Brazilian Streams Research Articles

The relationship between water quality and the microbial virulome and resistome in urban streams in Brazil

Urban streams that receive untreated domestic and hospital waste can transmit infectious diseases and spread drug residues, including antimicrobials, which can then increase the selection of antimicrobial-resistant bacteria. Here, water samples were collected from three different urban streams in the state of São Paulo, Brazil, to relate their range of Water Quality Indices (WQIs) to the diversity and composition of aquatic microbial taxa, virulence genes (virulome), and antimicrobial resistance determinants (resistome), all assessed using untargeted metagenome sequencing. There was a predominance of phyla Proteobacteria, Actinobacteria, and Bacteroidetes in all samples, and Pseudomonas was the most abundant detected genus. Virulence genes associated with motility, adherence, and secretion systems were highly abundant and mainly associated with Pseudomonas aeruginosa. Furthermore, some opportunistic pathogenic genera had negative correlations with WQI. Many clinically relevant antimicrobial resistance genes (ARGs) and efflux pump-encoding genes that confer resistance to critically important antimicrobials were detected. The highest relative abundances of ARGs were β-lactams and macrolide-lincosamide-streptogramin. No statistically supported relationship was detected between the abundance of virulome/resistome and collection type/WQI. On the other hand, total solids were a weak predictor of gene abundance patterns. These results provide insights into various microbial outcomes given urban stream quality and point to its ecological complexity. In addition, this study suggests potential consequences for human health as mediated by aquatic microbial communities responding to typical urban outputs.

Infection of guppies (Poecilia reticulata) with the Asian fish tapeworm Schyzocotyle acheilognathi in an urban stream in Brazil.

Schyzocotyle acheilognathi is a fish tapeworm native to Asia but has been reported as an alien species on practically all other continents. Its invasive potential is due to its low host specificity and high adaptability to different environments, and its spread to new areas can result in economic and ecological impacts. Studies reporting this species in South America are still scarce, indicating the need to monitor its dispersion to new areas. Herein, tapeworms found in guppies, Poecilia reticulata, from an urban stream located in Belo Horizonte, Minas Gerais, Brazil, in April 2021 were subjected to morphological and molecular characterization. As a result, 5/13 (38.5%) of the P. reticulata specimens evaluated were infected with intestinal tapeworms. It was verified a mean intensity of infection of 7.8 (1-25) and a mean abundance of infection of 3 (0-25). The morphology of the cestodes obtained was compatible with that of S. acheilognathi. Moreover, genetic analysis based on cytochrome c oxidase subunit 1 gene (Cox-1) revealed 97.89-99.77% similarity to isolates of this species from different localities. The possibility that S. acheilognathi is expanding to new regions of South America is discussed.

Parasites of Astyanax lacustris (Pisces, Characiformes) from Brazilian streams.

Astyanax lacustris is a small characid fish widely distributed in Brazil, with fast-growing and omnivorous feeding habits. Although the species presents economic and ecological importance, little is known about its parasitological fauna in stream environments. This study aimed to characterize the parasitic fauna of A. lacustris in two streams in the state of Paraná, Brazil. Fifty-two specimens of A. lacustris were collected, 22 from the Carolina stream (Lower Iguaçu River) and 30 from the Carreira stream (Upper Paraná River), in July and September 2018. In both streams, there was a low richness of parasites, and the structure of the parasitic community was predominantly composed of monogeneans. These findings may be associated with the gregarious behavior of the host species. Moreover, the low occurrence of endohelminths, may be associated with the fact that in streams, the energy flow is low, and depends directly on the input of allochthonous matter, which favors the formation of shelters for the establishment of macroinvertebrates, which represent important sources of food for the ichthyofauna, and may act as intermediate and paratenic hosts of parasites. These environments require further studies to support conservation measures aimed at maintaining the balance of ecological relationships in these preserved ecosystems.

