Challenges Using Extrapolated Family-level Macroinvertebrate Metrics in Moderately Disturbed Tropical Streams: a Case-study From Belize

Family-level biotic metrics were originally designed to rapidly assess gross organic pollution effects, but came to be regarded as general measures of stream degradation. Improvements in water quality in developed countries have reignited debate about the limitations of family-level taxonomy to detect subtle change, and is resulting in a shift back towards generic and species-level analysis to assess smaller effects. Although the scale of pollution characterizing past condition of streams in developed countries persists in many developing regions, some areas are still considered to be only moderately disturbed. We sampled streams in Belize to investigate the ability of family-level macroinvertebrate metrics to detect change in stream catchments where less than 30% of forest had been cleared. Where disturbance did not co-vary with natural gradients of change, and in areas characterized by low intensity activities, none of the metrics tested detected significant change, despite evidence of environmental impacts. We highlight the need for further research to clarify the response of metrics to disturbance over a broader study area that allows replication for confounding sources of natural variation. We also recommend research to develop more detailed understanding of the taxonomy and ecology of Neotropical macroinvertebrates to improve the robustness of metric use

Effects of exotic trout on benthic communities in high-Andean tropical streams

We explored the effects of introduced trout on primary and secondary producers at 2 spatial scales in 17 Andean stream reaches above 3000 m asl in 3 subbasins of the Guayllabamba watershed in Ecuador. At each stream reach, we measured trout density, biological factors, and environmental factors that might affect distribution and density of trout. We also carried out a field-inclusion experiment along a 105-m section of the Saltana stream (which has no trout), in which we introduced trout in experimental cages to assess their effects on aquatic invertebrate populations and algal biomass. Oncorhynchus mykiss (Rainbow Trout) is widely distributed in streams of the Andean páramo in northeastern Ecuador and was the only fish species found. Trout distribution was correlated with altitude, quality of riparian vegetation, substrate diversity, and conductivity. In the survey, invertebrate community composition did not differ between streams with and without trout, but trout density and invertebrate richness were positively related. Trout density and algal biomass were negatively related. In the experiment, trout reduced the density of invertebrates (predominantly Andesiops [Baetidae], Orthocladiinae, and Simuliidae sp. 1) in drift and benthic samples. Thus, trout appeared to have a significant effect on aquatic invertebrate communities at the local scale via direct predation, which affects the densities of certain taxa, and behavioral responses of certain invertebrates (i.e., reduced drift). However, trout did not appear to affect algal biomass. This result might have been a consequence of the limited time that trout were kept in the enclosures. We conclude that introduced Rainbow Trout in tropical high-altitude streams can strongly affect invertebrate behavior and densities, which in turn, might affect other levels of the food web (as seen in the survey), but their effect on primary producers remains to be tested. © 2015 by The Society for Freshwater Science

Effects of exotic trout on benthic communities in high-Andean tropical streams

We explored the effects of introduced trout on primary and secondary producers at 2 spatial scales in 17 Andean stream reaches above 3000 m asl in 3 subbasins of the Guayllabamba watershed in Ecuador. At each stream reach, we measured trout density, biological factors, and environmental factors that might affect distribution and density of trout. We also carried out a field-inclusion experiment along a 105-m section of the Saltana stream (which has no trout), in which we introduced trout in experimental cages to assess their effects on aquatic invertebrate populations and algal biomass. Oncorhynchus mykiss (Rainbow Trout) is widely distributed in streams of the Andean páramo in northeastern Ecuador and was the only fish species found. Trout distribution was correlated with altitude, quality of riparian vegetation, substrate diversity, and conductivity. In the survey, invertebrate community composition did not differ between streams with and without trout, but trout density and invertebrate richness were positively related. Trout density and algal biomass were negatively related. In the experiment, trout reduced the density of invertebrates (predominantly Andesiops [Baetidae], Orthocladiinae, and Simuliidae sp. 1) in drift and benthic samples. Thus, trout appeared to have a significant effect on aquatic invertebrate communities at the local scale via direct predation, which affects the densities of certain taxa, and behavioral responses of certain invertebrates (i.e., reduced drift). However, trout did not appear to affect algal biomass. This result might have been a consequence of the limited time that trout were kept in the enclosures. We conclude that introduced Rainbow Trout in tropical high-altitude streams can strongly affect invertebrate behavior and densities, which in turn, might affect other levels of the food web (as seen in the survey), but their effect on primary producers remains to be tested. © 2015 by The Society for Freshwater Science

The Cricotopus (Oliveiriella) (Diptera: Chironomidae) of the High Altitude Andean Streams, with Description of a New Species, C. (O.) rieradevallae

