Taxonomic and Feeding Trait-Based Analysis of Macroinvertebrates in the Antisana River Basin (Ecuadorian Andean Region).

High-elevation tropical streams are under increasing threat from human activities and climate change. Specifically, Ecuadorian Andean streams require priority actions such as bioassessment (e.g., biodiversity and functional ecology of macroinvertebrates) in order to generate adequate environmental management policies. Therefore, we investigated the distribution and composition of the macroinvertebrate taxa and their functional feeding groups in relation to the environmental variables in the Antisana river basin (Andean-Ecuadorian Region). We sampled macroinvertebrates from 15 locations to assess ecological conditions (ECs), expressed as the Biological Monitoring Working Party Colombia (BMWP-Col) classes, the Andean Biotic Index (ABI) and the Andean-Amazon Biotic Index (AAMBI). Results indicate that dissolved oxygen saturation, elevation, nutrient concentration and conductivity contributed significantly to the composition of the taxa and functional feeding groups (FFGs). Taxa diversity and FFGs were more abundant in the best EC sites. Shredders (SH) were, overall, dominant and abundant at sites with medium-high ECs. Scrapers constituted the second most prevalent assemblage, exerting dominance at moderate ecological conditions (high altitude and high oxygen saturation). Collector-gathers (CGs) are less sensitive to contamination than the previous two groups but were equally abundant at medium-high EC sites. Collector-filterers (CFs) and parasites (PAs) were less abundant, although the presence of the former was slightly related to better environmental conditions. Predators (PRs) were almost absent throughout the study, but they were collected from poor EC sites. CGs, PAs and PRs showed more tolerance to the presence of human disturbances (e.g., hydraulic constructions or slope erosion). The BMWP-Col index seems to be the best fit for this ecosystem, showing a significant difference in FFG between the index classes, compared to the other indices evaluated. The results of this investigation may be regarded as a fundamental starting point and used in future bioassessment work in other similar ecosystems, particularly high-altitude tropical Ecuadorian streams.

Assessment of functional feeding groups (FFG) structure of aquatic insects in North- western Rif - Morocco.

The involvement of trait-based approaches is crucial for understanding spatial patterns, energy flow and matter transfer in running water systems, which requires consistent knowledge of the functional structures of aquatic communities, with the advantage of combining physical properties and behavioral mechanisms of food acquisition rather than the taxonomic group. The present study indicated how functional feeding groups may be used as a proxy for classical taxonomic evaluation, as well as the potential interest in incorporating them as indicators of anthropogenic stressors. The composition and abundance of the functional feeding groups of aquatic insects were examined from September 2021 to August 2022 along the Western Rif Region. Benthic samples were collected from nine sampling points in the studied area using a Surber sampler with a mesh size of 500 µm and a diameter of 20*20 cm. The stations included in this work were chosen for their accessibility as well as their position on the hydrographic systems. The abundance of sampled aquatic organisms in the whole study area revealed 5,342 individuals belonging to 60 families and seven orders of aquatic insects, classified into five feeding functional groups. In terms of abundance, Collector-gatherers (Ephemeroptera and Diptera) were the most abundant trophic group at most of the sites, with a proportion of 38.47%. Predators (Coleoptera, Hemiptera and Odonata) were the second group at all sites, followed by Collector-filters, accounting for 39.53%, 28.14% and 22.37% respectively, while Scarpers and Shredders had the lowest representation across all sites with 4.16%. The high number of registered Collectors could be related to their ability to feed on a diverse range of food items compared to the remaining trophic guilds. According to the Canonical Correspondence Analysis results, physicochemical (i.e. T, pH, BOD5, Cl- and NO3-) and hydromorphological (i.e. current velocity and depth) variables were amongst the key predictors of shaping the functional structure of aquatic biota during this investigation. It is highly recommended to carry out suitable measures to largely attenuate anthropogenic pressures in order to preserve the integrity of freshwater bodies and their biota.

Arthropod and Pathogen Damage on Fossil and Modern Plants: Exploring the Origins and Evolution of Herbivory on Land.

The use of the functional feeding group-damage type system for analyzing arthropod and pathogen interactions with plants has transformed our understanding of herbivory in fossil plant assemblages by providing data, analyses, and interpretation of the local, regional, and global patterns of a 420-Myr history. The early fossil record can be used to answer major questions about the oldest evidence for herbivory, the early emergence of herbivore associations on land plants, and later expansion on seed plants. The subsequent effects of the Permian-Triassic ecological crisis on herbivore diversity, the resulting formation of biologically diverse herbivore communities on gymnosperms, and major shifts in herbivory ensuing from initial angiosperm diversification are additional issues that need to be addressed. Studies ofherbivory resulting from more recent transient spikes and longer-term climate trends provide important data that are applied to current global change and include herbivore community responses to latitude, altitude, and habitat. Ongoing paleoecological themes remaining to be addressed include the antiquity of modern interactions, differential herbivory between ferns and angiosperms, and origins of modern tropical forests. The expansion of databases that include a multitude of specimens; improvements in sampling strategies; development of new analytical methods; and, importantly, the ability to address conceptually stimulating ecological and evolutionary questions have provided new impetus in this rapidly advancing field.

Functional groups of Afrotropical EPT (Ephemeroptera, Plecoptera and Trichoptera) as bioindicators of semi-urban pollution in the Tsitsa River Catchment, Eastern Cape, South Africa.