Field-Scale Constructed Floating Wetland Applied for Revitalization of a Subtropical Urban Stream in Brazil

Constructed floating wetland (CFW) is an ecotechnology used to improve water quality using emergent macrophytes on a floating mat structure. The goals of this research were to design and evaluate a low-cost field-scale CFW for revitalization of a polluted lentic section of an urban stream, located in the subtropical coastal region of South Brazil. To attain these goals (i), the design parameters were selected from field-scale applications in the literature, and (ii) the influence of the meteorologic and hydraulic data over the CFW performance to improve water quality were analyzed during five months. Macrophyte leaves grew 1 cm·day−1. Biochemical oxygen demand (BOD) (72%), total phosphorus (TP) (52%), turbidity (53%), total solids (TS) (60%), dissolved oxygen (DO) (39%) and water temperature (WT) (0.4 °C) showed statistically significant reductions. The HRT was sufficient to reduce dissolved carbonaceous organic matter. HRT and solid particles-related parameters showed reductions both on high and low HRT. The resulting loading rates can be used for the design purposes of similar CFW field applications. The CFW promoted water quality improvement, attractiveness of fauna, temperature regulation, carbon sequestration, and is a potential ecotechnology towards the depollution of river basins in urban areas.

Land-use intensification systematically alters the size structure of aquatic communities in the Neotropics.

Land-use and land-cover transitions can affect biodiversity and ecosystem functioning in a myriad of ways, including how energy is transferred within food-webs. Size spectra (i.e. relationships between body size and biomass or abundance) provide a means to assess how food-webs respond to environmental stressors by depicting how energy is transferred from small to larger organisms. Here, we investigated changes in the size spectrum of aquatic macroinvertebrates along a broad land-use intensification gradient (from Atlantic Forest to mechanized agriculture) in 30 Brazilian streams. We expected to find a steeper size spectrum slope and lower total biomass in more disturbed streams due to higher energetic expenditure in physiologically stressful conditions, which has a disproportionate impact on large individuals. As expected, we found that more disturbed streams had fewer small organisms than pristine forest streams, but, surprisingly, they had shallower size spectrum slopes, which indicates that energy might be transferred more efficiently in disturbed streams. Disturbed streams were also less taxonomically diverse, suggesting that the potentially higher energy transfer in these webs might be channelled via a few efficient trophic links. However, because total biomass was higher in pristine streams, these sites still supported a greater number of larger organisms and longer food chains (i.e. larger size range). Our results indicate that land-use intensification decreases ecosystem stability and enhances vulnerability to population extinctions by reducing the possible energetic pathways while enhancing efficiency between the remaining food-web linkages. Our study represents a step forward in understanding how land-use intensification affects trophic interactions and ecosystem functioning in aquatic systems.

Linking fish ecomorphotypes to food categories and local‐scale habitat uses along a Brazilian coastal stream

AbstractFish ecomorphological analyses often deal with several traits simultaneously, making it challenging to interpret general patterns, and have not addressed the longitudinal component of streams in morphology‐habitat relationships. We identified ecomorphotypes of fishes and correlated their morphological variation with food, structural/hydrological variables, and abundances to detect their links with diet and local‐scale habitat categories. Eighteen morphometric traits were obtained from specimens collected by electrofishing in a coastal Atlantic stream in Brazil. To test for morphology‐habitat associations, headwaters, middle, and mouth reaches were divided into shorter sampling sites, with the middle reach being classified into riffle, run, and pool mesohabitats. Multivariate analyses highlighted the morphological variations and associated the form categories of 18 fish species with food and habitat categories. It resulted in four combined trophic and habitat ecomorphotypes: (1) benthic AB/lithophilic, composed of smaller to longer loricariids, detritivores, of fast‐water, and pebbly habitats; (2) benthic C/lithophilic of very fast‐waters, algal and detritus scrapers, with longer intestines than the other benthic species, wider suctorial mouths, inhabitants of headwaters, and riffles habitats; (3) nektobenthic/lithophilic with streamlined bodies, invertebrate feeders, and dwellers of faster‐water, cobbly habitats; and (4) nektonic/limnophilic composed mainly by characins, which had strong correlations with terrestrial insect consumption, and lentic/pool, sandy habitats. The morphology–environment correlations linked these ecomorphotypes to the broad habitat gradient arrayed in longitudinal and local scales. These results permit inferring the larger form patterns expected for local fish assemblages and emphasise the fish trait categorisation as a possible surrogate to reveal broader ecomorphological associations.

