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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.

The tropical tanner grass, Urochloa arrecta, is one of the worst aquatic plant invaders in Brazilian freshwater ecosystems. This study aimed to compare beds of macrophytes dominated and without U. arrecta in the Guaraguaçu River, a subtropical tidal river in South Brazil, to analyze effects that this invasive grass has on the biodiversity of native macrophytes at two spatial scales. We compared macrophyte beds dominated by tanner grass to macrophyte beds without, considering species richness, composition, and beta diversity at two scales of variation: among-beds and within-beds. We expected that beds dominated by tanner grass would have lower biodiversity, thus promoting macrophyte biotic homogenization. Our results confirmed our hypotheses, highlighting the lower species richness in beds dominated by tanner grass. Species composition differed among beds. In general, nestedness among beds dominated by U. arrecta was more related to variation in species composition. Beds dominated by tanner grass had lower turnover and higher nestedness within beds. This study indicates a prominent sign of biotic homogenization promoted by U. arrecta, and highlights the degree of biotic homogenization among and within beds.

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.

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