Effects of the non-native Arapaima gigas on native fish species in Amazonian oxbow lakes (Bolivia).

The introduction of non-native fish species into new environments has raised global concerns due to potential ecological impacts on recipient ecosystems. A previous study focusing on the introduced fish species Arapaima gigas in Bolivian Amazon waters showed that its isotopic niche significantly overlapped with most co-occurring native fish species, suggesting potential competition. To evaluate this hypothesis, we extended here the investigation by comparing the trophic position and isotopic niche width of eleven abundant native fish species inhabiting both colonized and non-colonized floodplain lakes.

Major shifts in biogeographic regions of freshwater fishes as evidence of the Anthropocene epoch.

Animals and plants worldwide are structured in global biogeographic regions, which were shaped by major geologic forces during Earth history. Recently, humans have changed the course of events by multiplying global pathways of introduction for nonindigenous species and propagating local species extirpations. Here, we report on how introductions and extirpations have changed the distributions of freshwater fishes worldwide and how it affected their natural biogeographic regions.

Post-2020 biodiversity targets need to embrace climate change.

Recent assessment reports by the Intergovernmental Panel on Climate Change (IPCC) and the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES) have highlighted the risks to humanity arising from the unsustainable use of natural resources. Thus far, land, freshwater, and ocean exploitation have been the chief causes of biodiversity loss. Climate change is projected to be a rapidly increasing additional driver for biodiversity loss.

The combined effects of climate change and river fragmentation on the distribution of Andean Amazon fishes.

Upstream range shifts of freshwater fishes have been documented in recent years due to ongoing climate change. River fragmentation by dams, presenting physical barriers, can limit the climatically induced spatial redistribution of fishes. Andean freshwater ecosystems in the Neotropical region are expected to be highly affected by these future disturbances.

A database of freshwater fish species of the Amazon Basin.

The Amazon Basin is an unquestionable biodiversity hotspot, containing the highest freshwater biodiversity on earth and facing off a recent increase in anthropogenic threats. The current knowledge on the spatial distribution of the freshwater fish species is greatly deficient in this basin, preventing a comprehensive understanding of this hyper-diverse ecosystem as a whole. Filling this gap was the priority of a transnational collaborative project, i.

Scientists' warning to humanity on the freshwater biodiversity crisis.

Freshwater ecosystems provide irreplaceable services for both nature and society. The quality and quantity of freshwater affect biogeochemical processes and ecological dynamics that determine biodiversity, ecosystem productivity, and human health and welfare at local, regional and global scales. Freshwater ecosystems and their associated riparian habitats are amongst the most biologically diverse on Earth, and have inestimable economic, health, cultural, scientific and educational values.

Freshwater fish diversity hotspots for conservation priorities in the Amazon Basin.

Conserving freshwater habitats and their biodiversity in the Amazon Basin is a growing challenge in the face of rapid anthropogenic changes. We used the most comprehensive fish-occurrence database available (2355 valid species; 21,248 sampling points) and 3 ecological criteria (irreplaceability, representativeness, and vulnerability) to identify biodiversity hotspots based on 6 conservation templates (3 proactive, 1 reactive, 1 representative, and 1 balanced) to provide a set of alternative planning solutions for freshwater fish protection in the Amazon Basin. We identified empirically for each template the 17% of sub-basins that should be conserved and performed a prioritization analysis by identifying current and future (2050) threats (i.

Unexpected fish diversity gradients in the Amazon basin.

Using the most comprehensive fish occurrence database, we evaluated the importance of ecological and historical drivers in diversity patterns of subdrainage basins across the Amazon system. Linear models reveal the influence of climatic conditions, habitat size and sub-basin isolation on species diversity. Unexpectedly, the species richness model also highlighted a negative upriver-downriver gradient, contrary to predictions of increasing richness at more downriver locations along fluvial gradients.

Drainage network position and historical connectivity explain global patterns in freshwater fishes' range size.

Identifying the drivers and processes that determine globally the geographic range size of species is crucial to understanding the geographic distribution of biodiversity and further predicting the response of species to current global changes. However, these drivers and processes are still poorly understood, and no ecological explanation has emerged yet as preponderant in explaining the extent of species' geographical range. Here, we identify the main drivers of the geographic range size variation in freshwater fishes at global and biogeographic scales and determine how these drivers affect range size both directly and indirectly.

Non-native species led to marked shifts in functional diversity of the world freshwater fish faunas.

Global spread of non-native species profoundly changed the world biodiversity patterns, but how it translates into functional changes remains unanswered at the world scale. We here show that while in two centuries the number of fish species per river increased on average by 15% in 1569 basins worldwide, the diversity of their functional attributes (i.e.

A global database on freshwater fish species occurrence in drainage basins.

A growing interest is devoted to global-scale approaches in ecology and evolution that examine patterns and determinants of species diversity and the threats resulting from global change. These analyses obviously require global datasets of species distribution. Freshwater systems house a disproportionately high fraction of the global fish diversity considering the small proportion of the earth's surface that they occupy, and are one of the most threatened habitats on Earth.

Context-dependent resistance of freshwater invertebrate communities to drying.

More freshwater ecosystems are drying in response to global change thereby posing serious threat to freshwater biota and functions. The production of desiccation-resistant forms is an important adaptation that helps maintain biodiversity in temporary freshwaters by buffering communities from drying, but its potential to mitigate the negative effects of drying in freshwater ecosystems could vary greatly across regions and ecosystem types. We explored this context dependency by quantifying the potential contribution of desiccation-resistance forms to invertebrate community recovery across levels of regional drying prevalence (defined as the occurrence of drying events in freshwaters in a given region) and ecosystem types (lentic, lotic) in temporary neotropical freshwaters.

