Large‐scale electricity policies that embrace renewable resources have led to continued investments in hydropower. Despite evolving viewpoints regarding the sustainability of large hydropower installations, there has been a major increase in support for the widespread development of small hydropower plants (SHPs). A global synthesis reveals that 82,891 SHPs are operating or are under construction (11 SHPs for every one large hydropower plant) and that this number is estimated to triple if all potential generation capacity were to be developed. Fueled by considerable political and economic incentives in recent decades, the growth of SHPs has greatly outpaced available ecological science. We provide evidence for not only the lack of scientifically informed oversight of SHP development but also the limitations of the capacity‐based regulations currently in use. The potential indiscriminate expansion of SHPs under the pretense of promoting sustainable energy is concerning, and we identify several important steps to help ensure new scientific advances, effective management, and policy reform in the future.

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Dynamic flow regimes maintain critical connections between main channel and adjacent floodplain habitats that provide fish access to shelter, foraging, and spawning opportunities. Our study advances the understanding of these processes by exploring the importance of coupled longitudinal–lateral connectivity for determining species occurrence in headwater streams of the Amazon. Using a multispecies occupancy model, we revealed a clear pattern of species addition in the downstream direction in temporary floodplain ponds, associated with changes in the pool of potential colonists present in the channel and with increasing lateral hydrologic connectivity. Species that are more tolerant of stagnant waters and those able to disperse in shallow habitats (e.g., Anablepsoides micropus) occurred frequently in ponds along the entire longitudinal extent, whereas those species preferring lotic habitats were present only in the most downstream sites. We also observed increasing similarity of pond and channel communities with distance downstream. This study provides insights on the spatial structuring of tropical fish communities in response to flood-induced hydrologic connectivity and further highlights the vulnerability of floodplain fishes to modification in flooding regimes.

This study aims to characterize the spatial and seasonal distribution of the fish assemblage and evaluate the integrity of streams in a sustainable use area that includes integral protection conservation units in Distrito Federal, Central Brazil (Cerrado biome). For the study, 12 stretches of 8 streams were sampled in 2008 (dry season) and 2009 (wet season). For that evaluation was estimated the Physical Habitat Index (PHI), vegetation cover (VC), pH, dissolved oxygen, turbidity, and conductivity. We recorded 22 species, about eight undescribed species, by a total of 2,327 individuals. The most representative families in number of species were Characidae (31.8%), Loricariidae (31.8%), and Crenuchidae (13.6%). Knodus moenkhausii was the most abundant species with 1,476 individuals, added to Astyanax sp., Phalloceros harpagos, and Hasemania sp. they represent over 95% of the total abundance. The species Astyanax sp. (occurring in 79.2% of the stretches) and K. moenkhausii (50.0%) were considered constant in both seasons. The longitudinal gradient (River Continuum) exerts a strong influence on the studied assemblage. According to CCA, the variables that structure the fish assemblage are based on aspects related to water volume and habitat complexity. No seasonal variation in richness, diversity, abundance, and mass were detected. A cluster analysis suggests a separation of species composition between the stretches of higher and lower orders, which was not observed for seasonality. The streams were considered well preserved (mean PHI 82.9±7.5%), but in some stretches were observed anthropogenic influence, detected in the water quality and, mainly, on the riparian vegetation integrity. The exotic species Poecilia reticulata was sampled in the two stretches considered most affected by anthropogenic activities by PHI, conductivity, and VC.Esse estudo teve como objetivo caracterizar a distribuição espacial e sazonal da taxocenose de peixes e avaliar a integridade dos córregos de uma área de uso sustentável que inclui unidades de conservação de proteção integral no Distrito Federal, Brasil Central (bioma Cerrado). Para o estudo, foram amostrados 12 trechos de oito cursos d'água em 2008 (estação seca) e 2009 (estação chuvosa). Para essa avaliação foram utilizados o Índice Físico do Habitat (IFH), cobertura vegetal (CV), pH, oxigênio dissolvido, turbidez e condutividade. Foram coletadas 22 espécies, sendo oito não descritas, em um total de 2.327 indivíduos. As famílias mais representativas em número de espécies foram Characidae (31,8%), Loricariidae (31,8%) e Crenuchidae (13,6%). Knodus moenkhausii foi a espécie mais abundante, com 1.476 indivíduos, que juntamente com Astyanax sp., Phalloceros harpagos e Hasemania sp. representaram mais de 95% da abundância total. As espécies Astyanax sp. (ocorrendo em 79,2% dos trechos) e K. moenkhausii (50,0%) foram consideradas constantes nas duas estações. O gradiente longitudinal (rio Contínuo) exerce forte influência na taxocenose estudada. De acordo com a CCA, as variáveis que estru...