We examined the distribution patterns of Ephemeroptera, Plecoptera, and Trichoptera functional feeding groups (EPT FFGs) in five streams that drain semi-urban landscapes in the Tsitsa River catchment, Eastern Cape Province of South Africa. We undertook macroinvertebrate and physicochemical analysis over four seasons between 2016 and 2017 at eight sites in three land-use categories (Sites 1, 2 and 3), representing an increasing gradient of semi-urban pollution. Five EPT FFGs (shredders, grazers/scrapers, predators, collector-gatherers and collector-filterers) were fuzzy coded and analyzed using RLQ-R (environmental characteristics of samples), L (taxa distribution across samples) and Q (species traits) and fourth-corner analyses. Physicochemical variables, including phosphate-phosphorus, total inorganic nitrogen and temperature, were the most influential variables that significantly influenced the distribution patterns of EPT FFGs in the Tsitsa River. RLQ and the fourth-corner model revealed varying responses of FFGs to semi-urban pollution. Of the five FFGs, collectors were the most abundant EPT FFGs in the study area, exhibiting disparate responses to disturbances, with collector-gatherers associated with impacted sites and significantly associated with phosphate-phosphorus. On the other hand, collector-filterers decreased with increasing semi-urban disturbance and exhibited a significant negative association with phosphate-phosphorus, total inorganic nitrogen and temperature. Overall, this study provides further insights into the environmental factors that influence the distribution patterns of FFGs in Afrotropical streams and the potential use of FFGs as indicators of anthropogenic pollution in tropical streams and rivers.

Photoautotrophs and macroinvertebrate trophic relations in calcareous semiarid streams: The role of Cyanobacteria.

Photoautotrophs and macroinvertebrate trophic relations in Mediterranean streams, especially from semiarid areas, are still poorly known, as is the role of Cyanobacteria, which is the most frequently dominant photoautotroph. To investigate the role of Cyanobacteria as a food resource in these systems, the fatty acid composition of primary and secondary producers was investigated in two streams on a semiarid climatic gradient between 200 and 500 mm of rainfall in SE Spain. Fatty acid composition of photoautotrophs and macroinvertebrates differed among streams in summer and among seasons in each stream. Fatty acid fingerprints show that macroinvertebrates usually fed on the dominant photoautotroph assemblage and that Cyanobacteria represent the main food for all the feeding groups in the Alhárabe stream in winter although filamentous green algae were preferred in summer. Only scrapers consuming Chlorophyta displayed a selective feeding behaviour. The results show the importance of cyanobacteria as food for all collected macroinvertebrates in winter in some semiarid streams and confirm that fatty acids can be used as temporal and spatial markers in fluvial systems.

Estimating Macroinvertebrate Biomass for Stream Ecosystem Assessments.

We propose a field procedure for estimating the dry biomass of stream macroinvertebrates. Estimates are calculated using the mean values of the a and b regression coefficients from unpublished data and an extensive review of the relevant literature. The regression equation employed for calculating dry biomass is one that has been extensively used: Y = aXb, where Y = mg dry mass of an individual macroinvertebrate; X = mm total body length of an individual macroinvertebrate; a = intercept coefficient of the Y on X regression; and b = slope coefficient Y on X. The procedure was developed for use in the field, but dry mass estimates can also be made on preserved specimens. The case is made for presenting stream macroinvertebrate dry biomass data categorized by functional feeding groups (FFGs) and their component higher level taxa. The tables summarize the FFGs and their food resources, mean regression coefficients, dry biomass estimates for FFG-taxa by size and a comparison of their numerical-to-gravimetric surrogate FFG ratios to predict the stream environmental condition. A sizing template for rapidly sorting macroinvertebrates in the field is described. Thresholds for surrogate FFG ratios that directly predict measured stream ecosystem conditions are described.

Functionally similar species of ciliates have similar dynamics: A biennial survey study in a large eutrophic lake.

The spatial and temporal planktonic ciliate community structure of a large shallow eutrophic lake was described in detail based on a monthly monitoring campaign over 2 years using the quantitative protargol stain approach. We found that there was a large variety and low constancy of ciliate plankton and a clear advantage of several small species. Balanion planctonicum, Rimostrombidium brachykinetum, and Urotricha farcta contributed 19.7%, 13.4%, and 10.7% to the total abundance, respectively. The ciliate community was significantly varied in different lake regions of different eutrophication levels, and the distribution of some of the main species, especially prostomatids and scuticociliatids, might be closely related to the nutrient level of the lake regions. The seasonal dynamics of ciliate taxa with similar functional feeding habits across regions at different trophic levels are more convergent than those of species with very different functions, and the top-down effect (cladocerans, rotifers), nutrition, and water temperature were the key factors shaping ciliate community structure. The results of this study accentuate the important effects of species functional diversity on community differences and may improve our knowledge of ciliate diversity and functional ecology in shallow eutrophic lakes.

Ephemeroptera, Plecoptera and Trichoptera (EPT) functional feeding group responses to fine grain sediment stress in a river in the Eastern Cape, South Africa.

