Search

Introduction: Coarse particulate organic matter originated in riparian vegetation is the main source of energy in many headwater streams. However, the transfer of such material is altered by the destruction of forests. Objective:To assess flow differences of this organic matter in streams with forests and grasslands. Methods:We comparedinput, storage and export of this organic matterin the riparian belts of streams with forests, and streams with grasslands, in the central Andean region of Colombia. For each stream, we measured vertical and lateral litter with baskets; stream bed litter with a quadrant, and matter export with drift nets, in a 100 m reach. Results:The streams with riparian forest received an average of 915 g m-2of coarse particulate organic matter annually, exported a total of 334 g m-3and stored 732 g m-2, values that were significantly higher than in grassland streams, where the corresponding values were: 125.4 g m-2; 128 g m-3and 205.5 g m-2. Conclusions:The removal of tree cover from the riparian zone reduced the organic matter in these headwater streams of Colombia. Introducción:La materia orgánica particulada gruesa originada en la vegetación ribereña es la fuente principal de energía en muchas cuencas de cabecera. Sin embargo, la transferencia de dicha materia es alterada por la destrucción de los bosques. Objetivo:Evaluar diferencias en la materia orgánica en quebradas con bosques y con pastizales. Métodos: Comparar las entradas, el almacenamiento y la exportación de esta materia orgánica en el cauce de quebradas con bosques y con pastizales, en la región central de los Andes de Colombia. En cada quebrada, se midieron los aportes verticales y laterales de hojarasca con canastas; hojarasca del lecho de las quebradas con cuadrantes, y la exportación de material con redes de deriva, con un alcance de 100 m. Resultados: Las quebradas con bosques ribereños recibieron un promedio anual de 915 g m-2de materia orgánica particulada gruesa, exportando un total de 334 g m-3y almacenando 732 g m-2, valores que fueron significativamente más altos que en quebradas con pastizales, donde los valores correspondientes fueron: 125.4 g m-2; 128 g m-3y 205.5 g m-2. Conclusiones: La remoción de cobertura boscosa de la zona ribereña reduce la materia orgánica en estas cuencas de cabecera en Colombia.

Riparian forests provide high amounts of leaf litter to tropical headwater streams (1–3 order) and its decomposition is controlled by interactions between leaf quality and macroinvertebrate activity. However, few studies have been conducted in North Andean streams. We conducted a leaf litter decomposition experiment using three native tree species (Heliocarpus americanus, Nectandra sp., and Cecropia telealba) in two headwater streams in the Colombian Coffee-growing Eco-Region. The interactive roles of intrinsic factors (quality) and extrinsic factors (presence/absence of macroinvertebrates) on decomposition rates were tested. Three single-species treatments, a species-mixture treatment, and an artificial substrate treatment were incubated in either coarse-pore mesh or fine-pore mesh bags to allow or exclude macroinvertebrate colonization, respectively. Bags were removed from the streams 7, 14, 28 and 56 days after starting the study. Toughness and chemical quality of senescent leaves of each species were determined in order to test their effect on the decomposition rates. The k-values for the three single-species and the species-mixture treatments indicated that decomposition occurred at medium to fast rates (0.009–0.01 day−1). H. americanus showed the greatest mass loss at the end of the trial, followed by C. telealba and Nectandra sp. Leaf toughness was positively correlated with carbon-to-nitrogen ratio (C: N) and carbon-to-phosphorus ratio (C: P) and, in turn, the three characteristics were negatively correlated with breakdown rate. A total of 3876 individuals from 13 orders, 35 families, and 47 genera colonized leaf-litter bags. Chironomidae, Lumbriculidae, and Hydropsychidae were the families with the highest abundance. The abundance and richness of macroinvertebrates in the leaf-litter bags showed no correlation with the descriptors of intrinsic characteristics (leaf quality). These results indicate that among the three tree-species in the study, the intrinsic characteristics of senescent leaves determine their mass loss rates, while the macroinvertebrate abundance or richness play a secondary role, probably due to the fact that shredders were not abundant.

