Abstract Functional diversity is an emergent approach in ecology that has been applied globally to better understand the relationships between organisms and the environment. However, assessing the functional diversity of freshwater fish is a challenge for scientists. Aiming to summarize the evolution of scientific knowledge on fish functional diversity, we performed a systematic review of the literature published from 1945 to 2021 using the Web of Science. Based on the 101 articles reviewed, we found that publications about functional diversity of fishes have increased over time, mainly in Neotropical, Indomalayan and Palearctic regions. Most studies were conducted in lotic ecosystems, especially to assess environmental impacts such as biological invasions and land use. Functional diversity has been assessed mainly by morphological traits that reflect feeding and locomotion dimensions. Functional richness was the most common index used in the studies. Our findings suggest that political neglect and lack of investments may hamper the research development in several places. The missing information about the functional traits of many species may limit the use of the functional approach. We also highlight the need for the incorporation of functional diversity in conservation programs once functional diversity is a key facet of biodiversity to maintain freshwater ecosystem functioning.

Resumo A diversidade funcional tem sido avaliada principalmente através de traços funcionais morfológicos que refletem as dimensões da alimentação e locomoção. A Riqueza Funcional foi a métrica mais comumente usada nos estudos. Esses resultados sugerem que a negligência política e a falta de investimentos podem dificultar o desenvolvimento de pesquisas em diversas regiões. A falta de informações sobre os traços funcionais de muitas espécies limita o uso da abordagem funcional. Destaca-se também a necessidade de incorporar a diversidade funcional em programas de conservação, uma vez que a diversidade funcional é uma faceta chave da biodiversidade para manter o funcionamento dos ecossistemas de água doce.

Resumo: Objetivo Avaliamos as mudanças na biomassa do perifíton e na composição das comunidades de diatomáceas bentônicas ao longo de um gradiente de urbanização em 10 riachos costeiros localizados na planície costeira do extremo sul do Brasil. Métodos Em cada riacho coletamos variáveis limnológicas e o material perifítico do estolão da macrófita aquática Hydrocotyle ranunculoides para posterior análises de clorofila a e de diatomáceas. Resultados Fósforo total foi a única variável limnológica selecionada pelos modelos, mostrando uma relação positiva com a biomassa e negativa com a riqueza de espécies de diatomáceas nesses riachos. A composição de espécies (para dados de presença e ausência e de abundância) também foi explicada pelas concentrações de fósforo total. Além disso, observamos uma distribuição aninhada de espécies ao longo dos riachos, de forma que as comunidades mais pobres de riachos com maiores concentrações de fósforo são subconjuntos de comunidades mais ricas com menores concentrações do nutriente. Conclusões Evidenciamos em nosso estudo que as modificações na qualidade da água causadas pela eutrofização estão levando à perda de espécies e mudanças na estrutura de comunidades em ecótonos como os riachos costeiros.

Abstract: Aim We evaluated changes in periphyton biomass and the composition of benthic diatom communities along a gradient of urbanization in 10 coastal streams located on the coastal plain of southernmost Brazil. Methods At each coastal stream, we obtained limnological variables and periphytic material from the stolon of the aquatic macrophyte Hydrocotyle ranunculoides for further analyses of chlorophyll a and diatoms. Results Total phosphorus was the only limnological variable selected by the statistical models, showing a positive relationship with periphyton biomass and a negative relationship with diatom species richness in these streams. Species composition (for both presence-absence and abundance data) was also explained by total phosphorus. Further, we observed a nested distribution of diatom species along the streams, in which poorer communities of streams with higher concentrations of phosphorous are subsets of richer communities from streams with lower concentrations of the nutrient. Conclusions Our study shows that water quality modifications caused by eutrophication are leading to the loss of species and changes in the structure of biological communities in ecotones such as coastal streams.

Resumo: Objetivo Neste estudo, analisamos os efeitos da presença de detritos foliares de espécies não-nativas no funcionamento de um ecossistema de riacho presente na Mata Atlântica. Métodos Testamos duas predições (i) os detritos foliares de espécies nativas, provavelmente com maior qualidade nutricional, irão decompor de forma mais rápida se comparado aos detritos foliares das espécies não nativas (ii) devido a presença de defesas químicas nos detritos foliares de espécies vegetais não-nativas, estes serão menos colonizados e apresentarão uma menor riqueza taxonômica em comparação com os detritos foliares de espécies nativas. Para isso, em um riacho inserido em uma área de Mata Atlântica (Florianópolis, SC, Brasil) conduzimos um experimento para comparar a decomposição e colonização biológica de detritos foliares entre duas espécies vegetais não nativas (Eucalyptus sp. e Pinus radiata D. Don) e duas espécies vegetais nativas (Ficus eximia Schott e Alchornea triplinervia (Spreng) Mull. Arg). Resultados Especificamente, as nossas hipóteses foram parcialmente corroboradas. A porcentagem de massa seca remanescente foi menor para a serapilheira nativa. A abundância e riqueza de invertebrados e grupos funcionais de alimentação variam entre serrapilheira nativa e não nativa. A abundância de invertebrados foi maior em detritos de Eucalyptus sp, em grande parte devido à grande abundância de Chironomidae (Dípteros). Conclusões Os nossos resultados indicam que, a presença de espécies vegetais não nativas na zona ripária podem modificar a decomposição foliar e as comunidades de invertebrados aquáticos em riachos subtropicais, com potenciais consequências para o funcionamento do ecossistema.

