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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.

Host-parasite metacommunities are influenced by a myriad of factors, although little is known about which processes affect this relationship at different scales. Here, we tested how local habitat characteristics and host traits explained the parasite metacommunity of a migratory fish in a large Brazilian river floodplain. The parasite metacommunity structure showed a Clementsian pattern, which indicates a more deterministic assembly pattern, in accordance with partial Redundancy Analysis results. Results indicated that species filtering is the predominant mechanism driving community assembly. Patterns were clearer in the dry season of the floodplain. Environmental determinism seems to explain ectoparasite metacommunities in the dry season, in contrast with endoparasites that were more correlated to host traits. Overall, our results indicated that ectoparasitism is an interaction marked by opportunity, whereas endoparasitism is likely related to host features. Thus, we argue that metacommunity structuring of parasites depends on the infection strategy. Our results show that floodplain dynamics are central not only for free-living animal organizations but also for symbiotic interactions. Here, we highlight the importance of understanding the factors influencing the distribution of parasites to predict their transmission, as well as the importance of floodplain dynamics and its hydrological regime on the maintenance of ecological interactions.

We described the spatial and temporal dynamics of aquatic macrophytes in a Neotropical coastal estuarine river, and identified the negative effects associated to the presence and dominance of the invasive tanner grass. We compared macrophyte beds along the Guaraguaçu River (South Brazil) over four years, using taxonomic and functional dimensions. Biodiversity descriptors were higher in the driest periods compared to the rainiest, although this difference seems to be decreasing over the studied years. Moreover, the spatial organization of biodiversity and community structure slightly changed over time. Such spatial community stability was highlighted by the dominance of the highly invasive tanner grass. In beds dominated by the invasive species, the biodiversity was reduced. As aquatic macrophytes represent an important group in water bodies, the long-term loss of seasonal differences in community structuring is of concern, mainly regarding its potential to impact other groups and ecosystem functioning. By analysing data from standardized monitoring, we were able to identify a poorly discussed facet of biotic homogenisation-the seasonal homogenisation. We also discussed the impact of massive development of invasive species and its consequences for biodiversity in a Neotropical river of outmost importance for biological conservation.The online version contains supplementary material available at 10.1007/s00027-022-00858-3.

Analizamos 54 especímenes de Hoplias aff. malabaricus colectados entre marzo de 2010 y marzo de 2011 en la planicie de inundación Neotropical del alto rio Paraná, Brasil. Todos los hospederos fueron parasitados por lo menos con una especie de Monogenea. Las especies de parásitos con las mayores prevalencias fueran Urocleidoides cuiabai (96,29 %) y U. malabaricusi (92,59%). La comunidad de ectoparásitos de branquias ha presentado patrón de distribución agregado. Urocleidoides cuiabai fue la especie dominante en la muestra (C > 0,25). La abundancia del parasitismo ha presentado correlación positiva y significativa con la longitud estándar del hospedero para las especies U. malabaricusi y U. eremitus Kritsky, Thacher & Boeger, 1986. Hubo diferencia significativa en la abundancia de parasitismo entre peces machos y hembras para los parásitos U. brasiliensis y U. cuiabai. La fase de maduración gonadal del hospedero no influyó los niveles de parasitismo. Cuatro especies de parásitos han presentado una correlación positiva y significativa con la abundancia de parasitismo y el factor de condición relativo. El rio Iviñeima ha presentado alta abundancia de parasitismo en relación a otros subsistemas. El estudio ecológico de monogeneas puede proveer un gran conocimiento de la biología de estos parásitos y sus hospederos, el sitio de colecta, y hasta como el hospedero responde a la presencia de estos parásitos. Este artículo presenta los factores que fueron fundamentales en los niveles de parasitismo en esta importante especie de pez en la planicie de inundación del alto rio Paraná.

