Changes in the structure of fish assemblages in streams along an undisturbed-impacted gradient, upper Paraná River basin, Central Brazil

A synthesis of land use impacts on stream biodiversity across metrics and scales

While land use intensification is a major driver of biodiversity change in streams, the nature of such changes, and at which scales they occur, have not been synthesized. To synthesize how land use change has altered multiple components of stream biodiversity across scales, we compiled data from 37 studies where comparative data were available for species' total and relative abundances from multiple locations including reference (less impacted) streams to those surrounded by different land use types (urban, forestry, and agriculture). We found that each type of land use reduced multiple components of within-stream biodiversity across scales, but that urbanization consistently had the strongest effects. However, we found that β-diversity among streams in modified landscapes did not differ from β-diversity observed among reference streams, suggesting little evidence for biotic homogenization. Nevertheless, assemblage composition did experience considerable species turnover between reference and modified streams. Our results emphasize that to understand how anthropogenic factors such as land use alter biodiversity, multiple components of biodiversity within and among sites must be simultaneously considered at multiple scales.

Influence of urbanization on stream fish assemblages in three microbasins in the Upper Paraná River Basin

The colonization pattern of fish assemblages in streams is often studied in the context of environmental filters. On the other hand, when fish assemblages are subjected to anthropogenic effects, variables associated with environmental quality assume more importance. Therefore, this work evaluated the richness and composition of fish from streams sampled at different urbanization levels, aiming to determine any direct effects on the structure of fish assemblages. To accomplish this, samples were collected from 2003 to 2011 at 31 sites distributed among 3 microbasins in the Rio Ivinhema Basin, Alto Rio Paraná. Based on environmental variables, physicochemical of the water and analysis of the use and occupation of the soil, the microbasins were classified into different urbanization levels (low, medium and high). A total of 4,320 individuals were sampled, out of which 57 fish species were recorded. Sampled sites with medium urbanization level presented higher richness compared to sampled sites with high urbanization level which presented lower richness. Species richness in these sites was explained mainly by water temperature and water velocity. Results confirmed that urbanization does directly affect environmental integrity, which, in turn, can lead to the homogenization of stream assemblages.

Natural diet of Macrobrachium brasiliense (Crustacea, Decapoda) in a Cerrado stream

ABSTRACT Knowledge about the diet of a given species is essential to provide information on the growth and maintenance of populations in a natural environment. Macrobrachium brasiliense (Heller, 1862) is a species of freshwater prawn widely distributed in Brazil, being frequent in aquatic environments inserted in the Cerrado biome. The aim of this study was to evaluate the natural diet of a population of M. brasiliense, comparing the consumed food items according to sex, seasonality and body size of individuals. Monthly collections were carried out between September 2018 and August 2019. The individuals collected had their sex identified and the length of the cephalothorax measured. Stomach content was assessed based on the degree of repletion, the method of points and the frequency of occurrence. There was a high frequency of plant material in the stomach contents and a smaller but significant frequency of aquatic insects. There were no significant differences regarding the diet of males and females and between the dry and rainy seasons. It was observed an increase in total insect consumption with the increase in size of males and females of M. brasiliense. A diet preference for Trichoptera was recorded in both sampling periods for males and females. The results obtained confirm an omnivorous diet for the species and suggest that the composition and proportion of items may vary depending on the size of the individuals and the availability of the items in the environment.

Elements of fish metacommunity structure in Neotropical freshwater streams

The identification of the mechanisms underlying patterns of species co-occurrence is a way to identify which process(es) (niche, neutral, or both) structure metacommunities. The current paper had the goal of identifying patterns of co-occurrence in Neotropical stream fish and determining which processes structure the fish metacommunity, and identifying any gradients underlying this structure. Results indicated that the metacommunity formed by the species pool was structured by a pattern of nested co-occurrence (hyperdispersed species loss) and a mass-effect mechanism. However, a set of core species, displaying a Clementsian pattern, was structured by a species-sorting mechanism. Both, hyperdispersed species loss and the Clementsian patterns point to a discrete set of communities within the metacommunity. These communities could be isolated by the water physicochemical conditions or morphological characteristics of the stream channel.