Sedimentation arising from agricultural run-offs, riparian habitat fragmentation and channel bank erosion has long been known to impair the structure and ecological functioning of stream and river ecosystems. This study examined the effects of fine sediment grain sizes on the functional feeding group structure of Ephemeroptera, Plecoptera and Trichoptera (EPT) in the Tsitsa River catchment in the Eastern Cape Province of South Africa. Fine sediments and EPT were sampled between August 2016 and April 2017 from eight selected sampling sites. The eight sites were classified into four groups in terms of fine sediments and turbidity to represent a gradient of sediment stress, with site groups 4 and 3 being less influenced and groups 2 and 1 as the highly influenced groups. EPT genera/species were assigned to five functional feeding groups (FFGs) and their responses to sediment stress assessed. The results of the study showed that of the five FFGs, four (i.e. collector-filterer, collector-gatherer, scraper/grazer and shredder) were significantly different between the four groups, separating the impacted groups from the less impacted groups. Redundancy analysis (RDA) showed that FFGs such as scraper/grazer, collector-gatherer and shredder were tolerant to fine sediment, especially during the dry season. Collector-filterers and predators were the most sensitive FFGs observed in the studied river systems. The RDA results showed that the coarser grain size fractions (very coarse and coarse silt, very fine sand and turbidity) displayed more severe negative effects on EPT FFGs when compared with the finer grain size fractions such as very fine and fine silt. The results obtained in this study provided more insights into the response patterns and functional dynamics of EPTs in the Tsitsa River systems, a knowledge that can contribute to trait-based biomonitoring in South Africa.

Variation of benthic macroinvertebrate communities in streams of three landscapes of South Brazilian grasslands

Introduction: Aquatic ecosystems in southern Brazil are presently under great environmental pressure. Changes in land use result in negative impacts on the ecosystem, affecting the functioning of stream communities. Objective: To compare the benthic macroinvertebrate community richness, abundances and compositions in streams of three South Brazilian grassland landscapes and correlate community patterns with environmental and spatial variables. Methods: Fifteen streams along riparian forests were selected in three landscapes (mean geographical distance of 285.1 km) inserted in the Paraná and Uruguai river basins. Of the three landscapes, two are inserted in conservation units (State Park of Guartelá and Palmas Wildlife Refuge). Invertebrates were collected in 20 kick net points along 150 m of the streams between June and November 2015. Invertebrates were sorted in the laboratory with three sieves and were identified to the lowest taxonomic level possible. The taxa were classified in functional feeding groups of shredders/detritivores, predators, scrapers, collectors/filters and gatherers/collectors. For each stream, we measured the environmental variables width and velocity, pH, dissolved oxygen, and temperature; and the relative cover of forest, grassland, plantation and silviculture in the catchments. Results: We found a total of 1 058 individuals, divided in 53 morphospecies and 34 families. Lower abundance of benthic macroinvertebrates was found in the northernmost landscape with higher temperature, and forest in the catchment. These streams were described mainly by predator groups, while streams inserted in the other two landscapes showed a more diverse guild composition of shredders/detritivores, gatherers/collectors, collectors/filterers, and scrapers. Geographical distance was the main factor influencing differences in community compositions among landscapes. Conclusions: Lower abundance of the northernmost landscape may be explained by (i) the low habitat heterogeneity due to dominance of sandy substrates, and by (ii) the anthropogenic land use of agriculture and extensive cattle breeding in the region that is ongoing and started before the creation of the conservation unit. Additionally, composition of macroinvertebrates may be correlated with environmental differences among landscapes that, in turn, are related to the geographical distance. Therefore, macroinvertebrate community responses may reflect different biota biogeographical histories that can also be associated with historical land use practices.

Introducción: Los ecosistemas acuáticos en el sur deBrasil están actualmente bajo gran presión ambiental. Cambios en el uso de la tierra pueden tener impactos negativos en el ecosistema que afectan el funcionamiento de las comunidades de arroyos. Objetivo: Comparar la riqueza, abundancia y las composiciones de macroinvertebrados bentónicos en arroyos de tres paisajes de pastizales del sur de Brasil, y correlacionar los modelos patrones de comunidad con variables ambientales y espaciales. Metodología: Quince arroyos a lo largo de los bosques ribereños fueron seleccionados en tres paisajes (distancia geográfica media de 285.1 km) insertados en las cuencas fluviales de Paraná y Uruguai. De los tres paisajes, dos están insertados en unidades de conservación (Parque Estatal de Guartelá y Refugio de Vida Silvestre de Palmas). Los invertebrados fueron recolectados en 20 puntos con una red a lo largo de 150 m de las corrientes entre junio y noviembre 2015. En el 2016, fueron clasificados en el laboratorio, con tres tamices de mallas, identificándolos al nivel taxonómico más bajo posible. Así, los taxones se clasificaron en grupos funcionales alimentícios: trituradores/detritívoros, depredadores, raspadores, colectores/filtradores y colectores/recolectores. En cada arroyo fueron medidas las variables ambientales: anchura, velocidad, pH, oxígeno disuelto y temperatura; en las cuencas, la cubierta relativa de bosques, pastizales, plantaciones y silvicultura. Resultados: Encontramos un total de 1 058 individuos, divididos en 53 morfoespecies y 34 familias. Se encontró una menor abundancia de macroinvertebrados bentónicos en el paisaje más septentrional con mayor temperatura, y bosques en la cuenca. Esos arroyos fueron descritos principalmente por grupos de depredadores, mientras que los arroyos insertados en los otros dos paisajes mostraron una composición más diversa de trituradores/detritívoros, colectores/recolectores, colectores/filtradores y raspadores. La distancia geográfica fue el principal factor que influyó en las diferencias de las composiciones comunitarias entre los paisajes. Conclusiones: La menor abundancia encontrada en el paisaje más septentrional puede explicarse por (i) la baja heterogeneidad constatada en el hábitat, debido al dominio de los sustratos arenosos, y por (ii) el uso antropogénico de la tierra: la agricultura y la cría extensiva de ganado en la región que está en curso, la cual comenzó antes de la creación de la unidad de conservación. Además, la composición de los macroinvertebrados puede estar correlacionada con diferencias ambientales entre paisajes que, a su vez, están relacionadas con la distancia geográfica. Por lo tanto, las respuestas comunitarias de los macroinvertebrados pueden reflejar diferentes historias biogeográficas de biotas que también pueden estar asociadas a prácticas históricas de uso de la tierra.

