Effects of food availability and habitat features on the Ephemeroptera species composition at seasonal and spatial scales from neotropical floodplain rivers / Efeitos da disponibilidade de alimento e características do habitat sobre a composição de espécies de Ephemeroptera nas escalas sazonal e espacial de rios de planície neotropicais

Abstract Brazilian floodplains have suffered great changes in their natural characteristics in recent decades, mainly in the flood pulse. The Upper Paraná River floodplain is one of the few places where are found remained areas in which such peculiar characteristics keep reflecting on its high biodiversity. Ephemeroptera nymphs are one of the higher density groups among benthic community, occurring in many water bodies like large rivers and secondary channels. We sought to understand which factors are needed for the species establishment and how much important is the species colonization, especially in environments with anthropogenic changes. The marginal areas, which are more structured with presence of macrophytes, showed the highest density and richness even in the Paraná River that has great human impact. We verified dominance of Americabaetis alphus, Tricorythopsis araponga, Tricorythopsis artigas on the Parana River, correlated with transparency, depth and electric conductivity, while the dominance of Traverella sp. was correlated with water temperature, especially in marginal areas. Consequently, the increasing transparency and electric conductivity due to the Porto Primavera dam in Parana River can be favoring those Ephemeroptera species. We demonstrated the importance of preserving the wetlands of Ivinhema River State Park mainly for Guajirolus sp., which was only registered in this region. Therefore, our study provides support for understanding gaps from previously studies using artificial substrates in three large rivers which are of great importance to the upper Paraná River floodplain.

Resumo Muitas planícies de inundação brasileiras vêm sofrendo enormes alterações em suas características naturais nas últimas décadas, principalmente no pulso de inundação. A planície de inundação do alto rio Paraná é um dos poucos lugares onde ainda há áreas nas quais essas características peculiares se mantêm, o que reflete em sua alta biodiversidade. Dentre a comunidade zoobentônica, Ephemeroptera é um dos grupos com maior densidade, ocorrendo em diversos corpos aquáticos como rios de grande porte e canais secundários. Nós buscamos compreender quais fatores são necessários para o estabelecimento das espécies e o quão importante é a colonização dessas espécies, principalmente em ambientes com modificações antrópicas. As áreas marginais mais estruturadas com presença de macrófitas apresentaram altas densidade e riqueza mesmo no rio Paraná que apresenta grande impacto antrópico. Verificamos que as dominâncias de Americabaetis alphus, Tricorythopsis araponga e Tricorythopsis artigas no rio Paraná foram correlacionadas com maiores valores de transparência, profundidade e condutividade, enquanto que a dominância de Traverella sp. foi correlacionada com temperatura, principalmente em áreas marginais. Consequentemente, o aumento da transparência e da condutividade devido à barragem de Porto Primavera no rio Paraná pode estar favorecendo essas espécies de Ephemeroptera. Nossos resultados demonstram a importância da preservação do Parque nacional das várzeas do rio Ivinhema, principalmente para o gênero Guajirolus sp., o qual apenas foi registrado nessa região. Portanto, nosso estudo vem trazer subsídios para compreensão de lacunas verificadas em estudos anteriores utilizando substratos artificiais em três rios de enorme influência na planície de inundação do alto rio Paraná.

Temperatura y emergencia diaria de siete géneros de Ephemeroptera(Insecta) en un río de la Selva Nublada de los Andes Tropicales / Temperature and daily emergence of seven genera of Ephemeroptera (Insecta) in a cloud forest stream of tropical Andes