La restauración de los bosques ribereños es una medida fundamental para la recuperación de ambientes acuáticos afectados por actividades ganaderas. Con el fin de determinar los cambios en quebradas asociadas con la restauración temprana de bosques ribereños, se hizo un seguimiento durante tres años a cuatro arroyos de primer orden ubicados en la cuenca del río La Vieja, Colombia. En cada arroyo se tomaron muestras puntuales de agua para análisis fisicoquímico y bacteriológico, se registraron aspectos de calidad de hábitat y se recolectaron macroinvertebrados. Durante los años de evaluación hubo una disminución significativa en los valores de DBO5, se presentaron cambios leves en la composición del sustrato y los patrones de flujo, y aumentaron los valores del índice de calidad de hábitat (ICH). En cuanto a los macroinvertebrados, se recolectaron 10.490 individuos, distribuidos en 19 órdenes, 53 familias y 56 géneros. Los órdenes más abundantes fueron Diptera (56 %), Trichoptera (22 %) y Basommatophora (7 %). Las familias Chironomidae e Hydropsychidae fueron las más abundantes, con el 53 y el 20 % del total. Chironomidae disminuyó significativamente a través de los años de monitoreo y los valores de los índices EPT (Ephemeroptera, Plecoptera, Trichoptera) y BMWP (Biological Monitoring Working Party) aumentaron. La exclusión de la ganadería del área ribereña y el inicio de procesos de restauración de la vegetación ribereña tuvo un efecto positivo en los parámetros de calidad de agua, del hábitat y en la comunidad de macroinvertebrados acuáticos, lo que constituye una alternativa valiosa para recuperar ambientes acuáticos en paisajes ganaderos. The restoration of riparian forests is a fundamental step for the recovery of aquatic environments affected by cattle production. To determine the changes in the aquatic environment in streams with early riparian restoration processes, four first-order streams of La Vieja River watershed (Colombia) were monitored for three years. In each stream, we analyzed water, habitat quality, and the aquatic macroinvertebrate assemblage. During the study period, there was a significant decrease in BOD5 values, the substrate composition and flow patterns changed, and the values of the habitat quality index increased. A total of 10490 macroinvertebrates were collected, distributed in 19 orders, 53 families, and 56 genera. The most important orders were Diptera (56%), Trichoptera (22%), and Basommatophora (7%). Chironomidae and Hydropsychidae were the most abundant families with 53% and 20%. Chironomidae decreased significantly through the years of monitoring and the values of the EPT and BMWP indexes increased. The exclusion of cattle from the riparian area and the beginning of the restoration process had a positive effect on water quality and habitat parameters, as well as on the community of aquatic macroinvertebrates, which constitutes a valuable alternative to recover aquatic environments in livestock landscapes.

