rearing the colonizing species. These results can be used as a standard to determine the postmortem interval in criminal investigations in the rural area of the Andean Amazon, Caquetá, Colombia.

RESUMO A entomologia forense é uma ferramenta frequentemente utilizada para estimar o intervalo de tempo entre a morte e a descoberta do corpo. Na área rural do município de Florencia, Caquetá, foi monitorada a sucessão de artrópodes associados à decomposição cadavérica, utilizando como modelo de estudo os cadáveres de três porcos (Sus scrofa). A amostragem de insetos e coleta de dados ambientais foram realizadas a cada cinco horas. A duração total do processo desde a morte até a esqueletização foi de 545 horas (22,7 dias). Foram coletados 30833 espécimes de insetos, distribuídos em nove ordens, 46 famílias, 95 gêneros e 106 espécies. Diptera foi o grupo mais representativo, com 23215 indivíduos (75,3%), seguido de Coleoptera, com 3711 indivíduos (12%) e Hymenoptera, com 3154 indivíduos (10,2%). Os estágios imaturos de Cochliomyia macellaria, Chrysomya albiceps, Hemilucilia semidiaphana e Ophyra aenescens foram as principais espécies envolvidas no consumo de tecidos e na aceleração do processo de decomposição. Devido à presença de formigas Cheliomyrmex sp., Camponotus sp. e Dinoponera sp. e de besouros Hister sp., Acylophorus sp. e Philonthus spp., não foi possível obter massas de ovos de Diptera suficientes para a criação de espécies colonizadoras. Nosso estudo fornece subsídios para determinar o intervalo post-mortem em investigações policiais e promover a entomologia forense em uma área rural da Amazônia Andina na Colômbia.

Plasmodium malariae in the Colombian Amazon region: you don't diagnose what you don't suspect.

BACKGROUND: Malaria is a worldwide public health problem; parasites from the genus Plasmodium spp. are the aetiological agent of this disease. The parasite is mainly diagnosed by microscope-based techniques. However, these have limited sensitivity. Many asymptomatic infections are sub-microscopic and can only be detected by molecular methods. This study was aimed at comparing nested PCR results to those obtained by microscope for diagnosing malaria and to present epidemiological data regarding malaria in Colombia's Amazon department. METHODS: A total of 1392 blood samples (taken by venepuncture) from symptomatic patients in Colombia's Amazon department were analysed in parallel by thick blood smear (TBS) test and nested PCR for determining Plasmodium spp. infection and identifying infecting species, such as Plasmodium vivax, Plasmodium malariae and/or Plasmodium falciparum. Descriptive statistics were used for comparing the results from both tests regarding detection of the disease, typing infecting species and their prevalence in the study region. Bearing the microscope assay in mind as gold standard, PCR diagnosis performance was evaluated by statistical indicators. CONCLUSION: The present study revealed great differences between both diagnostic tests, as well as suggesting high P. malariae prevalence from a molecular perspective. This differed profoundly from previous studies in this region of Colombia, usually based on the TBS test, suggesting that diagnosis by conventional techniques could lead to underestimating the prevalence of certain Plasmodium spp. having high circulation in this area. The present results highlight the need for modifying state malaria surveillance schemes for more efficient strategies regarding the detection of this disease in endemic areas. The importance of PCR as a back-up test in cases of low parasitaemia or mixed infection is also highlighted.

Does Plan B work? Home range estimations from stored on board and transmitted data sets produced by GPS-telemetry in the Colombian Amazon / ¿Funciona el plan B? Estimación de rango de hogar a partir de datos almacenados en instrumentos a bordo de animales y los obtenidos a partir de telemetría satelital de GPS en el Amazonas colombiano

Abstract:Telemetry based on Global Positioning Systems (GPS) makes possible to gather large quantities of information in a very fine scale and work with species that were impossible to study in the past. When working with GPS telemetry, the option of storing data on board could be more desirable than the sole satellite transmitted data, due to the increase in the amount of locations available for analysis. Nonetheless, the uncertainty in the retrieving of the collar unit makes satellite-transmitted technologies something to take into account. Therefore, differences between store-on-board (SoB) and satellite-transmitted (IT) data sets need to be considered. Differences between SoB and IT data collected from two lowland tapirs (Tapirus terrestris), were explored by means of the calculation of home range areas by three different methods: the Minimum Convex Polygon (MCP), the Fixed Kernel Density Estimator (KDE) and the Brownian Bridges (BB). Results showed that SoB and IT data sets for the same individual were similar, with fix ranging from 63 % to 85 % respectively, and 16 m to 17 m horizontal errors. Depending on the total number of locations available for each individual, the home ranges estimated showed differences between 2.7 % and 79.3 %, for the 50 % probability contour and between 9.9 % and 61.8 % for the 95 % probability contour. These differences imply variations in the spatial coincidence of the estimated home ranges. We concluded that the use of IT data is not a good option for the estimation of home range areas if the collar settings have not been designed specifically for this use. Nonetheless, geographical representations of the IT based estimators could be of great help to identify areas of use, besides its assistance to locate the collar for its retrieval at the end of the field season and as a proximate backup when collars disappear. Rev. Biol. Trop. 64 (4): 1441-1450. Epub 2016 December 01.