Abstract: Aim In this study, we examined the effects of non-native leaf litter on the functioning of an Atlantic Forest stream ecosystem. Methods Were tested two predictions: (i) Leaf litter from the native trees with high nutritional quality will have higher decomposer’s activity and faster litter decomposition; (ii) Given the presence of anti-grazing defenses, we also hypothesized that non-native leaf litter would be colonized by fewer invertebrates and that native species would be more species-rich. For this, in a forest stream (Florianópolis, SC, Brazil) we conduct the experiment to understand the decomposition and biological colonization of leaf litter among two non-native (Eucalyptus sp. and Pinus radiata D. Don) and two native trees (Ficus eximia Schott and Alchornea triplinervia (Spreng) Mull. Arg). Results Our predictions were partially corroborated. The percentage of dry mass remaining was lower for the native leaf litter. The invertebrate abundance and richness, and functional feeding groups vary between native and non-native leaf litter. Invertebrate abundance was higher in non-native Eucalyptus detritus, largely due to the high larval abundance of Chironomidae (Diptera). Conclusions Our results indicate that the presence of non-native riparian species can modify leaf decomposition and aquatic invertebrate communities in subtropical streams, with potential consequences for ecosystem functioning.

Resumen Introducción: La concentración de clorofila a representa la biomasa de fitoplancton la cual influye directamente en las funciones de producción de los ecosistemas acuáticos. Por lo tanto, es imperativo comprender su cinética espacio-temporal en el ambiente lótico con respecto a las variabilidades climáticas regionales en las aguas continentales tropicales. Objetivo: Se realizaron estudios in situ para examinar la influencia de varios parámetros ambientales en la biomasa del fitoplancton en la cuenca baja del Ganges durante 2014-2016. Métodos: En primer lugar, se determinaron los parámetros ambientales más influyentes en la concentración de Chl-a fluvial. Luego, el efecto directo en cascada de las variables climáticas sobre los parámetros ambientales clave, mediante el modelado y los cambios en la concentración media de Chl-a en el tramo inferior del río. Resultados: Solo cinco parámetros ambientales, entre ellos, temperatura del agua, sólidos disueltos totales, salinidad, alcalinidad total y pH, fueron factores clave que influyeron en la Chl-a (R2 múltiple: 0.638, P < 0.05). Las estimaciones actuales indican que si la tasa actual de variabilidad climática regional durante las últimas 3 décadas (temperatura media del aire + 0.24 °C, precipitación total anual -196.3 mm) permanece constante durante las próximas tres décadas (2015-2045), se presente un aumento en el promedio de la Chl-a en +170 µgL-1 y alcance aproximadamente 475.94 µgL-1 para el 2045 o más. Conclusiones: Este estudio presenta una metodología basada en modelos alternativos en situaciones de escasez de datos, la información generada también podría contribuir a mejorar la gobernanza del agua y a desarrollar un protocolo para la gestión sostenible del agua y de esta manera mejorar los servicios ecosistémicos.

Abstract Introduction: Chlorophyll a concentration proxies the phytoplankton biomass which directly involves in signifying the production functions of aquatic ecosystem. Thus, it is imperative to understand their spatio-temporal kinetics in lotic environment with reference to regional climatic variabilities in the tropical inland waters. Objective: In-situ studies were conducted to examine the changes in phytoplankton biomass in lower Ganga basin as influenced by various environmental parameters under regional climatic variability during 2014-2016. Methods: Firstly, the most key influential environmental parameters on riverine Chl-a concentration were determined. Then the direct cascading effect of changing climatic variables on key environmental parameters were derived through modeling and quantified probable changes in mean Chl-a concentration in the lower stretch of river. Results: Only five environmental parameters namely water temperature, total dissolved solid, salinity, total alkalinity and pH were key factors influencing Chl-a (Multiple R2: 0.638, P < 0.05). Present estimates indicate that if the present rate of regional climatic variability over the last 3 decades (mean air temperature + 0.24 °C, total annual rainfall -196.3 mm) remain consistent over the next three decades (2015-2045), an increase in mean Chl-a by + 170 µgL-1 may likely be expected grossly reaching about 475.94 µg L-1 by the year 2045 or more. Conclusions: The present study is first such comprehending a gross hint towards the probable ecosystem response with an alternative model based methodology in data-deficient situations. Subsequently, the output would also be of great benefit for increase water governance and developing strategy protocol for sustainable water management for greater ecosystem services.