Introducción: Los élmidos son organismos acuáticos frecuentemente asociados con aguas corrientes, limpias y bien oxigenadas. Sin embargo, algunos géneros de esta familia también se encuentran en aguas moderadamente contaminadas, lo cual puede ser un reflejo de su tolerancia a algún grado de deterioro del hábitat. Objetivo: Determinar la sensibilidad o tolerancia a la contaminación y los principales factores que influyen en la presencia y composición taxonómica de Elmidae en microcuencas colombianas. Métodos: Se muestrearon 60 localidades entre 450 y 4000 msnm, principalmente en la región Andina, los muestreos se realizaron entre 2002 y 2013 con 70 eventos no simultáneos en cinco zonas. En un transecto de 100 m, se registraron datos físico-químicos, bacteriológicos y de calidad del hábitat (ICH), se hicieron arrastres con red D y Surber, y se determinaron los géneros de Elmidae. Se realizó un Análisis de Correspondencia Canónica entre las variables ambientales y la composición de Elmidae, las relaciones significativas se confirmaron con una prueba de Mantel y se realizó una prueba Mantel parcial incluyendo la ubicación geográfica como tercera matriz. Se calcularon los Índices de Contaminación ICOs y de Calidad de Agua ICA-FSN y se definieron intervalos de aparición de géneros para variables ambientales e índices. Para obtener las significancias estadísticas, se realizaron Análisis de Varianza ANOVA, pruebas t de Student y Modelos Lineales Generalizados MLG con distribución Poisson. Resultados: Se encontraron 22 géneros y 15 especies que representan el 78.5 % de la riqueza nacional conocida. Tyletelmis y las especies Gyrelmis pusio, G. simplex, Xenelmis sandersoni, X. leechi, X. granatoides y X. teres, corresponden a nuevos registros para Colombia. Los principales factores que influyeron en la riqueza y composición de Elmidae fueron: saturación de oxígeno, deposición de sedimentos, sólidos suspendidos, disponibilidad de sustratos, altura, ubicación geográfica, conductividad, alcalinidad, turbidez, nitratos, nitrógeno amoniacal y fósforo. Conclusiones: Los géneros de Elmidae difieren en su tolerancia a la contaminación y, por lo tanto, no pueden ser clasificados bajo el mismo grado de sensibilidad. Esta información puede ser útil para la clasificación de los géneros de Elmidae de acuerdo con su sensibilidad a los cambios en las condiciones ambientales y la degradación del hábitat, lo cual será un primer paso para la incorporación en un índice biótico de calidad de agua adaptado para las condiciones locales o el ajuste de los índices preexistentes. Riffle beetles are aquatic organisms frequently associated with well-oxygenated clean running water. However, some genera of Elmidae can also be found in moderately polluted streams proving their tolerance to certain degree of habitat degradation. To determine the pollution sensitivity and tolerance of each genus of Elmidae in Colombian streams, and the main factors that influence its presence and taxonomic composition. Methods: Sixty locations between 450 and 4 000 m.a.s.l. were sampled, mainly in the Andean Region of Colombia. Collection was carried out between 2002 and 2013 with 70 non-simultaneous events in five zones. In a 100 m transect, physicochemical, bacteriological and environmental quality information was recorded. Samples of Elmidae were collected with D and Surber nets and determined taxonomically. A Canonical Correspondence Analysis of the Elmidae assembly and environmental data was carried out, significant relationships were confirmed with a Mantel test and a partial Mantel test was carried out including the geographic location as the third matrix. The Pollution (ICO) and Water Quality (ICA-NSF) Indices were calculated, and the occurrence intervals by genus were plotted for environmental variables and indices. Analysis of Variance ANOVA, Student?s t-test and Generalized Linear Models GLM with Poisson distribution, were calculated in order to establish the significance of the results.Twenty-two genera and 15 species were found in the evaluated streams; which represent 78.5 % of known national generic richness. Tyletelmis and the species Gyrelmis pusio, G. simplex, Xenelmis sandersoni, X. leechi, X. granatoides and X. teres correspond to new records for Colombia. The most important factors influencing the presence and composition of Elmidae were: oxygen saturation, sediment deposition, suspended solids, epifaunal substrate availability, altitude and geographic location, conductivity, turbidity, alkalinity, nitrates, ammonia nitrogen and phosphorus. The genera of Elmidae differ in their tolerance to contamination and therefore cannot be classified in the same degree of sensitivity. This information can be useful for classifying genera of Elmidae according to their sensitivity to changes in environmental conditions and habitat degradation, which will be a first step to incorporate Elmidae in water quality biotic indices adapted to local conditions or to adjust preexisting indices Fil: Gonzalez Cordoba, Marcela. Universidad del Valle; Colombia. 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 para la Investigación en Sistemas Sostenibles de Producción Agropecuaria; Colombia Fil: Zúñiga, María del Carmen. Universidad del Valle; Colombia. Centro para la Investigación en Sistemas Sostenibles de Producción Agropecuaria; Colombia Fil: Giraldo, Lina Paola. Centro para la Investigación en Sistemas Sostenibles de Producción Agropecuaria; Colombia Fil: Ramírez, Yuly Paulina. Centro para la Investigación en Sistemas Sostenibles de Producción Agropecuaria; Colombia Fil: Chará, Julián. Centro para la Investigación en Sistemas Sostenibles de Producción Agropecuaria; Colombia

The pressures of a growing population and a fluctuating economy have caused extensive landuse transformations in the Colombian Andes, and >63% of the natural land cover has been replaced by cattle and crop fields. Despite the obvious importance of agriculture as a driver of stream degradation, the specific effects of agriculture on low-order streams of the Andean region are poorly understood. We used aquatic macroinvertebrates as indicators of biological integrity and applied structural equation modeling (SEM) to explore mechanisms through which local agricultural practices degrade headwater streams of the Colombian coffee-growing region. Our results suggest that agriculture affects the aquatic macroinvertebrate community indirectly by increasing the concentration of NH3-N in the water and reducing the width of the riparian forest. Moreover, through the reduction of riparian forest width, agriculture increased % slow-flowing habitats and decreased the availability of coarse substrates in the reach...

