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The Neotropical region hosts 4225 freshwater fish species, ranking first among the world's most diverse regions for freshwater fishes. Our NEOTROPICAL FRESHWATER FISHES data set is the first to produce a large‐scale Neotropical freshwater fish inventory, covering the entire Neotropical region from Mexico and the Caribbean in the north to the southern limits in Argentina, Paraguay, Chile, and Uruguay. We compiled 185,787 distribution records, with unique georeferenced coordinates, for the 4225 species, represented by occurrence and abundance data. The number of species for the most numerous orders are as follows: Characiformes (1289), Siluriformes (1384), Cichliformes (354), Cyprinodontiformes (245), and Gymnotiformes (135). The most recorded species was the characid Astyanax fasciatus (4696 records). We registered 116,802 distribution records for native species, compared to 1802 distribution records for nonnative species. The main aim of the NEOTROPICAL FRESHWATER FISHES data set was to make these occurrence and abundance data accessible for international researchers to develop ecological and macroecological studies, from local to regional scales, with focal fish species, families, or orders. We anticipate that the NEOTROPICAL FRESHWATER FISHES data set will be valuable for studies on a wide range of ecological processes, such as trophic cascades, fishery pressure, the effects of habitat loss and fragmentation, and the impacts of species invasion and climate change. There are no copyright restrictions on the data, and please cite this data paper when using the data in publications. [ABSTRACT FROM AUTHOR]

Peacock basses (Cichla spp.) have been introduced in impoundments for decades, and their negative impacts on the native fish fauna have been documented. However, previous studies largely focused on the overall responses of fish assemblages, often neglecting specific predator–prey interactions and the underlying effects of environmental characteristics.Here, the effects of peacock bass introduction on the size structure (<120, 120–180 and >180 mm in total length) of fish assemblages in reservoirs of the Paraíba do Sul river basin were assessed. The abundance and time since the introduction of peacock basses were used as predictors, together with reservoir features, limnological variables and habitat composition as potential influencing factors.Descriptors of the overall community (richness, abundance and species composition) were only marginally associated with the occurrence of peacock basses. However, small and (to a lesser extent) medium‐sized fish were adversely affected by the abundance and introduction time of peacock basses. Two pelagic native characids – namely Astyanax cf. bimaculatus and Oligosarcus hepsetus – were the most affected.Redundancy analysis showed that reservoir age and macrophyte cover were the best predictors of fish assemblage composition. Older reservoirs and reservoirs with a higher cover of macrophytes showed a greater abundance of catfish and characids, respectively.Peacock basses appear to affect fish assemblages through predation on small fish. Therefore, analyses of assemblages by size are recommended, as the use of overall assemblage descriptors may not be sufficient to capture the adverse effects of peacock basses. Moreover, these findings underscore the importance of conserving and restoring habitats in littoral zones, which function as refuges for native fish species in reservoirs. Further educational and management measures are warranted to prevent the spread of peacock basses to other reservoirs in Brazil. [ABSTRACT FROM AUTHOR]

South American peacock basses (genus Cichla) have been widely introduced within and outside the Neotropical region due to their importance to fisheries, despite threats to the native fish fauna. We performed a literature review on the worldwide distribution of valid Cichla species by focusing on records of species richness and populations in their native and non‐native ranges. We tested for an effect of area, the number of large dams, human population density and gross domestic product as drivers of the distribution of peacock basses across the Freshwater Ecoregions of the World (FEOWs). A total of 544 studies led to 1,289 records of nine species. Their distributions within their native range (19 native FEOWs) were narrower than their distributions in their non‐native range (23 non‐native FEOWs), which encompass tropical and subtropical ecoregions of the Americas, Africa, Southeast Asia and the Pacific islands. Several of these FEOWs harboured more than one species, usually C. ocellaris and C. piquiti. Ecoregion areas were positively associated with species richness and population records in native FEOWs, whereas the number of reservoirs was positively related to the records of non‐native populations. These patterns provide further evidence of the role played by reservoirs as the main pathway for the introduction of peacock basses; thus, special attention should be given to the continuous monitoring of the spread of these invaders across watersheds in invaded ecoregions. Considering their broad distribution and the potential for peacock basses to thrive in human‐modified systems, severe damage to the native fish fauna is predicted. [ABSTRACT FROM AUTHOR]