How do local differences in saltmarsh ecology influence disease vector mosquito populations?

Saltmarsh breeding mosquitoes are an important source of vectors for arboviral transmission. In southern Australia, the most prominent vector borne disease, Ross River virus (Togaviridae: Alphavirus) (RRV), is transmitted by the saltmarsh mosquito (Diptera: Culicidae) Aedes camptorhynchus (Thomson). However, the factors driving the abundance of this mosquito within and among saltmarshes are poorly understood. To predict the abundance of this mosquito within saltmarshes, the environmental conditions and aquatic invertebrate ecology of three temperate saltmarshes habitats were monitored over two seasons. Up to 44% of first-instar mosquito numbers and 21% of pupal numbers were accounted for by environmental variables. Samphire vegetation cover was a common predictor of first-instar numbers across sites although, between saltmarshes, aquatic factors such as high salinity, temperatures less than 22 °C and water body volume were important predictors. The identified predictors of pupal numbers were more variable and included high tides, waterbody volume and alkalinity. The composition of invertebrate functional feeding groups differed between saltmarshes and showed that an increased diversity led to fewer mosquitoes. It was evident that apparently similar saltmarshes can vary markedly in invertebrate assemblages, water availability and conditions through tidal inundations, rainfall or waterbody permanency. The present study advances insight into predictors of vector mosquito numbers that drive the risk of RRV outbreaks.

Macroinvertebrate functional feeding group alterations in response to habitat degradation of headwater Austral streams.

Protecting the structural and functional integrity of lotic ecosystems is becoming increasingly important as many ecological systems face escalating pressures from human population growth and environmental impacts. Knowledge on the functional composition of macroinvertebrates in austral temperate streams is generally lacking hindering the design and implementation of water management and restoration goals. Therefore, this study examined the effects of urban land-use activities on the benthic macroinvertebrate functional feeding guild structure among different stream orders in an austral river system (Bloukrans River) in the Eastern Cape Province of South Africa. Water quality and macroinvertebrate community data were collected across two seasons from 18 sites in two different stream order categories (i.e. 1, 2 + 3), following standard methods. We separated macroinvertebrates into functional feeding groups (FFGs), which we then used to assess the effects of riparian condition on FFG organization. Linear mixed effects model (LMM) results demonstrated that total dissolved solids (TDS), canopy cover, phosphate and channel width were the key variables that described the major sources of variation in macroinvertebrate FFGs. Based on FFG proportions, collector-gatherers were the most abundant in the Bloukrans River and represented 71.3% of the macroinvertebrate assemblages. The FFG ratios indicated that all the eighteen sites were strongly heterotrophic (i.e. streams received additional sources of energy from leaf litter and other organic matter), showed below expected linkage with riparian input and stable substrates were limited. The FFG ratios offered some insights into the overall functioning of Bloukrans River system. Our results highlight the importance of including macroinvertebrate functional diversity as a complementary approach to assess the ecological integrity in management and restoration plans of river systems.

Efectos de la deforestación sobre la diversidad y la estructura del ensamblaje de macroinvertebrados en cuatro quebradas Andinas en Colombia / Effects of deforestation on macroinvertebrate diversity and assemblage structure in four Andean creeks in Colombia