Three new species of Leptohyphes Eaton,1882 (Ephemerotera: Leptohyphidae) are described,diagnosed and illustrated from nymphs collected in Colombia. Geographical ranges and ecological notes relating important environmental variables are given for each species. Leptohyphes andina sp. nov. is characterized by: forefemur length / maximum width 1.8-1.9,fore and hind margin of middle and hind femora with strong spine-like setae on elevated sockets,femoral surface covered by small pale spots,apex of femora with anterior margin roundly projected distally,tarsal claw only with 3-4 marginal denticles,pronotum with triangular lateral projection,hind wing pads present in female,gill formula 3/5/5/5/2,gill V with ventral extension on dorsal lamella. Leptohyphes quimbaya sp. nov. presents the following characters: body covered by hair-like setae,with paired short and blunt tubercles on abdominal terga V-IX,femora wide (forefemur length/ maximum width 1.6),fore and hind margin of femora with tiny spine-like setae,tarsal claws with 2-3 marginal denticles,pronotum with triangular (but apically blunt) lateral projection,hind wing pads present in females,gill formula 3/7/7/5/2,gill V without ventral extension on dorsal lamella. Leptohyphes calarca sp. nov. is distinguished by: pilose body,slender femora (forefemur length / maximum width 2.3),foremargin of middle and hind femora without setae,tarsal claws with 5 marginal denticles and 1 submarginal subapical denticle,pronotum strongly projected laterally,fore wingbuds blackish,hind wing pads present in females,gill formula 3/4/4/3/1,gill V with ventral extension on dorsal lamella. Fil: Molineri, Carlos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucuman. Instituto de Biodiversidad Neotropical. Universidad Nacional de Tucuman. Facultad de Ciencias Naturales e Instituto Miguel Lillo. Instituto de Biodiversidad Neotropical. Instituto de Biodiversidad Neotropical; Argentina Fil: Zuñiga, María del Carmen. Universidad del Valle; Colombia Fil: Ramos, Blanca. Universidad del Valle; Colombia Fil: Giraldo, Lina P.. Centro para la Investigación en Sistemas Sostenibles de Producción Agropecuaria; Colombia Fil: Cardona, William. Universidad del Valle; Colombia

Influence of cattle ranching on the community of aquatic macroinvertebrates in watersheds of central Andes, Colombia. In order to measure the impact of cattle ranching and riparian corridors on the composition and diversity of benthic macroinvertebrates in Andean watersheds, nine headwater streams were selected in the municipality of Villamaría (Caldas, Colombia), five of them with riparian corridors and four without protection. In july (2013) in each stream, macroinvertebrate samples were collected using D and Surber nets, and streams were characterized according to water quality, channel metrics and habitat quality score. In total 98 934 individuals were collected, distributed in nine classes, 17 orders, 56 families and 92 genera. Veneroidea was the most abundant order followed by Trichoptera, Diptera, Tubificida and Ephemeroptera. Coleoptera was the order with highest richness with 28 genera, followed by Diptera with 18, Trichoptera with 11, Ephemeroptera with 10 and Odonata with 8. Streams with riparian corridors were deeper, had higher proportion of coarse substrates and Habitat Quality Score and presented higher genus diversity than those unprotected (p

Objective. To determine the trophic structure of an aquatic insect assembly associated to eight streams in the Colombian coffee-growing ecoregion. Materials and methods. Aquatic insects were collected in eight forested streams located in La Vieja river basin. The taxa collected were assigned to dietary groups according to a regional classification based on the gut content analysis of aquatic insects associated to forested streams of the Otún river basin. Results. 2019 individuals belonging to 73 taxa were collected and 60 were classified into dietary groups. The most abundant group was collectors (55%), followed by shredders (31%) and predators (10%). Scrapers represented only 0.05% of the sample and the remaining 3.95% could not be classified due to lack of information. Conclusions. The dominance of collectors and shredders reveals the importance of coarse particulate organic matter (leaf litter) as a food resource for the insect fauna. Similarities between the trophic structure of this community and other communities studied in similar streams, suggest the possibility of a common pattern for Andean streams. This study evidenced the absence of knowledge on trophic ecology of tropical aquatic insects; 50% of the taxa collected had no associated information for the tropics and 20% had no information neither for the tropics nor temperate zones. Key words: Andean streams, aquatic insects, dietary groups, trophic structure, tropical ecosystems.