Body size has primacy over stoichiometric variables in nutrient excretion by a tropical stream fish community

Ecological Stoichiometry (ES) and the Metabolic Theory of Ecology (MTE) are the main theories used to explain consumers’ nutrient recycling. ES posits that imbalances between an animal’s body and its diet stoichiometry determine its nutrient excretion rates, whereas the MTE predicts that excretion reflects metabolic activity arising from body size and temperature. We measured nitrogen, phosphorus and N:P excretion, body N:P stoichiometry, body size, and temperature for 12 fish species from a Brazilian stream. We fitted competing models reflecting different combinations of ES (body N:P, armor classification, diet group) and MTE (body size, temperature) variables. Only body size predicted P excretion rates, while N excretion was predicted by body size and time of day. N:P excretion was not explained by any variable. There was no interspecific difference in size-scaling coefficients neither for N nor for P. Fitted size scaling coefficients were lower than the MTE prediction of 0.75 for N (0.58), and for P (0.56). We conclude that differences in nutrient excretion among species within a shared environment primarily reflect contrasts in metabolic rates arising from body size, rather than disparities between consumer and resource stoichiometry. Our findings support the MTE as the primary framework for predicting nutrient excretion rates.

Composition and structure of the parasitic fauna of Hypostomus spp. (Loricariidae: Hypostominae) from a Neotropical river in Brazil.

Hypostomus are abundant in Brazilian rivers and streams. In the Ivaí River, the loricariids represent 20.3% of the total species of the basin. Of these 13 species belong to Hypostomus. However, to date, there are no studies on these fish parasitic fauna. Thus, this research aimed to analyze the distribution of the parasitic infracommunity of six species of Hypostomus from the Ivaí River and investigate how the infracommunity is structured in these hosts. One hundred and twenty-eight fish were analyzed, belonging to six sympatric species of Hypostomus (Hypostomus hermanni, H. cochliodon, H. albopunctatus, H. regani, Hypostomus sp.1, and Hypostomus sp.2); of these, 92.9% were parasitized with at least one taxon, totaling 1478 specimens of parasites. The parasitic fauna was composed of the ectoparasites Trinigyrus anthus, T. carvalhoi, Unilatus unilatus (monogeneans), and Placobdella spp. (hirudinea), and the endoparasites Austrodiplostomum compactum (digenean) and Procamallanus annipetterae (nematode). The parasites exhibited similar patterns of infection in all hosts, including a low number of species, low diversity, and numerical dominance of a group of parasites. However, permutational multivariate analysis of variance (PERMANOVA) showed different parasite species compositions among the hosts. Hypostomus cochliodon and H. regani had the highest parasite richness, while Hypostomus sp.1 and Hypostomus sp.2 showed low abundance and intensity of parasitic infections. However, Hypostomus sp.1 showed the highest values of evenness, although the parasite composition in both species did not differ. The results presented herein contribute to increasing the knowledge about the parasitic fauna of Hypostomus spp. from the Ivaí River by presenting new hosts and locality records.

Urocleidoides spp. (Monogenea: Dactylogyridae) from the gills of Parodon nasus (Characiformes: Parodontidae) from a Brazilian stream with descriptions of two new species.

Urocleidoides spp. are reported from the gills of 20 specimens of Parodon nasus (standard length 8.512 cm), from the Indiana stream, Tiet River, Upper Paran River basin, municipality of Botucatu, So Paulo State, Brazil. Urocleoidoides tenuis and two new species were found. Urocleidoides indianensis n. sp. differs from its congeners mainly by the morphology of the vaginal sclerite that is robust, sickle-shaped, and forked at the distal end; and by the bulbous-shaped accessory piece of the male copulatory complex. Urocleidoides parodoni n. sp. resembles U. tenuis by presenting male copulatory organ with approximately 7 counterclockwise rings, but differs by the morphology of the accessory piece (lobate with a small hook-like projection versus pincer-shaped), vaginal sclerite (thumb-like subterminal projection vs. presence of a distal hook), vaginal tube (conspicuously sclerotized vs. slightly sclerotized), shape of the ventral bar (bowed vs. wide V-shaped), ventral and dorsal anchors (robust base and short shaft vs. considerably less robust base and long shaft), and hooks (slender shank with a weakly sclerotized subunit at base vs. dilated shank). Sequences of the partial 28S rDNA gene of the dactylogyrids found in this study are provided. Phylogenetic analyses showed Urocledoides spp. from Parodontidae clustering together with strong support values. This study increases the number of valid Urocleidoides species to 39, and the number of species described from parodontid hosts to four.