In this chapter, we reviewed the main studies on freshwater ecosystems of the Atlantic Forest, Brazil. We have firstly provided a list of the hydrographic basins that cross the Atlantic Forest and propose a classification of Atlantic Forest freshwaters based on a proposed wetland classification for Brazil. Anthropogenic disturbances and freshwater changes were discussed. We then made a panorama of studies on the main aquatic communities in the Atlantic Forest, ranging from vertebrates to microalgae. It is clear that basic research is still needed for many biological groups, although recent studies on aquatic biota deserve attention considering their theoretical advances in ecology. Common to studies on all biological groups are the concerns of anthropogenic actions, ranging from habitat alteration due to impoundments to water pollution, over- and illegal exploitation of vertebrates, and massive biological invasions. For many groups, such concerns are reflected in extinction risks of endemic species and biotic homogenization. We present prospects for future studies and urge for greater attention to preserve integrity of freshwaters in the Atlantic Forest.

La perca americana, Micropterus salmoides (Lacepéde, 1802), es un pez centrarchido de América del Norte que ahora tiene una distribución global debido a introducciones extendidas por pesca deportiva. Su introducción en Brasil data de 1920, principalmente en las regiones del sur. Sabemos que M. salmoides ha generado una serie de impactos en los ecosistemas en que se ha establecido. Sin embargo, sus parásitos en Brasil son desconocidos. Esto genera la posibilidad de nuevas interacciones y potenciales impactos. Por tanto, el objetivo de este estudio fue analizar los parásitos de M. salmoides en cuatro reservorios de agua en el sur de Brasil, midiendo la prevalencia y la abundancia media en cada reservorio. Analizamos un total de 59 individuos de M. salmoides, 15 en cada reserva, con excepción de la reserva Capivari-Cachoeira, con 14 individuos. De los peces analizados, 91,5% estaban parasitados por 1567 parásitos pertenecientes a cuatro especies, tres nemátodos: Contracaecum sp. (86,4%) en larvas, Procamallanus (Procamallanus) peraccuratus Pinto, Fábio, Noronha y Rolas 1976 (6,7%) y Hysterothylacium brachyurum Ward & Magath 1917 (6,7%), y una especie de monogenoideo Onchocleidus principalis (Mizelle, 1936) (57,6 %). De estos resultados podemos concluir que el proceso de co-introducción y “spillback” aún está en etapas tempranas, en la mayoría de las veces por la baja diversidad de parásitos. Sin embargo, el monitoreo y las acciones de control son altamente recomendadas para controlar los impactos de infecciones por parásitos y promover actividades de mitigación y campañas de prevención.

Among the topics related to invasion science, the least studied are parasite co-introduction and spillback. This leads to an uncertainty in invasion ecology theories and applications to management. Therefore, the present study brings a systematic review of published information on the metazoan parasite fauna of Micropterus salmoides, a widely introduced fish, with the aim of comparing information about the composition and richness of the associated parasite communities in its native and introduced regions. This review demonstrates that there were twice as many studies of M. salmoides in its native region in comparison with introduced regions, although most of the studies focused on the analysis of a single species or taxon of parasite. This bias impacts the number of parasite species observed and, consequently, the apparent importance of enemy release in introduced regions. The composition of the parasite community in the two regions showed high similarity, which indicates the introduction and acquisition of parasites in introduced regions. Otherwise, there was no pattern related to the geographic distance, highlighting the influence of the propagule pressure and vector strength on the introduction of novel parasites. This illustrates the importance of vector strength on fish-parasite co-introduction and the necessity of new research examining host-parasite interactions with the parasite community of the invaded ecosystems. We still do not know the major influences of the composition of the parasite fauna of M. salmoides or how we can manage to develop a more restrictive vector pathway of introduction. The future of our ecosystems depends on how to account for current and future interactions among novel interactions, habitat, and climate change.