The Influence of Forests on Freshwater Fish in the Tropics: A Systematic Review

Tropical forests influence freshwater fish through multiple pathways, only some of which are well documented. We systematically reviewed the literature to assess the current state of knowledge on forests and freshwater fish in the tropics. The existing evidence is mostly concentrated in the neotropics. The majority of studies provided evidence that fish diversity was higher where there was more forest cover; this was related to the greater heterogeneity of resources in forested environments that could support a wider range of species. Studies quantifying fish abundance (or biomass) showed mixed relationships with forest cover, depending on species-specific habitat preferences. We identify the key challenges limiting our current understanding of the forest-fish nexus and provide recommendations for future research to address these knowledge gaps. A clear understanding of the functional pathways in forest-freshwater ecosystems can improve evidence-based policy development concerned with deforestation, biodiversity conservation, and food insecurity in the tropics.

Knowing biodiversity: Fishes from the Guareí River basin, a tributary of the Jurumirim reservoir, Paranapanema River, Brazil

Abstract: The Guareí River is a tributary of the Paranapanema River (Brazil), located in the upper portion of the Jurumirim Reservoir. Fish fauna studies in this watershed began in the 2000s, but they were restricted to a few waterbodies. This work conducted a broad survey of the fish fauna in tributary streams and the main channel of the Guareí River. Sampling occurred between February 2017 and November 2018 at 36 sites and using different collection methods. We captured 2,169 specimens belonging to 50 species, 16 families and 6 orders. The species accumulation curve tended to stabilize but indicated that species richness is underestimated. Almost all species are native (46); only three were non-native (Hyphessobrycon eques, Oreochromis niloticus and Poecilia reticulata) and one was undefined (Gymnotus pantanal). Among the native species, two are unknown to science (Bryconamericus aff. iheringii and Hypostomus sp. n.) and three are migratory (Leporinus friderici, Megaleporinus obtusidens and Pimelodus maculatus). In this paper, we provide images of species collected. Results indicate that the Guareí River basin is a hotspot of fish diversity in the Upper Paranapanema River, stressing the need for adequate management and conservation actions.

Freshwater fishes of Pulosari mountain areas in Pandeglang Regency, Indonesia

Indonesia has many freshwater fish species but not recorded with completely, one of them from Banten Province especially in Pulosari Mountain areas of Pandeglang Regency. This study aimed to assess fish diversity, abundance, local distribution, potency, species status, bioecology aspects, and habitat condition. The study was conducted in September 2015 using survey methods. The site study was divided in five stations, the fishing gear mainly electrofishing and completed by cast net with diameter 2.5 meter. The operational of fishing gears using CPUE (catch per unit of efforts). Fish sample counted based on number of species and number of individuals for each species, then preserved and identified. Specimens were deposited in the Museum Zoologicum Bogoriense (MZB) Cibinong. The results recorded 12 species belonging to 11 families. St.2 (Cilagra river) is the most diverse with 8 species, following St.4 (Cijeruk lower) with 7 species. Barbodes binotatus is the most dominant species (19.2 ind./St.) and also widespread (100%). Two introduce species were found i.e. Poecillia reticulata and Oreochromis niloticus. Based on potency almost balance both consume and ornamental fish. The inland waters in these areas were suitable for fish habitat.

Restoration Effects of the Riparian Forest on the Intertidal Fish Fauna in an Urban Area of the Amazon River

Urbanization causes environmental impacts that threaten the health of aquatic communities and alter their recovery patterns. In this study, we evaluated the diversity of intertidal fish in six areas affected by urbanization (areas with native vegetation, deforested areas, and areas in process of restoration of vegetation) along an urban waterfront in the Amazon River. 20 species were identified, representing 17 genera, 14 families, and 8 orders. The different degrees of habitat degradation had a major effect on the composition of the fish fauna; the two least affected sectors were the only ones in that all 20 species were found. Eight species were recorded in the most degraded areas. The analysis revealed two well-defined groups, coinciding with the sectors in better ecological quality and degraded areas, respectively. The native vegetation has been identified as the crucial factor to the recovery and homeostasis of the studied ecosystem, justifying its legal protection and its use in the restoration and conservation of altered and threatened environments. These results reinforce the importance of maintaining the native vegetation as well as its restoration in order to benefit of the fish populations in intertidal zones impacted by alterations resulting from inadequate urbanization.