Resumen Las quebradas están fuertemente influenciadas por su vegetación ribereña y la deforestación afecta a la comunidad acuática. Se estudiaron los efectos de la deforestación sobre la diversidad taxonómica y funcional del ensamblaje de macroinvertebrados acuáticos en cuatro quebradas Andinas colombianas. El estudio incluyó 12 sitios, siete de ellos con cobertura arbórea en sus márgenes en áreas boscosas no perturbadas por la deforestación (estaciones de referencia) y los otros cinco sin cobertura arbórea en áreas deforestadas (estaciones alteradas). Se realizaron cuatro muestreos de campo entre junio 2011 y febrero 2012 y se recolectaron muestras de macroinvertebrados bentónicos utilizando el método D-net con malla de 500 μm y recolección manual, y se midieron diferentes variables fisicoquímicas in situ. Se calcularon los índices de Shannon-Wienner (H ') y Simpson (D). Se aplicaron análisis unidireccionales de varianza ANOVAs a cada variable ambiental y análisis canónicos discriminantes (CDA). Se recolectaron un total 8 370 individuos correspondientes a 80 taxones durante el estudio. La abundancia y diversidad fue mayor en las estaciones localizadas en áreas boscosas no perturbadas. Thraulodes, Anacroneuria y Rhagovelia, se asociaron con valores más altos de Calidad de Bosque de Ribera Andina (QBR-And), Índice de Hábitat Fluvial (IHF), Biological Monitoring Working Party Colombia (BMWP/Col) y temperatura en estaciones de referencia, mientras que Leptonema, Baetodes y Mayobaetis se asociaron con mayores valores de pH y altura sobre nivel del mar en estaciones alteradas. Los principales grupos funcionales tróficos (GFT) en las estaciones de referencia fueron colectores-recolectores/raspadores (27.2 %), raspadores (25.4 %) y depredadores (24.4 %), mientras que en estaciones alteradas fueron: Colectores filtradores (27.5 %), colectores-recolectores/raspadores (17.4 %) y raspadores (15.7 %). Los hábitos de vida más abundantes en las estaciones de referencia fueron agarradores (50.5 %), taxones con tres o más hábitos (28.7 %) y patinadores (16.1 %), mientras que en las estaciones alteradas fueron agarradores (68.1 %), taxones con tres o más hábitos (13.7 %) y excavadores (5.2 %). El conocimiento de las variables que determinan la estructura taxonómica y funcional de los ensamblajes de macroinvertebrados, y cómo responden a impactos como la deforestación, puede ayudar a determinar acciones de protección o restauración de las condiciones ambientales y ecológicas de las quebradas Andinas y los hábitats riparios.(AU)

Abstract The creeks are strongly influenced by their riparian vegetation, and the deforestation affect the aquatic community. The effects of deforestation on taxonomic and functional diversity of aquatic macroinvertebrate assemblage in four Colombian Andean creeks were evaluated. The study included 12 sites, seven of them with arboreal coverage at their margins in forested areas undisturbed by deforestation (reference stations) and the other five without tree cover in deforested areas (altered stations). Four field samplings were carried out between June 2011 and February 2012, and samples of benthic macroinvertebrates were collected using the D-net method with 500 μm mesh and manual collection, and different physicochemical variables were measured in situ. The Shannon-Wienner (H′) and Simpson´s index (D) were calculated. One-way analyses of variance (ANOVAs) to each environmental variable, and canonical discriminant analysis (CDA) to establish differences in environmental variables, taxonomic and functional diversity between references and altered stations were applied. 8 370 macroinvertebrate individuals corresponding to 80 taxa were collected in the study, with 6 758 individuals and 75 taxa in references stations and 1 612 individuals and 50 taxa in altered stations. The reference stations had higher values of diversity and the taxa that made major contributions to the variance between reference and altered stations were Thraulodes, Anacroneuria and Rhagovelia, which were associated with the highest values of Index of Andean riparian vegetation Quality (QBR-And), fluvial habitat index (IHF), Biological Monitoring Working Party Colombia BMWP/Col, EPT index (Ephemeroptera, Plecoptera, and Trichoptera) and temperature in reference stations, whereas Leptonema, Baetodes and Mayobaetis were associated with higher pH and elevation above sea level in altered stations. The main functional feeding groups (FFG) at the reference stations were collectors-gatherers/scrapers CG / SC (27.2 %), scrapers SC (25.4 %) and predators PR (24.4 %), and for altered stations were collectors-filterers CF (27.5 %), collectors-gatherers/scrapers CG / SC (17.4 %) and scrapers SC (15.7 %). The most abundant life habits were clingers Cg (50.5 %), taxa with three or more habits (28.7 %) and skaters Sk (16.1 %), in the reference stations, and clingers Cg (68.1 %), taxa with three or more habits (13.7 %) and burrowers Bu (5.2 %) in the altered stations. The knowledge of the variables that determine the taxonomic and functional structure of the macroinvertebrate assemblages, and how they respond to impacts such as deforestation, can help to determine actions of protection or restoration of the environmental and ecological conditions of the Andean streams and the riparian habitats.(AU)

The effect of macroinvertebrate exclusion on leaf breakdown rates in two upland Colombian streams / Efecto de la exclusión de macroinvertebrados sobre las tasas de descomposición de la hojarasca en dos ríos de alta montaña en Colombia

Abstract Macroinvertebrate shredders have been widely recognized as an important functional feeding group that contributes to leaf decomposition in temperate streams, but little is known about their role in upland Neotropical streams. In this study, we investigated the effect of macroinvertebrate exclusion on leaf breakdown rates in two upland streams in Colombia. The study was carried out between January and April of 2009, including the dry season and the beginning of the wet season. We measured leaf mass loss using coarse- (15 mm; accessible to macroinvertebrates) and fine- (200 µm; macroinvertebrates excluded) mesh litter bags that were anchored with wood stakes to the bottom of each stream and recovered after 7, 14, 21, 28, and 56 days. We selected leaves from two dominant plant species and used three leaf treatments: two single species (Palicourea cuatrecasasii and Critoniopsis ursicola) and mixed-species (P. cuatrecasasii and C. ursicola). We compared leaf breakdown rates between the Peña Bonita and Marianela stream, mesh-sizes, and leaf treatments. Macroinvertebrates that colonized the litter bags were measured for density and biomass and categorized in functional feeding groups. In general, there were no significant differences in breakdown rates between the streams and the mesh-sizes. In contrast, leaf breakdown rates had significant differences between all leaf species, where C. ursicola had higher breakdown rates than mixed-species, and P. cuatrecasasii. Macroinvertebrate exclusion did not affect leaf breakdown rates and their assemblages were composed by high densities of collectors (mainly Chironomidae) and few shredders with a large body size. The similar macroinvertebrate colonization between leaf species, the relatively slow breakdown rates, and the shredder scarcity, suggest that leaves were a refractory substrate. Further studies should include leaf species with different nutritional qualities and larger spatial-temporal scales to test the hypothesis of shredder presence and its role on leaf decomposition in upland Colombian streams. Rev. Biol. Trop. 66(1): 457-467. Epub 2018 March 01.