1. The diversity and ecology of Staphylinidae in the Neotropical region has been poorly investigated, especially in riverine landscapes where these beetles are among the dominant organisms. Therefore, the relation between the occurrence of Staphylinidae and environmental variables was investigated in riverine systems of Southwest and Central Colombia. 2. Samples were collected between 1984 and 2006 following standardised methods for biological sampling and water quality evaluation. Water quality indexes were calculated and six microhabitats were surveyed: riparian vegetation (light traps), sediments (surber net), rock, macrophytes and litter (manually). 3. The 1834 collected individuals belonged to seven subfamilies and 17 genera. The most frequent genera were Thinodromus, Stenus and Philonthus. Among all measured environmental variables, microhabitat explained to most extent the distribution patterns of the rove beetles. Preference to riparian vegetation was found for the family as a whole but preferences by subfamilies differed strongly. Steninae were absent in the riparian vegetation and showed close association to macrophytes. Oxytelinae and Staphylininae were frequently collected in riparian vegetation and litter, respectively. Although water quality and altitude were only of secondary importance to the Staphylinidae distribution, the tolerance of Steninae to waters of poorer quality and its concentration in the altitudinal range of 1001-1500 m a.s.l. is highlighted. 4. Preferences to certain microhabitats found for some Staphylinidae taxa supply more evidence to the habitat-specialisation of these beetles, representing an important contribution to both their ecological characterisation and to the fauna of riverine systemsin the Neotropical region.© 2009 The Royal Entomological Society.

The dynamics of leaf breakdown in a headwater Colombian stream were evaluated for the native tree species Myrsine guianensis, Cupania latifolia and Nectandra lineatifolia using coarse and fine mesh litter bags. Ten bags of each species (five of each mesh size) were retrieved from the stream at 1, 8, 15, 30, 60 and 120 days. k values ranged from 0.0008 to 0.0058 day -1 and density of macroinvertebrates from 35 to 55 individuals per leaf bag, peaking at day 8. Myrsine guianensis degraded more rapidly than the other species for both coarse and fine mesh bags. This species and Nectandra lineatifolia presented differences in k values between coarse and fine mesh bags, suggesting that macroinvertebrates influenced the decay rate. Despite the low densities of macroinvertebrates found, shredders represented 12.7% of individuals and 50 to 68% of the invertebrate biomass in bags, indicating that this functional feeding group was an important component of fauna associated with litter breakdown in this first order tropical stream.

The expansion of the agricultural frontier in Colombia has exerted significant pressure on its aquatic ecosystems during the last few decades. In order to determine the impacts of different agricultural land uses on the biotic and abiotic characteristics of first and second order streams of La Vieja river watershed, we evaluated 21 streams located between 1,060 and 1,534 m asl in the municipalities of Alcalá, Ulloa, and Cartago (Valle del Cauca, Colombia). Seven streams were protected by native vegetation buffers, eight had influence of coffee and plantain crops, and six were influenced by cattle ranching. Habitat conditions, channel dimensions, water quality, and aquatic macroinvertebrates were studied in each stream. Streams draining cattle ranching areas had significantly higher dissolved solids, higher phosphorus, higher alkalinity, higher conductivity, and lower dissolved oxygen than those covered by cropland and forests. Coarse substrates and diversity of flow regimes were significantly higher in cropland and protected streams when compared to streams affected by cattle ranching, whereas the percent of silt and slow currents was significantly higher in the latter. A total of 26,777 macroinvertebrates belonging to 17 orders, 72 families and 95 genera were collected. The most abundant groups were Diptera 62.8%, (Chironomidae 49.6%, Ceratopogonidae 6.7%), Mollusca 18.8% (Hydrobiidae 7.2%, Sphaeriidae 9.6%) and Trichoptera 5.7% (Hydropsychidae 3.7%). The Ephemeroptera, Trichoptera, and Plecoptera orders, known for their low tolerance to habitat perturbation, had high abundance in cropland and forested streams, whereas Diptera and Mollusca were more abundant in those impacted by cattle ranching. Results indicate that streams draining forests and croplands have better physical and biological conditions than those draining pastures, and highlight the need to implement protective measures to restore the latter.