Resumen Objetivo: El objeto de este artículo es cualificar las condiciones de la corriente del río Cesar en la zona de influencia del vertimiento del STAR del municipio de Valledupar, y su relación con los indicadores de contaminación biológica e índice de calidad BMWP/Col. Metodología: Se establecieron cuatro estaciones de muestreo sobre la corriente del río Cesar: E1 y E2, localizadas aguas arriba de la zona de mezcla de la descarga residual de la ciudad; E3, ubicada en el punto de mezcla del vertimiento y el río; y E4, situada aguas abajo de la descarga. Permitiendo conocer sus características fisicoquímicas y determinar la condición biológica de la corriente según el índice BMWP/Col para los cuatro puntos de muestreo establecidos. Resultados: En las estaciones E1 y E2, se obtuvieron macroinvertebrados indicadores de aguas limpias y bien oxigenadas, con una clasificación de agua aceptable; mientras que las estaciones E3 y E4, indicadores de aguas contaminadas de calidad dudosa; siendo E4 la más crítica con concentraciones de oxígeno y DBO5 de 4,61 mg/l y 51,42 mg/l, respectivamente. Conclusiones: La estación E4 evidencia la calidad de agua más contaminada según el índice aplicado, a pesar de la presencia de individuos de los géneros Hemíptera y Trichóptera que reciben una alta puntuación en el índice BMWP/Col. Se da también la aparición de grupos de macroinvertebrados indicadores de aguas de pésima calidad como los dípteros de la familia Ephydriidae, Culicidae y Chironomidae.

Abstract Objective: The purpose of this article is to qualify the conditions of the Cesar river stream in the area of influence of the dumping of the STAR of the municipality of Valledupar, and its relationship with the biological indicators of contamination and BMWP/ Col quality index. Methodology: Four sampling stations were established on the Cesar River: E1 and E2 located upstream of the mixture zone at the municipal wastewater discharge point, E3 located at the point of mixing of the discharge and the river; and E4 located downstream of the discharge, letting know its physicochemical characteristics and to determine the biological conditions of the stream according to the BMWP/Col index for each of the established stations. Results: In stations E1 and E2, macroinvertebrates indicators of clean and well-oxygenated waters were obtained, with an acceptable water classification; while the stations E3 and E4, were found macroin-vertebrates indicators of contaminated waters of doubtful quality; E4 has being the most critical area, with oxygen and BOD5 concentrations of 4.61 mg/L and 51.42 mg/L respectively. Conclusions: The station E4 shows the quality of the most contaminated water according to the index applied, since despite the presence of individuals from the Hemiptera and Trichoptera genus that receive a high score in the BMWP/Col index, also, the appearance of groups of macro invertebrates indicators of poor quality waters such as the Diptera of the family Ephydriidae, Culicidae and Chironomidae.

RESUMEN La serranía de La Lindosa hace parte de los afloramientos rocosos del escudo Guayanés colombiano. Aunque la vegetación de este ecosistema ha sido estudiada, en esta región y en Colombia la diversidad de plantas acuáticas ha sido pobremente investigada. En este trabajo se caracterizó la flora acuática de La Lindosa mediante recolecciones generales en cuerpos de agua lóticos y lénticos. Se encontraron 110 especies en 70 géneros y 46 familias. Las familias más importantes fueron Cyperaceae (seis géneros/17 especies), Poaceae (diez/catorce) y Lentibulariaceae (una/catorce). Se reporta a Eleocharis alveolatoides como nuevo registro para la flora de Colombia y 38 para el Guaviare. La mayoría de las especies se localizaban en la ribera de los caños y la forma de vida arraigada emergente fue predominante. La cantidad de nuevos registros exponen la escasez de muestreos de macrófitas en la región, se muestra la gran riqueza de plantas acuáticas albergada en este macizo rocoso, y se destaca la presencia de elementos de distribución restringida. Lo anterior puede tener importantes implicaciones para la generación de mejores estrategias de conservación de esta zona.

ABSTRACT The serranía La Lindosa is part of the rocky outcrops of the Colombian Guiana shield. Although the vegetation of this ecosystem has been studied, in this region and in Colombia the diversity of aquatic plants has been poorly investigated. The aquatic flora of the Serrania La Lindosa was characterized by general collections of lotic and lentic water bodies. 110 species in 70 genera and 46 families were found. The most important families were Cyperaceae (six genera/17 species), Poaceae (ten/fourteen) and Lentibulariaceae (one/fourteen). Eleocharis alveolatoides is a new record for the flora of Colombia and 38 for the Guaviare are reported. Most species were located on stream banks and the best-represented life form was rooted emergent. The number of new records shows the shortage of sampling of macrophytes in the region. This work shows the great richness of aquatic plants sheltered in this outcrop. This could have important implications for creation adequate conservation plans.