The genus Oliveiriella (Chironomidae, Orthocladiinae) was erected by Wiedenbrug & Fittkau (1997). The adults have characteristic black spots on their wings and other characteristics similar to the genus Cricotopus. Pupal skins are very characteristic with strong short spines in the anal lobe instead of setae, while larvae are distinguishable by the long anal papillae and the intense blue color of their body. However, Andersen et al (2013) consider Oliveiriella as a subgenera of Cricotopus. In this paper, using the sequences of the cox1 gene, we conclude that Oliveiriella should be considered a subgenus within Cricotopus, confirming its status in Andersen et al (2013). Furthermore, we describe Cricotopus (Oliveiriella) rieradevallae Prat & Paggi sp. n. from the Saltana river (Ecuador). The adult males, females, and preimaginal stages of the two species of subgenus Oliveiriella known from South America Cricotopus (O.) almeidai n. comb. from Peru, Brazil, and Argentina and Cricotopus (O.) sanjavieri n. comb. from Argentina are compared with those of Cricotopus (O.) rieradevallae sp. n. from Ecuador. The differences allow the distinction of the three species. The cox1 gene reveals that at least three different undescribed species of the same subgenus are present in the high-altitude tropical Andes. The morphology of the available pupae and pupal exuviae reveals the presence of several morphotypes that are candidates to be described as new species. A key used to distinguish these pupal morphotypes is provided, including the three described species. Additionally, the distribution of the subgenus is discussed

The Cricotopus (Oliveiriella) (Diptera: Chironomidae) of the High Altitude Andean Streams, with Description of a New Species, C. (O.) rieradevallae

The genus Oliveiriella (Chironomidae, Orthocladiinae) was erected by Wiedenbrug & Fittkau (1997). The adults have characteristic black spots on their wings and other characteristics similar to the genus Cricotopus. Pupal skins are very characteristic with strong short spines in the anal lobe instead of setae, while larvae are distinguishable by the long anal papillae and the intense blue color of their body. However, Andersen et al (2013) consider Oliveiriella as a subgenera of Cricotopus. In this paper, using the sequences of the cox1 gene, we conclude that Oliveiriella should be considered a subgenus within Cricotopus, confirming its status in Andersen et al (2013). Furthermore, we describe Cricotopus (Oliveiriella) rieradevallae Prat & Paggi sp. n. from the Saltana river (Ecuador). The adult males, females, and preimaginal stages of the two species of subgenus Oliveiriella known from South America Cricotopus (O.) almeidai n. comb. from Peru, Brazil, and Argentina and Cricotopus (O.) sanjavieri n. comb. from Argentina are compared with those of Cricotopus (O.) rieradevallae sp. n. from Ecuador. The differences allow the distinction of the three species. The cox1 gene reveals that at least three different undescribed species of the same subgenus are present in the high-altitude tropical Andes. The morphology of the available pupae and pupal exuviae reveals the presence of several morphotypes that are candidates to be described as new species. A key used to distinguish these pupal morphotypes is provided, including the three described species. Additionally, the distribution of the subgenus is discussed

Secondary production of caddisflies reflects environmental heterogeneity among tropical Andean streams

La historia de vida de los macroinvertebrados y la producción secundaria rara vez se han medido en las corrientes de las tierras altas tropicales a pesar de que estas corrientes son muy heterogéneas y muestran entornos ecológicos únicos en comparación con las de las tierras bajas tropicales o en la zona templada. Evaluamos la producción secundaria y los atributos de la historia de vida de la caddisfly de Grazer de perifiton (Helicopsyche spp.) Utilizando el método de frecuencia de tamaño en tres corrientes ecuatorianas de las tierras altasalcanza (2990–3727 metros sobre el nivel del mar) con características vegetativas ribereñas contrastantes y diferentes regímenes de flujo y temperatura y biomasa de perifiton (como clorofila-a). Helicopsyche mostró fuertes diferencias entre las corrientes en los atributos de la historia de vida y la producción secundaria . Estimamos que el alcance menos productivo (89 mg m −2 año −1 ) es un orden de magnitud menor que el de los dos alcances más productivos (1556–2164 mg m −2 año −1 ). La producción secundaria se correlacionó positivamente con la biomasa media anual de perifiton y se correlacionó negativamente con la temperatura media anual del agua. En comparación con estudios anteriores, la mediaLa producción secundaria de Helicopsyche fue relativamente alta. Concluimos que la producción secundaria de Helicopsyche en los arroyos de las tierras altas tropicales es muy heterogénea entre los tipos de arroyos . Esta fuerte variación entre las corrientes podría depender en última instancia de los factores ambientales que influyen en la disponibilidad de alimentos (biomasa de perifiton) y las tasas de desarrollo larvario (régimen de temperatura).Macroinvertebrate life history and secondary production have rarely been measured in tropical highland streams even though these streams are highly heterogeneous and display unique ecological settings compared to both those in the tropical lowlands or in the temperate zone. We evaluated secondary production and life history attributes of the periphyton grazer caddisfly (Helicopsyche spp.) using the size-frequency method in three Ecuadorian highland stream reaches (2990–3727 meters above sea level) with contrasting riparian vegetative characteristics and differing flow and temperature regimes and periphyton biomass (as chlorophyll-a). Helicopsychedisplayed strong differences among streams in life history attributes and secondary production. We estimated the least productive reach (89 mg m-2 - year-1) to be an order of magnitude less than that of the two more productive reaches (1556–2164 mg m-2 - year-1). Secondary production positively correlated with annual mean periphyton biomass and negatively correlated with annual mean water temperature. Compared to previous studies, mean secondary production of Helicopsyche was relatively high. We conclude that Helicopsyche secondary production in tropical highland streams is highly heterogeneous among stream types. This strong variation among streams might ultimately depend on environmental factors influencing food availability (biomass of periphyton) and larval development rates (temperature regime)