PEIXES NÃO-NATIVOS EM RIACHOS NO BRASIL: ESTADO DA ARTE, LACUNAS DE CONHECIMENTO E PERSPECTIVAS

Biological invasions are among the main causes of biodiversity loss on planet. Losses are accentuated in streams, which are sensitive to human impacts, since they have specialized fauna and higher degree of endemism. Despite this, studies on invasions by non-native fish in streams are incipient in Brazil. In this review, we present an introduction on the process (i.e., stages) of biological invasion, the environmental factors that influence the establishment and the impacts of non-native species in streams. A methodological step-by-step is also presented as a way to guide the conduct of studies on non-native species in Brazilian streams. In addition, management actions measures are presented to prevent new cases of introductions and suggestions for studies on invasions in streams. Avoiding propagule pressure and environmental education, as well as legal aspects of Brazilian legislation, are management actions that can prevent new introductions. Finally, gaps in knowledge and perspectives are raised as an incentive for interested parties to enter the subject and develop new studies on non-native fishes in Brazilian streams.

PAISAGENS FLUVIAIS E PEIXES DE RIACHO: UMA INTRODUÇÃO AOS DADOS, UNIDADES ESPACIAIS DE ANÁLISE E CLASSIFICAÇÃO

Research on riverscapes and stream fish ecology has undergone a wide progress since the 1990s. Several conditions have been pointed out as essential in this progress, including the following four: (a) availability of geo-technology and spatial data, (b) setting the regional context of study areas (biomes, large river basins, ecoregions); (c) defining hierarchical spatial units of analysis (watersheds, segments, reaches) and their attributes (e.g., area, slope, order, perennial/intermittent), and (d) classification of spatial units according to their attributes. Here we present an introduction to these topics, using examples from studies in Brazilian streams, where research progress on riverscapes and stream fish has occurred only more recently. We identify a few challenges in the Brazilian context, including the standardization and consolidation of regional and national spatial databases that support riverscape analyses, training fish ecologists in Geographic Information Systems (GIS) and spatial data, expanding the use of classification systems in different spatial coverages and resolutions, research on structural, spatial and temporal attributes of spatial units in riverscape analyses

MACROECOLOGIA DE PEIXES DE RIACHOS BRASILEIROS

Studies in Macroecology deal with patterns and processes on large scale (spatial, temporal and taxonomic) and that by definition are too comprehensive to be studied with replicated, manipulative and controlled experiments as it has been traditionally performed in Ecology. Macroecological studies are still conducted with a focus on terrestrial vertebrates and plants, while marine systems and especially freshwater systems remain little explored. The objective of this study is to highlight some advances in the fields of study of aquatic macroecology (spatial patterns of alpha and beta diversity), using fish from Brazilian streams as the object of analysis. By gathering stream fish occurrence information from large scale data sets, we found high total richness in Amazonia, Cerrado and Atlantic Forest, and found on average seven species per sampling unit, with small variation related to the identity of the analyzed biomes. Yet, species composition is distinct between biomes and we found high turnover levels within them. We will guide the reader through possible causes and mechanisms of the identified patterns.

AVALIAÇÃO DA INTEGRIDADE BIÓTICA DE RIACHOS A PARTIR DA ICTIOFAUNA

Almost four decades ago, ecologist James R. Karr published the first version of the Index of Biotic Integrity (IBI) to assess the health of aquatic ecosystems from fish assemblages. Since then, numerous adaptations, criticisms, and reinterpretations have emerged from this seminal study, covering diverse world biomes. In Brazil, the first versions of IBI for streams were developed in the South (in 2004). Over time, scientific production on this topic has shown a significant increase in the complexity of the approaches and methods used, mainly due to the advance in the basic knowledge about stream fish diversity, ecology, and biology. These studies include, for example, tests of metrics already proposed, proposals for new metrics, adaptations for different basins, and tests of the ecological responses of the ichthyofauna to different human-originated impacts. Even so, there are no standardized protocols for defining the metrics, nor for the introduction of these indexes in the stream monitoring routine. The objective of this article is to present a theoretical framework on the development of IBI for Brazilian streams, based on ichthyofauna, to discuss whether it is possible and feasible to standardize protocols for the development of IBIs and the prospects of applicability in Brazilian streams.

