The influence of environmental variables on the functional structure of headwater stream fish assemblages: a study of two tropical basins in Central Brazil

We investigated functional patterns of fish assemblages of two adjacent basins (Araguaia and Tocantins) to test whether their headwater stream fish assemblages are more functionally (dis)similar than expected by chance and whether these (dis)similarities are related to differences of environmental conditions between basins. We used an analysis of similarities (ANOSIM) on a functional dissimilarity matrix to test for (dis)similarities between fish assemblages of both basins. We performed RLQ and fourth-corner analyses to determine fish species trait-environment relationship. Our results revealed functional dissimilarities between fish assemblages of both basins and significant species trait-environment relationships, suggesting that environmental conditions are driving such dissimilarities. Inter-basin dissimilarities are mainly driven by altitudinal and water temperature gradients, whereas dissimilarities among streams within the basins are influenced by channel depth, turbidity and conductivity. These five environmental variables mostly affected six fish species traits (body mass, water column position, substrate preference, parental care, foraging locality and migration) in different manners. This study is an attempt to understand functional trends of fish assemblages in a tropical region that remains poorly known but severely threatened.

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Effects of deforestation on headwater stream fish assemblages in the Upper Xingu River Basin, Southeastern Amazonia

Neotropical Ichthyology ◽

10.1590/1982-0224-20180099 ◽

2019 ◽

Vol 17 (1) ◽

Cited By ~ 4

Author(s):

Paulo Ilha ◽

Sergio Rosso ◽

Luis Schiesari

Keyword(s):

Land Cover ◽

River Basin ◽

Fish Assemblages ◽

Headwater Stream ◽

Assemblage Structure ◽

Stream Fish ◽

Taxonomic Structure ◽

Fish Assemblage Structure ◽

Xingu River ◽

Stream Fish Assemblages

ABSTRACT The expansion of the Amazonian agricultural frontier represents the most extensive land cover change in the world, detrimentally affecting stream ecosystems which collectively harbor the greatest diversity of freshwater fish on the planet. Our goal was to test the hypotheses that deforestation affects the abundance, richness, and taxonomic structure of headwater stream fish assemblages in the Upper Xingu River Basin, in Southeastern Amazonia. Standardized sampling surveys in replicated first order streams demonstrated that deforestation strongly influences fish assemblage structure. Deforested stream reaches had twice the fish abundance than reference stream reaches in primary forests. These differences in assemblage structure were largely driven by increases in the abundance of a handful of species, as no influence of deforestation on species richness was observed. Stream canopy cover was the strongest predictor of assemblage structure, possibly by a combination of direct and indirect effects on the provision of forest detritus, food resources, channel morphology, and micro-climate regulation. Given the dynamic nature of change in land cover and use in the region, this article is an important contribution to the understanding of the effects of deforestation on Amazonian stream fish, and their conservation.

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Modeling and mapping fish abundance across wadeable streams of Illinois, USA, based on landscape-level environmental variables

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/cjfas-2015-0343 ◽

2016 ◽

Vol 73 (7) ◽

pp. 1031-1046 ◽

Cited By ~ 13

Author(s):

Yong Cao ◽

Leon Hinz ◽

Brian Metzke ◽

Jeffrey Stein ◽

Ann Holtrop

Keyword(s):

Fish Species ◽

Environmental Variables ◽

Fish Assemblages ◽

Common Species ◽

Natural Environments ◽

Soil Permeability ◽

Distribution Maps ◽

Wadeable Streams ◽

Stream Fish Assemblages ◽

Landscape Level

To effectively conserve and restore stream ecosystems, we need to better understand the distribution and abundance of individual fish species in relation to natural environments and anthropological stressors. In this study, we modeled the abundance of 97 fish species in small wadeable streams of Illinois, USA, based on random forests regression and landscape-level environmental variables. Model R2 values for intermediately common species were higher than for common species, but highly variable among rare ones. Models for 50 species reached R2 of 0.2–0.70 and were tested with a separate set of samples and applied to unsampled wadeable reaches to show the population hotspots of each species across the state. Furthermore, we evaluated the importance of individual environmental variables to a given fish species as well as the directional responses of each species to top 10 key predictors. Climate and land use were the best predictors for most species, followed by topography, geology, and soil permeability. Spatial connection of a stream also was associated with a large number of species. These findings improved our understanding of the relationships between fish species and landscape environments. The distribution maps could guide resource management, restoration, and monitoring of stream fish assemblages.

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Landscape influences on stream fish assemblages across spatial scales in a northern Great Plains ecoregion

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f07-165 ◽

2008 ◽

Vol 65 (2) ◽

pp. 245-257 ◽

Cited By ~ 11

Author(s):

Henry F Wilson ◽

Marguerite A Xenopoulos

Keyword(s):

Land Cover ◽

Great Plains ◽

Fish Species ◽

Fish Assemblages ◽

Spatial Scales ◽

Species Assemblages ◽

Northern Great Plains ◽

Stream Fish ◽

Stream Fish Assemblages ◽

Nms Ordination

We examined the relationship between multiple spatial scales of fish assemblage structure and land cover in streams of a northern Great Plains ecoregion. We used regional richness measurements, an index of biotic integrity (IBI), and nonmetric multidimensional scaling (NMS) ordination to characterize fish assemblages. These metrics were related to regional catchment landscape at two spatial scales (overall catchment, overall riparian) and then to a set of local subcatchments from within these catchments at three scales (overall subcatchment, overall riparian buffer, and reach). Relationships between catchment fish richness, IBI scores, and landscape predictors were strongest at the riparian scale, with the strongest single predictor being riparian forest (r2 = 0.63, P < 0.01). NMS ordination analysis showed clear similarities between fish species assemblages in agriculturally dominated catchments and assemblages found in smaller headwater streams. At the same time, forested catchments and catchments with larger areas exhibited similar fish species assemblages. Our results indicate that both local and regional stream fish assemblages are structured by broader-scale landscape characteristics, with land cover providing a better indication of overall available habitat volume than catchment area or stream order.

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

Neotropical Ichthyology ◽

10.1590/1982-0224-20150116 ◽

2016 ◽

Vol 14 (3) ◽

Cited By ~ 7

Author(s):

Nara Tadini Junqueira ◽

Diego Rodrigues Macedo ◽

Rafael Couto Rosa de Souza ◽

Robert Mason Hughes ◽

Marcos Callisto ◽

...

Keyword(s):

Land Use ◽

River Basin ◽

Fish Species ◽

Environmental Variables ◽

Fish Assemblages ◽

Spatial Scales ◽

Fish Fauna ◽

Stream Fish ◽

Fish Diversity ◽

Physical Habitat

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.

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