Abstract The mayflies are insects widely known as indicators of aquatic quality in freshwater systems, they are abundant and diverse in tropical streams. In this study, it was determined the influence of physical, chemical and bacteriological characteristics on the Ephemeroptera assembly in a period of low precipitation in the Ocoa river of Meta department. There were 5,332 nymphs belonging to 4 families, 10 genera and 3 species. Three new genera records and one species are presented for Meta: Cloeodes, Zelusia, Lumahyphes and Americabaetis alphus. The genera Camelobaetidius and Varipes were found associated with conditions of contamination by organic matter and water mineralization. Likewise, Americabaetis, Thraulodes, Lumahyphes and Tricorythodes were associated with contamination conditions, especially with nitrites and nitrates. Nanomis, Cloeodes and Zelusia showed greater sensitivity to the contamination condition and were related to high percentages of dissolved oxygen in the water and they were in the sampling stations of the upper part in the river. It is important to mention that there were not Ephemeroptera in most of the stations associated with the urban area. That reflects their high sensitivity to polluting conditions at low precipitation period.

Resumen Hydroptilidae es una de las familias más diversas del orden Trichoptera en el mundo. En el Neotrópico se han reportado 36 géneros y en Colombia se han registrado 14 en estado larval y 11 en estado adulto. Se registra por primera vez para Colombia la larva de Byrsopteryx. La larva se encontró en el río Orotoy (919 m s.n.m.), corriente del piedemonte del flanco oriental de la Cordillera Oriental del país (Orinoquia). El tramo se caracterizó por ser de tipo cascada, corriente rápida sobre rocas y guijarros, vegetación riparia conservada con dosel abierto y suelo franco-arcilloso. La temperatura del agua era de 19,7 °C, el pH de 5,8, la conductividad de 15,6 μS/cm y el oxígeno disuelto de 9,19,7 mg/1 O2. Dada la gran diversidad de ecosistemas acuáticos y el escaso conocimiento de géneros de esta familia en Colombia, se espera que en un futuro cercano se aunen esfuerzos que fomenten la investigación y el descubrimiento de nuevas especies para el país.

Abstract Hydroptilidae is one of the most diverse families of the order Trichoptera in the world. Neotropical fauna has 36 genera. In Colombia, 14 have been reported in the larval stage and 11 in the adult stage. In the present study, a Byrsopteryx larva is registered for the first time in Colombia. The larva was found in the Orotoy River (919 MASL), a stream from the foothills of the eastern flank of the country's Eastern Cordillera (Orinoquia) characterized as waterfall current with riffle on rocks and pebbles, preserved riparian vegetation with open canopy, and clay-loam soil. The water temperature was 19.7 °C, pH 5.8, conductivity 15.6 μS/cm, and dissolved oxygen 9.1-9.7 mg/lO2. Given the high diversity of aquatic ecosystems and the limited knowledge of Hydroptilidae genera in Colombia, we hope to open the way for new research and discovery of more species in the country.

Resumen En la región andina Colombiana, se han realizado diversas investigaciones en taxonomía y ecología de las comunidades de Ephemeroptera. Sin embargo, otras regiones, como la Orinoquia, se encuentran poco estudiadas. En esta región, se han reportado cuatro especies: Varipes lasiobrachius Lugo-Ortiz & McCafferty, Coryphorus aquilus Peters, Miroculis (Atroari) colombiensis Savage & Peters y Tricorythopsis rondoniensis (Dias, Cruz & Ferreira). El objetivo principal de este estudio fue reportar por primera vez para la región las especies: Mayobaetis ellenae (Mayo), Hydrosmylodon primanus (Eaton), Haplohyphes baritu Domínguez, Camelobaetidius edmundsi Dominique, Mathuriau & Thomasy Nanomis galera Lugo-Ortiz & McCafferty.

Abstract There is extensive research of the Ephemeroptera communities taxonomy and ecology in the Andean region of Colombia. However, other regions such as the Orinoquia have been insufficiently studied. From this region, in the Meta department, four species have been registered: Varipes lasiobrachius Lugo-Ortiz & McCafferty, Coryphorus aquilus Peters, Miroculis (Atroari) colombiensis Savage & Peters and Tricorythopsis rondoniensis (Dias, Cruz & Ferreira). The main objective of this study is to report for the first time for this region the species: Mayobaetis ellenae (Mayo), Hydrosmylodon primanus (Eaton), Haplohyphes baritu Domínguez, Camelobaetidus edmundsi Dominique, Mathuriau & Thomas and Nanomis galera Lugo-Ortiz & McCafferty.

Dada la diversidad y oferta de áreas naturales o artificiales en el piedemonte Llanero y cuenca del Orinoco para la avifauna, se hace necesario llevar a cabo inspecciones y monitoreos de focos de concentración de aves como posible peligro para la aeronavegación. Para este propósito se tomó como referencia al municipio de Villavicencio (Meta, Colombia) estableciendo dos niveles diferentes de evaluación, incluyendo las áreas de aeropuertos y el Parque Ecológico Reciclante. En cada nivel identificado se realizaron visitas de inducción, ajuste de categorías de hábitats, caracterización de la cobertura y uso del suelo y la identificación de los ecosistemas estratégicos partiendo del concepto de servicios ambientales prestados, especialmente la oferta de hábitat. Las observaciones permitieron la categorización de hábitats de influencia de los niveles 1 y 2, en ecosistemas boscosos, pastizales, ecosistemas acuáticos, agroecosistemas y la presencia de infraestructura urbana y productiva, focos importantes para aves de importancia potencial en el peligro aviario.

Given the diversity and range of natural or artificial areas for avifauna in the Plains piedmont and the Orinoco river basin, it is necessary to carry out inspections and monitoring of concentration of bird outbreaks as a potential hazard to air navigation. For this purpose, the municipality of Villavicencio (Meta, Colombia) was made reference to establish two different levels of evaluation, including the areas of airports and the Reciclante Ecological Park. At each level identified induction visits, adjustment of habitat categories, coverage characterization and land use, and identification of strategic ecosystems based on the concept of environmental services, especially habitat supply were performed. The observations allowed the categorization of level 1 and 2, habitats influence in forest ecosystems, grasslands, aquatic ecosystems, agro ecosystems and the presence of urban and productive infrastructure, central focus for birds of potential importance in aviary hazard.