MÉTODOS QUANTITATIVOS PARA MENSURAR A DIVERSIDADE TAXONÔMICA EM PEIXES DE RIACHO

Species diversity is defined as the variety of species and their relative abundances, and can be decomposed in local (alpha), regional (gamma) and between-communities (beta) diversity. For decades, studies with Brazilian stream fish focused on the relationship between local environmental variables and diversity patterns. However, dispersal gained notoriety for being important to the organization of communities. Besides, large scale variables are increasingly being perceived as good predictors of diversity, complementing the role of habitat variables. We present here a brief review of the methods to obtain alpha and beta taxonomic diversity, considerations regarding their predictors, and their main analysis.

Trends and gaps in studies of stream-dwelling fish in Brazil

The high diversity of fish species found in Brazilian streams has attracted scientific interest in recent years. However, it is not clear how studies have addressed biodiversity knowledge shortfalls. We conducted a scientometric analysis of stream fish studies in Brazil to identify trends and gaps in how objectives, spatial coverage, and biodiversity knowledge shortfalls have been studied. Our review covered 690 articles published between 1981 and 2019, and we found an increase in the number of publications, the spatial scale of studies, and the number of streams studied. We also found biases in the distribution of publications concerning regions, biomes, basins, and biodiversity knowledge shortfalls. The Southeast region, the Parana River basin, the Atlantic Forest biome, and the Hutchinsonian shortfall contributed to a greater number of studies while the Northeast region, the Pantanal biome, Parnaiba basin, Western Northeast Atlantic basin, and the Prestonian shortfall were less represented. Therefore, to improve our knowledge about stream fish, we recommend new collection efforts in under-sampled regions and new studies focused on filling less-addressed biodiversity knowledge shortfalls. Moreover, we emphasize the importance of standardized sampling protocols, a complete sharing of data, and an increase in scientific collaboration.

The relative importance of spatial and environmental processes in the assembly of larval Chironomidae (Insecta, Diptera) communities along a transition landscape in southern Brazilian streams

Metacommunity structure of stream invertebrates is contingent on complex interplays between species dispersal ability, spatial extent and watershed environmental specificities. Previous studies showed that high diversity of Chironomidae (Insecta, Diptera) is observed in southern Brazilian montane streams, although the knowledge of the processes driving such high diversity is poorly comprehended. In this study, we evaluated the relative contribution of environmental (in-stream and landscape) and spatial drivers to the metacommunity structure of larval Chironomidae in a watershed (N = 40 stream reaches) running across a forest–grassland transition landscape in southern Brazil. Overall, 51 taxa were recorded in the study region. We found similar contributions of the environmental (in-stream and landscape) and spatial (broad- and fine-scale spatial drivers) fractions to the metacommunity structure of larval Chironomidae. Our results suggest that environmental processes likely associated with the elevation and stream longitudinal gradients predominated in the assembly of the metacommunity structure of larval Chironomidae. Additionally, mass effects (exchange of individuals via dispersal) possibly associated with the short-range drift or flight and the contact zone between the fauna from each biome also accounted for the observed pattern. Finally, dispersal limitation associated with the spatial extent and the topographic heterogeneity of the study region likely played a minor role in the assembly of Chironomidae metacommunity structure.

Environmental factors structuring the assemblage of aquatic insects in an epigean and hypogean stretch of a Neotropical karst stream

The aim of the present study was to identify which variables structure the assemblage of aquatic insects in the subterranean environment, because knowledge about how subterranean communities are structured in rivers with hypogean sections is still emerging. In addition to identifying whether the hypogean assemblage is structured in the same way as the epigean assemblage, we sought to identify whether the environmental restrictions caused by the subterranean habitat resulted in reduced species richness and abundance compared with the epigean habitat. We sampled a 345-m stretch of a stream in Brazil and collected aquatic insects from both the epigean and hypogean environments. In the stream stretch investigated, there was a positive relationship between richness and the percentage of immersion, fine substrate and organic matter, and a negative relationship between richness and conductivity. We also verified differences between the epigean and hypogean environments regarding composition. The variables that best explained the overall assemblage structure included the epigean–hypogean environment and the percentage of coarse and fine substrate. Given the differences between these environments, we emphasise the need for management actions in karst regions that consider the discontinuity of these regions’ river communities to conserve all components of diversity.