RESUMEN La minería a cielo abierto de carbón posibilitará una serie de modificaciones a diferentes ambientes lóticos en Colombia. En este artículo analizamos el caso de una mina de carbón a cielo abierto ubicada en el departamento de La Guajira, Colombia, centrándonos en el estado de conocimiento de la ictiofauna, los potenciales efectos de las modificaciones sobre las comunidades acuáticas y la efectividad de las medidas de restauración/compensación. Para valorar el estado del conocimiento de la ictiofauna, revisamos bibliografía pertinente y utilizamos el estimador de riqueza de especies ICE. Para identificar los potenciales efectos de las modificaciones sobre la biota acuática y la efectividad de las medidas de restauración/compensación realizamos una revisión bibliográfica. Encontramos que cerca del 42 % de las especies de peces de la cuenca del río Ranchería y del área de concesión minera aún son desconocidas. Además, estudios relacionados indican que las transformaciones afectarán de manera negativa las características físicas de los cauces y, en consecuencia, la estructura y función de la biota acuática. Aunque aconsejamos la no intervención de los cuerpos de agua, planteamos algunas recomendaciones bajo un escenario de intervención, como realizar investigación abordando diferentes facetas de la biodiversidad, publicación de los resultados en medios arbitrados, acceso público a los datos, entre otras. Concluimos que si prevalece el beneficio económico derivado de la explotación de carbón sobre la preservación de los ambientes acuáticos habrá una pérdida de funciones y servicios ecológicos indispensables para el ser humano y el equilibrio del ecosistema.

ABSTRACT Open coal mining will cause a series of modifications to different lotic environments in Colombia. In this paper we analyzed the case of an open pit coal mine located in the Department of La Guajira, Colombia, focusing on the state of knowledge of the ichthyofauna, the potential effects of modifications on aquatic communities and the effectiveness of restoration/compensation measures. To assess the state of knowledge ofthe ichthyofauna, we reviewed relevant literature and used the ICE species richness estimator. To identify the potential effects of the modifications on aquatic biota and the effectiveness of the restoration/compensation measures, we carried out a literature review. We found that about 42 % of the fish species in the Ranchería river basin and the mining concession area are still unknown. Furthermore, related studies indicate that the modifications will negatively affect the physical characteristics of the channels and consequently, the structure and function of the aquatic biota. Although we advise the non-intervention of the lotic systems, we propose some recommendations under an intervention scenario, such as conducting research addressing different facets of biodiversity, publication of results in refereed journals, public access to data, among others. We concluded if the economic benefit derived from coal mining prevails over the aquatic environments preservation there will be a loss of functions and ecological services that are indispensable for the human well-being and the ecosystem balance.

Abstract Aquatic insects play an important role in aquatic ecosystem but little is known about their diversity, distribution and ecology in the Usumacinta River Basin. The objective was to analyze richness and diversity patterns of aquatic insect assemblages in the Usumacinta Basin in Mexico. Entomological collections and literature were revised for reported taxa for the Usumacinta watershed. Sampling was conducted in streams, rivers, and floodplain lakes in Centla, Tenosique-Palizada and Lacantún-Yaxchilán. The number of families was increased from 45 to 70 and the number of genera from 109 to 192. The Lacantún-Yaxchilán area showed the highest richness, with 70 genera, followed by Centla with 69 and Tenosique-Palizada with 62. Ephemeroptera and Trichoptera were very abundant and diverse in the lotic habitats of Lacantún-Yaxchilán, while Diptera, Hemiptera and Odonata dominated in the lentic habitats of Centla and Tenosique-Palizada. Abundance was lower during the rainy season in the three study areas. The highest diversity was associated to streams and rivers in Lacantún-Yaxchilán and a floodplain lake in Centla with abundant aquatic macrophytes, suggesting that habitats with greater diversity can occur at different points along the basin, including the lotic environments of the tributaries and in lakes of the Usumacinta floodplain.

Resumen A pesar de la importancia ecológica de los insectos acuáticos, se conoce poco sobre la distribución y ecología de este grupo de organismos en la cuenca del río Usumacinta. El objetivo fue analizar patrones de riqueza y diversidad de los insectos acuáticos en esta cuenca en México. Se realizaron revisiones de colecciones y literatura y muestreos en arroyos, ríos y lagunas en Centla, Tenosique-Palizada y Lacantún-Yaxchilán. Con las recolectas, el número de familias se incrementó de 45 reportadas a 72, mientras que el número de géneros aumentó de 109 a 192. La zona Lacantún-Yaxchilán presentó la riqueza más alta con 70 géneros, seguida por Centla con 69 y Tenosique-Palizada con 62. Ephemeroptera y Trichoptera fueron abundantes en los ambientes lóticos de Lacantún-Yaxchilán mientras que en Centla y Tenosique-Palizada dominaron Díptera, Hemiptera y Odonata. La menor abundancia se observó en la época de lluvias en las 3 áreas estudiadas. La mayor riqueza y diversidad se encontró en ríos y arroyos de Lacantún-Yaxchilán y en una laguna de Centla, lo cual sugiere que hábitats con mayor diversidad pueden encontrarse a lo largo de la cuenca tanto en ambientes lóticos de los tributarios como en el plano de inundación del río Usumacinta.