Resumen:La telemetría basada en los sistemas de geopocisionamiento global (GPS) hace posible recopilar gran cantidad de información a escalas muy finas, y trabajar con especies imposibles de estudiar en el pasado. Al trabajar con telemetría de GPS, la opción de guardar información en la memoria interna del instrumento puede ser más deseable que sólo tener acceso a la información enviada vía satélite, debido a la mayor cantidad de localizaciones disponibles para analizar. No obstante, la incertidumbre de recuperar el collar hace que las tecnología de trasmisión vía satélite deba ser tenida en cuenta. Diferencias entre las bases de datos almacenadas en el collar (SoB) y las trasmitidas vía satélite (IT), recolectadas de dos individuos de Tapir de tierras bajas (Tapirus terrestris), son consideradas, en términos de las áreas de los rangos de hogar calculados con cada uno y mediante el uso de tres metodologías diferentes: Mínimo Polígono Convexo (MCP), Estimador de Densidad de Kernel Fijo (KDE) y los Puentes Brownianos (BB). Las bases de datos SoB e IT son similares, con tasas de acierto de localizaciones que oscilan entre 63 % to 85 % y errores horizontales de 16 m y 17 m respectivamente. Dependiendo del número total de localizaciones disponibles para cada individuo, los rangos de hogar estimados muestran diferencias entre 2.7 % y 79.3 %, para el contorno del 50 % de probabilidades, y entre 9.9 % y 61.8 % para el contorno del 95 % de probabilidades. Estas diferencias implican variaciones en la coincidencia espacial de los rangos de hogar estimados. Concluimos que el uso de la información trasmitida vía satélite no es una buena opción para la estimación de rangos de hogar, si la programción de los collares no ha sido diseñada específicamente para tal fin. Sin embargo, las representaciones geográficas de los estimados a partir de las bases de datos IT pueden ser de gran ayuda para la identificación de áreas de uso, además de su utilidad para la localización y recuperación de collares tras su liberación de los individuos monitoreados y como una base de datos de soporte en caso de pérdida del collar.

Conversion from forests to pastures in the Colombian Amazon leads to contrasting soil carbon dynamics depending on land management practices.

Strategies to mitigate climate change by reducing deforestation and forest degradation (e.g. REDD+) require country- or region-specific information on temporal changes in forest carbon (C) pools to develop accurate emission factors. The soil C pool is one of the most important C reservoirs, but is rarely included in national forest reference emission levels due to a lack of data. Here, we present the soil organic C (SOC) dynamics along 20 years of forest-to-pasture conversion in two subregions with different management practices during pasture establishment in the Colombian Amazon: high-grazing intensity (HG) and low-grazing intensity (LG) subregions. We determined the pattern of SOC change resulting from the conversion from forest (C3 plants) to pasture (C4 plants) by analysing total SOC stocks and the natural abundance of the stable isotopes (13) C along two 20-year chronosequences identified in each subregion. We also analysed soil N stocks and the natural abundance of (15) N during pasture establishment. In general, total SOC stocks at 30 cm depth in the forest were similar for both subregions, with an average of 47.1 ± 1.8 Mg C ha(-1) in HG and 48.7 ± 3.1 Mg C ha(-1) in LG. However, 20 years after forest-to-pasture conversion SOC in HG decreased by 20%, whereas in LG SOC increased by 41%. This net SOC decrease in HG was due to a larger reduction in C3-derived input and to a comparatively smaller increase in C4-derived C input. In LG both C3- and C4-derived C input increased along the chronosequence. N stocks were generally similar in both subregions and soil N stock changes during pasture establishment were correlated with SOC changes. These results emphasize the importance of management practices involving low-grazing intensity in cattle activities to preserve SOC stocks and to reduce C emissions after land-cover change from forest to pasture in the Colombian Amazon.

Conversion from forests to pastures in the Colombian Amazon leads to differences in dead wood dynamics depending on land management practices.