Influence of environmental variables on stream fish fauna at multiple spatial scales

ABSTRACT Effects of environmental variables at different spatial scales on freshwater fish assemblages are relatively unexplored in Neotropical ecosystems. However, those influences are important for developing management strategies to conserve fish diversity and water resources. We evaluated the influences of site- (in-stream) and catchment-scale (land use and cover) environmental variables on the abundance and occurrence of fish species in streams of the Upper Araguari River basin through use of variance partitioning with partial CCA. We sampled 38 1st to 3rd order stream sites in September 2009. We quantified site variables to calculate 11 physical habitat metrics and mapped catchment land use/cover. Site and catchment variables explained > 50% of the total variation in fish species. Site variables (fish abundance: 25.31%; occurrence: 24.51%) explained slightly more variation in fish species than catchment land use/cover (abundance: 22.69%; occurrence: 18.90%), indicating that factors at both scales are important. Because anthropogenic pressures at site and catchment scales both affect stream fish in the Upper Araguari River basin, both must be considered jointly to apply conservation strategies in an efficient manner.

Integrated approach to the understanding of the degradation of an urban river: local perceptions, environmental parameters and geoprocessing

BACKGROUND

The use of interdisciplinary approaches such as the proposed report provides a broad understanding of the relationship between people and the environment, revealing reliable aspects not previously considered in the study of this relationship. This study compiled evidence on the environmental degradation of an urbanized river over the past few decades, providing a diagnosis of the consequences of this process for the river, its ichthyofauna, and the local human population.

METHODS

The study was focused on the Beira Rio community on the Capibaribe River in the municipality of São Lourenço da Mata, Pernambuco, Brazil. Data were collected using geoprocessing and ethnobiological approaches, as well as environmental parameters. This research was conducted with the most experienced long-term residents in the local community, through interviews and participatory methodologies to recovering information about the river environment, its ichthyofauna and its environmental services for the last decades.

RESULTS

According to the GIS analysis, the study area was subject to an accelerated process of urbanization, with the total urban area increasing from 73 565, 98 m(2) in 1974 to 383 363, 6 m(2) in 2005. The informants perceived the urban growth, especially in the late twentieth century, being this period recognized as the phase of greatest negative changes in the river environment. The perceived decline of fish stocks was indicated by the community as one of the effects of river degradation. According to the interviews, the deterioration of the river affected the ecosystem services and the relationship of the adjacent human community with this ecosystem. The environmental data indicated that the river is suffering eutrophization and has fecal coliform concentrations 160 times higher than the maximum level permitted by Brazilian legislation.

CONCLUSIONS

The interdisciplinary approach used in this research allowed the understanding of the degradation process of an urban river and some negative effects through the integration of environmental data, GIS and the local knowledge, revealing the complementarity of obtained data and the effectiveness of implementation of this approach.

Assessment of fish assemblages in streams of different orders in the Upper Paraná River basin, Central Brazil

The aim of this study was to test whether the richness observed and the biomass per trophic group of fish assemblages vary depending on the order (1st and 2nd) of the streams located in three different basins of the Upper Paraná River Basin, Central Brazil. Samples were collected between April and September, 2009, in 27 streams of the Meia Ponte, Piracanjuba and Santa Maria River basins. A total of 4,879 specimens were collected distributed in 59 species and 19 families. The statistical analyses carried out indicate that the observed richness and biomass of omnivore fish were influenced by the interaction of two factors: stream order and basin. The 2nd order streams located in the Santa Maria basin presented significant differences in the observed richness and omnivore biomass when compared to i) 1st order streams in the same basin (only richness) or in the Piracanjuba and Meia Ponte basin; ii) 2nd order streams in the Piracanjuba (only omnivore biomass) and Meia Ponte Rivers basins. Results are discussed considering the influence of geomorphic processes on fish assemblages and food availability.