Biological impacts of local vs. regional land use on a small tributary of the Seine River (France): insights from a food web approach based on stable isotopes.

As part of the landscape, streams are influenced by land use. Here, we contributed to the understanding of the biological impacts of land use on streams, investigating how landscape effects vary with spatial scales (local vs. regional).

[[Which factors determine the altitudinal distribution of tropical Andean riverine fishes]?].

Altitudinal gradients represent an appropriate system to assess whether there is a relationship between richness patterns, environmental variables, and the ecological processes that determine the species type and number inhabiting a given area. In mountain streams freshwater fishes, the most prevalent relationship is a monotonic decrease in species richness with elevation. The objective of this study was to evaluate four hypotheses that can explain the negative relationship between local fish species richness and altitude, 1) the hypothesis of decreasing energy availability, 2) the hypothesis of increasing climate severity, 3) the hypothesis of habitat diversity, and 4) the hypothesis of isolation by physical severity of the environment.

Global imprint of historical connectivity on freshwater fish biodiversity.

The relative importance of contemporary and historical processes is central for understanding biodiversity patterns. While several studies show that past conditions can partly explain the current biodiversity patterns, the role of history remains elusive. We reconstructed palaeo-drainage basins under lower sea level conditions (Last Glacial Maximum) to test whether the historical connectivity between basins left an imprint on the global patterns of freshwater fish biodiversity.

Global diversity patterns and cross-taxa convergence in freshwater systems.

Whereas global patterns and predictors of species diversity are well known for numerous terrestrial taxa, our understanding of freshwater diversity patterns and their predictors is much more limited. Here, we examine spatial concordance in global diversity patterns for five freshwater taxa (i.e.

Homogenization patterns of the world's freshwater fish faunas.

The world is currently undergoing an unprecedented decline in biodiversity, which is mainly attributable to human activities. For instance, nonnative species introduction, combined with the extirpation of native species, affects biodiversity patterns, notably by increasing the similarity among species assemblages. This biodiversity change, called taxonomic homogenization, has rarely been assessed at the world scale.

Partitioning global patterns of freshwater fish beta diversity reveals contrasting signatures of past climate changes.

Here, we employ an additive partitioning framework to disentangle the contribution of spatial turnover and nestedness to beta diversity patterns in the global freshwater fish fauna. We find that spatial turnover and nestedness differ geographically in their contribution to freshwater fish beta diversity, a pattern that results from contrasting influences of Quaternary climate changes. Differences in fish faunas characterized by nestedness are greater in drainage basins that experienced larger amplitudes of Quaternary climate oscillations.

Scenarios for global biodiversity in the 21st century.

Quantitative scenarios are coming of age as a tool for evaluating the impact of future socioeconomic development pathways on biodiversity and ecosystem services. We analyze global terrestrial, freshwater, and marine biodiversity scenarios using a range of measures including extinctions, changes in species abundance, habitat loss, and distribution shifts, as well as comparing model projections to observations. Scenarios consistently indicate that biodiversity will continue to decline over the 21st century.

Non-native species disrupt the worldwide patterns of freshwater fish body size: implications for Bergmann's rule.

In this study, we test whether established non-native species induce functional changes in natural assemblages. We combined data on the body size of freshwater fish species and a worldwide data set of native and non-native fish species for 1058 river basins. We show that non-native fish species are significantly larger than their native counterparts and are a non-random subset of the worldwide set of fish species.

Genus-level supertree of Cyprinidae (Actinopterygii: Cypriniformes), partitioned qualitative clade support and test of macro-evolutionary scenarios.

We used the supertree approach of matrix representation with parsimony to reconstruct to date the most exhaustive (genus-level) phylogeny of Cyprinidae. The supertree of Cyprinidae, representing 397 taxa (237 nominal genera) and 990 pseudocharacters, was well resolved (96%) through extended consensus majority rule, although 36 nodes (9.4%) were unsupported.

Broad-scale determinants of non-native fish species richness are context-dependent.

Identifying the factors determining the non-native species richness (NNSR) in a given area is essential for preventing species invasions. The relative importance of human-related and natural factors considered for explaining NNSR might depend upon both the spatial scale (i.e.

Distribution patterns, population status and conservation of Melanosuchus niger and Caiman yacare (Crocodylia, Alligatoridae) in oxbow lakes of the Ichilo river floodplain, Bolivia.

Caiman yacare (lagarto) and Melanosuchus niger (black caiman), sympatric species in the Bolivian Amazon basin, have been severely overexploited in the past. We present the results of a standardized survey of C. yacare and M.

Fish invasions in the world's river systems: when natural processes are blurred by human activities.

Because species invasions are a principal driver of the human-induced biodiversity crisis, the identification of the major determinants of global invasions is a prerequisite for adopting sound conservation policies. Three major hypotheses, which are not necessarily mutually exclusive, have been proposed to explain the establishment of non-native species: the "human activity" hypothesis, which argues that human activities facilitate the establishment of non-native species by disturbing natural landscapes and by increasing propagule pressure; the "biotic resistance" hypothesis, predicting that species-rich communities will readily impede the establishment of non-native species; and the "biotic acceptance" hypothesis, predicting that environmentally suitable habitats for native species are also suitable for non-native species. We tested these hypotheses and report here a global map of fish invasions (i.