While environmental alterations have made Homo sapiens the hyperkeystone species of the globe, biotic homogenization initiated a new era, the “Homogenocene.” Still, some terrestrial and aquatic ecosystems in South America are considered pristine and wild, which can lead to a general faith that economic progress is consistent with conservation strategies, even without scientific support. We compiled anthropogenic threats to fish biodiversity in a hierarchical meta‐analysis, along with an evidence synthesis of threats related to biological invasions, based on peer‐reviewed research with the aim to represent the actual conservation status of the South American ichthyofauna. We highlighted human‐related threats and synergistic effects of biological invasions, climate change, environmental alterations (e.g., pollution, aquaculture and damming) and fisheries. Considering measures that reinforce novel alien fish (e.g., artificial hybrids or genetically modified) introductions, it became clear why an eventual increase in local or regional species richness is not always beneficial to aquaculture, biodiversity, human well‐being or nature. In fact, citizens in all societal roles, including scientists, should revise their concepts about threats to fish biodiversity. Environmental policies require more than taxonomic diagnostics to achieve conservation goals under an incompatible scenario of a multiplying number of fish species and biotic homogenization. We advocate for countries in South America using science‐based strategies useful to maintain their social and economic growth along with their “remaining nature.” We live a crucial moment when the government overlooks threats to biodiversity and uses agribusiness as the most acceptable manner of fuelling the economy.

RESUMO A Avaliacao de Impacto Ambiental corresponde a um documento padrao obrigatorio para o Licenciamento Ambiental de atividades ou empreendimentos modificadores do meio ambiente. Apesar de toda base legislativa nacional e internacional, os estudos e relatorios de impacto ambiental ainda possuem uma serie de problemas em sua execucao e analise. Com isso, faz-se necessario a analise das diversas metodologias usadas para cada diagnostico ambiental e a eficiencia destas para identificacao dos possiveis impactos na area. O objetivo deste estudo foi comparar diferentes termos de referencias municipais de Relatorios Ambientais Previos e elencar as metodologias usadas na avaliacao do meio biologico, alem de analisar seus aspectos negativos e positivos na interpretacao dos impactos de empreendimentos imobiliarios. Foi analisado o Termo de Referencia de 3 cidades do sul do Brasil: Curitiba-PR, Novo Hamburgo-RS e Maringa-PR. Os termos de referencias das diversas Avaliacoes de impacto se mostraram bastante divergentes e vagos em relacao ao diagnostico biologico, o que possibilita falhas metodologicas e falta de dados, o que impossibilita uma melhor analise dos possiveis impactos causados pelo empreendimento. Uma das medidas para a melhora das AIA seria, portanto, a padronizacao metodologica dos estudos, isto para cada bioma e grupo biologico e termos de referencia que foquem em caracteristicas especificas de cada regiao. Palavras-chave: Relatorio Ambiental, Metodologia, Diagnostico Ambiental, Meio biotico. ABSTRACT The Environmental Impact Assessment is an obligatory document for the Environmental License for activities or enterprises that might modify the environment. Despite of all national and international guidelines, environmental impact studies and reports still have a number of problems in their implementation and analysis. Thus, it is necessary to analyze the various methodologies used in the environmental diagnosis and their efficiency identifying possible impacts in an area. The main objective of the following paper was to compare different Preliminary Environmental Reports city terms of reference and list the methodologies used in the biological elements assessment as well as its negative and positive aspects in interpreting real estate enterprise impacts. The Reference Term of 3 cities, Curitiba-PR, Novo Hamburgo-RS and Maringa-PR, in the south of Brazil, was analyzed. The terms of reference were very different and vague regarding the biological diagnosis, which leads to methodological deviations and a lack of data. Thus, it makes almost impossible to fully analyze potential impacts caused by the enterprises. One of the measures that can improve the Environmental Impact Assessment (AIA) diagnostic accuracy would be a methodological standardization of the studies, for each biome and biological group and terms of reference that indicate the specificities of each region under study. Keywords: Environmental Report, Methodology, Environmental Diagnosis, Biotic element. dx.doi.org/10.22292/mas.v15i7.845