ResumenLa emergencia diaria de los efemerópteros de ríos neotropicales y sus causas, han sido poco estudiadas. En zonas templadas, este proceso es mejor conocido y atribuido a diversos factores. En este trabajo, estudiamos la emergencia diaria de subimagos de varios géneros de Ephemeroptera en un río en una selva nublada andina venezolana, y sus posibles relaciones con cambios diarios de la temperatura ambiente. Cuatro trampas de emergencia fueron colocadas en un tramo de 50m del río, y cada una se examinó cada dos horas durante 24 horas para recolectar los subimagos recién emergidos. Este procedimiento fue repetido en ocho fechas, entre noviembre-2007 y febrero-2008, para un total de 32 observaciones en cada hora de muestreo. Los subimagos fueron criados hasta adultos e identificados hasta género. Para cada género y hora de muestreo calculamos la densidad relativa de emergencia por trampa. La temperatura del agua y del aire fueron medidas cada hora del ciclo diario de observación y, para cada hora calculamos la temperatura promedio y los gradoshoras promedio del aire y del agua, de las ocho fechas estudiadas. Se identificaron siete géneros: Leptohyphes Eaton, 1882 y Haplohyphes Allen, 1966 (Leptohyphidae); Prebaetodes Lugo-Ortiz y McCafferty, 1996, Andesiops Lugo-Ortiz y McCafferty, 1999, Baetodes Needham y Murphy, 1924 y Americabaetis Kluge, 1992 (Baetidae); y Thraulodes Ulmer, 1920 (Leptophlebiidae); siendo más abundantes Leptohyphes (38.4 %) y Thraulodes (20.5 %). La emergencia ocurrió entre las 11:00 am y 23:00 pm, y mostró lo siguiente: a) una emergencia iniciada en horas diurnas, por organismos de Leptohyphes, Prebaetodes y Haplohyphes; b) una emergencia nocturna, realizada por Thraulodes, Andesiops, Baetodes y Americabaetis; y c) dos máximos, uno diurno producido por Leptohyphes, y otro nocturno con predominancia de Thraulodes. Estos resultados son los primeros registros sobre la emergencia diaria diurna en Andesiops, Prebaetodes, Americabaetis, Haplohyphes y Leptohyphes; así como, de la emergencia nocturna en Thraulodes. Se evidenció que Leptohyphes, con ninfas pequeñas (ancho cefálico promedio = 1.05 mm), necesitó acumular menos grados-horas para iniciar la emergencia que los requeridos por Thraulodes, cuyas ninfas son más grandes (ancho cefálico promedio = 2.01 mm). Esta disparidad en los requerimientos energéticos para la emergencia, debe ser consecuencia de diferencias entre los tamaños de las ninfas maduras de ambos géneros; hechos que se apoyan sobre la constancia de tamaños que muestran ambos taxa en un gradiente térmico-altitudinal, y en la poca variabilidad diaria y estacional de la temperatura del agua en el río La Picón. En el lapso diario de emergencia, las temperaturas promedios del aire y del agua fueron superiores a aquellas registradas dentro del lapso de no-emergencia; en consecuencia, se propone que durante el lapso diario en el que ocurre este proceso, el ambiente es térmicamente favorable para la emergencia de los subimagos y su supervivencia fuera del agua.

AbstractDaily emergence of mayflies in Neotropical rivers and their causes have been poorly studied. In temperate zones, this process is better known and attributed to several factors. In this work, we studied the daily emergence of subimagines of several Ephemeroptera genera in La Picón River of a Venezuelan Andean cloud forest and its relation with changes of environmental temperature. Four emergence traps were placed along a reach of 50 m of the stream, each one was examined each two hours in a 24 hr cycle to capture the newly emerged subimagos. This procedure was repeated for eight dates between November-2007 and February-2008 for a total of 32 observations in each sampling hour. The subimagos were reared to adults and identified to genus. The relative density of emergence per trap was calculated for each genus and sampling hour. Water and air temperature were measured each hour during the daily cycle of observation, and the averages of temperature and hour-degrees of air and water were calculated for each hour from the eight dates studied. Seven genera were identified: Leptohyphes Eaton, 1882 and Haplohyphes Allen 1966 (Leptohyphidae); Prebaetodes Lugo-Ortiz and McCafferty, 1996, Andesiops Lugo-Ortiz and McCafferty, 1999, Baetodes Needham and Murphy, 1924 and Americabaetis Kluge, 1992 (Baetidae); and Thraulodes Ulmer, 1920 (Leptophlebiidae); being the more abundant Leptohyphes (38.4 %) and Thraulodes (20.5 %). The emergence occurred between 11:00 am and 23:00 pm showing the following: a) an emergence initiated during daylight hours by organisms of Leptohyphes, Prebaetodes and Haplohyphes; b) a nocturnal emergence, in Thraulodes, Andesiops, Baetodes and Americabaetis; and c) two peaks: one diurnal produced by Leptohyphes and other nocturnal with predominance of Thraulodes. These results are the first records on the diurnal daily emergence in Andesiops,Prebaetodes,Americabaetis, Haplohyphes, and Leptohyphes, as well as the nocturnal emergence in Thraulodes. It was evidenced that Leptohyphes, with small nymphs (average head width = 1.05 mm) needed to accumulate less hourdegrees to initiate the emergence than those required by Thraulodes whose nymphs are larger (average head width = 2.01 mm). This disparity in the emergence energy requirements must be consequence of differences between the sizes of mature nymphs of both genera; facts which rely on the constancy of sizes shown by these taxa along an altitudinal-thermal gradient and the little daily and seasonal variability of water temperature in La Picón River. In the daily lapse when the emergence occurred, the air and water average temperatures were higher than those registered in the no-emergence lapse; therefore; it is suggested that during the daily lapse, when this process occurs, the environment is thermally favorable for the emergence of subimagos and their survival out of water. Rev. Biol. Trop. 64 (1): 117-130. Epub 2016 March 01.

Leptohyphidae (Insecta: Ephemeroptera) from northeastern Brazil

New records of Leptohyphidae for Northeastern Brazil are provided. Previously, only Tricorythopsis bahiensis Dias, Salles & Ferreira had been recorded in this region, but we now record one species of Amanahyphes Salles & Molineri, one of Leptohyphes Eaton, three of Traverhyphes Molineri, three of Tricorythodes Ulmer, and seven of Tricorythopsis Traver. Two of these species are recorded for the first time in Brazil. As all of these species are reported, the Northeastern Brazil became the second most diverse geographic region in Brazil in Leptohyphidae.