Dead wood, composed of coarse standing and fallen woody debris (CWD), is an important carbon (C) pool in tropical forests and its accounting is needed to reduce uncertainties within the strategies to mitigate climate change by reducing deforestation and forest degradation (REDD+). To date, information on CWD stocks in tropical forests is scarce and effects of land-cover conversion and land management practices on CWD dynamics remain largely unexplored. Here we present estimates on CWD stocks in primary forests in the Colombian Amazon and their dynamics along 20 years of forest-to-pasture conversion in two sub-regions with different management practices during pasture establishment: high-grazing intensity (HG) and low-grazing intensity (LG) sub-regions. Two 20-year-old chronosequences describing the forest-to-pasture conversion were identified in both sub-regions. The line-intersect and the plot-based methods were used to estimate fallen and standing CWD stocks, respectively. Total necromass in primary forests was similar between both sub-regions (35.6 ± 5.8 Mg ha(-1) in HG and 37.0 ± 7.4 Mg ha(-1) in LG). An increase of ∼124% in CWD stocks followed by a reduction to values close to those at the intact forests were registered after slash-and-burn practice was implemented in both sub-regions during the first two years of forest-to-pasture conversion. Implementation of machinery after using fire in HG pastures led to a reduction of 82% in CWD stocks during the second and fifth years of pasture establishment, compared to a decrease of 41% during the same period in LG where mechanization is not implemented. Finally, average necromass 20 years after forest-to-pasture conversion decreased to 3.5 ± 1.4 Mg ha(-1) in HG and 9.3 ± 3.5 Mg ha(-1) in LG, representing a total reduction of between 90% and 75% in each sub-region, respectively. These results highlight the importance of low-grazing intensity management practices during ranching activities in the Colombian Amazon to reduce C emissions associated with land-cover change from forest to pasture.

Mycotoxins and cyanogenic glycosides in staple foods of three indigenous people of the Colombian Amazon.

A study was conducted to determine the incidence and levels of mycotoxins in the main staple foods of three indigenous people of the Colombian Amazon. A total of 20 corn, 24 rice and 59 cassava samples were analysed by a multi-analyte liquid chromatography-tandem mass spectrometry method covering the major classes of mycotoxins. In addition, cassava samples were also analysed for cyanogenic glycosides. The indigenous Amazon communities tested are exposed to potentially carcinogenic mycotoxins (particularly aflatoxins), as well as other mycotoxins, mainly through the intake of locally grown corn. Citrinin content in this corn was unusually high and has not been reported elsewhere. Two cassava samples contained high levels of cyanogenic glycosides. It is strongly recommended not to grow corn in the Amazon but instead purchase it from vendors capable of guaranteeing mycotoxin levels below the maximum allowable concentration in Colombia.

Consecuencias scciales del cultivo de la coca e comunidades afroColombianas deel caquetá: análisis de la relación entre la economía ilícita, las prácticas campesinas tradicionales y su papel en la seguridad alimnttaria / Socia consequencces of the cultivation of coca in afroColombian communities in caquetá: analysis of the relationship among the illicit economy, the traditional farming practices, and their role in food security

El artículo expone los principales resultados de una investigación sobre las consecuencias que la adopción del cultivo de coca, las lógicas productivas de la economía ilícita, y las políticas antinarcóticos del estado Colombiano han significado para la seguridad y soberanía alimentaria de comunidades afrocolombianas en el departamento del Caquetá. El trabajo se sustentó en un extenso trabajo de campo realizado en la zona rural de la inspección de Rionegro, municipio de puerto Rico. En el texto se analiza el papel que juegan la historia regional, el contexto social y económico en las razones que permiten explicar el por qué de la presencia de la coca. Se da cuenta de las principales características de la modalidad de producción familiar que caracteriza la coca en la región y finalmente, y se exponen los impactos que la política antinarcóticos tiene sobre la seguridad alimentaria de las comunidades en la región de estudio. En aras de aportar elementos para el debate de las alternativas para el cultivo de la coca, el artículo demuestra cómo las practicas productivas en la región, tanto legales e ilegales, no pasan por la construcción de un proyecto de soberanía alimentaria y no llegan a satisfacer los puntos básicos de seguridad alimentaria.

This article presents the main results of an investigation into the consequences of the adoption of the cultivation of coca, the productive logic of the illicit economy, and anti-drug policies of the Colombian State have meant for the safety and food sovereignty of Afrocolombian communities in the State of Caquetá. The work was based on extensive field work carried out in the rural area of inspection of Rionegro, Municipality of Puerto Rico. The text examines the role played by the regional history, the social and economic context in the reasons that help to explain the reason for the presence of coca. It gives an account of the main features of the mode of family production that characterizes the coca in the region and finally, and it shows the impact that the counter-narcotics policy has on food security of the communities in the study area. In order to provide elements for the discussion of the alternatives to the cultivation of coca, the article shows how the production practices in the region, both legal and illegal, do not pass through the construction of a project of food sovereignty and fail to meet the basics of food safety.