Resumo: A biodiversidade de parasitos de peixes é um campo de pesquisa com significativo crescimento mundial, seja pelo aumento das pisciculturas ou pelo importante papel desses organismos como indicadores da qualidade do ambiente e da saúde do ecossistema, tornando-os importantes ferramentas na conservação e manutenção da biodiversidade como um todo. O objetivo desse estudo foi de avaliar a estrutura e composição da fauna parasitária de Prochilodus lineatus coletados em dois trechos estruturalmente distintos do rio Batalha. Cinquenta espécimes de P. lineatus foram coletados entre junho de 2015 e junho de 2016. Desses 50 hospedeiros, foram coletados 875 espécimes de parasitos, divididos em 30 espécies, pertencentes a sete grupos: Myxozoa, Monogenea, Digenea, Acanthocephala, Nematoda, Copepoda e Hirudinea. Além dos novos registros para a localidade com parasitos já observados parasitando P. lineatus anteriormente, obteve-se o novo registro de 13 espécies parasitando este peixe, além do registro de uma nova espécie de monogenético (Tereancistrum sp. n.). Os achados desse estudo expandem a distribuição geográfica dessas espécies de parasitos e ajudam a aumentar o conhecimento da biodiversidade desses organismos em diferentes hospedeiros e ambientes. De modo geral, a estrutura e composição da fauna parasitária de P. lineatus não pareceu ser influenciada por características estruturais dos dois trechos estudados, devido aos hábitos migratórios do hospedeiro.

Abstract: Biodiversity of fish parasites is a field of significant growth worldwide, whether due to the advancement of fish farms or the important role of these organisms as indicators of environment quality and ecosystem health, making them useful tools in the conservation and maintenance of the biodiversity as a whole. The objectives of this study were to evaluate the structure and composition of the parasitic fauna of Prochilodus lineatus collected from two structurally distinct stretches of the Batalha River. Fifty specimens of P. lineatus were collected between June 2015 and June 2016. Of these 50 hosts, 875 parasite specimens were collected, divided into 30 species, belonging to seven groups: Myxozoa, Monogenea, Digenea, Acanthocephala, Nematoda, Copepoda and Hirudinea. In addition to new records of known parasites of P. lineatus for this locality, 13 species were newly recorded parasitizing this fish, including a new monogenean species (Tereancistrum sp. n.), with Monogenea being the most representative class in the study. The findings of this study expands the known geographic distribution of these parasite species and helps to increase the knowledge of the biodiversity of these organisms in different hosts and environments. In general, the structure and composition of the P. lineatus parasitic fauna did not seem to be influenced by the structural characteristics of the two stretches studied, due to the migratory habits of the host.

Resumen Los Heteroptera acuáticos y semiacuáticos presentan alta riqueza en el Pacífico de Colombia. Estudios sobre la biología, ecología y distribución geográfica y altitudinal son conocidos para algunas de las especies presentes tanto en ecosistemas litorales de aguas salobres como dulceacuícolas lénticos y lóticos. El objetivo de este estudio fue comparar tres comunidades de heterópteros acuáticos y semiacuáticos, de ecosistemas lóticos costeros del Pacífico de Colombia, con base en su composición, riqueza, diversidad y abundancia. Con el fin de alcanzar este objetivo se muestrearon tres áreas entre los 0 y 35 m de altitud sobre el nivel del mar del litoral Pacífico en Tumaco (departamento de Nariño): dos asociadas con hábitats lóticos permanentes de los ríos Mejicano y Caunapí y una tercera asociada con un arroyo de flujo lento en Candelillas. Se determinó la composición, riqueza, diversidad y abundancia de cada uno de los tres ecosistemas lóticos, la diversidad beta con base en el análisis de similitud de Jaccard y el valor de importancia de las especies por su abundancia. Se recolectaron 339 individuos pertenecientes a siete familias y 25 especies. Cada ecosistema presentó 11 especies y la familia más abundante en los tres fue Gerridae. La composición específica, la diversidad y la abundancia, tanto de géneros como de especies, difirieron entre los tres sistemas. La similitud entre los tres ecosistemas lóticos fue inferior al 20%. El ecosistema acuático con mayor diversidad en heterópteros, según el índice de Shannon-Wiener, fue el arroyo de Candelillas. En río Mejicano el género con mayor número de especies y de individuos fue Rhagovelia y la especie más abundante fue Telmatometra whitei; en río Caunapí el género con mayor número de especies y de individuos fue Rhagovelia y la especie más abundante fue Martarega lofoides; en el arroyo de Candelillas el género con mayor número de especies y de individuos fue Rheumatobates y la especie más abundante fue R. peculiaris. La especie con mayor valor de importancia fue Telmatometra whitei. Los tres ecosistemas lóticos costeros estudiados presentaron diferente composición de especies de heterópteros y una estructura disímil en un rango altitudinal muy estrecho.

