Human land use and non-native fish species erode ecosystem services by changing community size structure.

Organism body size influences ecosystem services, and human pressures alter the size structure of ecological communities. However, our understanding of how different human-induced pressures (such as land use and biotic invasion) interact to drive community size structure and ecosystem services remains limited. Combining 21 years of fish size spectrum data and fishery potential (fishery monetary value in the Upper Paraná River Floodplain, Brazil), we demonstrate that the size spectrum exponent of native species has become more negative over time, indicating a relative decrease in the biomass of large versus small individuals.

Non-Native Species Abundance Decreases the Co-Occurrence Between Native and Non-Native Species Through Time at Any Phylogenetic Distance.

Non-native species may cause cumulative impacts on native communities if their abundance continues to increase through time. This negative effect can reflect on the spatial distribution of native species, especially when native and non-native species are phylogenetically similar. Here, we assessed the spatial co-occurrence between native and non-native fish species using long-term abundance data from six locations in a Brazilian floodplain.

Unsustainable land use trajectories in the Tocantins/Araguaia basin: Insights from future scenario modeling.

Effective watershed management is essential for biodiversity conservation and mitigating environmental impacts like deforestation and ecosystem disruptions, especially in the context of climate change. The Tocantins/Araguaia Basin (TOAR), Brazil's second-largest watershed, faces significant challenges due to unsustainable land use practices. To address this, we modeled future land use and cover changes (2015-2045) using the CLUE model under three scenarios: Business-as-usual (BAUS), Conservation-based (CONS), and Production-based (PROD).

Drivers of interspecific synchrony and diversity-stability relationships in floodplain fish communities.

Diversity and interspecific synchrony are among the main drivers behind the temporal stability of community abundance. Diversity can increase stability through the portfolio effect, while higher synchrony generally decreases stability. In turn, species interactions and similar responses to environmental variation are considered the main factors underlying the strength of interspecific synchrony, despite the challenges in determining their relative roles.

Irrigation dams threaten Brazilian biodiversity.

Brazil is among the main contributors to global biodiversity, which, in turn, provides extensive ecosystem services. Agriculture is an activity that benefits greatly from these ecosystem services, but at the same time is degrading aquatic and terrestrial ecosystems and eroding Brazilian biodiversity. This conflict is growing, as emerging unsustainable legislative proposals that will benefit the agricultural sector are likely to accelerate the decline of biodiversity.

Assessing the role of protected areas in the land-use change dynamics of a biodiversity hotspot.

Although protected areas (PAs) are designed to safeguard natural ecosystems from anthropic modifications, many PAs worldwide are subjected to numerous human-induced impacts. We evaluated whether the establishment of PAs in the Upper Paraná River floodplain region could reduce anthropic landscape changes and whether there is a difference in protection when using different PA restriction categories. We analyzed the overall landscape dynamics using 30 years of land-use time series data and evaluated the change intensity via a partial land-use intensity analysis.

Assessing the short-term response of fish assemblages to damming of an Amazonian river.

The enormous biodiversity of tropical freshwater combined with a considerable increase in the construction of reservoirs urges to understand the ecological effects caused by damming. Using rarely available data obtained before (one year) and after (four years) the filling of a hydroelectric plant on the Teles Pires River (Amazon River basin), the effects on abundance, biomass, and diversity of the fish assemblage were evaluated using two complementary approaches: a BACI (before-after-control-impact) design with mixed models and analyses of covariance. Significant Before-After × Control-Impact interactions in abundance, biomass, and species richness were observed, with decreases of abundance and species richness and more stable biomass after filling.

Large-scale Degradation of the Tocantins-Araguaia River Basin.

The Tocantins-Araguaia Basin is one of the largest river systems in South America, located entirely within Brazilian territory. In the last decades, capital-concentrating activities such as agribusiness, mining, and hydropower promoted extensive changes in land cover, hydrology, and environmental conditions. These changes are jeopardizing the basin's biodiversity and ecosystem services.

Spatial segregation in the reproductive activity of Neotropical fish species as an indicator of the migratory trait.

This study focused on the distribution of fish with high reproductive activity along a basin, using a 430 km stretch of the Cuiabá River in Brazil as a model. The main objective of this study was to identify those fish that migrate long distances for reproduction, among all the basin species. Thus, a set of working criteria are proposed to classify species according to their reproductive behaviour (i.

Negative effect of turbidity on prey capture for both visual and non-visual aquatic predators.

Turbidity plays an important role in aquatic predator-prey interactions. Increases in turbidity are expected to reduce prey capture rates, especially for visually oriented predators. However, there is also evidence indicating that turbidity may have little or no effect on predation rates.

Coupling environment and physiology to predict effects of climate change on the taxonomic and functional diversity of fish assemblages in the Murray-Darling Basin, Australia.

This study uses species distribution modeling and physiological and functional traits to predict the impacts of climate change on native freshwater fish in the Murray-Darling Basin, Australia. We modelled future changes in taxonomic and functional diversity in 2050 and 2080 for two scenarios of carbon emissions, identifying areas of great interest for conservation. Climatic-environmental variables were used to model the range of 23 species of native fish under each scenario.

Aquaculture expansion in Brazilian freshwaters against the Aichi Biodiversity Targets.