Aim: Fish community composition is shaped by current and historical factors. In recently formed ecosystems, however, as the Quaternary coastal lagoons of South America, the influence of historical factors has less frequently been investigated. The low rate of endemism in these lagoons suggests a limited role for speciation while their dynamic formation history suggests local extinction and dispersal limitation could have affected present species composition. We aimed to assess the influence of past and current factors on the beta diversity of those communities and explore the main processes involved. Location: Atlantic coast of South America. Taxon: Fishes (173 species). Methods: We built a dataset of species occurrence in 129 lagoons across eight freshwater ecoregions of the world (FEOWs) located between latitudes 0° and 36°, and calculated beta diversity (βjac) and its turnover (βjtu) and nestedness (βjne) components. We used a partial Mantel test and multiple regressions on distance matrices to evaluate the importance of past and current factors, and of geographical distance in determining beta diversity. Past variables were those representing the historical freshwater habitat during the last glacial maximum (LGM), and contemporary variables were those related to current habitat. Results: We found high values of βjac within the FEOWs, with βjtu prevailing over βjne. Both past (palaeodrainage) and current (drainage area, salinity and lagoon area) factors affected species dissimilarity (βjac = 46%) and its components (βjtu = 44% and βjne = 20%), although explanation was, in part, shared with geographical distance. Individually, the influence of past factors was prevalent in beta diversity and its components. Main conclusions: The large influence of the past factors on beta diversity suggests that major changes in the availability of freshwater habitats and connectivity since the Pleistocene must have affected the colonization, extinction and recolonization processes of fishes along the eastern coast of South America. We suggest that the high beta diversity values result from limited dispersal after extinctions in the LGM. The dissimilar freshwater fish communities currently seen result from heterogeneous subsets of the regional species pool that persisted in landscape refuges during past sea level increases and then recolonized coastal lagoons. [ABSTRACT FROM AUTHOR]

The interest in understanding ecosystem functioning has grown in recent years due to the effects of species loss on ecosystem processes. Even though biotic and abiotic factors control ecosystem processes, their relative influence may vary according to ecosystem dynamics. In flood and coastal plains, these dynamics are mainly represented by flood pulses and hydroregime, respectively. The objective of this study was to investigate the importance of abiotic and biotic factors for the ecosystem processes represented by zooplankton secondary production (SP), biomass (ZB), and resource use efficiency (RUE) in lentic waterbodies subjected to different hydrological regimes. We hypothesised that abiotic factors would more strongly determine the ecosystem processes in temporary waterbodies and floodplain lakes, given their greater susceptibility to environmental changes. Biotic factors would be more relevant in coastal lagoons due to their greater temporal stability.Sampling was undertaken quarterly over 1 year in eight coastal lagoons, 10 temporary ponds and five floodplain lakes. The environments were characterised in relation to limnological variables, and zooplankton functional divergence, functional dispersion (FDis), functional evenness, functional richness, and taxonomic richness were measured. Analysis of variance (ANOVA) was used to verify seasonal changes in SP, ZB, RUE, functional diversity, richness, and abiotic factors. Linear mixed models were used to determine which abiotic and biotic factors were the most important for ZB, SP, and RUE.In the coastal lagoons, RUE differed over time. In the temporary ponds and floodplain lakes, no seasonal significant differences were observed for any of the zooplankton production variables. The linear mixed model analyses showed that models composed mainly of biotic factors were better fitted to the production variables. For coastal lagoons, phytoplankton density affected ZB, SP, and RUE increasing them by 9.9 mg DW/m3, 12.4 mg DW/m3, and 1.23, respectively. For temporary ponds, FDis lowered ZB by 6.9 mg DW/m3 and taxonomic richness increased SP and RUE by 14.2 mg DW/m3 and 1.17, respectively. For floodplain lakes, FDis lowered ZB it by 9.9 mg DW/m3 and functional divergence lowered RUE by 0.81.The present study demonstrates that biotic factors are the main determinants of ecosystem processes in neotropical lentic waterbodies, irrespective of their annual hydrological regimes. Complementarity effects and high functional diversity are more important in more stable environments, whereas redundancy and low functional diversity prevail in environments subject to more frequent environmental changes. Biotic factors play a major role in ensuring the functioning of aquatic ecosystems and indicate the important role of biodiversity in enabling ecosystem states to be maintained after disturbances and to prevent changes in ecosystem processes. [ABSTRACT FROM AUTHOR]

Understanding whether and how ambient ecological conditions affect the distribution of personality types within and among populations lies at the heart of research on animal personality. Several studies have focussed on only one agent of divergent selection (or driver of plastic changes in behavior), considering either predation risk or a single abiotic ecological factor. Here, we investigated how an array of abiotic and biotic environmental factors simultaneously shape population differences in boldness, activity in an open-field test, and sociability/shoaling in the livebearing fish Poecilia vivipara from six ecologically different lagoons in southeastern Brazil. We evaluated the relative contributions of variation in predation risk, water transparency/visibility, salinity (ranging from oligo- to hypersaline), and dissolved oxygen. We also investigated the role played by environmental factors for the emergence, strength, and direction of behavioral correlations. Water transparency explained most of the behavioral variation, whereby fish from lagoons with low water transparency were significantly shyer, less active, and shoaled less than fish living under clear water conditions. When we tested additional wild-caught fish from the same lagoons after acclimating them to homogeneous laboratory conditions, population differences were largely absent, pointing toward behavioral plasticity as a mechanism underlying the observed behavioral differences. Furthermore, we found correlations between personality traits (behavioral syndromes) to vary substantially in strength and direction among populations, with no obvious associations with ecological factors (including predation risk). Altogether, our results suggest that various habitat parameters simultaneously shape the distribution of personality types, with abiotic factors playing a vital (as yet underestimated) role. Furthermore, while predation is often thought to lead to the emergence of behavioral syndromes, our data do not support this assumption. [ABSTRACT FROM AUTHOR]