Resumen Los macroinvertebrados fragmentadores han sido ampliamente reconocidos como un importante grupo funcional alimenticio que contribuye a la descomposición de la hojarasca en quebradas del hemisferio norte, pero poco se sabe sobre su papel en quebradas de montaña neotropicales. En el presente estudio investigamos el efecto de la exclusión de los macroinvertebrados sobre las tasas de fragmentación de la hojarasca en dos quebradas de montaña en Colombia. Nuestra hipótesis es que la fragmentación de la hojarasca es mediada principalmente por macroinvertebrados fragmentadores en quebradas de montaña en Colombia. Este estudio fue llevado a cabo entre enero y abril 2009, incluyendo la época seca y el comienzo de la época de lluvias. Se midieron las pérdidas de masa de hojarasca usando bolsas de malla gruesa (15 mm; accesible a macroinvertebrados) y fina (200 µm; macroinvertebrados excluidos); estas fueron atadas con estacas de madera al fondo de cada quebrada y recuperadas transcurridos 7, 14, 21, 28 y 56 días. Se seleccionó hojarasca de dos especies dominantes en los sitios de estudio y se usaron tres tratamientos para las bolsas de hojarasca: Critoniopsis ursicola, Palicourea cuatrecasasii y una mezcla de estas dos especies. Se compararon las tasas de fragmentación de la hojarasca entre las dos quebradas, los dos tipos de malla y las especies de hojarasca. Los macroinvertebrados que colonizaron las bolsas de hojarasca fueron medidos en términos de densidad, biomasa y categorizados en grupos funcionales alimenticios. En general, nuestros resultados no mostraron diferencias significativas en las tasas de fragmentación de la hojarasca entre las quebradas y entre los tipos de malla. En contraste, las tasas de fragmentación presentaron diferencias significativas entre las especies de hojarasca; específicamente, C. ursicola tuvo tasas más altas de fragmentación que las especies mezcladas y que P. cuatrecasasii. Con respecto a los macroinvertebrados, el presente estudio encontró que su exclusión no tuvo un efecto sobre las tasas de fragmentación y los ensamblajes estuvieron compuestos por una alta densidad de recolectores (principalmente de la familia Chironomidae) y pocos fragmentadores con gran tamaño corporal. La colonización similar de macroinvertebrados entre las especies de hojarasca, las relativamente lentas tasas de fragmentación, sugieren que las hojas fueron un sustrato refractario. Futuros estudios deberían incluir especies de hojarasca con diferentes calidades nutricionales y una mayor escala espacio-temporal para estudiar la hipótesis de la presencia de fragmentadores en quebradas de montaña en Colombia.

Impervious area percentage predicated influence of rapid urbanization on macroinvertebrate communities in a southwest China river system.

Urban areas and their development depress water physicochemical properties, river habitats and aquatic biotic integrity worldwide. Benthic macroinvertebrates at 61 sites representing three types of river reach locations (upstream rural areas, intermediate and downstream of urban areas) on the Liangtan River, a rapidly urbanized river with untreated sewage discharge in southwest China, were examined to compare their community composition and diversity. Their relationships with environmental variables were also explored. The results indicate a significant reduction in sensitive EPT (Ephemeroptera, Plecoptera and Trichoptera) species, dominance by a few tolerant taxa (Oligochaeta and Chironomidae), a significant decline in biodiversity and dominance of collector-gatherers at intermediate and downstream urban sites compared with aquatic macroinvertebrates at rural sites. The community composition of urban sites were different from those of rural sites and were quite similar to those of downstream sites, but maintained a much higher Oligochaeta density. The species-environment relation was predominately explained by the percentage of impervious area (PIA) and farmland at the catchment scale. At the local scale chemical oxygen demand (COD) and pH-value explained this relationship. Six community indicators, including richness, the Shannon-Wiener index, EPT(%), collector-filterers(%), scrapers(%) and collector-gatherers(%), had exponential relationships with PIA. Density of macroinvertebrates, Oligochaeta density, Oligochaeta(%), predator(%) and shredder(%) exhibited stepped threshold response patterns with PIA. Pielou's index had an approximately negative linear relationship with PIA. For exponential pattern, a threshold value of PIA between 10.6% and 14.4% was found. For stepped threshold response pattern, the first threshold was between 11.2% and 13.8%, and the second threshold was 23.8%. Our study indicates particularly great influences of urbanization with untreated sewage on macroinvertebrates and river ecosystems. PIA also showed to be a good indicator of urbanization and an accurate predictor of urban impacts on river macroinvertebrate integrity.