Comunidades de hongos actinomicetos en tres tipos de vegetación de la Amazonia colombiana: abundancia, morfotipos y el gen 16s ADNr

Communities of Actynomicetes fungy in three vegetation types of the Colombian Amazon: abundance, morphotypes and the 16s rDNA gene. Among soil microorganisms, Actinomycetes play an important role in the sustainability of natural and agricultural systems: decomposition of organic matter; degradation of recalcitrant compounds like lignin; nitrogen fixation; degradation of agricultural chemicals and biological control in plants and animals. We evaluated their diversity in soils under three different vegetation covers (pasture, tropical primary forest and stubble) at two depths in the Southern Colombian Amazon border. We collected five replicates per vegetation type (in each, three samples at 0-20cm and three at 20-30cm; for a total of 30 samples). Abundance and phenotypic diversity were determined by plate counting. Genomic DNA was extracted from the isolates: the 16s rDNA gene was amplified with specific primers, and its genetic diversity was estimated by means of an amplified restriction analysis (ARDRA). Actynomicetes abundance varied with vegetation and depth, possibly reflecting presence of earthworms, macro-fauna and physico-chemical characteristics associated to fertility, as well as organic matter, total bases, and optimal capacity to cationic interchange. Primary forests had the highest diversity. Sixteen morpho-types (six genera) were identified; Streptomyces was the most abundant everywhere. The heterogeneity of ARDRA patterns prevented species identification because of the intra-species variability in sequences of 16s rDNA operons. This community is a biological indicator of landscape alteration and could include new bio-active compounds of pharmaceutical interest. Rev. Biol. Trop. 57 (4): 1119-1139. Epub 2009 December 01.

Los actinomicetos son importantes en la sostenibilidad de sistemas naturales. Su diversidad fue evaluada en suelos de bosque, pastizal y rastrojo, y dos profundidades en el Sur del Trapecio Amazónico Colombiano. Se analizaron suelos de cinco repeticiones por cobertura para un total de 15 unidades. Se tomaron seis muestras en cada unidad y dos profundidades, para un total de 30. Los actinomicetos cultivables se determinaron por recuento en placa, se extrajo ADN, se amplificó el gen ADNr 16s y su diversidad genética se estimó por ARDRA. Hubo diferencias de abundancia entre coberturas y profundidades, relacionadas con la vegetación, presencia de lombrices, macrofauna, altos niveles de materia orgánica, y bases totales. Se obtuvieron valores de diversidad fenotípica similares para las tres coberturas, pero los bosques son más diversos. Se identificaron 16 morfotipos, agrupados en séis géneros, siendo Streptomyces el más abundante. La heterogeneidad de los patrones ARDRA no permitió la asignación de especies, reflejándose variaciones en las secuencias de diferentes operones ADNr 16s en un mismo organismo. Las perturbaciones en la cobertura influyen sobre los actinomicetos, generando cambios en su abundancia y diversidad. Su importancia ecológica permite proponerlos como indicadores biológicos de alteración del paisaje.

Producción primrria en un lago de aguas claras de la amazonía Colombiana (lago boa) / Primary Production In A Clear Water Lake Of Colombian Amazon (Lake Boa)

Dentro de los aspectos funcionales de un sistema acuático uno de los más determinantes es la producción fitoplanctónica. En este trabajo se midió la producción primaria del fitoplancton (método del 14C) en un lago de aguas claras de la Amazonía colombiana, en diferentes momentos del ciclo hidrológico. La producción primaria osciló entre 0,6 y 2,3 g C m-2 d-1, valor este último medido durante la fase de aguas bajas. Estos resultados indican que la comunidad fitoplanctónica del lago Boa fluctúa desde condiciones de muy baja capacidad de asimilación de carbono inorgánico (aguas altas), hasta momentos en que este potencial se incrementa hasta cuatro veces (aguas bajas). Tales cambios drásticos obedecen a las fluctuaciones en la abundancia de microalgas, las que a su vez se presentan como respuesta a la variación trófica que tiene el lago durante el ciclo hidrológico. De esta manera, se pasa de condiciones oligotróficas en la época de inundación a un estado eutrófico cuando el sistema se desconecta del río en aguas bajas.