Abstract Aquatic and semiaquatic heteropterans present high richness in the Colombian Pacific Region. Studies about biology, ecology, as well as geographical and altitudinal distribution have provided a great amount of data about some species inhabiting brackish waters, as well as lentic and lotic freshwaters. Based on that, the aim of this study was to compare three communities of aquatic and semiaquatic heteropterans of lotic freshwater ecosystems from the Pacific coastal region in Colombia based on species composition, richness, diversity and abundance. In order to meet this objective, sites were sampled at altitudes ranging from 0 and 35 m of altitude above sea level in the Pacific littoral in Tumaco (Department of Nariño): two sites were located in permanent lotic ecosystems in the Mejicano and Caunapí rivers and a third site was located in a slow-flow intermittent stream in Candelillas. The composition, richness, diversity and abundance for each ecosystem, as well as the beta diversity on the basis of the Jaccard similarity coefficient and the value of importance of species for abundance were determined. A total of 339 individuals, seven families and 25 species were recorded. Each ecosystem presented 11 species, with Gerridae the most abundant family in the three ecosystems. Differences between the specific composition, diversity and abundance of the three ecosystems, in terms of genera and species, were deter mined. The similarity between the three aquatic ecosystems was lower than 20%. The intermittent stream in Candelillas was the aquatic ecosystem with the greatest diversity of heteropterans, according to the index of Shannon-Wiener. In the Mejicano River, Rhagovelia was the genus with a greatest number of species and individuals, and Telmatometra whitei was the most abundant species. In the Caunapí river, Rhagovelia was the genus with the greatest number of species and individuals and Martarega lofoides was the most abundant species. In the intermittent stream in Candelillas, Rheumatobates was the genus with the greatest number of species and individuals, and R. peculiaris was the most abundant species. The species with the highest Importance Value Index was Telmatometra whitei. The three coastal lotic ecosystems presented different compositions of heteropteran species and dissimilar structure over a very narrow altitudinal range.

The objective of the present study was to investigate the influence of environmental conditions on the bacterial community composition in water, sediment and riparian soil during different water flow periods. For this purpose, samples of three habitats (water, sediment and riparian soil) were collected from five polluted sites and one reference site along the Suquía River during high and low water flow periods. The pH, dissolved oxygen, conductivity and water temperature were measured “in situ”, with total organic carbon content, nitrate and ammonia concentration being evaluated for all samples. In addition, pH, conductivity and total N were determined in the sediment and riparian soil samples, and the bacterial community composition of water, sediments and riparian soil samples was monitored using restriction fragment length polymorphism of the 16S rRNA gene. The results showed that the bacterial community composition of water was different from that of sediments or riparian soil. A redundancy analysis indicated that the changes in the bacterial community composition in the Suquía River were primarily correlated with variations in dissolved oxygen, conductivity and pH. The water bacterial community composition was very variable among sites and water flow periods, while that of sediments differed according to the water flow period, which was associated with temperature variation. Lastly, in riparian soil, differences were found in the bacterial community composition of the sites located before and after Cordoba city. Our findings suggest distinct distribution patterns in the bacterial community compositions of the three habitats evaluated.

El objetivo de este estudio fue investigar la influencia de la contaminación del Río Suquía sobre la composición de la comunidad bacteriana en agua, suelo de ribera y sedimentos en dos períodos de caudal de agua. Para ello se tomaron muestras de los tres hábitats (agua, sedimento, y suelo de ribera) en cinco sitios contaminados y un sitio de referencia a lo largo del Río Suquía en las épocas de alto y bajo caudal de agua. Se midió “in situ” el pH, el oxígeno disuelto, la temperatura y la conductividad del agua, mientras que en todas las muestras se determinó el contenido de carbono orgánico total, nitrato y amonio. Además, se midió el pH, la conductividad y el contenido de N total en sedimento y suelo de ribera. La composición de la comunidad bacteriana del agua, sedimento y suelo de ribera se analizó mediante polimorfismo de fragmentos largos de restricción del gen 16S ARNr. Los resultados mostraron que la composición de la comunidad bacteriana del agua fue diferente de la del sedimento y suelo de ribera. De acuerdo al análisis de redundancia realizado los cambios en la composición de la comunidad bacteriana en el Río Suquía fueron principalmente correlacionados con el oxígeno disuelto, la conductividad y el pH. La composición de la comunidad bacteriana en agua fue muy variable entre sitios y períodos de caudal de agua, mientras que la comunidad bacteriana de los sedimentos difiere según el período de flujo de agua asociado a la variación de temperatura. Por último, en el suelo de rivera se evidenciaron diferencias entre las comunidades bacterianas de los sitios localizadas antes y después de la ciudad de Córdoba. Estos resultados mostraron que existen diferentes patrones de distribución en la composición de la comunidad bacteriana de los tres hábitats evaluados.

Abstract: Macrophytes play an important role in lotic systems increasing habitat heterogeneity and providing food and shelter for wildlife. The aim of the study was to analyze the structure and composition of the invertebrate community associated with macrophytes in headwater streams in mountain grasslands (Ctalamochita sub-basin, Córdoba, Argentina) in two hydrological periods. The structure of the invertebrate assemblages in different macrophyte species (Hydrocotyle spp., Rorippa nasturtium-aquaticum and Ranunculus flagelliformis) was also evaluated. Three streams were sampled during high water (March 2012) and low water (August 2012) period. In each period, samples of invertebrates associated with the dominant macrophyte in each stream were collected. Seventy-two taxa of phytophilous macroinvertebrates were identified. The most frequent and abundant taxa were Naidinae, Hyalella curvispina, Americabaetis spp., Corynoneura spp. and Rheotanytarsus spp. Assemblages composition differed between hydrological periods and greater abundance of invertebrates was detected in R. nasturtium-aquaticum. The results showed that macrophyte patches in grassland headwater streams harbor an abundant and diverse invertebrate fauna and provide important base information for biomonitoring.