The Convention on Biological Diversity proposed the Aichi Biodiversity Targets to improve conservation policies and to balance economic development, social welfare, and the maintenance of biodiversity/ecosystem services. Brazil is a signatory of the Aichi Biodiversity Targets and is the most diverse country in terms of freshwater fish, but its national policies have supported the development of unsustainable commercial and ornamental aquaculture, which has led to serious disturbances to inland ecosystems and natural resources. We analyzed the development of Brazilian aquaculture to show how current aquaculture expansion conflicts with all 20 Aichi Targets.

Early ontogeny of (Ihering, 1930) (Osteichthyes, Auchenipteridae), a small catfish from Neotropical region.

The early development of Tatia neivai (Ihering 1930) was analyzed (i) to characterize its morphological, morphometric and meristic development; and (ii) to examine its possible ontogenic variation as a result of the development of structures and organs necessary for survival. Samples were collected in the Baía River, basin Paraná River, Mato Grosso do Sul State, Brazil, between February 1999 and April 2000. After identification, the specimens were separated according to notochord development, and the morphometric and meristic characters were measured and counted.

Two sides of a coin: Effects of climate change on the native and non-native distribution of Colossoma macropomum in South America.

Climate change and species invasions interact in nature, disrupting biological communities. Based on this knowledge, we simultaneously assessed the effects of climate change on the native distribution of the Amazonian fish Colossoma macropomum as well as on its invasiveness across river basins of South America, using ecological niche modeling. We used six niche models within the ensemble forecast context to predict the geographical distribution of C.

Is There a Relationship between Fish Cannibalism and Latitude or Species Richness?

Cannibalism has been commonly observed in fish from northern and alpine regions and less frequently reported for subtropical and tropical fish in more diverse communities. Assuming all else being equal, cannibalism should be more common in communities with lower species richness because the probability of encountering conspecific versus heterospecific prey would be higher. A global dataset was compiled to determine if cannibalism occurrence is associated with species richness and latitude.

The metabolic theory of ecology convincingly explains the latitudinal diversity gradient of neotropical freshwater fish.

In the context of diversity gradients, the metabolic theory of ecology (MTE) posits that the logarithm of species richness should decrease linearly with the inverse of temperature, resulting in a specific slope. However, the empirical validity of this model depends on whether the data do not violate certain assumptions. Here, we test the predictions of MTE evaluating all of its assumptions simultaneously.

Loss of rare fish species from tropical floodplain food webs affects community structure and ecosystem multifunctionality in a mesocosm experiment.

Experiments with realistic scenarios of species loss from multitrophic ecosystems may improve insight into how biodiversity affects ecosystem functioning. Using 1000 L mesocoms, we examined effects of nonrandom species loss on community structure and ecosystem functioning of experimental food webs based on multitrophic tropical floodplain lagoon ecosystems. Realistic biodiversity scenarios were developed based on long-term field surveys, and experimental assemblages replicated sequential loss of rare species which occurred across all trophic levels of these complex food webs.

Impoundment effects in the population of Auchenipterus osteomystax (Siluriformes: Auchenipteridae): a Neotropical reservoir case.

New impoundments provide opportunities to check whether species that present enough feeding flexibility in natural conditions may take advantage of this situation and, without reproductive restriction, can occupy the most conspicuous habitat in a large reservoir (open areas) and present higher success in the colonization of the new environment. We examined variations in the abundance and feeding of A. osteomystax in two environments, one natural (Sinhá Mariana floodplain lake) and one dammed (Manso Reservoir), during two periods: the first year after the filling phase and three years later.

Patterns of interactions of a large fish-parasite network in a tropical floodplain.

1. Describing and explaining the structure of species interaction networks is of paramount importance for community ecology. Yet much has to be learned about the mechanisms responsible for major patterns, such as nestedness and modularity in different kinds of systems, of which large and diverse networks are a still underrepresented and scarcely studied fraction.

Fish colonization of artificial reefs in a large neotropical reservoir: material type and successional changes.

Artificial reefs have barely been used in Neotropical reservoirs (about five studies in three reservoirs), despite their potential as a fishery management tool to create new habitats and also to understand fish ecology. We experimentally assessed how reef material (ceramic, concrete, and PVC) and time modulated fish colonization of artificial reefs deployed in Itaipu Reservoir, a large reservoir of the mainstem Paraná River, Brazil. Fish richness, abundance, and biomass were significantly greater in the reef treatments than at control sites.

Fish migration, dams, and loss of ecosystem services in the Mekong basin.

The past decade has seen increased international recognition of the importance of the services provided by natural ecosystems. It is unclear however whether such international awareness will lead to improved environmental management in many regions. We explore this issue by examining the specific case of fish migration and dams on the Mekong river.

Effects of river impoundment on ecosystem services of large tropical rivers: embodied energy and market value of artisanal fisheries.

Applying the ecosystem services concept to conservation initiatives or in managing ecosystem services requires understanding how environmental impacts affect the ecology of key species or functional groups providing the services. We examined effects of river impoundments, one of the leading threats to freshwater biodiversity, on an important ecosystem service provided by large tropical rivers (i.e.

Fish-passage facilities as ecological traps in large neotropical rivers.

At present most of the large rivers of South America are impounded. Management plans historically have relied on the construction of fish passages, specifically ladders, to mitigate the impact of these waterway blockages on fisheries and biodiversity. Nevertheless, the design of these facilities is not ecologically sound and they are not monitored continually.