Length-weight relationship and diet of the catfish Cambeva guareiensis (Siluriformes; Trichomycteridae)

Abstract: The length-weight relationship (LWR) and diet of a small trichomycterid catfish, Cambeva guareiensis, was studied based on 58 specimens captured in Corrente stream, Guareí River basin, São Paulo, Brazil. LWR analyses showed values of a ranged from 0.0097 to 0.0149 and b from 2.858 to 3.250. The analysis of the diet showed that high amounts of aquatic insects (93.75% of total items) were consumed by the species. In addition, we found no statistically significant differences when comparing the diet between the dry and rainy periods. Our study contributes to the knowledge on populational biology and feeding ecology of trichomycterid fishes in Brazilian streams.

Upper Tropospheric Cyclonic Vortex and Brazilian Northeast Jet Stream over Alagoas State: Circulation Patterns and Rainfall

Abstract Interaction between Brazilian Northeast Jet Stream (BNEJS) and Upper Tropospheric Cyclonic Vortexes (UTCV) isn't still well known, as well as its seasonal variability and relation with rainfall pattern. This study's aim is to determine the air circulation patterns in UTCV events with BNEJS in La Niña and El Niño years and its connections with rainfall in the Alagoas State. These connections were analyzed for 9 years between 1988 and 2000 in El Niño, La Niña and Neutral years. NCEP Reanalysis data, rainfall data from 71 meteorological stations and satellite images were used. Fifty-eight percent of 140 observed UTCVs were associated with BNEJS events located in the Brazilian Northeast and 26%, located over the Alagoas State. Three types of BNEJS patterns, denominated as Meridional (M), Zonal (Z) and Transversal (T), have been identified. The M-type BNEJS was the most frequent in Alagoas State, especially in El Niño years. Z and T-types occurred less frequently and were rarely seen in La Niña years. The results showed that in the M-type BNEJS events in 48% of days were not registered precipitation, while Z and T events recorded rainfall in almost 96% of the days.

Effects of spatial distances on the assemblage dissimilarity of macroinvertebrates with different dispersal pathways and abilities in southern Brazilian streams

AbstractThe magnitude of distance–decay relationships (DDRs) in stream macroinvertebrates can vary with their preferential dispersal pathways (overland and watercourse) and abilities as well as with environmental dissimilarity. We assessed DDRs in the compositional dissimilarity of macroinvertebrate assemblages in southern Brazilian streams using overland and watercourse distances (WD) as explanatory variables. We conducted additional separate assessments for taxonomic groups and according to a classification that took into account differences in the dispersal abilities and main pathways among macroinvertebrates. Assessments were conducted separately for (a) strong‐flying insects with overland dispersal (Anisoptera), (b) weak‐flying insects dispersing preferably through riparian corridors (Chironomidae, Ephemeroptera, Plecoptera, Trichoptera and Zygoptera), and (c) watercourse dispersers (Mollusca, Psephenidae and Elmidae). The environmental dissimilarity associated with spatial extent was accounted for via partial Mantel tests. Overland and WD were positively correlated with the dissimilarity of the total macroinvertebrate assemblage, weak‐flying insects, watercourse dispersers, and most taxonomic groups. DDRs were stronger with overland than WD. However, no consistent pattern emerged after accounting for environmental dissimilarity. Strong‐ and weak‐flying insects were correlated with environment, while watercourse dispersers, with geographic distances. Additionally, taxonomic groups were differently related with environment and geographic distances. The distinct responses of each taxonomic group to the environmental specificities of the study area such as substrate composition and land use likely explain the observed results. Thus, our findings indicate that combining taxonomic and natural history information is an effective approach for comprehending the underlying mechanisms generating spatial structure in stream macroinvertebrate assemblages.