Phytoplankton production is one of the most significant aspects in aquatic ecosystems. In this paper primary production of the phytoplankton community was measured (14C method) in a clear water lake in the Colombian Amazon region in different periods of the hydrological cycle. Primary production varied between 0.6 and 2.3 g C m-2 d-1, the last recorded at low water phase. Results show that the phytoplankton community of Lake Boa fluctuates from very low capacity of carbon assimilation during high water but increased four times during low water. The strong change in productivity follows the variation in algal abundance, which in turn reflects changes in water quality conditions during the hydrologic cycle. Thus, the lake passes from oligotrophic conditions during the flooding period to eutrophic conditions when the lake is disconnected from the river at low water phase.

Actividad diari de colonización del recurso almenticio en un ensamblaje de esscarabajos coprófagos (coleoptera: scarabaeidae) en la amazonía Colombiana / Daily colonization of food resourses by Dung Beetles (Coleoptera: Scarabaeidae) in the Colombian Amazone Region

Los escarabajos coprófagos pertenecientes a la familia Scarabaeidae presentan una fuerte competencia por el recurso alimenticio, debido a la baja agregación espacial y al carácter efímero del mismo. Un mecanismo que puede contribuir a diluir la competencia es la segregación temporal, conduciendo a una especialización en las horas de actividad. El objetivo de este trabajo fue estudiar la actividad diaria en un ensamblaje de escarabajos coprófagos en un bosque húmedo tropical en la amazonía colombiana. Se establecieron dos transectos lineales de 225 m y en cada uno se montaron diez tram-pas de caída por 24 horas, cebadas con excremento humano de dos investigadores, colectando su contenido cada hora, en la época de sequía. Se registraron un total de 23 especies, contenidas en diez géneros y cinco tribus. La abundancia del gremio de los cavadores fue mayor que la de los otros grupos. Igualmente, los escarabajos diurnos fueron más abundantes que los crepusculares y los nocturnos. Se presentaron algunas especies con horas de actividad muy específicas, evidenciando el problema de tomar tiempos de captura muy amplios donde se pierde el detalle de la restricción horaria. La riqueza y abundancia de especies en los cebos de los dos investigadores mostró diferencias, insinuando que pueden existir variaciones dentro del excremento humano, como cebo. Finalmente, se propone que la restricción en la actividad diaria puede ser un mecanismo importante de dilución de la competencia inter e intraespecífica, que facilita a las especies la coexistencia y repartición del recurso en el tiempo.

Dung beetles belonging to the Scarabaeidae family have strong competition for food resources given the low spatial aggregation and ephemeral character of those resources. Temporal segregation through specialization in hours of activity is a mechanism that can decrease that competition. The objective of this paper is study the daily activity of an assemblage of dung beetles in a tropical wet forest in the colombian amazon. During the dry season, two linear transects of 225 m were established, with 10 pitfall traps mounted for 24 hours, baited with human excrement of two researchers. Trap contents were collected hourly. 23 total species were recorded, within 10 genera and 5 tribes. The abundance of the diggers guild were higher then the others groups. Diurnal beetles were more abundant than nocturnal and crepuscular species. Some species with very specific hours of activity were present, evidencing the problem of allowing a long time between collections, thus losing the detail of restricted activity. Differences existed in the abundance and richness of species on the bait, implying that there can be variations between human excrement. Finally, it was shown that restriction in daily activity can be an important mechanism for diminishing inter and intra specific competition, which facilitates the coexistence of species and the division over the resource in time.

Diatoms from the Colombian Amazon: some species of the genus Eunotia (Bacillariophyceae)

This research was carried out in three of the most important basins of the Colombian Amazon (Upper Solimões, Iça and Japurá Rivers). The creeks and lakes that were studied contain abundant diatom species, particularly those of the genus Eunotia. Ten species are described; five of them are registered for the first time in the Amazon basin, and six in all of Colombia. All taxa were photographed with scanning electron microscopy. Fine valve morphology of E. anamargariate, E. pseudoindica, E. triodon, and E. zydodon var. compacta is described for the first time.

O trabalho realizou-se nas três bacias mais importantes da Amazônia Colombiana (Alto Solimões, Içá e Japurá). Os igarapés e lagos estudados apresentam alta riqueza de diatomáceas, principalmente do gênero Eunotia. Foram descritas 10 espécies e, pela primeira vez, a morfologia das valvas de E. anamargaritae, E. pseudoindica, E. triodon e E. zydodon var. compacta, foram descritas ao microscópio eletrônico. Dentre as espécies de Eunotia, encontradas no presente estudo, seis são primeiras citações para a Colômbia e cinco para a região amazônica.