Variaciones espaciales y ontogenéticas en la dieta de un plecóptero de amplia distribución Claudioperla tigrina (Plecoptera: Gripopterygidae) / Spatial and ontogenetic variations in the diet of a widely distributed stonefly Claudioperla tigrina (Plecoptera: Gripopterygidae)

Resumen: La determinación de los hábitos alimentarios permite la comprensión de muchos procesos ecológicos que se dan en los ecosistemas lóticos. El objetivo de este trabajo es: 1) conocer los hábitos alimentarios de ninfas de Claudioperla tigrina en un amplio gradiente altitudinal y latitudinal en Argentina; 2) asignar el grupo funcional trófico (GFT) de C. tigrina; 3) evaluar diferencias entre dietas de los sitios estudiados. Las ninfas estudiadas fueron recolectadas a lo largo de un amplio rango espacial en el noroeste de Argentina e incluyen diferentes estados del desarrollo (cuatro clases de tamaño). El material ingerido fue extraído de la parte anterior del tubo digestivo mediante disección ventral del tórax. Los perfiles dietarios fueron analizados a través de la estimación de parámetros de la distribución multinomial de Dirichlet. Se efectuaron ANOVA's para cada rubro alimentario en función de los sitios. Se utilizó la técnica Multidimensional Scaling (MDS) para identificar los sitios con perfiles alimentarios promedios similares. Se realizó un análisis de amplitud de nicho trófico para evaluar la diversificación de los recursos consumidos en cada sitio. El aparato bucal no muestra variaciones a lo largo del desarrollo ninfal, excepto una mayor esclerotización con la edad. Poseen palpos mandibulares y maxilares relativamente cortos y mandíbulas y maxilas fuertes, esclerozadas y dentadas. Las ninfas ingirieron más de un ítem alimentario, sugiriendo que se trata de una especie flexible en su alimentación. El ítem dominante en la dieta fue la MOPG, los signos de haber sido masticado indican hábitos trituradores. Se encontraron diferencias entre sitios para los ítems MOPF, invertebrados, algas y sedimento, pero no para MOPG. Se obtuvieron las correlaciones para cada eje del análisis MDS. Con el eje 1 se correlacionaron negativamente los sitios AP, LT, LI, C y M (Selva de Yungas y Pastizal de neblina) asociados a un mayor consumo de MOPF, en el lado positivo del eje se encontró el sitio P (Altos Andes) asociado a los ítems invertebrados y sedimento. Para el eje 2 se relacionaron positivamente IN (Pastizal neblina) y LR (Monte de Sierras y Bolsones) con la presencia de algas. Los resultados del análisis de amplitud de nicho revelaron diferencias en el uso de los recursos secundarios de la dieta en los sitios estudiados que puede deberse a la oferta ambiental en las ecorregiones consideradas. El GFT de C. tigrina es triturador/ recolector en Selva de Yungas y Pastizales de Neblina y triturador/ depredador en Altos Andes. La definición del GFT de C. tigrina y el establecimiento de su rol como procesador primario de materia orgánica representa un paso importante para futuros estudios de redes tróficas y otras metodologías basadas en los grupos funcionales.

Abstract: Dietary information gives insight into several ecological processes acting in lotic ecosystems. This work aimed: 1) to identify the dietary habits of Claudioperla tigrina immature stages along a wide altitudinal as well as latitudinal gradient in North Argentina; 2) to define the functional feeding group (FFG) of C. tigrina; 3) to evaluate differences in diet in the studied sites. Studied nymphs were collected from localities widely scattered in Northwestern Argentina and they fell into different developmental stages (four size classes). The ingested material was extracted from the foregut and midgut by using thorax ventral dissection. Dietary profiles were analyzed through the estimation of parameters associated with a Dirichletmultinomial distribution. ANOVA's were performed for each food item using sites as factor. Multidimensional Scaling was used to identify sites with similar dietary profiles. An analysis of food-niche breadth was also performed to evaluate the degree of dietary diversification for the resources consumed in each site. Mouthparts are similar across the different size classes, excepting the increasing sclerotization recorded with age. Mouthparts retained most of the typical chewing groundplan, showing relatively short labial and maxillar palps, and strong, sclerotized and denticulated mandibles and maxillae. Our results pointed out that the nymphs of C. tigrina always ingest two or more food items (CPOM, FPOM, invertebrates and algae), suggesting thus a flexible diet. The diet changed in relation to body size, while finer particles were consumed in the early stages, larger particles were ingested in final stages. Coarse particulate organic matter was the dominant food item, with signals of shredding during ingestion. Differences between sites for FPOM, invertebrates, algae and sediment were detected, but not for MOPG. Correlations were obtained for the first two axis of the MDS analysis. Sites AP, LT, LI, C and M (Yungas Rainforest and Humid Grassland) were negatively correlated with the axis 1 which was associated with increased consumption of FPOM. On the positive side of the axis the site P (High Andes) is associated with a greater proportion of invertebrates and sediment. The sites IN (Humid Grassland) and LR (Argentine Northwest Monte and Thistle of the Prepuna) were located at the positive domain of axis 2 which is in turn associated with a greater count of algae in the dietary contents. We found significant differences in the quantity of secondary items, and this is likely related with the resources environmental availability. The FFG of Claudioperla tigrina is primarily shredder/collector-gatherer in Yungas Rainforest and Humid Grassland shredder/predator in High Andes. FFG classification of C. tigrina and the definition of their role for organic matter processing is an important step for future studies based on functional groups such as analysis of food webs. Rev. Biol. Trop. 65 (3): 1174-1184. Epub 2017 September 01.