Resumen: Las macrófitas cumplen un rol importante en los sistemas lóticos, incrementando la heterogeneidad del hábitat, proveyendo alimento y refugio para la fauna. El objetivo del estudio fue analizar la estructura y composición de la comunidad de macroinvertebrados asociados a macrófitas en arroyos de cabecera en pastizales de altura (subcuenca Ctalamochita, Córdoba, Argentina) en 2 períodos hidrológicos. Asimismo, se evaluó la estructura de los ensambles de macroinvertebrados presentes en diferentes especies de macrófitas (Hydrocotyle spp., Rorippa nasturtium-aquaticum y Ranunculus flagelliformis). Se muestrearon 3 arroyos durante los periodos hidrológicos de aguas altas (marzo de 2012) y aguas bajas (agosto de 2012). En cada período se colectaron muestras de macroinvertebrados asociados a la macrófita dominante en cada arroyo. Se identificaron 72 taxones de macroinvertebrados fitófilos. Los más frecuentes y abundantes fueron Naidinae, Hyallela curvispina, Americabaetis spp., Corynoneura spp. y Rheotanytarsus spp. La composición de los ensambles difirió entre períodos hidrológicos y se detectó una mayor abundancia de macroinvertebrados en R. nasturtium-acuaticum. Los resultados demuestran que los parches de macrófitas en los arroyos de cabecera en pastizales de altura albergan una fauna de macroinvertebrados abundante y diversa, y proporcionan a su vez importante información de base para el biomonitoreo de estos sistemas acuáticos.

Resumo O crescimento populacional em áreas urbanas causa alterações em ecossistemas aquáticos continentais com consequência sobre as comunidades de macrófitas. Este fato vem ocorrendo nos municípios que margeiam o rio Capibaribe, Pernambuco, Brasil. Este trabalho analisa os efeitos da urbanização sobre a composição e estrutura das macrófitas em trechos do referido Rio. Levando em consideração áreas urbanizadas e não urbanizadas, foram escolhidos os seguintes Pontos de Coleta: Pontos 1 e 2 no Município de Santa Cruz do Capibaribe, Pontos 3 e 4 no Município de Toritama, Pontos 5 e 6 na Região Metropolitana do Recife. Estes pontos foram visitados bimestralmente (janeiro – julho/2013), para a observação da variação sazonal (estações seca e chuvosa). Foram identificadas 31 espécies. Geralmente, os pontos das áreas não urbanizadas apresentaram um número maior de espécies. As análises multivariadas indicaram diferenças globais significativas entre áreas urbanizadas e não urbanizadas (R = 0,044, p < 0,001) e também entre as estações (R = 0,018; p < 0,019). Devido à grande variação física, química e biológica entre as áreas urbanizadas e não urbanizadas, observou-se que o fator urbanização influenciou significativamente na composição florística e na estrutura das comunidades de macrófitas.

Abstract Population growth in urban areas changes freshwater ecosystems, and this can have consequences for macrophyte communities as can be seen in the municipalities that border the Capibaribe River, Pernambuco, Brazil. This study reports the effects of urbanization on the composition and structure of macrophyte communities in areas along that river. The following urbanized and non-urbanized sampling sites were chosen: Sites 1 and 2 (municipality of Santa Cruz do Capibaribe), Sites 3 and 4 (municipality of Toritama), and Sites 5 and 6 (metropolitan region of Recife). These sites were visited every two months from January to July 2013 to observe seasonal variation (wet and dry seasons). Thirty-one species were identified. Generally, the non-urbanized sites had a higher number of species. Multivariate analyses indicated significant overall differences between urbanized and non-urbanized areas (R = 0.044; p < 0.001) and between seasons (R = 0.018; p < 0.019). Owing to the large variation in physical, chemical, and biological characteristics between urbanized and non-urbanized areas, we found that urbanization significantly influenced the floristic composition and structure of macrophyte communities.

Resumo: Objetivo Compreender o ciclo fluvial do carbono é uma questão essencial para ecólogos de riachos. Nos últimos 60 anos, avanços importantes na dinâmica do carbono e fluxo de energia do ecossistema foram feitos principalmente através das abordagens de Budget e Metabolismo. Apesar disso, pouco foco tem sido dado à quantificação do movimento longitudinal da matéria orgânica. O conceito “Espiral do Carbono Orgânico” (SOC) foi formulado no início dos anos 80, e representou um avanço substancial no entendimento do fluxo longitudinal dos elementos em ecossistemas lóticos. Métodos Nessa revisão, nós resumimos a história por trás do conceito de SOC, cobrimos os principais avanços na época de sua criação, descrevemos as variáveis operacionais e a equação para o cálculo de SOC, e discutimos direções futuras e aplicações atuais dessa abordagem. Resultados/Conclusões Nós enfatizamos a necessidade de integrar a abordagem de espiral de C em outras regiões do globo, dado que medidas de SOC são quase que exclusivas da América do Norte. Tais estudos comparativos poderiam elucidar importantes variáveis controladoras da exportação, estocagem e oxidação do carbono fluvial. Avanços na caracterização do carbono orgânico dissolvido, e melhorias nas medidas de respiração heterotrófica são necessários para aumentar a acurácia nos cálculos de SOC, assim como estimativas realistas de estoque bêntico. Com o recente interesse em examinar como sistemas lóticos contribuem para o balanço regional e global de C, nós argumentamos que a abordagem de espiral é uma maneira efetiva de atingir esses objetivos e auxiliar a responder questões clássicas da ecologia de riachos.