Longitudinal patterns of fish assemblages in mountain streams from tropical forest biome

The aim of this study was to verify structure patterns in fish assemblages in mountain streams of the Rio Tibagi basin through the characterization of spatial and temporal variations in the composition of fish species. Samples were collected in three segments of the Varanal, João Pinheiro and Rio Preto streams. We collected 1154 specimens belonging to 21 species. The most abundant orders were Characiformes (59.01 ± 2.84%) and Siluriformes (39.34 ± 2.82%). Phalloceros harpagos was the most abundant species with 433 individuals, followed by Trichomycterus aff.davisi, with 292 individuals. No temporal variations (between seasons) were detected, but the cluster analysis suggests a separation of species composition between the segments closer to the headwaters and those more distant. The first two axes of the Canonical Correspondence Analysis (CCA) explained 80.09% of the variation in species abundance, and the variables that structured the fish assemblages in those streams were the stream width, depth, water speed, flow rate, conductivity and pH.

Trophic organization and fish assemblage structure as disturbance indicators in headwater streams of lower Sorocaba River basin, Sao Paulo, Brazil

Studies that investigate the relationship patterns between environmental structure complexity and fish fauna provide crucial information to stream restoration efforts. In order to test the hypothesis that streams with more complex environmental structure sustain more diverse and functionally more complex fish communities we sampled fish fauna from Sorocaba River headwater stream reaches (SE - Brazil). Reaches represented two distinct treatments: (1) a simplified reach, characterized by unstable fine substrate, clay, deeper channel and higher water velocity and (2) structurally complex reaches, characterized by coarse substrate, with gravel, pebble, rock, stems and branches and leaves inside the channel, producing a diverse pattern of microhabitat, associated with sequences of pools, runs, and riffles. Both trophic structure and taxonomic composition varied significantly between treatments. Invertivorous trophic group exclusively occurred in structurally complex reaches, which also presented greater diversity and species richness. We suggest enhancing in-stream environmental structure that suffered simplification processes due to human impacts in order to reestablish fish communities and ecossistemic functioning.

Measuring the ecological integrity of an industrial district in the Amazon estuary, Brazil

The aim of the present study is to provide information on the ecological integrity of an industrial district located in the estuary of Pará River (Amazon estuary), by applying a selection of fish based multimetric indices of ecosystem integrity: Abundance Biomass Comparation (ABC); Biological Health Index; Estuarine Fish Community, Transitional Fish Classification and Estuarine Biotic Integrity Indexes. To evaluate the impacts of the industrial area and cargo terminal, three areas were considered: Zone 1, (maximum impact), Zone 2 (median risk) and Zone 3 (reference area). All the biological indices used were considered to be excellent indicators of the ecological integrity of the different sectors of the study area and were especially effective for the demonstration of the critical alterations of the fish community of Zone 1 and Zone 2. The simultaneous use of different indices family, with different assumptions, did strengthen the results enhancing the confidence in the diagnostic.

Fish assemblages in two sandy beaches in lower Purus river, Amazonas, Brazil

Fish assemblages from two sandy beaches in the lower Purus river (Amazonas, Brazil) were compared. Four sampling groups were represented by: day and night samples in sandy beach inside the Reserva Biológica de Abufari (biological reserve) and day and night samples in the Reserva de Desenvolvimento Sustentável Piagaçu-Purus (sustainable development reserve). Samples were collected during low water levels (November) in 2007. The fish were sampled by means of seines with mesh size of 5 mm between opposing knots, 11 m long and 6 m wide. A total of 112 fish species belonging to nine orders and 27 families was captured. The vast majority of the dominant forms consisted of small fishes (< 100 mm SL) or juveniles. Samples collected in Abufari at night presented more specimens (3,540), higher richness (84 spp.), larger total biomass (76,614 g) and higher diversity (H'= 2.57) than the other groups. The composition of fish assemblages was significantly different among all analyzed groups (ANOSIM, p < 0.0001, R= 0.71). NMDS analysis also clustered all species in four distinct groups according to species composition per period and site. SIMPER analyses showed that 80% of variation of species composition among the groups examined was due to 12 species. However, fish composition did not show any correlation with the abiotic factors examined. Different levels of use in both reserves may explain differences in fish composition.