Combined effects of hydrologic alteration and cyprinid fish in mediating biogeochemical processes in a Mediterranean stream.

Flow regimes are important drivers of both stream community and biogeochemical processes. However, the interplay between community and biogeochemical responses under different flow regimes in streams is less understood. In this study, we investigated the structural and functional responses of periphyton and macroinvertebrates to different densities of the Mediterranean barbel (Barbus meridionalis, Cyprinidae) in two stream reaches differing in flow regime. The study was conducted in Llémena Stream, a small calcareous Mediterranean stream with high nutrient levels. We selected a reach with permanent flow (permanent reach) and another subjected to flow regulation (regulated reach) with periods of flow intermittency. At each reach, we used in situ cages to generate 3 levels of fish density. Cages with 10 barbels were used to simulate high fish density (>7indm-2); cages with open sides were used as controls (i.e. exposed to actual fish densities of each stream reach) thus having low fish density; and those with no fish were used to simulate the disappearance of fish that occurs with stream drying. Differences in fish density did not cause significant changes in periphyton biomass and macroinvertebrate density. However, phosphate uptake by periphyton was enhanced in treatments lacking fish in the regulated reach with intermittent flow but not in the permanent reach, suggesting that hydrologic alteration hampers the ability of biotic communities to compensate for the absence of fish. This study indicates that fish density can mediate the effects of anthropogenic alterations such as flow intermittence derived from hydrologic regulation on stream benthic communities and associated biogeochemical processes, at least in eutrophic streams.

Assessing drivers of benthic macroinvertebrate community structure in African highland streams: An exploration using multivariate analysis.

Understanding the drivers of community structure is fundamental for adequately managing ecosystems under global change. Here we used a large dataset of eighty-four headwater stream sites in three catchments in the Eastern Highlands of Zimbabwe, which represent a variety of abiotic conditions and levels of impairment, to examine the drivers of benthic macroinvertebrate community structure. We focused our assessment on macroinvertebrate family level community composition and functional feeding group classifications. Taxonomic richness was weakly positively correlated with ammonium, phosphates and pH, and weakly negatively correlated with detrital cover and dissolved oxygen. Measured abiotic variables, however, had limited influence on both macroinvertebrate diversity and functional feeding group structure, with the exception of ammonium, channel width and phosphates. This reflected the fact that many macroinvertebrate families and functional feeding guilds were well represented across a broad range of habitats. Predatory macroinvertebrates were relatively abundant, with collector-filterers having the lowest relative abundances. The findings of the study suggest that for certain ecological questions, a more detailed taxonomic resolution may be required to adequately understand the ecology of aquatic macroinvertebrates within river systems. We further recommend management and conservation initiatives on the Save River system, which showed significant impact from catchment developmental pressures, such as urbanisation, agriculture and illegal mining.

Partitioning taxonomic diversity of aquatic insect assemblages and functional feeding groups in neotropical savanna headwater streams.

Biological diversity can be divided into: alpha (α, local), beta (ß, difference in assemblage composition among locals), and gamma (γ, total diversity). We assessed the partitioning of taxonomic diversity of Ephemeroptera, Plecoptera and Trichoptera (EPT) and of functional feeding groups (FFG) in neotropical savanna (southeastern Brazilian cerrado) streams. To do so, we considered three diversity components: stream site (α), among stream sites (ß1), and among hydrologic units (ß2). We also evaluated the association of EPT genera composition with heterogeneity in land use, instream physical habitat structure, and instream water quality variables. The percentage of EPT taxonomic α diversity (20.7%) was smaller than the ß1 and ß2 diversity percentages (53.1% and 26.2%, respectively). The percentage of EPT FFG collector-gatherer α diversity (26.5%) was smaller than that of ß1 diversity (55.8%) and higher than the ß2 (17.7%) diversity. The collector-gatherer FFG was predominant and had the greatest ß diversity percentage among stream sites (ß1, 55.8%). Our findings support the need for implementing regional scale conservation strategies in the cerrado biome, which has been degraded by anthropogenic activities.

Functional Process Zones Characterizing Aquatic Insect Communities in Streams of the Brazilian Cerrado.

Stream ecology studies see to understand ecological dynamics in lotic systems. The characterization of streams into Functional Process Zones (FPZ) has been currently debated in stream ecology because aquatic communities respond to functional processes of river segments. Therefore, we tested if different functional process zones have different number of genera and trophic structure using the aquatic insect community of Neotropical streams. We also assessed whether using physical and chemical variables may complement the approach of using FPZ to model communities of aquatic insects in Cerrado streams. This study was conducted in 101 streams or rivers from the central region of the state of Goiás, Brazil. We grouped the streams into six FPZ associated to size of the river system, presence of riparian forest, and riverbed heterogeneity. We used Bayesian models to compare number of genera and relative frequency of the feeding groups between FPZs. Streams classified in different FPZs had a different number of genera, and the largest and best preserved rivers had an average of four additional genera. Trophic structure exhibited low variability among FPZs, with little difference both in the number of genera and in abundance. Using functional process zones in Cerrado streams yielded good results for Ephemeroptera, Plecoptera, and Trichoptera communities. Thus, species distribution and community structure in the river basin account for functional processes and not necessarily for the position of the community along a longitudinal dimension of the lotic system.