Abstract: Aim Understanding riverine carbon cycling is a major issue for stream ecologists. Over the past 60 years, important advance in carbon dynamics and ecosystem energy flow have been made mainly through the Budget and Metabolism approaches. However, much less focus has been given to the quantification of longitudinal movement of organic matter. The concept “Organic Carbon Spiraling” (SOC) was formulated in the early 80s, and represented a substantial advance in the understanding of the longitudinal flow of elements in lotic systems. Methods In this review, we summarize the history behind the SOC concept, cover the major advances at the time of its creation, describe the operational variables and the equation for SOC calculation, and discuss future directions and current applications of this approach. Results/Conclusions We emphasize the need for integrating the C spiraling approach in other regions of the globe, given that measurements are almost exclusive of North America. Such comparative studies can elucidate important drivers of C export, storage and oxidation. Advance in dissolved organic carbon characterization, and improvements in heterotrophic respiration measurements are required to improve SOC accuracy, as well as realistic estimates of benthic stock. With the current interest in examining how lotic systems contribute to regional and global C budgets, we argue that SOC is an effective way to achieve this goal and answer classical questions in stream ecology.

Chironomidae is one of the most abundant and diverse families in freshwater ecosystems, however its highly complex systematic has led to its scarce development in many limnological studies. The aim of this study was to analyze benthic and drifting Chironomidae assemblages in a mountain stream of central Argentina assessing abundance, diversity and taxa composition in different fluvial habitats and seasons. Quantitative benthic and drift samples were taken in the Achiras stream (Córdoba, Argentina) in rifles and runs, and environmental variables were measured in each season between 2007 and 2008. A total of 25 taxa were registered belonging to four subfamilies. Benthic chironomids represented 19% of the macroinvertebrate community, whereas they constituted 33% in drift. Thienemannimyia sp. dominated in benthos and Corynoneura sp. in drift. According to the two-way ANOVAs results, the highest taxonomic richness and benthic density were registered during the low flow period (autumn and winter) and the highest benthic diversity was found in riffles. On the contrary, in the drifting assemblage only evenness was different between habitats and among seasons. TWINSPAN analysis showed a spatio-temporal segregation of benthic samples, whereas drift samples were separated only temporally suggesting that the dislodgment of invertebrates downstream homogenize the spatial variation observed in benthos. Benthic and drift density varied in a similar manner through seasons and Jaccard coefficient showed a high similarity index between benthos and drift (86%). This study allowed knowing the spatio-temporal dynamic of benthic and drifting Chironomidae in a mountain stream. The increase of knowledge in relation to taxonomy, biology and ecology of Chironomidae will allow to adequate and apply management and conservation strategies of lotic ecosystems in the central region of Argentina.

Chironomidae es una de las familias más abundantes y diversas en los ecosistemas de agua dulce, sin embargo su complejidad sistemática ha sido motivo de su escaso desarrollo en muchos estudios limnológicos. El objetivo de este estudio fue analizar los ensambles de Chironomidae bentónicos y derivantes de un arroyo serrano de la región central de Argentina evaluando abundancia, diversidad y composición de especies en diferentes hábitats fluviales y distintas estaciones del año. Se tomaron muestras cuantitativas de bentos y deriva en el arroyo Achiras (Córdoba, Argentina) en hábitats de rabión y corredera, y se registraron variables ambientales en las cuatro estaciones del año, entre 2007 y 2008. Se registró un total de 25 taxones pertenecientes a cuatro subfamilias. Los quironómidos bentónicos constituyeron el 19% de la comunidad de macroinvertebrados, mientras que en deriva representaron el 33%. En el bentos dominó Thienemannimyia sp. y en la deriva, Corynoneura sp. De acuerdo con los resultados de ANOVAs de dos vías, los mayores valores de riqueza taxonómica y densidad bentónica se registraron en el periodo de aguas bajas (otoño e invierno) y la diversidad de quirónomidos bentónicos fue mayor en rabión. Por el contrario, para el ensamble de derivantes sólo la equitatividad fue diferente entre hábitats y entre estaciones. El análisis TWINSPAN mostró una separación espacio-temporal de las muestras de bentos, mientras que las muestras de deriva se segregaron sólo temporalmente lo que sugiere que el transporte aguas abajo de los invertebrados homogeniza la variación espacial observada en el bentos. La densidad de bentos y deriva varió de manera similar a través de las estaciones del año y el coeficiente de Jaccard presentó un alto índice de similitud entre bentos y deriva (86%). Este trabajo posibilitó conocer la dinámica temporal y espacial de los quironómidos bentónicos y derivantes en un arroyo serrano. La ampliación del conocimiento taxonómico, biológico y ecológico de Chironomidae posibilitará adecuar e implementar estrategias de manejo y conservación de los ecosistemas lóticos en la región central de Argentina.