Riverine floodplains are biologically diverse and productive ecosystems. Although tropical floodplains remain relatively conserved and ecologically functional compared to those at higher latitudes, they face accelerated hydropower development, climate change, and deforestation. Alterations to the flood pulse could act synergistically with other drivers of change to promote profound ecological state change at a large spatial scale. State change occurs when an ecosystem reaches a critical threshold or tipping point, which leads to an alternative qualitative state for the ecosystem. Visualizing an alternative state for Amazonian floodplains is not straightforward. Yet, it is critical to recognize that changes to the flood pulse could push tropical floodplain ecosystems over a tipping point with cascading adverse effects on biodiversity and ecosystem services. We characterize the Amazonian flood pulse regime, summarize evidence of flood pulse change, assess potential ecological repercussions, and provide a monitoring framework for tracking flood pulse change and detecting biotic responses.

Migratory species are the most important commercial fishes in the Amazon. They are also now the most threatened directly by some combination of overfishing, floodplain deforestation, and dam construction. Limited governmental monitoring and implemented regulations impede adequate management of the fisheries at adequate scale. We summarize the current stock status of the three most heavily exploited long-distance migratory species, which are two goliath catfishes (Brachyplatystoma rousseauxii and B. vaillantii) and the characiform Colossoma macropomum. In addition, we analyze impacts beyond overfishing on these species. Our results indicate: (i) the overfishing trends for these important species are either ominous or indicate the verge of collapse of the commercial fisheries based on them, and (ii) a dangerous synergy between overfishing, hydroelectric dams, and floodplain deforestation further challenge fisheries management of migratory species in the Amazon. We propose eight direct governmental actions as a proactive approach that addresses the main impacts on the fisheries. We consider that the most practical way to assess and manage overfishing of migratory species in the short run in an area as large as the main commercial fishing area in the Amazon is at market sites where enforced regulations can control fish catch. The management of the three species considered here has implications beyond just their sustainability. Their management would represent a paradigm shift where the governments assume their legal responsibilities in fishery management. These responsibilities include regulation enforcement, data collecting, inter-jurisdictional cooperation to protect migratory species at realistic life history scales, mitigation of the Madeira dams to assure goliath catfish passage to the largest western headwater region, and recognition of monitoring and managing wetland deforestation for the protection of fish and other aquatic and terrestrial biodiversity.

Every year, field excursions engage students of ecology in experiential learning that results in wide‐ranging and well‐documented pedagogical benefits. Much less appreciated, however, is the potential for these excursions to contribute long‐term data that advance scientific knowledge and natural resource management. Here we explore this potential by providing a global synthesis of field data collection, mapping the geography, temporal extent, and type of data collected by students worldwide, and calling attention to the associated benefits and challenges for course instructors. We then offer perspectives on how undergraduate courses in ecology can more broadly contribute to science, management, and policy. Finally, we highlight how several aspects – namely, existing frameworks, resources, and networks; enhanced institutional support; and synergies with the broader science community – can help undergraduate ecology courses achieve their full potential for contributing to both education and science for society.